Excitable Cells- Lecture 1 Reiser

Question 1

3 types of channels

Answer 1

1. ligand sensitive (chemically regulated)
2. voltage sensitive
3. mechanosensitive

Question 2

the membrane resting potential is most permeable to…

Answer 2

K+

Question 3

the Pk/Pna ratio at the resting membrane potential is

Answer 3

~60

Question 4

The resting membrane is slightly permeable to Na, therefore Na diffuses into the cell down both of its… amd… and this is what keeps the resting membrane potential slightly lower than Ek

Answer 4

concentration and electrical gradient

Question 5

change of the membrane toward 0 mV is referred to as

Answer 5

depolarization

Question 6

change in membrane potential away from 0 mV in the negative voltage direction is referred to as

Answer 6

repolarization

Question 7

an increase in potential from the resting value (more negative) is reffered to as

Answer 7

hyperpolarization

Question 8

the peak of the AP (~40mV) approaches the …

Answer 8

equilibrium potential for Na+ (~58mV)

Question 9

axons with large diameters have …. conduction velocities

Answer 9

higher

Question 10

are the Na and K channels at the motor endplate chemically or voltage gated

Answer 10

chemically

Question 11

end plate potentials: are they spontaneous?

Answer 11

no

Question 12

EPPs occur after

Answer 12

an AP in a motorneuron

Question 13

what is the amplitude of an EPP

Answer 13

10mV

Question 14

EPPs are confined to the

Answer 14

end plate region

Question 15

Miniature EPPs occur at…

Answer 15

rest

Question 16

MEPPs: spontaneous or no?

Answer 16

spontaneous

Question 17

MEPPs are confined to the

Answer 17

end plate region

Question 18

MEPPs follow the release of the contents of

Answer 18

one synaptic vesicle

Question 19

MEPP amplitude?

Answer 19

1-2 mV

Question 20

role of acetylcholinesterase is to breakdown… into which two products?

Answer 20

• acetylcholine

- acetic acid (acetate) and choline

Question 21

Breakdown of acetylcholine: Acetate enters the… and choline is taken up by the …. where it reacts with…., by the action of…. to form….

Answer 21

• circulation
• presynaptic terminal
• acetyl-CoA
• choline acetyltransferase
• acetylcholine

Question 22

Curare ( a plant derivative) binds to … so … cannot bind. As a result Ach will still be released at the presynaptic terminal but no APs will occur

Answer 22

acetylcholine receptor

ACh

Question 23

Botulinum toxin blocks… so skeletal muscle activation cannot occur

Answer 23

ach release

Question 24

Organophosphates block action of …. so ach cannot be hydrolyzed; cannot activate skeletal muscle in its presence because Na channels remain in refractory state

Answer 24

acetylcholinesterase