Exam 3: Lecture 34

Question 1

What type of cells rely on a potassium balance?

Answer 1

Excitable cells - nerves, skeletal and cardiac muscle

Question 2

Which area of fluid contains the majority of the body’s potassium?

Answer 2

Intracellular fluid

Question 3

Distribution of K+ across cell membranes is called _____________ K+ balance.

Answer 3

Internal

Question 4

Renal mechanisms to manage variations in K+ intake are called _____________ K+ balance

Answer 4

External

Question 5

Internal/External K+ balance is primarily affected by hormones or drugs.

Answer 5

Internal

Question 6

Internal/External K+ balance is primarily affected by dietary intake.

Answer 6

External

Question 7

A drug was given that increased a patients K+ concentration within the ECF. Would you expect to see in regard to the cell’s action potential?

Answer 7

Hyperpolarization - cells are easily excitable

Question 8

If more K+ shift into the cells, how would that affect the cells action potential?

Answer 8

Hyperpolarization - cell becomes harder to reach threshold.

Question 9

Which hormone helps to protect against hyperkalemia?

Answer 9

insulin

Question 10

How would a diagnosis of type 1 diabetes affect the balance of K+?

Answer 10

Causes hyperkalemia

Question 11

If a patient is presenting with alkalemia, what do you expect to see in terms of K?

Answer 11

Hypokalemia - K+ enters cells

Question 12

T/F: You would always see an effect on K+ as a result of acid/base disturbances.

Answer 12

False - not always, especially if it is a respiratory disturbance

Question 13

How do beta2-adrenergic receptors cause hypokalemia?

Answer 13

Increases the activity of Na+/K+ ATPase

Question 14

If the osmotic pressure in the ECF is greater than that in the ICF - how would that affect K+ balance?

Answer 14

K+ is driven out of the cell- hyperkalemia

Question 15

What would you expect the K+ balance to be of a patient being treated for an osteosarcoma?

Answer 15

Hyperkalemia - K+ moves from ICF to ECF because of breakdown of cell membrane

Question 16

You decide to run blood work on a working dog right after its afternoon training session. What to do you expect to see for its K+ balance?

Answer 16

Normal levels - in healthy animals the shift of K+ out of the cell is minor.

Question 17

What is the condition called when K+ moves into cells?

Answer 17

Hypokalemia

Question 18

What are the three mechanisms used to handle a wide range of dietary K+ variability?

Answer 18

• Filtration/filtered load
• Reabsorption
• Secretion

Question 19

Where is the most K+ reabsorbed?

Answer 19

Proximal convoluted tubule

Question 20

Which area of the nephron is responsible for fine tuning of K+ excretion?

Answer 20

Distal tubule and collecting ducts

Question 21

In the presence of a low K+ diet what would the effects be in the DT?

Answer 21

Reabsorption by the alpha-intercalated cells

Question 22

In the presence of a high K+ diet what would the effects be in the DT?

Answer 22

Secretion of K+ by principle cells

Question 23

What determines the magnitude of K+ secretion?

Answer 23

The size of the electrochemical gradient for K+

Question 24

What are the two primary methods of transport for K+ across the luminal membrane of principle cells?

Answer 24

Na+/K+ ATPase and K+ channels

Question 25

What is the action of K+ in the presence of aldosterone?

Answer 25

Increases K+ secretion by principle cells

Question 26

What is the major mechanism to reabsorb K+ into alpha-intercalated cells?

Answer 26

H+/K+ ATPase

Question 27

During alkalosis, what is the direction of travel for K+?

Answer 27

From ICF to ECF - hypokalemia

Question 28

During acidosis, what is the direction of travel for K+?

Answer 28

From ECF to ICF - hyperkalemia

Question 29

What is a side effect of loop and thiazide diuretics?

Answer 29

Hypokalemia

Question 30

Loop and thiazide diuretics inhibit Na+ reabsorption where? Relative to K+ secretion.

Answer 30

Upstream to the site of K+ secretion - so more Na+ is delivered to principal cells

Question 31

Non-reabsorbed luminal anions (increase/decrease) secretion of K+.

Answer 31

Increase

Question 32

In the Thick Ascending limb, what type of drug inhibits the Na+/K+/2Cl- co-transporter?

Answer 32

Loop diuretics