Chapter 4

Question 1

active transporters

Answer 1

are membrane proteins that create and maintain ion gradients
an important example is the Na/K pump
two categories: ATPase pumps and ion exchangers

Question 2

ion channels

Answer 2

give rise to ion permeability changes

Question 3

voltage gated channels

Answer 3

open and close in response to the magnitude of the membrane potential

Question 4

properties of channels

Answer 4

1. they have to be capable of moving ions across the membrane at high rates
2. channels have to use gradients across the membrane because the currents depend on them
3. different channels for different ions
4. channels have to be able to sense the membrane potential so they need to open only when the voltage is at a certain level

Question 5

whole cell recording

Answer 5

allows us to inject substances into the inside of the patched cell

Question 6

inside out patch recording

Answer 6

allows us to change the medium to which the intracellular surface of the membrane is exposed to
used to study the influence of molecules on ion channel functions

Question 7

outside out patch recording

Answer 7

allows us to study how channel activity is influenced by chemical signals like NTs

Question 8

microscopic currents

Answer 8

currents flowing through single channels and are due to the opening of the voltage gated Na channels

Question 9

alpha toxins

Answer 9

slow down the inactivation of Na channels and therefore if injected will result in a prolonged AP

Question 10

beta toxins

Answer 10

cause Na channels to open at potentials much more negative than normal
leads to uncontrolled firing

Question 11

voltage gated Ca channels

Answer 11

in some neurons they can give rise to APs and in others they can prolong the APs

Question 12

ligand gated ion channels

Answer 12

are neurotransmitter receptors so they activated when binded to an NT in their extracellular portion
are essential for synaptic transmission

Question 13

ATPase pumps

Answer 13

get their energy from the hydrolysis of ATP

example: Na/K pump and Ca pumps

Question 14

ion exchangers

Answer 14

use electrochemical gradients of other ions as the energy source
carry ions up their electrochemical gradient while at the same time taking other ions down their gradient
two types: antiporters and cotransporters

Question 15

antiporters

Answer 15

exchange intracellular and extracellular ions

example: Na/Ca exchanger: most important job is keeping intracellular Ca concentration low

Question 16

contransporter

Answer 16

carry multiple ions in the same direction