BM 1041:03 Lecture Notes - Lecture 7: Axon Hillock, Schwann Cell, Synapse
23 May 2018
School
Department
Course
Professor
Describe the organisation of the Nervous system structurally and
functionally
Describe the cellular components of nervous tissue
Basic functional unit
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Conducts impulses
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Communication
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Branching cells - receive and transmit electrical impulses
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Long-lived, non dividing
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Neurons
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Supports cells of nervous system (supporting cells)
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Provide structure, nutrients, defense and myelin
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More than neurons
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Neuroglia (glia)
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2 classes of cells in nervous tissue
Compare and describe the organisation of grey and white matter in
the spinal cord and brain
Describe the components of a "typical" neuron (dendrites, soma,
axon, myelin, Nodes of Ranvier and synaptic terminals) and spinal
nerve
dendrites
bring in graded potential ie. Input, may initiate output
Summation of info coming in
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Small deviation from the resting potential that makes the membrane either
more or less polarised
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Graded potential
Soma
Axon/axon
hillock
conducts action potential to next cell ie. Output
All or nothing
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Sequence of rapidly occurring events that decrease and reverse the
membrane potential, then eventually restore it to a resting state
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Action potential
Myelin sheath
Makes conducting quicker, can jump areas of axon
Contains Schwann cell around it
Nodes of
Ranvier
Periodic gap
Facilitates rapid conduction of nerve impulses
Synaptic
terminals
L1 - Nervous system 1
Wednesday, 14 March 2018
9:42 PM
Week 4 Page 1
Describe the structural and functional classifications of neurons
(motor, pseudounipolar, bipolar) and glia cells
Pseudo-
unipolar/sensory
Responds to specific stimuli
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Triggers action potential from periphery
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Sends info to other neurons, integrates info
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AP triggered at axon hillock
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Screen clipping taken: 14/03/2018 10:21 PM
Motor/multipolar
Integrated before initiating an AP at the axon hillock
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Integrates info from the brain and sends messages
to activate muscles of the body
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Screen clipping taken: 14/03/2018 10:22 PM
Bipolar
2 extensions
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Transmission of special senses ie. Part of sensory
pathways for smell, sight, taste, hearing and
vestibular functions
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Screen clipping taken: 14/03/2018 10:38 PM
Surround neurons and hold them in place
Supporting cells of the nervous system
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Glial/supporting cells
Week 4 Page 2
Surround neurons and hold them in place
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Supply nutrients and oxygen
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Insulate one neuron from another
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Destroy and remove dead neuron material
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Provide support, insultation between neurons
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DO NOT participate directly in synaptic interactions and electrical signalling
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e.g. Schwann cells - surround axons in PNS, myelinate peripheral axons, participate in
repair process post injury
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Types
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Astrocytes - maintain blood-brain barrier, structural support, regulation
ion/nutrient/dissolved gas concs, absorb and recycle neurotransmitters, form scar tissue
after injury
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Oligodendrocytes - myelinate CNS axons, provide structural framework
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Microglial - remove cell debris, wastes and pathogens by phagocytosis
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Ependymal - line ventricles (brain) and central canal (spinal cord),
produce/circulate/monitor cerebrospinal fluid
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CNS
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Schwann cells - surround axons in PNS, myelinate peripheral axons, repair process after
injury
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Satellite cells - surround neuron cell bodies in ganglia, regulate
oxygen/CO2/nutrient/neurotransmitter levels
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PNS
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Grey and white matter
Soma (bodies) of neurons embedded in supporting neuroglial cells
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Grey in appearance
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Cortex of brain
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Centre of spinal cord
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Ganglia/nuclei
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Found in
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Grey matter
Consists of fibres of neurons (predominantly axons) embedded in supporting neuroglial cells
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White colour - due to lipid material (myelin) produced by glial cells
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Peripheral nerves
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Central fibre tracts
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Found in
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White matter
Week 4 Page 3
Document Summary
Describe the organisation of the nervous system structurally and functionally. Branching cells - receive and transmit electrical impulses. Compare and describe the organisation of grey and white matter in the spinal cord and brain. Describe the components of a typical neuron (dendrites, soma, axon, myelin, nodes of ranvier and synaptic terminals) and spinal nerve dendrites bring in graded potential ie. input, may initiate output. Small deviation from the resting potential that makes the membrane either more or less polarised. Axon/axon hillock conducts action potential to next cell ie. output. Sequence of rapidly occurring events that decrease and reverse the membrane potential, then eventually restore it to a resting state. Myelin sheath makes conducting quicker, can jump areas of axon. Describe the structural and functional classifications of neurons (motor, pseudounipolar, bipolar) and glia cells. Integrated before initiating an ap at the axon hillock. Integrates info from the brain and sends messages to activate muscles of the body.
