Ch 12 Nervous System - Neurophysiology

Question 1

what happens when neurotransmitters are released so we get different outcomes?

Answer 1

synaptic transmission

Question 2

what makes electricity flow in the axon?

Answer 2

actions potentials

Question 3

how do dendrites governs whether an axon will fire?

Answer 3

integration of signals

Question 4

excitable/input

Answer 4

graded action potentials convert into action potentials
few voltage gated Na+ and K+ channels
many ligand gated mechano gated channels (depending on location)

Question 5

conductive

Answer 5

action potentials
only Na+ and K+ voltage gated channels

Question 6

transmissive

Answer 6

Ca++ voltage gated channels
vesicles containing neurotransmitter
release of neurotransmitter

Question 7

polarization

Answer 7

charge differential

Question 8

is there a higher charge inside or outside cell

Answer 8

outside cell

Question 9

what is resting membrane potential

Answer 9

-70mV

Question 10

hyperpolarization

Answer 10

more + ions leaking out than coming back in

Question 11

depolarization

Answer 11

more + ions leaking in than coming back out

Question 12

how does a neuron regulate its charge?

Answer 12

K+ and Na+ voltage gated channels and K+ and Na+ leak channels

Question 13

explain one action potential

Answer 13

Na+ begins to move into neuron and raises the charge to -55mV. at this threshold, voltage gated Na+ channels open, and Na+ rushes into the cell. the charge is raised to +30mV, and channels close. at this point, the voltage gated K+ channels open, and K+ rushes out of the neuron, lowering the charge. at -70mV, these channels close, but slowly, so the charge lowers to -90, the channels finishing closing, and neuron returns to normal charge through leak channels.

Question 14

explain graded potentials

Answer 14

ligand binds to a ligand gated K+ channel. this causes the channel to open, and K+ to move out of the cell, lowering the charge. the ligand quickly falls off, and the channel closes. the cell returns back to -70mV due to the K+/Na+ pump. called inhibitory
for Na+, same process except Na+ pours into cell and raises the charge closer to the threshold. this is called excitatory

Question 15

electrical synapses

Answer 15

less common than chemical synapses
correspond to gap junctions found in other cells types
important in CNS for arousal from sleep, mental attention, emotions and memory, and ion and H2O homeostasis

Question 16

chemical synapses

Answer 16

specialized for the release and reception of neurotransmitters
composed of axon terminal of the presynaptic neuron, which contains synaptic vessels, and reception region on dendrite(s) or soma of the postsynaptic neuron

Question 17

chemical synapse process

Answer 17

when +30mV is reached at the synapse, it will open Ca++ voltage gated channels. this causes the vesicles to move to surface of cell and release neurotransmitters

Question 18

cleaning up neurotransmitters

Answer 18

reuptake (resorbed by astrocytes or presynaptic terminals)
enzymatic breakdown
diffusion (slowest)