PNB Exam 3

Question 1

excitable cells

Answer 1

cells that recive and send electrical signals across plasma membrane

Question 2

electrophysiology

Answer 2

Originally called Galvanism, the study of excitability

Question 3

K+

Answer 3

higher concentration in the cell

Question 4

Na+

Answer 4

Higher concentration outside of the cell

Question 5

Cl

Answer 5

Higher concentration outside of cell

Question 6

Ca

Answer 6

Higher concentration outside of the cell

Question 7

Concdntration Gradient

Answer 7

Gradient = [Ion]
outisde
​
− [Ion]
inside
​

Question 8

Voltage-gated ion channels

Answer 8

ated by changes in the relative distribution of charges in their local environment. Any positive or negative change is “sensed” by charged amino acid residues in the channel protein, causing a change in conformation

Question 9

Ligand-gated ion channels

Answer 9

gated by a chemical messenger (a ligand) that binds to the channel on the inside or outside of the cell (Figure 8.3b). These channels contain a binding site for a hormone or neurotransmitter

Question 10

ion channels only allow passive transport of ions.

Question 11

relative concentration gradients never change because of the large cytoplasmic volume.

Question 12

by what process is sodium moved out of the cell?

Answer 12

Active transport

Question 13

ions are charged particles, their movement is influenced

Answer 13

by their concentration gradient, but also by electrostatic forces

Question 14

membrane potential

Answer 14

difference in charge between the two environments creates a form of potential energy, stored eneger

Question 15

electrochemical equilibrium,

Answer 15

Eventually, however, the entry of Na+ would be slowed and stopped by like-charge repulsion arising from the accumulation of positive charges inside the cell