Nervous System Flashcards
part of the neuron the protrudes from the cell body
receives the stimulus
dendrites
part of the neuron that contains the nucleus and metabolic machinery
cell body (cell soma)
part of the neuron the transmits action potentials and nerve impulses
has a sheath composed of Schwann cells
axon
sheath around axon composed of Schwann cells
speeds up the impulse since the impulse jumps from node to node (nodes of Ranvier)
myelin sheath
nodes that separate Schwann cells
electrical impulses jump from node to node – speeds up transmission of nerve impulse
nodes of ranvier
part of the neuron the secretes neurotransmitter into the synapse
synaptic terminals
a neurotransmitter diffuses across the synapse and binds to receptors on the _______, causing an action potential
postsynaptic cell
Neurotransmitters must either be _______ or _____ quickly (i.e. acetylcholine degraded by acetylcholinesterase)
reabsorbed or degraded
3 effectors of a neuron
nerve, gland, or muscle
connects the axon to the cell body
axon hillock
impulses that travel the length of the axon and cause neurotransmitter to be released at the axon terminal
action potential
membrane potential at which membrane is polarized
prior to being stimulated, a neuron is at its __________ potential, meaning there is a high [Na+] outside the cell and low [Na+] inside the cell and high [K+] inside the cell and low [K+] outside the cell.
resting potential
At its resting potential, there is a high concentration of ________ outside the cell and a high concentration of ______ inside the cell.
high [Na+] outside
high [K+] inside
At its resting potential, ______ cannot diffuse back into the cell, but ______ can diffuse out through its appropriate channel
Na+ can’t diffuse in
K+ can diffuse out through K+ channel
At its resting potential, the _____ of the membrane is positive due to the concentration of Na+ and K+ ions.
positive.
During an _______, the sodium channels open and the membrane is depolarized
action potential
If a stimulus comes along which excites the cell sufficiently (to reach the threshold level), then an ________ will occur
action potential
If an action potential is generated, the _____ channels open quickly and ions flood in with its concentration gradient. This results in depolarization of the cell (or reversal of polarity), and the action potential spreads down the neuron
Na+
After the action potential, Na+ channels have shut, and the resting potential must be restored in a process called _____. This is accomplished by actively (using ATP) pumping 3 Na+ out and 2 K+ in.
Repolarization
type of neuron
afferent neurons - conducting toward central nervous system
travel from nerves to CNS
sensory neurons
type of neuron
efferent neuron - conducting away from central nervous system
travel from CNS to nerves
motor neurons
connect sensory and motor neurons
interneurons
two major divisions of the nervous system
central and peripheral
nervous system that includes the brain and spinal cord
central nervous system
