PSYC10003 Lecture Notes - Lecture 3: Resting Potential, Schwann Cell, Saltatory Conduction
6 Jun 2018
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PSYC10003 – MIND, BRAIN, & BEHAVIOUR 1
BEHAVIOURAL NEUROSCIENCE
Lecture 3 (Week 1 . 3): Neurons, Glia, & Mechanisms of
Communication within the Neuron
Withdrawal reflex: Touch something very hot / painful dendrites of
sensory neuron respond to noxious (harmful) stimulus signal sent
back along axon to terminal buttons (located in spinal cord) which
release neurotransmitter into synapse excites interneuron (resides in
spinal cord) interneuron sends message down its axon, which in turn
releases a neurotransmitter to excite the motor neuron axon of motor
neuron joins a nerve (bundle of motor neurons) & travels to a muscle in
the arm muscle contracts & ‘withdraws’ from the painful stimulus
• Inhibition of withdrawal reflex: excitation of motor neurons in
spinal cord counteracted by inhibition from brain (processes
stimuli + situation + options + consequences sends message to
spinal cord excites inhibitory interneuron releases inhibitory
neurotransmitter inhibition of withdrawal reflex)
Neuron: the basic info-processing & info receiving unit of NS
• Many diff shapes & sizes, (generally) structure reflects function
• Structure:
• Cell body: contains nucleus (genetic material) & internal
organelles necessary for cell maintenance.
• Cytoplasm: jelly-like substance inside the cell
• Mitochondria: use glucose to produce energy (ATP -
adenosine triphosphate)
• Nucleus: contains cell’s chromosomes (instructions to make
proteins)
• Dendrites: tree-like branches that receive info from other neurons
• Axon: long, slender fibre - carries signals (action potentials) from the cell body
• Myelin sheath: insulates axon, preventing interference from neighbouring neurons. Segments of
myelin with small gap on uncoated myelin between them (nodes of ranvier)
• Terminal buttons: small knobs at the ends of axon branches – secretes neurotransmitters that
cross synaptic gap to either excite / inhibit postsynaptic neuron (transmit info to other neurons).
Form synapses with cell body / dendrites of other neurons
Glial cells: important role in providing physical support, oxygen & nutrients for neurons
Astrocytes: physical support for neurons, clean up waste, provide nutrients, maintain
correct chemical composition of extracellular fluid surrounding neurons
Oligodendrocytes: forms myelin sheath around neurons in CNS, & physical support
Microglia: smallest glial cells. Phagocytes, also act as the brain’s immune system
(attack invading micro-organisms inflammation after brain damage.
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