Active Transport and the Sodium Pump

Question 1

How is the steady-state intracellular ionic concentrations maintained across the membrane?

Answer 1

1- Constant movement of ions

2- Passive diffusion and active transport

Question 2

Describe the structure of the sodium-potassium pump.

Answer 2

1- Globular protein tetramer, two α proteins and two β proteins
2- α subunit 95000 MW
3- β subunit 40000 MW
4- Total weight 270000 MW
5- Two ATP binding sites
6- Two cardiac glycoside binding sites (inhibit)
7- 3 Na+ bind internally on α proteins
8- 2 K+ bind externally on α proteins

Question 3

How can the sodium pump be inhibited?

Answer 3

Removing K+

Question 4

How can the sodium pump be stimulated?

Answer 4

Increasing Na+

Question 5

What are cardiac glycosides?

Answer 5

1- Steroid glycoside molecule attached to sugar and R group
2- Increase force/output of heart muscles
3- Decrease heart rate

Question 6

In regards to cardiac glycosides and the sodium pump, what happens when the concentration of K+ is decreased?

Answer 6

Affinity between cardiac glycosides and sodium pump increases

Question 7

How is therapeutic index calculated?

Answer 7

Dose producing toxicity in 50% of population/minimum effective dose for 50% of population

Question 8

What is the use of remifentanil and what is its therapeutic index?

Answer 8

1- Synthetic opiod
2- Patient controlled analgesia during labour
3- 33000:1

Question 9

What is the use of diazepam and what is its therapeutic index?

Answer 9

1- Sedative

2- 100:1

Question 10

What is the use of ethanol (medicinally) and what is its therapeutic index?

Answer 10

1- Sedative

2- 10:1

Question 11

What is the use of digoxin and what is its therapeutic index?

Answer 11

1- Congestive heart failure

2- 2:1

Question 12

What happens when blood potassium concentration is too low?

Answer 12

1- Hypokaelaemia
2- Low if less than 3.5 mEq/L
3- Moderate if between 2.5-3.0 mEq/L
4- Severely low if less than 2.5 mEq/L
5- Abnormal heart rhythms
6- Rhabdomyolysis: muscle damage
7- Muscle weakness or spasms
8- Paralysis
9- Increased digoxin binding

Question 13

What are the symptoms of hypokalaemia?

Answer 13

1- Abnormal heart rhythms
2- Rhabdomyolysis: muscle damage
3- Muscle weakness or spasms
4- Paralysis

Question 14

What is the range for normokalaemia?

Answer 14

3.6-5.2 mEq/L

Question 15

What happens when blood potassium concentration is too high?

Answer 15

1- Hyperkalaemia
2- High is more than 5.5 mEq/L
3- Moderate if between 6.1-6.9 mEq/L
4- Severely high if higher than 7.0
5- Nausea
6- Palpitations
7- Muscle weakness

Question 16

What are the symptoms of hyperkalaemia?

Answer 16

1- Nausea
2- Palpitations
3- Muscle weakness

Question 17

In regards to digoxin, what happens when the concentration of potassium is decreased?

Answer 17

Increased digoxin binding

Question 18

What is the role of diuretics?

Answer 18

1- Increase urine output by the kidneys

2- Treatment for HBP and excessive fluid retention

Question 19

What are the side effects of diuretics?

Answer 19

Increased urinary secretion of potassium

Question 20

What may happen when patients are on both digoxin and diuretics?

Answer 20

1- May become hypokalaemic
2- Lower concentration of K+ leads to inceased digoxin binding to Na+ pump
3- May lead to digoxin toxicity

Question 21

How is digoxin toxicity treated?

Answer 21

1- Digibind

2- Rapidly binds to digoxin, causing it to dissociate from sodium pump and reverses toxicity

Question 22

What are the five types of glucose transporters?

Answer 22

1- GLUT1
2- GLUT2
3- GLUT3
4- GLUT4
5- GLUT5

Question 23

Where is GLUT1 found?

Answer 23

1- Placenta

2- Brain

Question 24

Where is GLUT2 found?

Answer 24

1- Liver

2- Pancreatic β cells

Question 25

Where is GLUT3 found?

Answer 25

Brain

Question 26

Where is GLUT4 found?

Answer 26

Skeletal muscle

Question 27

What is GLUT4 function dependent on?

Answer 27

Insulin

Question 28

Where is GLUT5 found?

Answer 28

Small intestine

Question 29

What does GLUT5 transport?

Answer 29

Fructose

Question 30

What are two transporters of glucose which display secondary active transport, and where are they found?

Answer 30

1- SGLT1
2- SGLT2
3- Small intestine

Question 31

What part of the Sodium potassium pump is the catalytic driver?

Answer 31

The 2 alpha units