Channel-linked receptors

Question 1

Name an example of a channel-linked receptor

Answer 1

Nicotinic acetylcholine receptor

Question 2

Can a channel-linked receptor have a ligand bound and still be closed?

Answer 2

Yes, the channel will close prior to ligand dissociating

Question 3

What are channel-linked receptors also known as?

Answer 3

Receptor-gated ion channels

Question 4

WHat is the difference between channel-linked receptors and voltage-gated ion channels?

Answer 4

Channel-linked receptors open due to binding of agonist, not change in membrane potential

Question 5

Where are channel-linked receptors mainly found?

Answer 5

Muscle cells

Nerve cells

Question 6

How fast can receptor-gated ion channels signal?

Answer 6

Within milliseconds

Question 7

What is the receptor and function of Acetylcholine in skeletal muscle?

Answer 7

muscular nicotinic acetylcholine receptor

Opens cation channel to depolarize for muscle contraction

Question 8

What is the receptor and function of Acetylcholine in neurons?

Answer 8

Neuronal nicotinic acetylcholine receptor

Opens cation channel for neuron excitation

Question 9

What is the receptor and function of Glutamate/Aspartate in neurons?

Answer 9

NMDA

Opens cation channel for neuron excitation

Question 10

What is the receptor and function of GABA in neurons?

Answer 10

GABA-a

Opens chloride channel for hyperpolarization (no action potential)

Question 11

What is the receptor and function of Glycine in neurons?

Answer 11

Glycine

Opens chloride channel for hyperpolarization

Question 12

Describe signaling through voltage-gated Ca+ channels

Answer 12

Contraction or release of vesicles that contain another signaling molecule

Question 13

Describe signaling through Na+ voltage-gated channels

Answer 13

Contraction or propagation of information via action potentials

Question 14

What is the Nernst equation?

Answer 14

Ek = -60/z * log [K+] inside/[K+] outside

Question 15

If a membrane potential is at -70mV and a Na+ channel (+60mV) opens, wha can be expected of the membrane potential?

Answer 15

Moves towards 60 (+)

Depolarization

Question 16

If a membrane potential is at -70mV and a Cl- channel (-90mV) opens, what can be expected?

Answer 16

Hyperpolarization

Moves to -90 (-)

Question 17

If a membrane potential is at -70mV and a cation channel (0mV) opens, what can be expected?

Answer 17

Depolarization

Moves toward 0 (+)

Question 18

Is intracellular or extracellular calcium higher?

Answer 18

Extracellular

Question 19

Name the 3 intracellular calcium stores

Answer 19

mitochondria
Sarcoplasmic reticulum
Endoplasmic reticulum

Question 20

Name the 5 pathways to increase cytosolic Ca+

Answer 20

Receptor-activated channel
Receptor-gated channel
Voltage-gated channel
IP3 receptor-gated channel
Ryanodine receptor-gated channel

Question 21

How do IP3 receptor-gated channels and Ryanodine receptor-gated channels increase cytoslic Ca+?

Answer 21

IP3 opens intracellular stores of Ca+

Question 22

What are the 4 pathways to decrease ctosolic Ca+?

Answer 22

Ca+-ATPase in plasma membrane

Na+/Ca+ exchanger pump

Ca+ ATPase in endoplasmic/sarcoplasmic reticulum

Ca+/H+ exchanger in mitochondria

Question 23

How do Ca+ ATPases decrease cytosolic Ca+?

Answer 23

Ca+ is pumped out of cell by Ca+ATPase in the plasma membrane

Ca+ is pumped in to intracellular stores by Ca+ ATPase

Question 24

How many ATP molecules are required to run the Ca+ATPase pumps?

Answer 24

1

Question 25

What powers the Na+/Ca+ exchanger pump?

Answer 25

Na+/K+ ATPase

Question 26

What powers the Ca+/H+ exchanger pump?

Answer 26

H+ gradient

Question 27

Describe the pathway of neurotransmitter release

Answer 27

Action potential causes membrane depolarization Depolarization opens Ca+ channel Ca+ causes transmitter release from vesicles Transmitters cross synapse to receptors

Question 28

Describe the insulin secretion pathway

Answer 28

Glucose enters to Beta cell through GLUT2 Glucose is oxidized to create ATP ATP blocks pump from excreting K+ out of cell Increasing intracellular K+ causes depolarization Depolarization opens Ca+ voltage-gated channel Ca+ triggers vesicles to release insulin

Question 29

Describe the contraction pathway of a cardiac ventricular myocyte

Answer 29

Small depolarization occurs due to gap junctions and opens Na+ voltage-gated channel Na+ voltage-gated channel causes large depolarization Depolarization activates voltage-gated Ca+ channels Ca+ enters cell and activates ryanodine-receptor Ryanodine-receptor allows large amounts of Ca+ in to cell from Sarcoplasmic reticulum Increase is cytosolic Ca+ causes contraction

Question 30

Describe the relaxation of cardiac muscle

Answer 30

Large depolarization activates delayed K+ channels K+ are pumped out to restore resting membrane potential CA+ATPase pumps Ca+ from cytosol back to SR and to extracellular compartment by Na+/Ca+ exchanger

Question 31

What powers the Na+/Ca+ exchanger?

Answer 31

Na+/K+ ATPase

Question 32

What receptor is responsible for the bulk of Ca+ inflow during cardiac contraction?

Answer 32

Ryanodine receptor

Question 33

How many times do ion channels pass through the membrane?

Answer 33

4