Lecture 3- Membrane Physiology 1

Question 0

What is voltage?

Answer 0

Force motivating electrons to flow

-difference between electrons I two places

Question 1

What is current?

Answer 1

I - the continuous movement of free electrons through a circuit ‘flow’

Question 2

What is resistance?

Answer 2

Opposition to movement of electrons(must be between two points)

Question 3

What is the reciprocal of resistance?

Answer 3

Conductance

Question 4

What is ohms law?

Answer 4

V=IR

Question 5

What provides resistance to the flow of ions in a cell system?

Answer 5

Membrane channels

Question 6

Where is there more Na at rest?

Answer 6

Outside the cell

Question 7

Where is there more K at rest?

Answer 7

Inside the cell

Question 8

Where is there more Cl and Ca at test?

Answer 8

Outside the cell

Question 9

What is the Nerst equation used for?

Answer 9

To calculate the equilibrium potential for any ion in a system

Question 10

What determines the force moving an ion through the membrane (net driving force)?

Answer 10

Membrane voltage-equilibrium potential for that ion

Question 11

What ion is the membrane most permeable to?

Answer 11

K

Question 12

What does g represent?

Answer 12

Conductance of an ion

Question 13

What is the electrical equivalent of membrane permeability?

Answer 13

Membrane conductance

Question 14

At rest the drive force of which ion is larger, Na or K?

Answer 14

Na

Question 15

At rest is the resting membrane potential close to the equilibrium potential for K or Na?

Answer 15

K

Question 16

What is the function of the Na-K ATPase enzyme?

Answer 16

Uses cellular energy to move 2K into the cell and 3Na out of the cell against their concentration gradients. This is needed to maintain a voltage across the membrane

Question 17

What is the inhibitor of the Na-K ATPase enzyme?

Answer 17

Ouabain

Question 18

What are 3 factors that affect the activity of the Na-K pump?

Answer 18

1. Ouabain- metabolic inhibitor
2. Low temp- decrease activity
3. Removal of external K from around the cell will inhibit pump

Question 20

What is the main cause of the resting membrane potential? What mechanism also contributes?

Answer 20

Main cause- passive loss of K

Contributor- Na removal by pump

Question 21

What are 2 neurological disorders caused by mutations in the calcium channel?

Answer 21

Familial Hemiplegic Migraine

Congenital Stationary Night Blindness

Question 22

Why is the cell membrane called a capacitor?

Answer 22

Has capacity to store charge with an insulator (membrane) sandwhiched between two conductors (extracellular fluid and cytoplasm?

Question 23

What are the 5 gating mechanisms of ion channels?

Answer 23

1. Voltage-gated
2. Ligand-gated
3. Mechanically gated
4. Light gated
5. Thermogated

Question 24

What does the gNa tell you?

Answer 24

the Na conductance, i.e.. the # of Na channels

Question 25

Why is the membrane closer to the equilibrium potential of K rather than Na at rest?

Answer 25

Because of K leak channels, the membrane is 20x more permeable to K than Na

Question 26

What mechanism counteracts the constant leak of K out of the cell and small amounts of Na into the cell to maintain the resting membrane potential?

Answer 26

Na/K ATPase pumps 3 Na out and K in to the cell to maintain the resting membrane potential along with K leak channels