membrane potential

Question 1

EKG

Answer 1

allow detection of heart

Question 2

EEG

Answer 2

identify bundles of nerves firing action potentials nearly simultaneously

Question 3

neuron bypass

Answer 3

reduce/eliminate chronic pain
control bladder/bowel movements for paraplegics

Question 4

bioelectricity

Answer 4

charge separated across a membrane b/c of hydrocarbon fats don’t conduct electricity

Question 5

what does every cell have

Answer 5

has a transmembrane electrical potential, voltage across a membrane
- in cells - 0.7 mV
- out cells - 0.9 mV
- PM - 1 mil volts/L

Question 6

electricity in fluids

Answer 6

charge carriers - mostly electrolytes (Na, K, Cl, Ca)
voltage/electric potential - separation of charge

Question 7

graded potential

Answer 7

changes in electrical signaling due to stimulus/sensory input

Question 8

action potential

Answer 8

rapid changes in electrical signaling of PM of one cell

Question 9

movement of potassium

Answer 9

K+ passes through K+ channel to outside cell, making the cell more negatively charged. the concentration gradient wants to push it out, the electrical gradient pulls it in. K+ equilibrium = -90.8 mV.

Question 10

movement of sodium

Answer 10

Na+ passes through Na+ channel to inside cell, making the cell more positively charged. Na+ equilibrium potential = +61.5 mV

Question 11

final membrane voltage

Answer 11

both K+ & Na+ move across membrane until equilibrium membrane - constant flux: takes advantage of K+/Na+ equilibrium potential & relative conductance (ease of crossing the membrane)

Question 12

distribution of charge across the PM

Answer 12

Na+ & K+ have biggest effects
Ca2+ - if too much coming in, cell more pos = depolarization
Cl- & K+ make cell more negative
Protein anions of ionic gradients = membrane potential

Question 13

Electrical triggering by depolarization

Answer 13

all cells at rest are negative
depolarization = rise in cytosolic Ca2+ which causes
1. exocytosis of NTs
2. exocytosis of amino acid based hormones
3. contraction of muscle
Open an ion channel = equilibrium potential drive for that ion

Question 14

depolarization

Answer 14

more positive
= open Na+ channels
= open Ca2+ channels
= close K+ channels

Question 15

RMP

Answer 15

voltage difference btw inside/outside of PM of resting neuron
inside is negatively charged = -70 mV
inequality of charge occurs only across membrane b/c it is made of hydrocarbon/fatty tails = electrical insulators

Question 16

RMP established

Answer 16

1. Differences in ion concentrations across PM - K+ channels is most permeable in resting cells - almost always open (facilitated membrane)
2. Na+/K+ pump (2K+ in, 3Na+ out) - electrogenic pump - net movement of positive charge out, driving the inside of the cell more negative.
   K+ leak channels