neural tissue (wilcox)

Question 1

t/f. theres higher [potassium] inside the cell and higher [sodium] outside the cell.

Answer 1

true.

Question 2

transmembrane potential of sodium

Answer 2

+66 mV

Question 3

transmembrane potential of potassium

Answer 3

-90 mV

Question 4

Na/K ATPase

Answer 4

powered by ATP and carries 3 NA out and 2K in, balanaces passive forces of diffusion to maintain the resting potential

Question 5

passive channels

Answer 5

aka leak channels, always open, permeability changes with conditions

Question 6

active channels

Answer 6

aka gated channels, open and close in response to stimuli; at rest, most gated channels are closed

Question 7

3 classes of gated channels

Answer 7

chemical, voltage, mechanical

Question 8

how do chemical gated channels open and where are they found?

Answer 8

open by binding chemical (like ACh), and found on neuron cell bodies and dendrites

Question 9

how do voltade gated channels open and where are they found?

Answer 9

open in response to change in transmembrane potental, and found on axons, skeletal muscle sarcolemma, cardiac muscle

Question 10

what is a characteristic of an excitable membrane?

Answer 10

voltage gated channel

Question 11

how do mechanical gated channels open and where are the found?

Answer 11

open in response to membrane distortion, found on sensory receptors (touch, pressure, vibration)

Question 12

what happens in depolarization?

Answer 12

transmemb potential moves toward 0 because NA is rushing through channel to produce a local current

Question 13

what happens in repolarization

Answer 13

stimulus is removed and transmemb potential returns to normal by potassium leaving the cell

Question 14

what happens in hyperpolarization

Answer 14

the negativity of the resting potential increases

Question 15

4 characteristics of graded potentials

Answer 15

1. effect decreases with distance 2. effect spreads passively due to local currents 3. depolarization or hyperpolarization 4. the stronger the stimulus, the greater the change in TM potential and the larger the area affected

Question 16

how do you initiate an AP?

Answer 16

a graded depolarization of an axon hillock must be large enough to change the resting potential to the threshold level of the voltage gated sodium channels

Question 17

t/f. if a stimulus excess the threshold amount, the AP is the same, no matter how large the stimulus.

Answer 17

true.

Question 18

how do you stop an AP?

Answer 18

inactivate the Na channels and activate the voltage gated K channels (repolarization) and return to normal permeability (resting potential)

Question 19

t/f. during the refractory period, the membrane can respond normally to additional stimuli

Answer 19

false. it cannot respond to any additional stimuli

Question 20

absolute refractory period

Answer 20

no AP possible

Question 21

relative refractory period

Answer 21

membrane potential almost normal, a very large stimulus can initiate AP

Question 22

continuous propagation

Answer 22

unmyelinated axons

Question 23

saltatory propagation

Answer 23

myelinated axons

Question 24

type A axon fibers

Answer 24

myelinated, large diameter; for position, balance, touch, and motor impulses

Question 25

type B axon fibers

Answer 25

myelinated, medium diameter; for sensory info, peripheral effectors

Question 26

type C axon fibers

Answer 26

unmyelinated, small diameter; for invountary muscle, gland controls

Question 27

electrical synapses

Answer 27

direct physical contact between cells

Question 28

chemical synapses

Answer 28

signal transmitted across a gap by a chemical NT

Question 29

excitatory NT

Answer 29

cause depolarization of postsynaptic membranes and promote AP

Question 30

inhibitory NT

Answer 30

cause hyperpolarization of postsynaptic membranes and suppress AP

Question 31

after the AP reaches the synaptic end, the extracellular influx of what ion causes NT to be exocytosed?

Answer 31

calcium

Question 32

what removed ACh from the post synaptic receptors?

Answer 32

AChE

Question 33

t/f. fewer synapses mean fewer synaptic delay

Answer 33

true.

Question 34

when NT cannot recycle fast enough to meet demands of intense stimmuli

Answer 34

synaptic fatigue

Question 35

what are the 4 important NT we need to know

Answer 35

NE, dopamine, serotinin, GABA

Question 36

t/f. GABA is both excitatory and inhibitory.

Answer 36

false. ALWAYS INHIBITORY

Question 37

3 ways nt and neuromodulators work

Answer 37

1. direct effects on membrane channels 2. indirect effects via G proteins 3. indirect effects via intracellular enzymes

Question 38

t/f. G proteins activate adenylate cyclase, producing the second messenger cAMP

Answer 38

true.

Question 39

excitatory postsynaptic potential (EPSP)

Answer 39

graded depolarization of postsynaptic memb

Question 40

inhibitory postsynaptic potential (IPSP)

Answer 40

graded hyperpolarization of post synaptic memb

Question 41

t/f. inhibition of a postsynaptic neuron happens when it receives many IPSPs

Answer 41

true.

Question 42

temporal summation

Answer 42

keep using the same stimuli until you trigger an AP, one synapse

Question 43

spatial summation

Answer 43

use more than one stimuli until you trigger an AP, multiple synapses

Question 44

t/f. neruomodulators and hormones can change membrane sensitivity to NT.

Answer 44

true.