Lecs 9-16

27 Pages
Unlock Document

University of Toronto Scarborough
Biological Sciences
Catherine Nash

Physiology Midterm 2 Review Lecture 9 o Central Nervous System = brain & spinal cord (contains neurons that communicate within the CNS and the rest of the body) o Peripheral Nervous System = Autonomic (involuntary) Nervous System (cardiac, smooth muscle(liver), adipose tissue(fat), endocrine system), Enteric Nervous System(digestive) & Somatic Motor Division(skeletal muscles) Evolution of the Brain o Lines of the Jellyfish represent the nervous system; In jelly fish the nerve net functions together to co- ordinate movement o In flat worms, nerve cords represent bundles of nerves in the brain and the primitive brain is a collection of cell bodies within the head; Flat worms = simple nervous system. Nerve cell bodies restricted to the head. o Annelids and segmented worms have clusters of nerve cells (ganglia = swellings where synapse are) through the body o Allows functions equivalent to spinal reflexes(involuntary) in humans to be carried out o In vertebrates the forebrain is more complex e.g structures like cortex and cerebellum o Animals increase in complexity and specialisation as move up phylogenetic tree o The cortex increases in size in higher mammals. Thicker cortexs help us to perform higher processes(awareness, analysis of perception) the cortex decodes information and decides how it will respond Development of the Nervous System o During the developmental stage in the fetus, 2 cells divide and form the neural tube( which ultimately becomes the CNS o Neural Plate: region in the embryo that forms the CNS o On day 20 of the embryonic stage, cells in the neural plate move upwards towards the neural crest and what this does is it causes a neural groove to form o cells migration elevates the neural crest and deepens the neural groove o The neural crest eventually increases in size until it flops over onto each other and makes a neural tube o Lumen forms the central cavity (ventricles or gaps/spaces) of the CNS o Lining of lumen becomes gap function cells and neural stem cells o Outer layers become neurons and glia(supportive cells) (central nervous system (CNS)) o Neural crest becomes sensory and motor neurons of (peripheral nervous system (PNS)) o Stem cells are cells that can take on any form that are present or developing through a lifetime o At week 4 cerebrum (cortex) is similar in size to other brain regions and by week 6, 7 major regions of the CNS have formed o By week 11, the CNS look similar to that that we see at birth www.notesolution.com o Week 11: Growth of cerebrum (cortex) accelerates o At birth the cerebrum surrounds the diencephalon, midbrain and pons o Cranial nerves: Carry information to and from brain from entire body o At birth, the cerebrum becomes invaginated which creates a large surface area for neurons etc.. to be maintained in our brain How the Brain is Protected and Maintains its Function 1. Bone protects the Central Nervous System (CNS): CRANIUM protects the brain and VERTICAL COLUMN protects the spinal cord * 3 protective layers surround the brain: Bone Connective tissue Fluid 2. Meniges(connective tissue) support and protect the CNS *3 layers: 1. Dura mater (thickest). Contains veins that drain blood (away from the brain) through sinuses (cavities); forms the outside protective layer 2. Arachnoid mater (loose) 3. Pia mater (thin); Tightly associated with the brain. Contains arteries that supply blood to the brain. Beneath pia matter is EC fluid that bathes neurons 3. Cerebrospinal fluid (CSF) cushions the CNS o Provides physical and chemical protection o Compared to EC and plasma, the CSF has a Lower [K ] and [Ca ], higher [H ], same [Na ] o Little protein; no red blood cells; red blood cells are toxic to neurons because of high Iron concentration o CSF is secreted from the choroid plexus into ventricles o flows through subarachnoid space to cushions brain and spinal cord o CSF and EC communicate through pia mater and ventricle membranes o CSF flows through the subarachnoid space between pia mater and arachnoid membrane o CSF is reabsorbed into blood villi (hair-like structures) on arachnoid membrane o Allows removal of wastes (toxins, metabolites) o Entire volume of CSF (approx 400ml) is replaced 3 times / day o To discover any type of illness occurring in the CNS, doctors perform a lumbar puncture: removal of CSF from subarachnoid space at lower end of spinal column 4. Ventricles of the brain www.notesolution.com 5. The Blood-Brain Barrier protects the brain from harmful substances in the blood (barrier between CSF and the blood) o Acts as a barrier between cerebrospinal fluid (CSF) and blood o Protects against fluctuations in hormones and chemicals (e.g neurotransitters) o Prevents pathogens e.g. Blood born bacteria entering CNS o Formed by tight junctions and glial cells that prevent solute movement o Selectivity of membrane carriers and channels enables nutr2ents, O to enter the CSF 6. Blood Supply to the Brain o Brain constitutes 2% of total body weight; receives 15% of cardiac output; 20% total body oxygen and 50% total glucose consumption o Blocking of blood supply (e.g. cardiac arrest) can cause unconsciousness within 10 seconds o Grey matter and white matter are the 2 main types of matter within the brain and both types are located in the brain and spinal cord o Grey matter = dendrites, cell body & synapse; White matter = axons of neurons, glial cells and myelin sheath The Spinal Cord o Major pathway for information flowing between brain, skin, joints, muscles o Carries neural network for locomotion o Provides communication between the brain and the rest of the body o Divided into 4 regions: - cranial - thoracic - lumbar - sacral o Each region subdivided into segments each gives rise to a bilateral pair of spinal nerves o Where spinal nerve joins spinal cord = root o In ALS, the spinal cord degenerates o Spinal cord is divided into 2 portions: the ventral(front) and the dorsal(back) o The dorsal root receives afferent (entering the brain) nerves; terminate (end) in the dorsal horn o Efferent (leaving the brain) nerves originate in the ventral horn; terminate on different body parts outside the brain Functions of the Brain Stem o Consists of:edulla Oblongata & Pons o Medulla Oblongata(involuntary/unconscious) Arousal and sleep Muscle tone and muscle stretch reflexes www.notesolution.com Co-ordination of breathing Blood pressure regulation Modulation of pain Swallowing and vomiting o Pons bridge: relay between cerebellum and cerebral cortex & medulla oblongata and the brain Primary relay circuit between cerebellum and cerebral cortex Pons and medulla oblongata control breathing The Cerebellum o Functions:o-ordinates execution of movement, Receives inputs from sensory neurons of the body, Receives inputs from sensory neurons of the body and processes sensory information & Receives inputs receptors in inner ear controlling balance and equilibrium o The Diencephalon controls homeostasis and consists of the thalamus, hypothalamus, pituitary gland and pineal gland o Thalamus Receives inputs from optic tract, ears, spinal cord Motor information from cerebellum Projects to cerebrum where information is processed Relay station through which most sensory information from lower brain is processed Also can modify information o Hypothalamus Beneath the thalamus Centre for controlling homeostasis and behaviour (e.g desire to eat and drink, sex drive, body temperature) Pituitary and pineal gland release hormones o The basal ganglia is involved in motor control o Brain structures: striatum, subthalamic nucleus, substantia nigra, globus pallidus Lecture 11 Function of Different Regions of the Brain o Cortex: understanding (cognition), awareness, personality; most developed in humans compared to other mammals o Diencephalon(sub-cortical): hypothalamus, thalamus, basal ganglia, pineal and pituitary gland o Hypothalamus: controls homeostasis and behaviour (e.g desire to eat and drink, sex drive, body temperature) o Brain stem is important for involuntary control Medulla oblongata: Arousal (sleep), muscles (reflex responses), breathing, blood pressure regulation, pain, swallowing and vomiting Viscera function is often integrated in the spinal cord and brain stem Viscera (inside the body): organs, bwww.notesolution.com
More Less

Related notes for BIOD27H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.