Block A Lecture 3: Where do Drugs Act? Part 2 - Electric Boogaloo

Question 1

What is a transporter?

Answer 1

A protein which helps move molecules across a membrane in or out of the cell
(Lecture 3, Part 1, Slide 3)

Question 2

What is the full name of serotonin?

Answer 2

5-hydroxytryptamine (5-HT)
(Lecture 3, Part 1, Slide 9)

Question 3

What is serotonin?

Answer 3

A neurotransmitter released from the nerve cells in the brain and affects other target nerve cells
(Lecture 3, Part 1, Slide 9)

Question 4

What does serotonin interact with on its target cells?

Answer 4

A 5-HT receptor
(Lecture 3, Part 1, Slide 9)

Question 5

Serotonin is an excitatory neurotransmitter. What does this mean?

Answer 5

It increases brain activity
(Lecture 3, Part 1, Slide 9)

Question 6

What type of drug is prozac?

Answer 6

An SSRI (selective serotonin re-uptake inhibitor)
(Lecture 3, Part 1, Slide 12)

Question 7

What is the mechanism of action of prozac in helping treat depression?

Answer 7

Prozac blocks the 5HT reuptake transporter which results in more serotonin (5-HT) hanging around in the space between the two neurons, which are more likely to stimulate the 5-HT receptor on the target neuron resulting in more activity and a better mood
(Lecture 3, Part 1, Slide 12)

Question 8

What does a proton pump do?

Answer 8

It transports H+ ions
(Lecture 3, Part 1, Slide 16)

Question 9

How do proton pump inhibitors reduce the volume of stomach acid?

Answer 9

They inhibit H+K+ATPase irreversibly, preventing it from secreting acid
(Lecture 3, Part 1, Slide 17)

Question 10

What are 3 examples of things that proton pump inhibitors can be used to treat?

Answer 10

Peptic ulcers
GERD (gastroesophageal reflux disease)
Gastrin producing tumour
Too much stomach acid
(Lecture 3, Part 1, Slide 18)

Question 11

What are the 4 types of ion channel?

Answer 11

Ligand-gated
Mechanically-gated
Voltage-gated
Always open
(Lecture 3, Part 2, Slide 4)

Question 12

What are ion channels?

Answer 12

They are pores in the membrane which allow ions to go in and out of the cell
(Lecture 3, Part 2, Slide 5)

Question 13

What are ion channels made up of?

Answer 13

Protein subunits
(Lecture 3, Part 2, Slide 5)

Question 14

What does differing protein subunit compositions in ion channels result in?

Answer 14

Many different channel types and variations due to subunit composition
(Lecture 3, Part 2, Slide 5)

Question 15

Why do cells that are “excitable” have lots of ion channels?

Answer 15

As they have to respond quickly
(Lecture 3, Part 2, Slide 5)

Question 16

Name 3 “excitable” cells that have lots of ion channels.

Answer 16

Nerve(neurons), skeletal muscle and heart (cardiac) cells
(Lecture 3, Part 2, Slide 5)

Question 17

How quickly do ion channels open?

Answer 17

In milliseconds
(Lecture 3, Part 2, Slide 5)

Question 18

What can many ion channels combine to make?

Answer 18

An action potential
(Lecture 3, Part 2, Slide 6)

Question 19

What is an action potential?

Answer 19

A change in membrane potential
(Lecture 3, Part 2, Slide 6)

Question 20

What mV value does membrane potential sit at?

Answer 20

-70
(Lecture 3, Part 2, Slide 6)

Question 21

What are the first 3 steps of an action potential in neurons?

Answer 21

1. Na+ channels open allowing Na+ (Sodium) to enter the cell - increasing membrane potential
2. K+ channels open allowing K+ (Potassium) to leave the cell - this would decrease membrane potential, but more sodium goes in than potassium goes out, so membrane potential still increases
3. Na+ channels become refractory, allowing no more Na+ to enter the cell
   (Lecture 3, Part 2, Slide 6)

Question 22

What does refractory mean?

Answer 22

The period of time in which a cell can’t repeat an action potential
(Lecture 3, Part 2, Slide 6)

Question 23

What are the last 3 steps of an action potential in neurons (after sodium channels close)?

Answer 23

4. K+ (Potassium) continues to leave the cell and causes membrane potential to return to the resting potential
5. K+ channels close and Na+ channels rest - membrane potential goes slightly below resting level
6. Extra K+ outside diffuses away, bringing membrane potential back to the resting potential level
   (Lecture 3, Part 2, Slide 6)

Question 24

How does action potential travel down a nerve?

Answer 24

It relays down the nerve until it gets to the end where transmitter release happens
(Lecture 3, Part 2, Slide 7)

Question 25

Other than neurons, name a cell that can have an action potential.

Answer 25

Cardiac (heart) cells
(Lecture 3, Part 2, Slide 8)

Question 26

Why do sodium channel blockers have different classes?

Answer 26

They are different strengths for different conditions
(Lecture 3, Part 2, Slide 9)

Question 27

What are the 3 classes of sodium channel blockers?

Answer 27

1A, 1B and 1C
(Lecture 3, Part 2, Slide 9)

Question 28

What is lidocaine?

Answer 28

It is a local anaesthetic
(Lecture 3, Part 2, Slide 10)

Question 29

What type of drug is lidocaine?

Answer 29

A sodium channel blocker
(Lecture 3, Part 2, Slide 10)

Question 30

How does lidocaine block the sodium channel?

Answer 30

It binds to the inner pore of the sodium channel, blocking sodium ion influx into the cell
(Lecture 3, Part 2, Slide 10)

Question 31

What do Ca2+ (Calcium) channels in the vascular (blood vessel)smooth muscle mediate?

Answer 31

Contraction (which leads to vasoconstriction)- controlling blood pressure
(Lecture 3, Part 2, Slide 15)

Question 32

What do calcium channel blockers do?

Answer 32

They block the “L-type voltage gated Ca channel” and prevent muscle contraction - lowering blood pressure
(Lecture 3, Part 2, Slide 16)

Question 33

What are 3 examples of conditions that calcium channel blockers are used to treat?

Answer 33

Cardiac arrhythmia (irregular heartbeat)
Hypertension (high blood pressure)
Angina Pectoris (angina)
(Lecture 3, Part 2, Slide 17)