PSYC 1020H Chapter Notes - Chapter 3: Axon Terminal, Neuroglia, Myelin
14 Jun 2018
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Chapter 3- The Biological Bases of Behaviour
• Behaviour depends on rapid information processing
• Information travels almost instantaneously from your eye to your brain; nervous system
is a complex communication network in which signals are constantly being transmitted,
received, and integrated
• Nervous system handles information, it falls into two major categories: glia and
neurons.
• Neurons are individual cells in the nervous system that receive, integrate and transmit
information
• The soma or cell body contains the cell nucleus and much of the chemical machinery
common to most cells
• Dendrites are the parts of a neuron that are specialized to receive information
• Axon is a long, thin fiber that transmits signals away from the soma to the other neurons
or to muscles or glands
• The myelin sheath is insulating material, derived from glial cells, that encases some
axons
• Axon ends in a cluster of terminal buttons, which are small knobs that secrete chemicals
called neurotransmitters
• A synapse is a junction where information is transmitted from one neuron to another
• Information is received from the dendrites along the axon to the soma where other
dendrites transmit information through meeting points called synapses
• Gila are cells found throughout the nervous system that provide various types of
support for neurons→ help supply nourishment to neurons, helps reoe euro’s
waste products, provides insiulation
• Recent studies show that glial calles may play an important role in memory formation
and chronic pain
• Hodgkin and Huxley learned that the neural impulse is a complex electrochemical
reaction; inside and outside the neuron are fluids containing ions
• The resting potential of a neuron is stable, negative charge is when the cell is inactive
• Atio potetial: ery rief shift i a euro’s eletrial harge that traels alog a
axon
• The absolute refractory period is the minimum length of time after an action potential
during which another action potential cannot begin
• All or none law- weaker stimuli do not produce smaller action potential.
• Synaptic cleft, a microscope gap between the terminal button of one neuron and the
cell membrane of another
• Neurotransmitters- chemicals that transmit information from one neuron to another
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• Postsynaptic potentials- a voltage change at a receptor site on a postsynaptic cell
membrane (when a neurotransmitter and receptor molecule combine)
o Postsynaptic potentials are graded, they vary in size and increase or decrease the
probability of a neural impulse in the receiving cell in proportion to the amount
of voltage change
o An excitatory PSP is a positive voltage shift that increases the likelihood that it
will fire an action potential
o An inhibitory PSP is a negative voltage that decreases the likelihood that the post
synaptic neuron will fire action potentials
1) Synthesis and storage of neurotransmitter molecules in synaptic vesicles
2) Release of neurotransmitter molecules into synaptic cleft
3) Binding of neurotransmitters at receptor sites on postsynaptic membrane
4) Inactivation by enzymes or removal drifting away of neurotransmitters
5) Reuptake of neurotransmitters sponged up by the presynaptic neuron
Glutamate: amino acid that has both excitatory and inhibitory effects. It has been
implicated in learning and memory
• Agonist: chemical that mimics the action of a neurotransmitter
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find more resources at oneclass.com
