Practical 3 Study Guide with Diagrams.docx

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University of Maryland
Biological Sciences Program
BSCI 201
Justicia Opoku

CHAPTER 14- Nervous System Divisions & their functions • PNS- cranial/ spinal nerves, ganglia, sensory receptors (ganglia)  axons myelinated by Schwann cells • CNS- brain and spinal cord (nuclei)  oligodendrocytes Cell groups & their functions • Neurons- basic functional units of nervous tissue • Ganglia- collection of neuron cell bodies outside CNS • Nerve- bundle of axons in PNS wrapped by CT, classified by direction transmit impulses o Sensory Nerves- carry sensory processes toward CNS o Motor Nerves- ventral roots of spinal cord carry motor fibers o Mixed Nerves- carry both sensory and motor fibers • Tract- bundle of axons in CNS wrapped by CT Neuroglia/ Glial Cells- supporting cells [Pg. 210 figure 14.1] CNS o Microglia- acts as phagocyte (ingest/ destroy foreign matter, defensive cells) o Oligodendrocytes- myelinate and insulate neurons o Astrocytes- control chemical envi around neurons (facilitate capillary- nerve exchanges) o Ependymal cells- circulate cerebrospinal fluid PNS o Schwann cells- myelinate/ insulate extensions of the neurons o Satellite cells- surround cell body of neuron Neuron parts & their function [Pg. 211 figure 14.2a] • Cell Body • Dendrites- receptive regions • Axon- nerve fibers • Axon terminal- store neurotransmitters • Axon hillock- junction between cell body and axon • Myelin Sheath- white fatty protein covering axons • Neurofibrils- intermediate filaments in neurons  provide tensile strength • Nissl bodies- specialized rough ER  protein synthesis • Nodes of Ranvier- gaps in myelin sheath • Neurilemma- schwann cells external to myelin sheath housing nucleas and cytoplasm (sheath of Schwann) Functional classification of neurons • Sensory/ Afferent- neurons carry impulses from sensory receptors [unipolar] • Motor/ Efferent- neurons carry impulses from CNS to viscera/ body muscles/ glands [multipolar, in CNS] • Association/ Interneurons- contribute to pathway connecting sensory and motor neurons [multipolar, always in CNS] Structure of a nerve/tract & coverings [Pg. 216 figure 14.8a] Structural classification of neurons & local [Pg. 214 figure• Nerve/tract covered by epineurium 14.5a] • Fascicle covered by perineurium • Unipolar- 1 short process divides into peripheral and Axon covered by endoneurium central processes (extend from cell body) • Bipolar- two process attached to cell body (receptors of eye, ear, and olfactory mucosa) • Multipolar- many processes issue from cell body (all classified as dendrites except for a single axon) Chapter 15- Nerve Impulses Nerve impulse:  Name of each step,  What happens at each step Resting Membrane Potential- difference in electrical charges produced Depolarization- interior of membrane becomes less negative Threshold/ Action Potential/ Nerve Impulse- stimulus great enough to depolarize initial segment of axon generated Repolarization- interior of membrane becomes more negative than exterior Absolute Refractory Period- when Na+ permeability rapidly chaning/ maximal and perior following when Na+ permeability becomes restricted  time when neuron is insensitive to urther stimulation and can’t generate another action potential Relative Refractory Period- Na+ permeability gradually restored to resting levels during repolarization, strong stimulus to neuron provoke another AP Compound Action Potential- electrical signal recorded from nerve represents summed electrical acitivty of all nerve fibers Nerve Impulse Neurons are Excitable [respond to stimuli by producing an 1. Resting State- neuron is polarized electrical signal]  Resting membrane potential- charge separation • Conductivity- ability to transmit impulse to other  Cytoplasmic surface of plasma membrane more neurons, muscles or glands neg than pos exterior surface  Mnemonic: On occasion our trust truck acts funny – very good  High Na+ conc. outside cell, high K+ conc. inside vehicle anyhow cell Cranial Nerves i) Olfactory- sensory, carries afferent impulses  Maintained by active sodium-potassium pumps 2. Stimulation- associated w/ sense of smell [olfactory epithelium]  Neuron activated by threshold stimulus ii) Optic- sensory, carries afferent impulses associated w/ vision [retina of eye]  Interior less negative, and iii)Oculomotor- motor, direct eyeballs [dorsal midbrain] depolarized (more pos) iv) Trochlear- motor, provide somatic motor fibers to move  Sod+um gates open in the eyeball [midbrain] membrane and Na ions move into the cell, down their concentration gradient v) Trigeminal- mixed, conduct sensory impulses from 3. Generation of Nerve Impulse skin of face to scalp [pons]  When threshold potential reached, action vi) Abducens- carries somatic motor fibers to lateral potential is generated all or none AP rectus muscle that moves eyeball [eye socket]  Transmitted AP referred to as nerve impulse vii)Facial- mixed, supplies somatic motor fibers to  Depolarization occurs when charge across plasma muscles of facial expression [face] membrane reverses from neg to pos charge viiiVestibulocochlear- sensory, transmit impulses 4. Repolarization- becomes more neg associated w/ sense of equilibrium [pons]  Membrane repolarizes ix) Glossopharyngeal- mixed, carry impulses from  Potassium gates open, and K+ ions move out of tonsils, tongue [throat] the cell, down their concentration gradient x) Vagus- mixed, transmit sensory impulses from viscera 5. Return to Resting State [thorax and abdomen]  Sodium potassium pump reestablishes [] gradients of resting membrane potential so neuron can fire xi) Accessory- mixed, provides somatic motor fibers to again sternocleidomastoid [muscles of neck/ back]  Absolute Refractory Period- nothing comes in xii)Hypoglossal- mixed, carries somatic motor fibers to until relative refractory period/ repolarization tongue muscles [tongue] o Occurs when sodium gates still open (depolarization phase) and neuron unable to initiate new AP  Relative Refractory Period- neuron undergoing repolarization and sodium gates close  strong stimulus causes initiation of another AP Chapter 16- BRAIN Brain parts [Pg. 227 figure 16.2, pg. 230 figure 16.4] Protective brain structures Pg. 233 figure 16.7 • Cranium- bony helmet composed of 8 cranial bones Cerebrum- cerebral hemispheres (most superior of brain) • Meninges- 3 connective membranes surrounding brain 1. Cerebral cortex= highly convoluted, 40% brain mass  Dura mater (outermost menix)- double o Composed of gray matter (cell bodies, dendrites) layered o Location of our conscious mind  Periosteal layer- outer layer  Meningeal layer- inner layer 2. White matter- deep to cerebral cortex  Arachnoid mater (middle menix)- weblike o Composed of tracts w/ myelinated axons w/ whitish appearance extensions from arachnoid mater to subarachnoid 3. Basal nuclei- islands of nuclei in cerebral white matter space  Pia mater (innermost menix)- clings to • Gyri- elevated ridges of tissue brain surface  Subarachnoid space- separates arachnoid mater and subarachnoid space • Sulci- shallow grooves or fissures- deeper grooves separate gyri • Cerebrospinal Fluid (CSF)- filtered from blood, located in ventricles and in subarachnoid space (liquid • Longitudinal Fissure- separates right and left cushion, provide nutrients, remove waste) hemispheres  Choroid plexuses- produces CSF • Corpus Callosum- holds hemispheres together • Blood-brain-barrier- selective barrier prevents harmful • Septum pellucidum- lateral ventricles separated by substance in blood from crossing to brain membrane o Frontal lobe Brainstem 1. Pons- contains fiber tracts connecting cerebrum to o Temporal lobe o Insula lobe cerebellum o Occipital lobe 2. Midbrain- o Parietal lobe a. Corpora quadrigemina- pair of… • Central Sulcus- divides frontal from parietal lobe i. Superior colliculi-visual reflex • Parieto-occipital sulcus- medial surface of each ii. Inferior colliculi- auditory reflex hemisphere divides occipital from parietal lobe (not b. Cerebral aqueduct- pathway for cerebral visible externally) spinal fluid c. Cerebral peduncles- tracts in midbrain, • Precentral sulcus- in frontal lobe in front of central connects pons to cerebrum sulcus • Postcentral sulcus- of parietal lobe 3. Medulla oblongata- regulate autonomic fx • Lateral Sulcus- separates temporal from parietal lobe Cerebellum Pg. 232 figure 16.6 • Arbor Vitae- deep layer of white layer Diencephalon 1. Thalamus- relay center for all sensory info (except • Vermis- longitudinal fissure separate 2 hemispheres smell) to cerebral cortex 2. Hypothalamus- regulation of visceral activities and body functions, emotions, instincts, secrete hormones 3. Epithalamus- contains pineal gland, secrete melatonin (hormone) 4. Pineal gland (retina) Sheep brain Ventral view A. olfactory bulb B. optic nerve (II) C. optic chiasma D. infundibulum E. Mammillary body F. cerebral peduncle G. pons H. medulla oblongata I. oculomotor nerve (III) J. Trigeminal nerve (V) K. Abducens nerve(VI) Dorsal view: A. pineal body B. superior colliculi of corpora quadrigemina C. inferior colliculi of corpora quadrigemina D. cerebellum • cerebrum • arbor vitae Sagittal view A. cerebral hemisphere B. corpus callosum C. frontal lobe of cerebrum D. fornix E. intermediate mass of thalamus F. cerebral peduncle G. optic chiasma H. parietal lobe I. cerebellum J. pineal gland K. arbor vitae L. corpora quadrigemina N. medulla oblongata O. pons Thyroid gland Adrenal gland Pituitary gland Testis Pancreas Parathyroid gland Ovary Chapter 19- Vision Accessory structures & their function Pg. 274 figure Layers Pg. 276 figure 19.3 19.1 Fibrous • Palpebrae- eyelid • Sclera- outer white membrane layer of eyeball • Medial & Later
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