Neurons, Synapses, Signaling

Question 1

What did Luigi Galvini discover

Answer 1

the role of electricity in nerves by observing frog muscle, proposed the theory of animal electricity

Question 2

what did Galvani conclude from his frog experiments

Answer 2

in an animal there is a particular machine capable of generating disequilibrium = animal electricity

Question 3

What is a membrane potential

Answer 3

the voltage across a cells plasma membrane

Question 4

when does the resting potential occur

Answer 4

when the neuron is not sending signals

Question 5

how to neurons transmit information

Answer 5

via changes in membrane potential = action potentials

Question 6

what ion channels are open at rest

Answer 6

K+

Question 7

when is a cell at equilibrium/equilibrium potential

Answer 7

when both electrical and chemical forces are balanced

Question 8

which way does K+ diffuse

Answer 8

out of cell down the concentration gradient

Question 9

where do negative charges build up

Answer 9

along the inner membrane, creating an opposing electrical force

Question 10

how are ions located in neurons

Answer 10

neurons maintain a certain concentration gradient across their membranes which is different for each ion

Question 11

What does Na+/K+ ATPase do

Answer 11

maintain resting membrane potentials by maintaining na and k gradient by pumping 3 na+ out and 2 k+ in

Question 12

how much energy does Na/K ATPase use

Answer 12

20-30% of body’s resting enrgy, 60% of brains neuronal ATP

Question 13

What drug targets ATPase

Answer 13

Digoxin and Oubain blocks it

Question 14

How can you find the equilibrium potential

Answer 14

by knowing the concentrations of an ion (like K) inside and outside the cell

Question 15

What is depolarization

Answer 15

when the cell is more positive than resting potential

Question 16

which way does K flow during depolarization

Answer 16

out of the cell

Question 17

which way does K flow at equilibrium

Answer 17

equal rates in and out

Question 18

what is hyperpolarization

Answer 18

when the cell is more negative than resting potential

Question 19

where does K flow during hyperpolarization

Answer 19

into the cell

Question 20

what causes the membrane potential to change

Answer 20

flow of ions

Question 21

do ions have their own equilibrium potential

Answer 21

yes

Question 22

what functions as a resistor

Answer 22

ion channels, slow current

Question 23

what acts as a capacitor

Answer 23

phospholipid cell membranes, store charge, once saturated then allows current to flow

Question 24

what do the resistor and capacitor result in

Answer 24

neurons respond with a delay

Question 25

what are graded potentials

Answer 25

changes in polarization where the magnitude of the change varies with the strength of the stimulus

Question 26

can graded signals be propagated through great distances

Answer 26

no

Question 27

what needs to happen to generate an action potential

Answer 27

depolarization above a certain threshold resulting in a massive change in membrane voltage

Question 28

what are three characteristics of APs

Answer 28

constant magnitude all or none may transmit over longer distances

Question 29

why do APs arise

Answer 29

because some ion channels are voltage gated, opening or closing when the membrane potential passes distinct levels

Question 30

what structure receive signals

Answer 30

dendrites

Question 31

what happens to signals after they are received

Answer 31

graded and funneled to stoma (cell bodY)

Question 32

where does the stoma extend into

Answer 32

cone-shaped axon hillock

Question 33

what is the function of the axon hillock

Answer 33

site of AP generation

Question 34

what is the axon

Answer 34

a longer extension that transmits APs

Question 35

What occurs in the resting state

Answer 35

Na and K channels are closed

Question 36

What occurs during slow depolarization

Answer 36

slowly brought to threshold

Question 37

what occurs during depolarization

Answer 37

Na channels activated, Na flows into the cell, positive feedback loop ensures a rapid rising phase of the action potential

Question 38

what occurs once the AP peaks, during repolarization

Answer 38

Na channels close, slower K channels open, K flows out of the cell leading to the falling phase

Question 39

what occurs at hyperpolarization

Answer 39

cell goes to Ek, Na channels are reset, Na is pumped out and K pumped into neuron, K channels close

Question 40

what happens during refractory period

Answer 40

time it takes to return to resting potential, second AP cannot be generated

Question 41

how are APs conducted

Answer 41

an electrical current spreads and depolarizes neighbouring region of the axon membrane, causing cycle to repeat

Question 42

how is the AP prevented from travelling backwards

Answer 42

Na channels are inactivation behind the zone of depolarization

Question 43

What direction do APs travel

Answer 43

toward synaptic terminals

Question 44

where might APs back propogate

Answer 44

to stoma/dendrites

Question 45

how does the axon diameter affect the speed of the AP

Answer 45

increased diameter = increased speed

Question 46

what is the myelin sheaths function

Answer 46

insulates vertebrate axons, speeding up the AP

Question 47

what are myelin sheaths made of

Answer 47

glia in CNS, schwann cells in PNS

Question 48

where are APs formed in myelinated neurons

Answer 48

nodes of ranvier = gaps in sheath where Na channels are found

Question 49

what is saltatory conduction

Answer 49

APs jump between nodes of Ranvier