PSYC-1105EL Lecture Notes - Lecture 3: Axon Terminal, Neuroglia, Cell Nucleus
12 Jun 2018
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Chapter 3: The Biological Bases of Behavior
Erin Myers, PSYC 1105, P. Valliant
Communication in the Nervous System
Neurons: Individual cells in the nervous system that receive, integrate, and transmit
information.
Soma/Cell Body: Contains the cell nucleus and much of the chemical machinery common to
most cells.
Dendrites: The parts of the neuron specialized to receive information. Branching structures.
Axon: A long, thin fibre that transmits signals away from the soma to other neurons, muscles,
or glands. Axons can be over a metre long. Often encased in a myelin sheath. A thicker axon will
transmit neural impulses more quickly than a thinner axon.
Myelin Sheath: White, fatty insulating material, derived from glial cells, which encases some
axons. Speeds up transmission of signals that move along axons.
Terminal Buttons: Small knobs in a cluster at the end of an axon, secrete neurotransmitters.
Synapse: Junction (space, gap) where information is transmitted from one cell to another.
Glia: Cells found throughout the nervous system that provide various types of support for
euros. Muh saller tha euros, ut aout for ore tha half of the rai’s olue.
Resting Potential: The stable, negative charge of a neuron when the cell is inactive.
Action Potential: A er rief shift i a euro’s eletrial harge that traels do the ao.
When the neuron is stimulated, channels in its cell membrane open briefly. Positively charged
ions flow into the cell, and negatively charged ions flo out. This is ho a euro fires, or
communicates with other neurons.
Absolute Refractory Period: The minimum length of time after an action potential fires during
which another action potential cannot begin. Usually 1-2 milliseconds. It is followed by a brief
relative refractory period, where the neuron can fire but has an elevated threshold and requires
more stimulation to do so.
All-or-None Law: A euro either fires or does’t, ad eer atio potetial is the sae size
(not stronger or weaker based on stimuli. Compare to firing a gun.). The strength of a stimulus
is instead conveyed by the frequency of which an action potential is activated.
Synaptic Cleft: Microscopic gap between the terminal button of one neuron and the cell
membrane of another neuron. Signals must cross this gap in order for neurons to communicate.
Neurotransmitters: Chemicals that transmit information from one neuron to another.
Postsynaptic Potential (PSP): A voltage change at a receptor site on a postsynaptic cell
membrane. Unlike an action potential, PSPs 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.
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Document Summary
Neurons: individual cells in the nervous system that receive, integrate, and transmit information. Soma/cell body: contains the cell nucleus and much of the chemical machinery common to most cells. Dendrites: the parts of the neuron specialized to receive information. Axon: a long, thin fibre that transmits signals away from the soma to other neurons, muscles, or glands. A thicker axon will transmit neural impulses more quickly than a thinner axon. Myelin sheath: white, fatty insulating material, derived from glial cells, which encases some axons. Speeds up transmission of signals that move along axons. Terminal buttons: small knobs in a cluster at the end of an axon, secrete neurotransmitters. Synapse: junction (space, gap) where information is transmitted from one cell to another. Glia: cells found throughout the nervous system that provide various types of support for (cid:374)euro(cid:374)s. mu(cid:272)h s(cid:373)aller tha(cid:374) (cid:374)euro(cid:374)s, (cid:271)ut a(cid:272)(cid:272)ou(cid:374)t for (cid:373)ore tha(cid:374) half of the (cid:271)rai(cid:374)"s (cid:448)olu(cid:373)e.
