chapter 2 Flashcards
neurons (what do they do? What are the main components of a neuron?)
Basic building blocks of the nervous system Transmit messages throughout the brain and between the brain and the rest of the body
glial cells (what are they? functions?)
• Provide physical and functional support for neurons • Create a matrix to hold neural circuits together Chapter 2-1a: Neurons: Into the Fabulous Forest • Provide neurons with nutrients
myelin sheath (what does it do? speed of action potential? Why is it important?)
Immune cells produce too much
glutamate, which damages/kills
myelin producing glial cells
efferent (motor) neurons (what do they do? which division of the nervous
system?)
carry information from the Central Nervous System (CNS) to
destinations outside the brain (muscles, glands)
interneurons (what do they do? which division of the nervous system?)
- process information
- CNS is made entirely of interneurons
- About 99% of neurons in nervous system are interneurons
action potential (what is it? approximate voltage of action potential pulse?)
a brief electrical charge that travels down the axon.
Neurons are bathed in liquid, and this liquid is rich in ions.
ions (what is an ion?)
atoms that carry an electrical charge (+/-)
resting potential of neuron (what is it? what voltage?)
-70
excitatory vs. inhibitory impulses
Excitatory - more likely to cause an action potential (make inside of cell more positively
charged compared to outside)
Inhibitory - less likely to cause an action potential (make inside of cell more negatively
charged compared to outside)
excitation threshold (what is it? what voltage?)
Excitation threshold is about -55mv for mammals
• if voltage changes from -70mv resting potential to the -55mv excitation threshold, neuron
will fire
• if voltage doesn’t change all the way to threshold (e.g. -60mv), neuron will not fire
ions involved in action potential (how does ionic activity create action potential)?
• There are ions inside and outside the cell
• They are distributed differently inside and outside the cell because of the cell’s
membrane – it has the property of selective permeability
selective permeability (what is it?)
some ions pass through membrane more easily than others
sodium-potassium pump (what is it?)
active mechanism that pumps out Na+ ions
at same rate that they leak in, and pumps in K+ ions at same rate that
they leak out
basic action potential process (what triggers it? voltage-gated ion channels?)
– K+ ions continue to exit cell, lowering inner voltage
– Na+ ions also start moving outside cell again (sodium-potassium pump helps out)
– Once repolarized, K+ channels gradually close, causing a few extra K+ ions to exit and
leaving axon hyperpolarized momentarily before stabilizing at resting potential again
hyperpolarization (what causes it?)
momentarily before stabilizing at resting potential again
refractory period (what is it? how long does it last?)
• brief period (1-2ms) after action potential when neuron is unable to fire • axon not sufficiently polarized to fire
difference between absolute refractory period and relative refractory period?
Absolute Refractory Period
• brief period (1-2ms) after
action potential when neuron is
unable to fire
• axon not sufficiently polarized
to fire
Relative Refractory Period
Chapter 2-1b: The Neural Impulse: “The Body Electric”
• period of time where axon has sufficiently repolarized, but
hyperpolarization makes it more difficult to elicit another action
potential
• Higher-than-normal stimulation is required to elicit another action
potential during this period, but it is possible
all-or-none response of neuron (how nervous system signals different degrees of
neural stimulation?)
Action potential always has the same strength and
speed
The neuron either fires, or it doesn’t!
synapse (what is it?)
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron
synaptic gap (what is it?)
The minute space between the cell membrane of an axon terminal and of the target cell with which it synapses
vesicles (what are they?)
a fluid- or air-filled cavity or sac, in particular.
neurotransmitters (what are they?)
When a neurotransmitter makes contact with a matching receptor
site, it triggers a voltage change in the receiving neuron
receptor sites (what are they?)
the place that revises neurotransmitters
reuptake (what is it? why is it important?)
The effects of neurotransmitters normally only last long enough to
affect a voltage change in the post-synaptic neuron
• If reuptake didn’t occur, receptor sites would be continuously
stimulated.
