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KIN 1A03 EXAM REVIEW.docx

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Department
Kinesiology
Course
KINESIOL 1A03
Professor
Tracy Mc Donald
Semester
Fall

Description
KIN 1A03 – Human Anatomy and Physiology I Exam Review Homeostasis Definition: The ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes. - The existence and maintenance of a relatively constant environment within the body - Values of variables fluctuate around the set point to establish a normal range of values - Set Point: the ideal normal value of a variable - Normal Range: produced by variable increasing and decreasing around set point Feedback Systems - Two types: negative (good) and positive (not so good) - 3 components: o Receptor: monitors the value of some variable o Control Centre: establishes the set point o Effector: can change the value of the variable - Stimulus: deviation from the set point; detected by receptor - Response: produced by effector Negative Feedback - Homeostasis is maintained - Any deviation from the set point is made smaller (resisted) - Examples: regulation of blood pressure, body temperature, blood sugar levels Positive Feedback - Homeostasis is not maintained - When a deviation occurs, the response is to make the deviation greater - Unusual in normal, healthy individuals, leads away from homeostasis and can result in death - Normal example: childbirth - Harmful example: after hemorrhage, blood pressure drops and heart’s ability to pump blood decreases - Consequences of homeostasis disruption? Disease, death Embryology and Development Where it all began - 200 million sperm released during ejaculation, only 1% make it through cervix (sperm only viable 48 hours) o Developed flagella help allow sperm to move through uterine tubes o Muscle contractions of the uterus + uterine tubes helps move the sperm as well - Ovulation occurs unilaterally (one egg released a month from each side – only viable 24 hours) - Ampulla-site of Fertilization: sperm cell penetrates oocyte Prenatal Development - From conception to birth: three stages 1. Germinal Period: first 2 weeks of development during formation of primitive germ layers 2. Embryonic Period: weeks 3-8 of development, organ systems develop 3. Fetal Period: last 30 weeks, organ systems grow and mature Terms for timing of events - Clinical/Medical Events: date since last menstrual period - Embryologists: post-ovulatory age – dated from actual date of fertilization Fertilization Capacitation: making the sperm capable (5-7 hours) - Interactions btwn secretions of uterus activated enzyme in sperm – flagella beat more rapidly - Cap on head of sperm (acrosome) has enzymes which activate and releases lysosomes to help break down protective layers around secondary oocyte Oocyte has first polar body (indicated meiosis) - Oocyte has a plasma membrane and 2 protective layers: o Zona Pellucida: glycoproteins o Corona Radiata: collection of granulose cells - Sperm must penetrate all 3 layers to join with 23 chormosomes of oocyte 1. Sperm binids to zona pellucida (species specific) receptor accepting ZP3 2. Acrosomal Reaction 3. As sperm binds to oocyte (a6B1), depolarization occurs (shock around oocyte so no other sperm can bind) 4. Fast block to polyspermy 5. Depolarization 6. Slow block to polyspermy a. Intracellular release of Ca – exocytosis of H O 2 b. Oocyte shrinks – zona pellucida denatures c. ZP b3comes inactivated 7. Female nucleus undergoes 2 meiotic division – female pronucleus 8. Male pronucleus 9. Fusion of haploid pronuclei produces diploid zygote Early Cell Division - 18-36 hours after fertilization, zygote begins dividing - Totipotent: cell has potential to develop into any tissue type - Pluripotent: cell has ability to develop into a wide range of tissues but not al Morula and Blastocyst - Morula: once embryo has divided into 12+ cells  solid sphere of smaller spheres - 4-5 days: 32 cells - Blastocele: fluid filled cavity  results in hollow sphere called blastocyst - Trophoblast cells surround the blastocele  these cells are pushed to the outside by uterine milk) - Inner Cell Mass: cells that become embryo - 8-12 days: blastocyst embeds uterine wall Implantation of Blastocyst and Formation of Placenta - Implantation: Blastocyst implants in uterine endometrium w/inner cell mass close to endometrium - Trophoblast cell produces HCG hormone (detected in pregnancy tests) o Helps maintain lining of uterus in thickened and vascular phase - Placenta: exchange of nutrients and waste between mother and embryo (2 portions – matermal and fetus portion) - Syncytiotrophoblast: multinucleated cell (outside) that invades uterine wall – non- antigenic (no immune system response triggered) - Cytotrophoblast: remains close to the embryonic tissue (inside) - Sycytiotrophoblast cells surround and digest wall of maternal blood vessels  Lacunae - Cords of cytotrophoblasts surround syncytiotrophoblasts and lacunae - Finger-like extensions called chorionic villi sprout from the cords of the cytotrophoblasts and enter the lacunae - Chorion: embryonic structure facing maternal tissue - Developed Fetus o Connecting cord changes to umbilical cord o O blood is in lacunae for fetus 2 o Deox. Blood exists fetus through umbilical arteries into placenta using maternal venules o Cytotrophoblasts differentiate into basement membrane + can no longer be seen o Basement membrane + embryonic blood in capillary form chorion + small layer of syncitiotrophoblasts o O 2ses diffusion to move into membrane Formation of Germ Layers Embryonic Disk - Amniotic Cavity: forms inside inner cell mass + surrounded by layer of cells (amnion)  eventually surrounds fetus - Embryonic disk is composed of 2 layers: 1. Epiblast: forms 3 germ layers that eventually become all tissues in developing embryo 2. Hypoblast: extraembryonic membranes that help develop membranes outside of embryo - Yolk Sac: forms inside the blastocele from the hypoblast and eventually becomes part of gut/digestive system Primitive Streak - Groove that starts to develop in epiblast cells (from caudal  cephalic end) o Opening for anus – cloacal membrane o Opening for mouth – oropharyngeal membrane - 3 germ layers: o Ectoderm: forms epidermis of skin + NS structure o Mesoderm: muscle, bone, CT, peritoneum o Endoderm: epithelial lining of GI and respiratory tract - Notochord: extends from cephalic to caudal end of primitive streak and performs INDUCTION o Notochord cells influence cells in proximity and induce cells to be diff features Neural Tube Formation - Ectoderm at cephalic end of primitive streak is stimulated after 18 days of fertilization - Forms neural plate (stimulated by notochord) - Edges of the neural plate begin to rise + come together - Neural Folds: edges - Neural Groove: space between the edges - Neural Tube: when the crest begins to meet in the middle o Neural tube is responsible for brain and spinal cord formation o Cells of neural tube called, neuroectoderm o Epidermis forms once the two crests are joines - Population of cells that break away from the neuroectoderm called, neural crest cells, migrate down side of neural tube and become structures o Sensory + post ganglionic autonomic portions of PNS o Part of skull, dentin of teeth, some skeletal muscles o General CT of the head - Mesenchyme: cells of either neural crest or mesoderm origin Somite Formation - Somites: notochord stimulates mesoderm adjacent to tube to form collection of cells o Part of skull, vertebral column, skeletal muscles Formation of Gut and Body Cavities Day 20: - Oralpharyngeal membrane develops w/primitive streak, cloacal membrane also develops - Embryo starts becoming tube along part of yolk sac o Amniotic cavity will curve over embryo - Yolk sac is distinguished into 2 portions: o Foregut: oralpharyngeal end o Hindgut: cloacal end - Evaginations: outpouchings occurring along digestive tract (developing digestive tract) o Allantois o Anterior pituitary, thyroid gland, lungs, liver, pancreas o Branchial arches: solid bars of tissues form laterally developing head  Pharynx, auditory tubes, ears, tonsils, thymus, parathyroid gland - Yolk sac forms into allantois (connecting stalk) – will form urinary bladder - Midgut – middle area of gut - Coelom: forms body cavities o Pericardial: cranial group, fuses around heart o Pleural: coelomic cavity, caudal o Peritoneal: coelomic cavity, cephalic o Cavities are separate entities Limb Bud Development - Arm bud and leg bud appear at approx. 28 days - Apical Ectodermal Ridge: thickening of the ectoderm, stimulates outward growth bilaterally - Limb tissue laid down in proximal to distal sequence - Thalidomide inserts in DNA associated w/blood vessel cells o Endothelial cells: line the CV system o Stops blood vessels from forming + newly blood vessels get broken down o Halts development of limb buds o Used in cancer treatments or skin conditions Facial Development - 3 processes: o Frontonasal process o 2 Maxillary process o 2 Mandibular process - Maxillary + Mandibular processes move toward midline + fuse - Cleft Lip: when frontonasal + one/both maxillary processes fail to fuse Muscles and Nerves - Muscle: myoblasts (derived from somites) are early embryonic cells that develop skeletal muscle fibers - Nervous System: derived from neural tube and neural crest cells Circulatory System (in embryo) - Blood Islands: on surface of yolk sac and inside embryo - 16-20 days: developing blood islands from mesodermal tissue – primitive streak also appears o Gather together and form CV tissue - Mesoderm: blood vessels on outside + blood cells on inside - Some cells form perimeter of blood island – become blood vessels + walls of heart - Some cells become endothelium – lining of CV system - Some cells are left in blood island – blood cells - Blood vessel development begins in placenta then in embryo – - First area to make blood vessels – liver, then in bone marrow and spleen Heart Development - Started by collection of blood islands formed into 2 parallel tubes fused together to make primitive heart tube - Induction – endoderm below mesoderm sends signals to make primitive heart tube (not notochord) - Primitive heart tube - 4 main dilations 1. Sinus Venosus – superior + inferior vena cava 2. Atria 3. Ventricle 4. Bulbus Cordis – vessels come out (pulmonary trunk + aorta) - 2 atria, 2 ventricles – 4 heart chamber - Complete fusion and bending - Ventricle enlarges + forms anteriorily, atria tucks behind heart + twists sidewars - 46-50 days: left and right ventricle (2 sides of primitive tube that fused) o Interventricular Septum: walls of 2 separate portions of primitive tube o Interatrial septum: not as thick/developed as interventricular septum o Septum Secundum: close to right atrium o Septum Primum: close to left o Hole in each, but not aligned – blood can flow through right atrium to left atrium through FORAMEN OVALE o Foramen ovale helps blood bypass lungs o After birth, septums close + forces blood to lungs, if not fully closed = PATENT FORAMEN OVALE o After birth foramen ovale becomes FOSSA OVALIS Respiratory System - Lungs begin as a single mid-line evagination of foregut - Lung buds branch off of developing trachea - Brancing of bronchi continues for up to 17 generation Urinary System 21 days: - Mesoderm differentiates into pronephros (non-functional) - Mesonephros: caudal extension of pronephros o Similar function to developing kidney – associated w/filtration of blood o Not necessary b/c blood gets filtered in placenta - Mesonephros develops + caudal end of hindgut enlarges to form cloaca o Urorectal septum divides cloaca int o2 parts (rectum + urethra) - Cloaca is associated w/ allantois and hindgut - Part of allantois nearest cloaca enlarges to form urinary bladder, remainder degenerates - Mesonephric duct extends caudally and joins w/cloaca - Metanephros develop after mesonephros degenerate (mature kidney) - Mesonephric duct remains in males - Ureters form from metanephros + eventually join bladder Reproductive System - Gonodal Ridges: undifferentiated, contain primary germ cells (cells become primordial germ cells) - Primordial Germ Cells: differentiate into primitive germ cells + form gametes (sperm and oocyte) - Paramesonephric duct: eventually become vagina, uterus, uterine tubes – disappear in males - Hormone signals provide info for male, if no signal – becomes female - Testes descend into scrotum - Mesonephric duct – ductus deferens + seminal vesicle – activated by testosterone - Ovaries -descend into pelvis - Changes in paramesonephric duct for female structures - Mullerian-Inhibiting Hormone: secreted by testes, causes paramesonephric duct to degenerate - Genital tubercle  glans penis (urethra is the common urinary + reproductive duct) glans clitoris - Genital folds: females don’t have closure, maintained and eventually end up w/labia minora - Labioscrotal Swelling: forms exterior body of penis (scrotum) or labia majora - Dihydrotestosterone: hormone that indicates change into male Changes at Birth Fetus - Blood bypasses lungs because maternal placenta is providing oxygen o Lungs are collapsed and there is not air exchange or O – DU2TUS ARTERIOSUS - Blood bypasses liver because placenta filters blood and transports waste away o Blood skips over and connect at umbilical vein structures – DUCTUS VENOSUS Newborn Before Birth 1. Ductus arteriosus diverts blood back to heart 2. Foramen ovale diverts flow from lungs (high pressure in right atria, low pressure in left) 3. Ductus Venosus diverts flow from liver 4. O 2ich blood returned to fetus by umbilical vein 5. O 2oor blood carried from fetus through umbilical arteries During Birth - Increased pressure in left atria will push septum primum up against septum secundum and close foramen ovale After Birth 1. Air enters lungs – forces blood into pulmonary arteries 2. Foramen ovale closes as pressure builds 3. Ductus venosus degenerates 4. Umbilical vein degenerates 5. Umbilical arteries degenerate (The removal of umbilical cord induces degeneration) Tissues Embryonic Tissue Germ Layers - Endoderm o Inner layer o Forms lining of digestive tract + derivatives - Mesoderm o Middle layer o Forms tissues such as muscle, bone, blood vessels o Urinary system - Ectoderm o Outer layer o Forms skin and neuroectoderm Epithelial Tissue - Covers and protects surfaces, both outside + inside of body 1. Mostly composed of cells (little extracellular matrix) 2. Covers body surfaces + forms glands  Outside surface of body  Lining of digestive, respiratory, and urogenital systems  Heart and blood vessels  Linings of many body cavities 3. Has free (apical) surface w/no attachment, basal surface attached to basement membrane, and a lateral surface attached to other cells + components of epithelial tissue 4. Basement membrane 5. Specialized cell contacts 6. Avascular – no direct blood supply (receives O an2 nutrients by diffusion) 7. Capable of regeneration Basement Membranes - Extracellular: formed by secretions of both epithelium + CT - Acellular “glue” o Attachment btwn superficial epithelium + underlying CT o Guides cell migration during tissue repair o Acts as filter in nephron of kidney Classification of Epithelium Cell Layers + Functions: - Simple: one layer of cells o Allows for diffusion of gases, filtration of blood, secretion, absorption - Stratified: 1+ layer of cells, shape of cells in apical layer are used to name tissue (shapes differ as you get close to basement membrane) o Protection, particularly against abrasion Cell Shapes + Functions: - Squamous: flat, scale like o Allows for diffusion/filtering - Cuboidal: equal in height + width (cube like) - Columnar: taller than wide - Cuboidal and columnar are both responsible for secretion/absorption, and also may include goblet cells that produce + secrete mucus Free Surface - Smooth: reduce friction - Microvilli: increase SA for absorption/secretion o Stereocilia: elongated microvilli for sensation/absorption (inner ear) - Cilia: move materials across surface - Folds: help change shape in transitional epithelium (urinary system – bladder gets larger or smaller based on content) Simple Squamous Epithelium - Structure: single layer of flat cells - Function: diffusion, filtration - Location: lining of blood/lymphatic vessels + small ducts, alveoli of lungs, loop of Henle in kidney tubules, lining of serous membranes, inner surface of eardrum Simple Cuboidal Epithelium - Structure: single layer of cube-shaped cells - Function: secretion/absorption in kidney, secretions of glands in choroid plexus, movement of mucus from terminal bronchioles by ciliated cells - Location: kidney tubules, glands + some ducts, choroid plexuses of brain, lining of terminal bronchioles of lungs, surfaces of ovaries Simple Columnar Epithelium - Structure: single layer of tall, narrow cells; some have microvili and cilia - Function: movement of particles out of lungs by ciliated cells, move oocytes through uterine tubes by ciliated cells, secretions of stomach + intestines, and look at absorption of cells+intestines - Location: glands + some ducts, bronchioles of lungs, auditory tubes, uterus, uterine tubes, stomach, intestines, gall bladder, bile ducts, ventricles of brain Stratified Squamous Epithelium - Structure: multiple layers of cells that are cuboidal in basal layer, and get flatter toward surface o Nonkeratinized – moist epithelium o Keratinized – surface cells are dead - Function: protection against abrasion, barrier against infection, reduction of water loss - Location: o Keratinized – skin o Nonkeratinized – mouth, throat, larynx, esophagus, anus, vagina, inferior urethra, cornea Stratified Cuboidal Epithelium - Structure: multiple layers of somewhat cube-shaped cells - Function: secretion, absorption, protection against infection - Location: sweat gland ducts, ovarian follicular cells, salivary gland ducts Stratified Columnar Epithelilum - Structure: multiple layers of tall/thin cells resting on cube shaped cells. Ciliated in larynx - Function: protection, secretion - Locations: mammary gland ducts, larynx, portion of male urethra Psuedostratified Columnar Epithelium - Structure: single layer of cells, some cells are tall + thin and reach free surface, some are not o All cells reach basement membrane – appear stratified b/c nuclei are at various levels o Almost always cilated + associated w/goblet (mucus-producing) cells - Function: synthesize + secrete mucus onto free surface - Locations: lining of nasal cavity, nasal sinuses, auditory tubes, pharynx, trachea, bronchi of lungs Transitional Epithelium - Structure: stratified cells that appear cube shaped when organ/tube isn’t stretched and squamous when organ/tube is stretched - Function: accommodate fluctuations in volume of fluid in organs/tubes - Location: lining of urinary bladder, ureters, superior urethra Cell Connections - Found on lateral + basal surfaces of cells - Functions o Form permeability layer o Bind cells together o Prvide mechanisms for intercellular communications - Types o Desmosomes o Tight junctions o Gap junctions Glands - Secretory organs - Epithelium w/supporting network of CT - 2 types of glands formed by infolding/outfolding of epithelium: o Endocrine: no open contact w/exterior, no duct, produces hormones  Extensive blood vessels in CT of glands o Exocrine: open contact maintained w/exterior; ducts - Exocrine glands classified either by structure of method of secretion: o Multicellular glands: composed of many cells o Unicellular glands: composed of single cell – have goblet cells Connective Tissue - Abundant, found in every organ and cells are separated by extracellular matrix - Diverse types perform variety of important functions - Bones + blood are a type of CT - CT not found on outer surfaces of body, and it is vascular (good blood supply) - Exception is cartilage (no blood supply) and tendons (slight blood supply) Cells of CT - Specialized cells produce extracellular matrix - Descriptive word stems: o BLASTS: create matrix (ex. osteoblasts) o CYTES: maintain the matrix (ex. chondrocyte) o CLASTS: break the matrix down for remodeling (ex. osteoclasts) - Other types of cells in CT are WBC, macrophage cells (specialized WBC that digest), mast cells (produce histamine), adipocytes, fibroblasts Extracellular Matrix - Protein fibre of matrix: o Collagen: most common protein in body; strong, flexible, inelastic (found in large bundles) o Reticular: fill spaces btwn tissues + organs; fine collagenous, form branching networks (smaller bundles surrounded by glycoproteins) o Elastic: returns to original shape after distention or compression. Contains molecules of elastin (coiled springs); cross linked molecules  Made up of elastin + fibrilin  Fibrilin plays role in marfan syndrome Other Matrix Molecules - Ground Substance includes: o Hyaluronic Acid: polysaccharide, good lubricant. (ex. vitreous humor of eye, synovial joint) o Proteoglycans: protein + polysaccharide. Protein attaches to hyaluronic acid, traps water to provide fluid-like properties o Adhesive Molecules: hold proteoglycans together (chondronectin, osteonectin, fibronectin) Adult CT - Connective Tissue Proper o Loose (aerolar): collagenous fibers loosely arranged o Dense: fibers form thick bundles that nearly fill all extracellular space - Supporting CT o Cartilage o Bone - Fluid CT o Blood Loose (aerolar) CT - Loose packing material of most organs and tissues – STROMA - Attaches skin to underlying tissues - Has collagen, reticular, elastic fibers, fibroblasts, mast cells, lymphocytes, macrophage cells, adipose cells - Seen in association w/ other types of CT CT w/Special Properties: Adipose - Predominant cells are adipocytes (specialized fibroblasts designed to store triglycerides) - Yellow (white): most abundant, wide distribution. White at birth, yellows w/age - Brown: found only in specific areas of body: axillae, neck, near kidneys. Usually found in fetus + young babies, rarely in adults (tons of mitochondria) CT w/Special Properties: Reticular Tissue - Forms superstructure of lymphatic and hemopoietic tissues - Network of fine reticular fibers and cells, spaces between the cells contain white and dendritic cells (nerve cells) Dense Regular Collagenous CT - Abundant collagen fibers to resist stretching o Tendons: connect muscle to bones; fibers don’t have to be parallel (concentric circles) o Ligaments: connect bones to bones; flattened, form sheets or bands Dense Regular Elastic CT - Ligaments in vocal chords; nuchal ligament - Give strength and have ability to recoil back when stretched b/c of elastic properties - Locations: vocal chords, ligaments btwn vertebrae, posterior aspect of neck - Fibroblasts located within CT Dense Irregular Collagenous CT - Protein fibers arranged in randomly oriented network, matrix is densely packed - Found in dermis of skin, scars (white part), capsules of kidney + spleen Dense Irregular Elastic CT - Bundles of sheets of collagenous + elastic fibers oriented in multiple directions - Strong, yet elastic w/wavy feature b/c of coiled elastic spring - Found in walls of arteries, blood vessels, heart Supporting CT: Cartilage - Composed of chondrocytes in matrix, surrounded by lacunae (spaces in tissue) - Firm consistency – found in areas btwn bones - Ground Substance: proteoglycans + hyaluronic acid - Avascular + no nerve supply therefore heals slowly - Perichondrium: dense irregular CT that surrounds cartilage – fibroblasts of perichondrium can differentiate into chondroblasts - Types of cartilage: o Hyaline o Fibrocartilage o Elastic Hyaline Cartilage - Structure: large amount of collagen fibers evenly distributed in proteoglycan matric - Locations: areas for strong support + flexibility (ribcage, trachea, bronchi) o Embryo skeleton o Involved in growth – increases bone length Fibrocartilage - Structure: thick collagen fibers distributed in proteoglycan matrix, slightly compressible + tough - Locations: areas of body where great deal of pressure is applied to joints o Knee, jaw, btwn vertebrae, in between bony surfaces – fibrocartilage pad Elastic Cartilage - Structure: elastic + collagen fibers embedded in proteoglycans, rigid but elastic properties - Locations: external ears, epiglottis, auditory tubes - Function: provides rigidity w/more flexibility than hyaline cartilage b/c of elastic properties Supporting CT: Bone - Hard CT composed of living cells (osteocytes) and mineralized matrix (mineral deposits which make bones hard) - Mature osteocyte in lacunae (space) - Contain collagen fibers, hydroxyapitate gives them flexibility - Matrix: provides strength + rigidity (organic: collagen fibers, inorganic: hydroxyapitate) - Types: o Spongy bone (cancellous) – more open spaces o Compact bone – more dense, don’t see gaps - Can withstand forces Fluid CT: Blood - Matrix: plasma (fluid) – no fibers o Matrix formed by other tissues (not CT) o Moves through vessels, and nor formed by cells of blood o Water + other elements - Elements: RBC, WBC, platelets - Hemopoietic Tissue o Forms blood cells o Two types of bone marrow: yellow and red o Spleen Organization of the Nervous System Functions of the Nervous System 1. Senses changes w/sensory receptors, interprets, and decides what to do with them 2. Integration: interprets and remembers changes 3. Homeostasis 4. Mental activity: consciousness, thinking, memory, emotion 5. Controls muscles and glands: cardiac, smooth, skeletal The Nervous System - Components: brain, spinal cord, nerves, sensory receptors - Subdivisions: o Central Nervous System (CNS): brain and spinal cord o Peripheral Nervous System (PNS): sensory receptors + nerves Basic Structures of the Nervous System Peripheral Nervous System (PNS) - Sensory Receptors: specialized cells that detect such things as temp, pain, etc. o Ex. retina at back of eye - Nerve: a bundle of axons + sheaths that connect CNS to sensory receptors, muscles, and glands o Cranial Nerves: originate from brain; 12 pairs o Spinal Nerves: originate from spinal cord; 31 pairs - Ganglion: collection of neuron cell bodies outside CNS - Plexus: extensive network of axons located outside CNS Divisions of PNS - Sensory (afferent): transmits AP from receptors to CNS o Travels through back of spinal cord through dorsal root spinal nerve and dorsal root ganglion - Motor (efferent): transmits AP from CNS to effectors (muscles, glands) Motor Divisions of PNS 1. Somatic Nervous System: CNS  skeletal muscle o Voluntary control o Single neuron system o Synapse w/skeletal muscle: junction of nerve cell w/another cell (NEUROMUSCULAR JUNCTION) 2. Autonomic Nervous System (ANS): from CNS  smooth muscle, cardiac muscle, and certain glands o Involuntary control o Two neuron system: preganglionic neuron: first from CNS  ganglion; postganglionic neuron: second from ganglion  effector Divisions of ANS o Sympathetic: prepares body for physical activity – fight or flight o Parasympathetic: regulates resting or vegetative functions such as digesting food o Enteric: plexuses within wall of digestive tract (controls independently of the CNS, but still part of ANS b/c of parasympathetic and sympathetic neurons contributing to plexus) Cells of Nervous System - Neurons or nerve cells receive stimuli and transmit AP to other neurons/effector organs/glands o Cell body or soma o Dendrites: input (more than one) – short, extensions of cell body o Axons: output (one axon)  Arises at cone shaped axon hillock  Start of axon called initial segment  Diameter is constant, length varies  Cytoplasm – axoplasm, membrane – acolemma  Terminal end – presynaptic terminal  Myelinated: wrapped in protective sheath (lipid + protein); insulates nerve + speeds conduction  Glial cells responsible for myelination; CNS: oligodendrocites, PNS: neurolemocytes (Schwann cells)  In between gaps: Nodes of Ranvier - Neuroglia or glial cells o Non-neural cells o Support + protect neurons - Axonal Transport o Transmit packaged vesicles in axoplasm o Vesicles – Neurotransmitters – can release to stimulate/inhibit postsynaptic cell, can move up and down axon Types of Neurons - Functional Classification o Sensory or Afferent: AP toward CNS o Motor or Efferent: AP away from CNS o Interneurons or Association Neurons: within CNS from one neuron to another - Structural Classification o Multipolar: many dendrites, single axon o Bipolar: one dendrite, one axon o Unipolar: single process extending from cell body – divides into 2 branches  Specialized to receive signals in periphery + transmit signals to CNS  Neurons still have cell body  No axon hillock Supporting Cells of the CNS Neuroglia - Account for > 50% of weight of brain, 4 types of neuroglial cells o Astrocytes: star shaped  Cytoplasmic extensions branch to form foot processes – cover surface of blood vessels, neuron, pia mater (CT layer of CNS)  Release chemicals to form tight junctions/links btwn endothelial cells of capillaries  Blood Brain Barrier: protects against toxic substances  Cavities in brain filled w/fluid – cerebrospinal fluid (CSF)  Opening in middle of neural tube – 4 ventricles in brain  Want to keep blood separate from CSF – astrocytes help do this o Ependymal Cells  Line ventricles of brain + central canal of spinal cord  Helps form choroid plexus – produce CSF  CSF is fluid composed of water from filtering blood (no RBC or cellular matter)  Parches contain cilia – help move CSF through ventricles o Microglia  Specialized macrophages in CNS  Phagocytic – inflammation o Oligodendrocytes  Cytoplasmic extensions (surround axons) – contain plama membrane, lipid, protein  Form myelin sheaths  can wrap many axons Supporting Cells of Peripheral Nervous System - Schwann Cells o Wrap around axons o Forms myelin sheath around a portion of only one axon - Satellite Cells o Surround neuron cell bodies in ganglia o Provides nutrients to cell body + enhance function of cell body in neuron o Unipolar neuron - Myelinated o Myelin protects + insulates axons from one another o Conduct signals more rapidly - Unmyelinated o Oligodendrocytes/Schwann cells nearby but not wrapping it in same fashion Organization of Nervous Tissue - White Matter: myelinated axons, nerve tracts propagate AP from one area in CNS to another - Gray Matter: unmyelinated axons, cell bodies, dendrites, neuroglia; integrative functions - In brain: gray is outer cortex as well as inner nuclei; white is deeper - In spinal cord: white is outer, gray is deeper Brain and Cranial Nerves Brain: Gross Anatomy - Part of CNS contained in cranial cavity – separate from CNS that makes up spinal cord - Brainstem: connects spinal cord to brain; integration of reflexes necessary for survival o Inferior portion of brain – vital basic reflexes such as BP, respiration, core reflexes for functioning (cough, vomiting, sneezing) – linked to neurons in brainstem - Cerebellum: involved in control of locomotion, balance, posture o Posterior, inferior aspect of cranial cavity – role in coordination - Diencephalon: thalamus, subthalamus, epithalamus, hypothalamus o Deep, interior structures – area of fluid-filled cavities called ventricles - Cerebrum: conscious thought, control Brainstem - Has specialized collections of nerve tissues Medulla Oblongata - Transmits ascending and descending impulses between the brain and spinal cord - Pyramids: nerve tracts – conscious control of skeletal muscle, DESCENDING signals - Collections of neurons w/common functions – central vital reflexes – HR, BP, respiration, swallowing, coughing, sneezing - Olives: nuclei involved in balance, coordination, modulation of sound, nerve cell bodies Pons - Ascending/descending nerve tracts - Provides connections posterior to cerebellum, superior to superior brain structures - Sleep centre, respiratory centre – together with medulla help provide info about control of respiration – consciously + unconsciously breathe - Anterior: o Pontine nuclei – communication btwn cerebrum + cerebellum - Posterior: o Nuclei of cranial nerves V, VI, VII, VIII, IX Midbrain - Most superior portion of brainstem - Nuclei of cranial nerves III, IV, V - Tectum: 4 nuclei – form mounds on dorsal surface of midbrain o Each separate part is colliculus – little hill o Two superior colliculi (right + left) involved in visual reflexes 1. Reflex required to control eye muscles if tracking a moving object 2. Pupil Reflex – dilation of pupil to adjust to light o Two inferior colliculi involved in hearing 1. Startle reflex – regulates skeletal muscle to turn head, eyes, and body towards noise to gather more info about it Reticular Formation (Reticular Activating System - Group of nuclei scattered throughout brainstem + axons associated w/neurons – controls sleep-wake cycle Cerebellum - Posterior to brainstem – connected to variety of points - White matter deep inside – arbor vite - Accounts fo 10% of brain mass, but 50% of neurons - Monitoring + correcting station for movements - Communicates w/other regions of CNS o Superior Cerebellar Peduncle – midbrain o Middle Cerebellar Peduncle – pons o Inferior Cerebellar Peduncle – medulla oblongata - 3 regions: 1. Flocculonodular lobe: balance 2. Vermis: gross motor coordination (anterior), fine motor coordination (posterior) 3. Lateral Hemisphere: fine motor coordination Diencephalon - Acts as relay station for all sensory info throughout body - Between brainstem + cerebrum - 4 main components: o Thalamus o Subthalamus o Epithalamuus o Hypothalamus Thalmus - Largest part; mostly made up of gray matter - Gray matter – unmyelinated axons, cell bodies - White matter – axons, myelinated - Lateral portions connected by interthalamic adhesion – surrounded by third ventricle - Receives major portion of sensory input - Medial Geniculate Nucleus – auditory impulses - Lateral Geniculate Nucleus – visual impulses Subthalamus - Inferior to thalamus - Primarily white matter, some gray matter - Ascending + descending nerve tracts - Subthalamic Nuclei - controls motor function Epithalamus - Posterior + superior to thalamus - Habenula: visceral + emotional responses to odor - Pineal Gland: may influence onset of puberty, releases melatonin creating sleepiness (biological clock) Hypothalamus - Most inferior part of diencephalon - Infundibulum: connects pituitary gland to hypothalamus - Pituitary Gland: controls metabolism, reproductive system, response to stress, helps with urine production - Hypothalamus can make hormones, store them in pituitary gland, and send signals for the release of the hormones - Link between nervous + endocrine system - Control bodily functions – hunger, HR, body temp, sex drive, mood, emotion Cerebrum - Planning, analyzing, storing info, accessing + storing memories - Perceives and interprets all sensory info from body and dictates motor responses - Coordinates complex motor functions – speaking, breathing rate - Outer layer – cerebral cortex (gray matter) - In between – cerebral medulla (white matter) - Upward part of folds – Gyri - Downward part of folds – Sulci - Fissures – deeper grooves - Frontal + parietal lobe separated by central sulcus - Anterior to central sulcus – precentral gyrus; posterior to central sulcus – postcentral gyrus - Temporal lobe separated by lateral fissure Frontal Lobe: Motor function, aggression, mood Temporal Lobe: Olfactory, auditory input, memory Parietal Lobe: Touch, taste, pressure, blood pH, Occipital Lobe: Reception + integration of visual input Cerebral Medulla - White matter – nerve tracts connect cortex to other areas of cortex or other parts of CNS - Association Fibers: connect areas of cerebral cortex within same hemisphere - Commisural Fibers: connect cerebral hemispheres - Projection Fibers: between cerebrum + other parts of brain + spinal cord Meninges - 2 basic jobs - 3 meningeal layers + spaces between layers o Dura Mater (most superficial) – dense irrefular CT  Periosteal dura: layer of CT that covers surface of all bone in body  Meningeal dura: tightly adhered to periosteum in spinal cord  Epidural space: space exists in spinal canal, but only a potential space in the brain  dural folds + dural venosus sinus o Arachnoid Mater – thinner – orientation of collagen and elastin fiber  Subdural Space: separates dura mater from arachnoid mater (contains serous fluid) o Pia Mater – adheres tightly to surface of brain  holds spinal cord in place  in brain, involved in CT structure that create CSF  Subarachnoid Space: space between arachnoid mater and pia mater – contains CSF, blood vessels, and fibers from arachnoid mater - All provide protective layer around the brain and continue down to spinal cord Ventricles - 4 ventricles in brain – numbered in order at which CSF moves through them - 2 largest – lateral ventricle (2 – one in each hemisphere) in corpus callosum region located in cerebrum - Third Ventricle – connects with the 2 lateral ventricles via interventricular foramen; located around thalamus - Fourth ventricle – connects to the third ventricle via cerebral aqueduct; smaller ventricle located in pons, medulla oblongata + cerebellum - Ventricles lines w/ependymal cells that produce CSF – most found in lateral ventricles Cerebrospinal Fluid - 3 jobs o Acts as shock absorber o Provides nutrients – main nutrient is glucose o Provides optimal chemical environment for neural impulses - Looks like: o Serum-like fluid lacking proteins but containing nutrients o CSF has few proteins o Bathes + protects brain + spinal cord o Most synthesized in choroid plexus – lateral ventricles Cranial Nerves - Roman numerals I-XII from anterior to posterior - Sensory (special or general) – carrying axons related to transmitting sensory impulses (touch, hear, taste, smell) - Somatic Motor (control of skeletal muscle) – descending impulses for control of skeletal muscle - Parasympathetic (regulation of glands, smooth muscle, cardiac muscle) - Arise directly from brain - 12 pairs - Mneumonics: o Cranial Nerves: Oh Once One Takes The Anatomy Final Very Good Vacations Are Heavenly o Functions: Some Say Marry Money, But My Brother Says Big Brains Matter More Cranial Nerves and Functions • I – Olfactory – Sensory – Smell o Ethmoid bone – specialized receptors of cranial nerve I located in epithelilum lining of nasal cavity which project through ethmoid bone • II – Optic – Sensory – Vision o Optic nerve bilaterally comes out through posterior surface of eyeball o Gather together at optic chiasm which connects to optic tract then penetrates deep into brain for origin in diencephalon • III – Oculomotor – Motor (sensory component to all motor) o Movement of eyeball + upper eyelid o Parasympathetic – change diameter of pupil o Sensory – proprioception – body’s position within space • IV Trochlear – Motor – Movement of Eyeball o Superior oblique muscle – pulls eyeball in diagonal position to look down and at an angle • V – Trigeminal – Motor/Sensory o 3 branches – ophthalmic (sensory), maxillary (sensory), mandibular (sensory/motor) o Nerve transmits most sensory info from supraficial structure of face o Originates in middle of pons o Mastication – motor portion • VI – Abducens- Motor – Movement of Eyeball o Similar to IV o Lateral rectus muscle • VII – Facial – Motor/Sensory o Sensory – taste, info from external surface and skin around external ear o Motor – facial expression o Parasympathetic – Salivary (saliva), lacrimal (tears) • VIII – Vesibulocochlear Sensory – Hearing/Balance o Specialized structures that detect sound + body position • IX – Glossopharyngeal – Sensory/Motor o Sensory – taste on epiglottis o Motor – swallowing o Parasympathetic – parotid gland (production of saliva) o Also can contribute to regulating BP • X- Vagus – Motor/Sensory o Motor – innervates skeletal muscle involved w/voice production, swallowing o Sensory – BP, taste o Parasympathetic – GI, respiratory systems • XI – Accessory – Motor – Swallowing, Head Movements o Originates at spinal roots coming off spinal cord o innervates muscles in neck – sternocleidomastoid + trapezius • XII – Hypoglossal Motor – Speech/Swallowing o Branch which innervates intrinsic + extrinsic muscles associated w/tongue o Tongue + skeletal muscles assist w/swallowing + speech Cranial Nerve Reflexes - X (Vagus): reflexes associated w/HR, BP, and respiration - Reflexes involving both cranial nerves + brainstem: o Turning eyes towards noise, touch on skin, flash of light o Eyes tracking a moving object o Chewing reactions to texture of food, movement of tongue pushing food under tooth-row and out of harm’s way Membrane Potential and Neurotransmission Membrane Potential - Potential for electrical signal to be transmitted - Difference in charge across a membrane (+ve and –ve) - Creates electrical potential - Phospholipid bilayer – stops molecules from freely moving through membrane - Control what can pass through using proteins embedded in membrane that can act as a channel or pore - Nervous tissue and muscle are electrically excitable tissue that produce signals that can travel Electrical Signals - Cells produce electrical signals called action potential - Signal that can propagate/send info to various part of body - Transfer of information from one part of body to another - Electrical properties result from ionic concentration differences across plasma membrane + permeability of membrane - Use properties of ions to set a concentration gradient – things want to move from area of HIGH LOW concentration - Like charges repel, unlike charges attract - Charges want to be joined once again, +ve environment on outside, -ve on inside - Anion = negative, cation = positive - Separated: move back together; creates an electrical force - Separation of charge = potential difference - Inside of cell is more –ve, outside of cell is more +ve Resting Potential of the Membrane + + - Ion concentrations are a result of 2 processes: the Na /K pump and Membrane Permeability - Concentration “highlights” o Cations:  Potassium (K ) > inside +  Sodium (Na ) > outside o Anions:  Proteins > inside – made inside cell therefore hard to leave cell unless specific transport vesicles - helps set up –ve charge on inside of cell - Transporters in cell membrane that are open and allow ions to move freely back and forth between membranes (potassium and sodium channels) - If let things be, will eventually reach equilibrium b/c channels are always open + + - Use the Na /K pump and membrane permeability to set up concentration gradient Na /K Pump + + - Concentration gradient maintained by Na /K pump - Pumps against concentration gradient – ions go towards HIGH concentration + + - Active transport 2K in, and 2 Na out - Leakage of Na and K needs to be addressed by sodium pump 1. ATP binds 2. ATP converted to ADP and P i + + 3. Pump activated and 3Na exit and 2K enter cell 4. ADP and P dissiciate + pump stops (cyclical process) Membrane Permeability Two Types of Ion Channels - Leak (non-gated) ion channels always open – can move at rest – ions specific to specific leak ion channels - Ligand-gated – molecule, channel specific to ion – only certain ions move (based on size + charge of ion) - - Voltage-gated – senses changes in permeability across membrane, when change is sensed, will open - Other-gate ; mechanically gated (physically open gates), pressure gated - Neurons focus on ligand + voltage gated Permeability - Number of open channels - Size of ions – proteins are made big, -vely charged - Number of gated channels Establishing the Resting Potential - Na higher concentration outside cell, K higher inside - Proteins don’t move through membrane - Potential Difference: electrical charge differentiated across the plasma membrane - K and Na leak channels + + 1. Set up concentration gradient using sodium pump (2Na out, 2 K in) 2. Leakage of K through leak channels towards extracellular side of membrane makes +vely charged environment on outside of cells, negative on inside – makes membrane polar 3. Becomes so negative on inside of membrane, K is attracted back inside (electrical gradient) – eventually will reach equilibrium btwn chemical, electric, and concentration gradient - RESTING POTENTIAL – movement of potassium out of cell = movement of potassium into cell Changing the Membrane Potential - Gated ion channels - 2 ways to change electrical membrane potential 1. Voltage gated – located primarily in axons – AP production- electrical signals spread across axons move neuron to neuron 2. Ligand-gated – located more in dendrite region – chemical binding to ligand gated ion channels to change potential by allowing ions to move through – eventually if change is large enough it can be detected by voltage gated channels Electrical Signals in Neurons - Neurons are electrically excitable due to the resting potential - 2 types of electric signals o Local or graded potentials: localized to one part of membrane o Action Potentials: signal that travels along axon - Flow of ions in living cells occurs through ion channels in membrane Local or Graded Potentials - Localized changes in membrane potential - Small deviations from resting -70 mV o Depolarization (-70mV to -40mV) – toward 0 o Hyperpolarization (-70mV to -90mV) – away from 0 Action Potential - Large enough graded potential may cause membrane to reach threshold + get AP - Voltage gated channel – allow ions to move through, create more voltage changes - If reach threshold, will signal all voltage gates channels to open - ALL OR NONE - Spreads over cell, magnitude of response is constant - Depolarization followed by repolarization then restoration of membrane potential Voltage-Gated Ions and the Action Potential Resting Membrane Potential + - Inactivation gate of Na open, activation gate is closed - K channels which have one gate, are closed Depolarization Phase of Action Potential + + - Activation gate of Na channels open, K open more slowly - Once threshold is reached, Na will open and sodium rushes in + - K open but much more slowly, - Depolarization occurs b/c more Na diffuse into cell than K diffuse out of it Repolarization Phase of Action Potential + - When membrane potential reaches max. depolarization, Na begin to close therefore decreasing Na permeability until they are fully closed + + - K channels continue to open, therefore increasing permeability of K - Will result in resting state Afterpotential Phase of Action Potential - K open a little longer than needed to – hyperpolarization - K closes and the sodium pump reestablishes resting potential Refractory Period of Action Potential - If we want another action potential, must wait a certain amount of time - Absolute refractory period: complete insensitivity exists to another stimulus - Relative refractory period: stronger than threshold stimulus can initiate another AP during this period o During period, membrane more permeable to K because many voltage-gated K + channels are open Action Potential Frequency - More APs can be signaled in a shorter time if you have a greater stimulus - More than one AP can be created if stimulus strength is increased - Max stimulus dictated by absolute refractory period Neurotransmission - How to transmit AP down axon, as well as move signal/electrical impulse from one neuron to another Propagation of AP - AP spreads over surface of axon - As Na flows into cell during depolarization, voltage of adjacent areas is effects + channels open - Self propagating along membrane, travelling AP = nerve impulse Unmyelinated Axon - Continuous conduction - AP occurs at one spot but has ability to propagate by stimulating adjacent reigons - APs spread in one direction - Local current: movement of +ve ions attracted to –ve regions on membrane - AP can’t restimulate area Myelinated Axon - AP conducted from node of ranvier to node of ranvier – Saltatory Conduction - Local current flows btwn nodes - Myelin sheath is insulator – allows axons to have local current + - Voltage-gated Na channels concentrated at nodes –HIGH CONCENTRATION; therefore when depolarized will cause greater response, greater local current, greater things will move along - Flow of APs is faster b/c of leaping effect - Energy efficient Nerve Fiber Types - Type A: large-diameter, myelinated. Conduct 15-120 m/s – supply skeletal + most sensory neurons - Type B: medium-diameter, lightly myelinated. Conduct 3-15 m/s – part of ANS - Type C: small-diameter, unmyelinated. Conduct 2 m/s or less. Part of ANS Synapse - Synapse: junction btwn cells that allows one to communicate w/one another - Presynaptic cell, synapse, post synaptic cell Electrical Synapse - Doesn’t happen in NS - Occurs more often in smooth + cardiac muscle tissue - Junction btwn 2 cells important for coordinated contractions - Local current goes through connection + can cause depolarization on plasma membrane - Sync coordinated contraction – smooth muscle – all cells connected to each other through electrical synapses Chemical Synapse - Presynaptic terminal: end of axon - Postsynaptic terminal: cell membrane in close association w/presynaptic terminal (dendrite of another axon, muscle, gland) - Synaptic Cleft: space btwn postsynaptic and presynaptic terminal - No direct transfer of AP from nerve to tissue, rely on neurotransmitters to relay info (chemical signal = acetylcholine) - Presynaptic terminals produce, store, and release NT from synaptic vesicles, which can bind to synaptic terminal + release contents into synaptic cleft Neurotransmitter Release - AP move along axon and arrive at presynaptic terminals causing voltage-gated Ca 2+ 2+ channels to open and allow Ca into cell increasing its permeability of presynaptic terminal - Ca enters presynaptic terminal and initiates release of NT from synaptic vesicles - Diffusion of NT across synaptic cleft and binding to NT receptors on postsynapit cell + membrane causes increase permeability of ligang-gated Na channels - Increase in permeability results in depolarization of postsynaptic membrane; once threshold reased, AP results Removal of Neurotransmitter - Want to continually excite/inhibit post-synaptic membrane - Diffusion: move down concentration gradient - Enzymatic Degradation: acetylcholinesterase breaks down acetylcholine and then taken up by presynaptic terminal - Uptake by neurons or glial cells: NT transporters reuptake, repackage, and reuse o Prozac = serotonin reuptake inhibitor which blocks transporter, build up of serotonin in synaptic cleft therefore greater/loner binding to ligand-gated channels allowing them to be open for longer Postsynaptic Potentials - Once NT binds to ligand-gated channel can cause EPSP or IPSP - Excitatory Postsynaptic Potential (EPSP) o Depolarization occurs and response stimulatory - Inhibitory Postsynaptic Potential (IPSP) o Hyperpolarization and response inhibitory Presynaptic Inhibition and Facilitation - Axoaxonic Synapses: axon of one neuron synapses w/the presynaptic terminal (axon) of another (many synapses of CNS) - Presynaptic Inhibition: reduction in amount of NT released - Presynaptic Facilitation: amount of NT released increases Autonomic Nervous System Organization Peripheral Nervous System  Sensory (afferent) – transmits AP to CNS from periphery  Motor (efferent) – transmits AP from CNS to effector organs Motor  Somatic Autonomic Somatic - Skeletal muscle in response to consciously perceived sensation, 1 neuron system - Cell bodies in anterior horn of spinal cord exit through ventral root and travel through spinal nerve - Travel to effector/target tissuemuscle – release NT acetylcholine causing EPSP muscle contraction Autonomic - Cardiac, smooth, glands in response to unconsciously perceived visceral sensations in body, 2 neuron system - Preganglionic neuron has cell bodies in lateral horn of spinal cord – leaves through ventral roon into spinal nerve then synapses w/postganglionic neuron at autonomic ganglion - Postganglionic neuron can synapse with effector organ – release of NT acetylcholine or norepinephrine can result in EPSP or IPSP Divisions of ANS - Sympathetic - Parasympathetic - Enteric – innervates contraction of digestive tract - Most organs have dual innervations from sympathetic + parasympathetic o One speeds up, one slows down Sympathetic - Thoracolumbar division – cell bodies originate at lateral horn of spinal cord (T1- L2) - Exit through ventral root, joins spinal nerve, enters sympathetic ganglia - Sympathetic ganglia – chains on either side of vertebral column o Sympathetic Chain Ganglia: collection of postganglionic cell bodies close to spinal cord connect to form 2 chains on either side of spinal cord o Colateral Ganglia: collection of postganglionic cell bodies closer to effector/target tissues Parasympathetic - Craniosacral division – cell bodies associated with nuclei of 4 diff cranial nerves - Oculomotor (III) – PSNS stimulates ciliary muscles of eye + sphincter pupilae - Facial (VII) – stimulates glands for tears, saliva + nasal secretions - Glossopharyngeal (IX) – stimulates parotid gland - Vagus (X) – supply heart, pulmonary system, GI tract up until midpoint of colon - Pelvic nerves (S2-S4) – supply smooth muscle, glands from midpoint of colon on, ureters, bladder + reproductive organs Enteric - Nerve plexuses in wall of digestive tract - 3 points of nervous input 1. Digestive  CNS 2. ANS motor neurons connect CNS  digestive tract 3. Enteric neurons  control autonomic reflexes - Major types of enteric neurons: o Enteric Sensory neurons – maintain homeostasis by detecting stretch + chemical composition o Enteric Motor Neurons – stimulate/inhibit smooth muscle, control secretion from glands o Enteric Interneurons – connect sensory and motor Neurotransmitters - Acetylcholine (cholinergic) - Norepinephrine (adrenergic) Sympathetic - Preganglionic neurons (cholinergic)  postganglionic neurons (adrenergic) Parasympathetic - Preganglionic neurons (cholinergic)  postganglionic neurons (cholinergic) Receptors Cholinergic Receptors - Nicotinic Receptors: excitatory, bind Na channels – located in cell bodies of all postganglionic neurons + plasma membrane of skeletal muscle - Muscarinic Receptors: excitatory/inhibitory, G-protein – located on plasma membrane of PSNS effectors/target tissues Adrenergic Receptors - Found in sympathetic NS effectors except sweat glands - 2 classes: o Alpha receptors (A1, A2) o Beta receptors (B1, B2) - Both can excite/inhibit; A1,B1 excite and A2,B2 inhibit ANS Regulation - ANS – homeostasis - Autonomic reflexes – loop created by direct link btwn visceral sensory input + ANS motor responses - Ex. Baroreceptors in walls or larger arteries detect stretch/changes in BP Generalizations of ANS 1. Both divisions produce IPSP or EPSP 2. Most organs receive dual innervations 3. Can have opposing effects 4. Can produce cooperative effects 5. General(sympathetic) vs. Localized (parasympathetic) effects 6. Rest vs. Activity – PSNS controls SLUDD responses (salivation, lacrimation, urination, digestion, defecation) and SNS controls 4Es (emergency, embarrassment, excitement, exercise) and fight/flight response Spinal Cord and Spinal Nerves - Spinal cord is long structure comprised of nervous tissue - Part of CNS, connect brain to PNS - Made up of nervous tissue: neurons + glial cells - Bony structures that surround the cord – vertebrae (stacked to form vertebral column) Spinal Cord - Communication link btwn the brain and PNS + integrates info + produces responses - Provides pathway for nerve impulses – go to and from the brain - Extends from the foramen magnum to L2 - Composed of cervical, thoracic, lumbar, and sacral segments - 31 pairs of spinal nerves - Exit spinal cord at various levels throughout vertebral column - Not uniform in diameter, circular in cross section - Two enlargements 1. Cervical Enlargement (occurs between C4-T1) 2. Lumbosacral Enlargement (T9-T12) - Filum Terminale: anchor spinal cord to bony structures of vertebral column on inferior aspect and longitudinally - Conus Medullaris: inferior end of spinal cord – nerves continue down vertebral column and exit at respective foramine - Cauda Equina: hairlike structures Meninges - Dura Mater: most superficial, dense irregular CT – thickest + strongest o Epidural Space: space between dura mater + periosteum filled w/fat, blood vessels, CT, - Arachnoid Mater: thin, squamous epithelial, delicate network of collagen fibers o Subdural space: separates dura mater and arachnoid mater – small amount of serous fluid - Pia Mater: deepest layer, tight to spinal cord, blood vessels which supplies spinal cord o Subarachnoid space: space between arachnoid and pia mater – has CSF and cushions + protects cord, delivers nutrients, removes waste o Small extensions of pia mater go toward dura mater... help anchor spine laterally Cross Section of the Spinal Cord - White Matter: two halves; three columns in each half o Each column subdivided into nerve tracts (fasciculi) – bundled together o When grouped together, allows info to be transmitted in organized fashion down spinal cord o Dorsal, ventral, lateral column – each will have groups of ascending/descending tracts (myelinated) - Gray Matter: composed of posterior, anterior, lateral horns; made up of neuron cell bodies, dendrites, supporting cells, axon terminals, shorter neurons that connect various parts of spinal cord – interneurons o Lateral horns: autonomic nervous system o Posterior horns: sensory neurons o Anterior horns: motor neurons o Gray and White Commissures: axons that cross from one side of spinal cord to other Organized in the Spinal Cord - Sensory Neurons pass into the posterior horn , synapse w/interneurons or enter white matter and ascend/descend the cord - Cell bodies are in dorsal root ganglion - Neuron cell bodies that originate in lateral horn – autonomic neuron- smooth muscle, cardiac muscle, glands - Motor Neurons – anterior horn exit the ventral root – diseases associated w/anterior horn is degeneration of gray matter o Polio: caused by polio virus which attacks motor neurons in anterior horn and results in motor loss/paralysis o ALS: amyotrophic lateral sclerosis, attacks motor neurons in anterior horn and brain resulting in loss of ability to speak, swallow, breathe - Spinal Nerve: after motor neurons exit ventral root + sensory come into dorsal root – form to make spinal nerve when dorsal and ventral root come together – mixed function – sensory + motor Spinal Nerve - 31 pairs of spinal nerves - First pair exit vertebral column between skull and first cervical vertebrae - Four pair exit via sacral foramina - Others exit through intervertabral foramina - 8 cervical pairs, 12 thoracic pairs, 5 lumbar pairs, 5 sacral pairs, 1 coccygeal pair - Functions - Cranial Nerves o Diaphragm movement o Neck + Shoulder Movement o Upper Limb Movement - Thoracic Nerves o Rib movement in breathing o Vertebral column movement o Tone in postural back muscles - Lumbar Nerves o Hip movement - Sacral Nerves o Lower limb movement - Arise from rootlets along dorsal + ventral surfaces of spinal cord (6-8 rootlets) - Ventral and dorsal roots – pass through subarachnoid space, pierce arachnoid + dura mater, and joint ot form spinal nerve - Each dorsal root contains ganglion Branches of Spinal Nerves - Branches of spinal nerve – rami - Dorsal Ramus: innervate deep muscles of trunk responsible for movements of the vertebral column - Ventral Ramus: o Thoracic Region: form intercostal nerves – innervate intercostals muscles involved w/breathing and skin in thoracic region o Remaining spinal nerve ventral rami (roots of plexus): 5 plexuses  Ventral rami C1-C4 = cervical plexus  Ventral rami C5-T1 = brachial plexus  Ventral rami L1-L4 = lumbar plexus  Ventral rami L4-S4 = sacral plexus  Ventral rami S5and Co = coccygeal plexus o Plexuses – nerve fibers coming out of spinal cord – several different spinal nerves recombining after leaving spinal cord Structure of Peripheral Nerves - Consists of axons, schwann cells, and CT - Bundled in parallel – both sensory + motor axons together – grouped depending on functions and etc. - Axons surrounded by 3 CT layers o Endoneurium o Fascicle (bundles) covered by perineurium o Nerve covered by epineurium (continuous w/dura mater) Cervical Plexus - C1-C4, smaller - Branches off + merge w/other branches - Run parallel to cranial nerves XI and XII - Innervates superficial neck structures, skin of neck, posterior portion of head, superior part of shoulders + chest - Phrenic Nerve (C3-C5: cervical + brachial plexuses) o Innervates diaphragm (breathing process) - Important to disease and injury Brachial Plexus - C5-C8, as well as T1 - 3 trunks, 6 divisions, 3 cords - 5 branches o Axillary – deltoid, teres minor o Radial – posterior aspect of arm + forearm o Musculocutaneous – flexors of forearm (biceps brachi) o Ulnar – some of forearm + most hand muscles o Median – most of anterior forearm + hand muscles associated w/thumb movement Lumbosacral Plexus - Lumbar Plexus: ventral rami L1-L4 o Obturator o Femoral  Lateral ab walls, genital, lower limbs - Sacral Plexus: ventral rami L4-S4 o Tibial o Common Fibular (personal) o Known as sciatic Coccygeal Plexus - S5-Co; coccygeal nerve - Muscles of pelvic floor - Sensory info from skin over coccyx – most inferior bone in vertebral column Special Senses Types of Senses - Difference between general senses + special senses o General has receptors throughout whole body  Somatic: info about external environment + position about body in space  Visceral: come from inside body, sensory info coming back to brain from internal organs o Special Senses: localized to specific regions of body – only certain organs use them  smell, sight, taste, hearing, balance  use specialized receptors that take in variety of info from environment to make AP Types of Sensory Receptors - Mechanoreceptors: physically changing something about ion channel to open gates (compression, bending, stretching of cells; ex. touch, pressure, proprioception, hearing, and balance) - Chemoreceptors: chemicals become attached to receptors on their membranes causing ions to change movement in membrane and result in depolarization (ex. smell and taste) - Thermoreceptors: respond to changes in temperature - Photoreceptors: respond to light (ex. vision) - Nocioreceptors: extreme mechanical, chemical or thermal stimuli. (ex. pain) Visual System Accessory Structures - Eyebrows +eyelashes help protect eye from foreign objects, perspiration and shade from sun - Eyelids o Palpebrae: upper eyelid – superior, lower eyelid – inferior; provide shade during sleep, protect from eye and secrete solutions for eye (tears) o Palpebral Fissues: opening for eyeball o Canthi: medial and lateral canthus (pink mound called caruncle) o Caruncle: modified oil + sweat glands – produce whitish material - Conjunctiva: mucus membrane that forms inner membrane of eyelid. It attaches at palpebra fissure and folds back to cover anterior white of eye up until cornea o Forms a pocket to stop debris/objects from entering posterior portion of eye where there is optic nerve + blood vessels o Can respond to irritants – inflammation of conjunctiva known as conjunctivitis, blood shot eyes, bacterial infection (pink eye) - Lacrimal Apparatus: collection of structures involved in the production of tears o Larimal gland: produces tears + releases on surface of eye through ducts o Tears move towards medial canthas, if excess it collects on medial corner of eye and inter into puncta o Move down lacrimal canaliculi into lacrimal sac, then into nasolacrimal duct (why nose runs when you cry) - Extrinsic Muscles of the Eye o 4 Rectus: superior, inferior, medial and lateral; attach to sclera and bony structure of eye orbit, allow movement up, down, left, right o 2 Oblique: superior and inferior; involve rotation of eye  Superior: inferior lateral rotation of eye  Inferior: superior lateral rotation Anatomy of Eye - Composed of 3 tunics: superficial to deel o Fibrous Tunic: white of eye  Sclera: shape protection, attachment of muscles  Continuous with cornea: anterior curve shaped structure that allows for focusing light – avascular o Vascular Tunic  Cells that have melanin (pigment makes inner surface of eye black to reduce light from reflecting inside eye – improves visual acuity + sharpness of images  Choroid: blood supply  Ciliary Body: continuous w/choroid  Iris: attached at lateral margins to ciliary body  Ciliary body consists of ciliary ring and ciliary processes attached to lens by suspensory ligaments  Ciliary body contains smooth muscles called ciliary muscles  Ciliary muscles function as sphincter + contraction can alter shape of lens  Ciliary processes produce aqueous humour  Iris is contractile structure consisting mainly of smooth muscle – surrounding opening called pupil • Sphincter Pupillae: circular group – decreases diameter of iris • Dilator Pupillae: radial group – increases diameter of iris o Retina – neural tunic, posterior portion of eye up until ciliary body  Inner most layers of eye containing specialized photoreceptors, 2 types:  Cones: colour, vision, visual acuity  Rods: low light, black and white  More rods and cones exist, used to turn light into AP  Macula: dark centre spot made up of a high density of cones, greatest visual acuity, target for light entering eye  Fovea Centralis: middle of macula, contains cones  Retinal Layer: 2 main layers • Pigmented Layer: outer; composed of cells filled w/melanin, enhances visual acuity + decreases scatter of light that enters eye; • Neural Layer: inner; o Photoreceptor Layer: specialized rods + cones w/modified dendrites sensitive to light, can synapse w/bipolar cells o Bipolar Layer: cells can synapse w/ganglion cells o Ganglion Layer: can synapse w/optic nerve  Light must travel through all layers to be detected Chambers of the Eye - 3 chambers: 1. Vitreous Chamber: filled w/vitreous humor (jelly-like substance that keeps shpe of eye) 2. Anterior Chamber: filled w/aqueous humor (produces by ciliary processes and helps maintain interocular pressure to maintain shape of eye. Also provides nutrients to cornea + lens which are both avascular) 3. Posterior Chamber: filled with aqueous humor - Lens: solid tissue that is transparent and won’t scatter light Focusing Images on the Retina - Light rays must reach eye and focus on fovea centralis + macular region of retina - Far point of vision = light rays enter in parallel fashion, curve cornea bends rays - Rays are bent because light rays from top + bottom of object meet at a focal point where there is no image. Beyond that, the image is inverted on retina and brain uses sensory info to flip it - Distant Vision: ciliary muscles relaxed, suspensory ligament tension high, lens flattened - Near Vision: ciliary muscles contract, suspensory ligament tension low, lens is spherical - 3 events bring image to focus: o Accomodation: ciliary muscles contract, lens becomes more spherical; greater light refraction, focused object o Pupil Constriction: diameter of pupil determines depth of focus; small diameter – greater depth, large diameter – smaller depth o Convergence: binocular vision – eyes rotate medially to continue to pick up light rays as object moves closer Function of the Retina 1. Rods: rhodopsin – noncolour vision, lowlight bision o Rhodopsin: opsin and retinal – photosensitive molecule made up of protein (opsin) and pigment (retinal); retinal located in opsin protein and has vit. A 2. Cones: iodopsin – colour vision, high light, increased visual acuity o Iodopsin: retinal and red, blue, green opsin – allows for cones to detect colour - Both cells have photosensitive molecules linked to sodium-gated channels that are open at rest (depolarized) Change in Membrane Potential with Light Stimulus - Unstimulated condition – retinal molecule is inactive and opsin in dark configuration, sodium channels are open (held open by cGMP) - When light stimulus is introduced it converts retinal pigment and ospin to light configuration - This activates cGMP ph+sphodiestarase which converts cGMP  GMP and caus+s it to difuse away from Na channels therefore closing them – no more Na moves through membrane therefore hyporalization - Phosphodiesterase becomes inactive and cGMP reforms, concentration increases, and binds to sodium channel leading to depolarization - Retinal uses ATP to return to inactive form, attaches to ospin and returns to dark configuration Hyperpolarization in Rods+Cones to Produce Signal for Brain + - Rod cell unstimulated in dark configuration, rhodopsin inactive, gated Na channels are open (depolarizaed) - Constantly releases glutamate (NT) detected by bipolar cell in postsynaptic membrane causing an IPSP + - When light stimulus introduces- Na channels close, rhodopsin changes to light configuration and causes hyperpolarization, NT release decreases therefore no binding to ligand-gated channels on bipolar cell, causing it to get AP, releases NT towards postsynaptic membrane of ganglion cells which causes AP that travels to optic nerve Neural Pathways for Vision - Each eye has visual field: temoral (ear) and nasal (nose) - Nasal field project onto temporal side, temporal side project on nasal side - Neurons from retina converge into optic nerves, which converge at optic chiasm - Neurons then go to superior colliculi (visual reflexes) and the rest of nerves will go to lateral geniculate colliculi (interpretation of visual cortex) Olfaction - Odorant: molecule released from something that is taken up through nares (nostrils; 2 nasal cavities separated by septum) - Each cavity made up of 9 different bones, total of 14 (some are shared) o Hard Palate: roof of mouth/base of nasal cavity o Frontal Bone: roof of nasal cavity o Nasal Bones (2): right and left o Ethmoid Bone: important for sensible fashion + involved in olfaction; has cribiform plate filled with a bunch of holes o Rest is cartilage o Ridges in nasal cavity help create turbulent air flow to deliver odorants Olfactory Region - Olfactory Bulb: terminal end of olfactory nerve - Olfactory Tract: axons w/olfactory neuron bundled together - Olfactory Epithelium: layer of cells that line inner nasal cavity surface containing specialized neurons for detecting smell - Olfactory Neuron: bipolar neuron, modified dendrite ends receive odorants; modified bulbur structure called olfactory vesicles w/cila on them (olfactory hairs) - Olfactory Epithelial Layer: supporting cells that hold olfactory neurons in place - Basal cells: make whole layer - CT layer: contains glands that make mucus in mucus layer to dissolve odorants before they can bind - Odorants bind to olfactory hairs and depolarization occurs - 7 primary classes of odors: o Camphoraceous: mothball smell o Musky o Floral o Peppermenty o Ethereal: fruity o Pungent o Putrid - Olfaction bypases thalamus and goes directly to cortex - APs terminate at 3 regions 1. Lateral Olfactory Area: conscious perception of smell (in temporal lobe) 2. Medial Olfactory Area: visceral and emotional reactions to smell (in frontal lobe) 3. Intermediate Olfactory Area: inhibition role in olfaction (frontal lobe) Taste - Chemoreceptor basis – tastant instead of odorant - Specialized chemoreceptors in taste buds (oval structures located on tongue called papillae) - 4 different types of papillae: o Filiform: most abundant, no taste buds, rough surface o Vallate: largest, least abundant, v-shaped, taste buds o Foliate: found in grooves on sides of tongues, look like leaves, taste buds o Fungiform: scattered irregularly, small red dots, tast buds - Taste cell: modified neuron, no dendrites/axon, microvilli projections that move through taste pore into oral cavity – taste hairs (receptors where depolarization occurs - Tastant: dissolved in saliva, binded to receptors on taste hair, taste cells depolarize, skip AP part, go down axon and release NT on other side - Taste buds for salt, sour, bitter, sewet, umami + + - Salt/Sour –ions, Na ions and H ions – bind to channel, open it and change membrane potential - Sweet/Bitter/Umami – molecules of specific size, shape, chemical composition that bind to taste receptors and use protein to open ion channel – causes depolarization Neural Pathways for Taste - Taste (Gutatory) Cells (depolarization)  Cranial nerves VII, IX, X (7-anterior 2/3 of tongue, 9 – posterior 1/3 of tongue, 10 – epiglottis taste buds)  Medulla Oblongata  Thalamus  Postcentral Gyrus Hearing Auditory Function - Sound: interpretation of vibrations - Compressed air – peak of wave, less compressed – valley of wave - Volume: wave amplitude (lower volume - less amplitude, higher volume – higher amplitude) - Pitch: wave frequency (high pitch – high frequency, low pitch – low frequency); pitch detected in cochlea External Ear - Auricle funnels sound waves from external environment to external auditory canal - Sounds are transmitted through canal which moves through temporal bone and into next area called middle ear (air filled space) through a border called the tympanic membrane (delicate thin membrane that vibrated when sound waves hit it) - External ear is air filled Middle Ear - Air filled space embedded in bone w/chambers or canals for structures - Contains 3 small bones called the auditory ossicles o Malleus, Incus, Stapes (MIS) joined by ligaments + muscles and move w/respect to each other o Malleus: hammer, handle attached to tympanic membrane (when it vibrates, moves malleus) o
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