HSE208 Study Guide - Final Guide: Angiotensin, Food Intolerance, Hypoxic Hypoxia
HSE208
Integrated Human Physiology
TOPIC 1: Neural Control Mechanisms
Week 1: Neuronal Structure & Communication
Neurons & Glial Cells
-Around 100 billion neurons and glia cells
-Glia 10x more numerous
-Neurons communicate
Basic classification system
-Shape: multipolar, bipolar, unipolar – how many poles determined by the cell body
-Function: afferent, efferent, interneuron
-Type: neuron – stellate, pyramidal, glial cell - astrocyte
-Locus: central, peripheral, presynaptic, postsynaptic
Structure of neuron
-Size/length, shape, function
-Multipolar neuron: no. of dendrites coming off
cell body & axon
-Anaxonic neuron: lacks an axon, not obvious
where the axon is
-Bipolar neuron: 2 poles, info coming from top
through to bottom
-Unipolar neuron: one process coming off cell
body
3 functional classes of neurons
-Afferent: sensory neuron, approaching the CNS
-Interneuron: intrinsic - receives info from one
neuron & gives info to another neuron (always
within CNS)
-Efferent: exciting NS going to a target along axon, out to the periphery.
-< 99% of all neurons are interneurons
Pre/postsynaptic classification
-All relative to position of cells in pathways
-Presynaptic: before the synapse
-Postsynaptic: after the synapse
Glial Cells
-Oligodendrocytes: form myelin at points along the axon, conserves space
-Astrocytes: form the blood brain barrier, star shaped cells, ECF composition
-Microglia: macrophage-like, large immune cells that engulf pathogens ex. Bacteria/viruses or
old cells
-Ependymal cells: line fluid filled cavities, produce cerebral spinal fluid
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-Oligodendrocytes: produces myelin in a number of places (CNS)
-Schwann cells: do this job in the periphery
Neuronal structure & function
-Cell body/soma
-Dendrites: apical: come of the apex,
basal: come of the base,
-Axon hillock (initial)
-Axon: comes off the base of the
pyramid and moves down
-Axon terminals
-Myelin
-Nodes of Ranvier: tiny gaps between
myelin
Neural communication
-Ions: NA+/K+
-Assortment of large proteins: negatively charged called Anions
-Electrical gradients
-Chemical gradients (diffusion potentials)
Ion channels & membrane states
-1. Resting potential: NA+/K+ pump (electrogenic pump)
-2. Action potential: depolarisation, opens Na+ channels
-3. Hyperpolarisation: inactive Na+ channels but K+ channels open
-4. Back to resting potential: voltage channels close & membrane goes back to resting state
Nervous System
Week 2a: Synapses & Gross Functional Anatomy
Action Potential Propagation in Myelinated Neurons
One-way propagation of an action potential
-Membrane is refractory: local current can’t stimulate a second action potential, only moves in
one direction
-Resting membrane depolarized toward threshold by local current
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Saltatory Conduction
-Saltatory: jumping/leaping
-Myelin insulates the axon: gets salutatory
conduction
-This occurs as the sodium ions that move in to the
cell, move inside the cell to create a current at the
next intermodal point to create the jumping motion
Chemical Synapse
-Synaptic cleft: tiny fluid filled space between pre/post
synaptic membrane
-Synaptic vesicles: filled with neurotransmitter, carries the
message to the post synaptic cell
-Exocytosis: process of the vesicles spilling contents
-Endocytosis: membrane taken in and pinched to create a new
vesicle
-Excitatory: would increase the receptors activity
-Inhibitory: a neurotransmitter released could inhibit the
postsynaptic receptors
-Agonist: neurotransmitter an agonist for the receptor, bind to and stim the receptor in a
positive way
-Antagonist: substance might bind then prevent the receptor from having its normal activity:
ex. Wrong key broken in the lock: blocks the normal action
Structure of the Nervous System
-CNS: brain & spinal cord
-PNS: outside brain/spinal cord
-Somatic NS: sensory and motor nerves: afferent division
-Autonomic NS: control of organs: subconscious level
Autonomic Nervous System
-Sympathetic: STRESS: arousal, <breathing, <HR, >digestive activity, release noradrenaline
-Parasympathetic: PEACE: vegetative, nonemergency responses, <digestive activity, release
acetylcholine
Central Nervous System
Spinal Cord:
-Grey matter: cell bodies, integration of signals, control centre
-White matter: mylenated axons
-Ganglion: collection of cell bodies lying outside the
CNS
-Reflex arc: information processing occurs at the level
of the spinal cord, reaches consciousness after body
has dealt with issue
The Forebrain
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Document Summary
Around 100 billion neurons and glia cells. Shape: multipolar, bipolar, unipolar how many poles determined by the cell body. Type: neuron stellate, pyramidal, glial cell - astrocyte. Multipolar neuron: no. of dendrites coming off cell body & axon. Anaxonic neuron: lacks an axon, not obvious where the axon is. Bipolar neuron: 2 poles, info coming from top through to bottom. Unipolar neuron: one process coming off cell body. Interneuron: intrinsic - receives info from one neuron & gives info to another neuron (always within cns) Efferent: exciting ns going to a target along axon, out to the periphery. All relative to position of cells in pathways. Oligodendrocytes: form myelin at points along the axon, conserves space. Astrocytes: form the blood brain barrier, star shaped cells, ecf composition. Microglia: macrophage-like, large immune cells that engulf pathogens ex. Ependymal cells: line fluid filled cavities, produce cerebral spinal fluid. Oligodendrocytes: produces myelin in a number of places (cns)
