Active Transport and the Sodium/Potassium Channel

Question 1

What is the intracellular and extracellular concentrations of sodium and potassium?

Answer 1

Na- 140mM out, 10mM in

K- 5mM out, 140mM in

Question 2

How do we control the electrochemical gradient?

Answer 2

Through Na/KATPase

Question 3

What is the structure of the sodium pump?

Answer 3

2 alpha subunits with an ATP binding site each

2 beta units with cardiac glycoside binding sites

Question 4

What is the Km for Na?

Answer 4

20mM

Question 5

What is the Km for K?

Answer 5

1mM

Question 6

What limits the activity of the sodium pump?

Answer 6

Decreasing intracellular sodium concentration

Decreasing potassium concentration extracellularly

Question 7

How many times does the sodium pump go a second?

Answer 7

100

Question 8

How can you inhibit the sodium pump?

Answer 8

Digoxin binding to cardiac glycosides

Question 9

What happens when to the dose response curve if you decrease the extracellular concentration of K when digoxin is present?

Answer 9

Moves to the left

Question 10

What is the therapeutic index?

Answer 10

The difference between the toxic effect and the therapeutic effect

Question 11

How do you calculate the therapeutic index?

Answer 11

Minimum effective dose for 50% of the population

Question 12

What do you use remifentanil for and what is its TI?

Answer 12

Patient controlled analgesia during labour

33000:1

Question 13

What do you sue diazepam for and what is its TI?

Answer 13

Sedative

100:1

Question 14

What do you use ethanol for and what is its TI?

Answer 14

Sedative

10:1

Question 15

What do you use digoxin for what is its TI?

Answer 15

Congestive heart failure 2:1

Question 16

What is the range of hypokalaemia?

Answer 16

Less than 3.5mM

Question 17

What is the range of normokalaemia?

Answer 17

3.6-5.3 mM

Question 18

What is the range of hyperkalaemia?

Answer 18

More than 5.5

Question 19

What are the symptoms of hypokalaemia?

Answer 19

Abnormal heart rhythms

Muscle damage

Muscle weakness or spasms

Paralysis

Question 20

What are the symptoms of hyperkalaemia?

Answer 20

Nausea

Palpitations

Muscle weakness

Question 21

Why is potassium level important for giving digoxin

Answer 21

If you are hypokalaemic then you increase the affinity for digoxin

This means you have to take into account the change in concentration as the therapeutic index has now changed as well

Question 22

What condition will lead to an increase in digoxin binding?

Answer 22

Hypokalaemia

Question 23

How does a diuretic treat pulmonary oedema?

Answer 23

Increases the volume output of the kidneys meaning there is a pressure that pulls the excess fluid out of the lungs

Question 24

What does diuretic used for?

Answer 24

High blood pressure

Excessive fluid retention

Question 25

What are the side effects of diuretics?

Answer 25

Increases urinary excretion of potassium

Question 26

How are digoxin and diuretics related?

Answer 26

Patients on digoxin who start diuretics may become hypokalaemic A reduction in competition between K and digoxin results in increased digoxin binding to the sodium pump Because of the very narrow therapeutic index, the patient develops digoxin toxicity

Question 27

What do you treat digoxin toxicity with?

Answer 27

Digibind

Question 28

What are the different concentrations of the sodium calcium exchanger?

Answer 28

Na- 140mM out, 10mM in Ca- 2mM out

Question 29

What is the internal voltage inside the cell?

Answer 29

-70mW

Question 30

What is the function of GLUT1?

Answer 30

Basal uptake in placenta and brain

Question 31

What is the function of GLUT2?

Answer 31

Trans epithelial transport, Beta cells

Question 32

What is the function of GLUT3?

Answer 32

Basal uptake in the brain

Question 33

What is the function of GLUT4?

Answer 33

Skeletal muscle

Question 34

What is the function of GLUT5?

Answer 34

Intestinal absorption of fructose

Question 35

Describe intestinal uptake of glucose?

Answer 35

Sodium potassium pump pushes sodium out of the cell 2 sSodium enters through co transported with glucose