regulation of Potassium - C

Question 1

how much potassium in an average 70 kg person

Answer 1

3,500 mmol

Question 2

the majority of the potassium content of the body is stored in the ________

Answer 2

intracellular compartment

Question 3

of that contained in the intracellular compartment, the majority of the potassium is contained in _______

Answer 3

muscle cells

Question 4

only 2% of the total potassium is in the _________

Answer 4

extracellular compartment

Question 5

how many folds difference is there between the intracellular and extracellular compartment in terms of [K+]

Answer 5

30 folds

Question 6

how is the 30 fold concentration difference between the intra and extra cellular compartments maintained in the body

Answer 6

the N+/K+ ATP pump

Question 7

N+/K+ ATPase pumps _____Na+ _____ and ______K+______

Answer 7

3 sodium out and 2 potassium into the cell

Question 8

what does the short term regulation of the potassium concentration

Answer 8

the N+/K+ ATP pump

Question 9

what does the long term regulation of the potassium concentration

Answer 9

kidneys

Question 10

which factors increase extracellular [K+]?

Answer 10

• acid base balance (also decreases) - acidemia increases potassium
• catecholamines (also decreases)
• hypoxia
• hyperosmolarity
• exercise
• alpha adrenergic agonist

Question 11

which factors decrease extracellular[K+}?

Answer 11

• insulin
• acid base balance (also increases)
• Beta 2 adrenergic agonists
• aldosterone

Question 12

what does insulin do to potassium concentration?

Answer 12

decrease

Question 13

what does exercise do to potassium concentration?

Answer 13

increase

Question 14

what does acid/base balance do to potassium concentration?

Answer 14

can both increase and decease.
Acidaemia causes increase in potassium concentration
Alkalaemia causes decrease in potassium concentration

** potassium goes where hydrogen goes and hydrogen goes where potassium goes

Question 15

what does hypoxia do to potassium concentration?

Answer 15

increase

Question 16

what does hyperosmolarity do to potassium concentration?

Answer 16

increase

Question 17

what does use of diuretics do to potassium concentration?

Answer 17

it can cause a decrease in potassium concentration

Question 18

what does renal failure do to the potassium concentration?

Answer 18

it can cause build up of potassium ions in the body

Question 19

membrane potential of potassium is

Answer 19

around -70mV

Question 20

what is the time course of potassium distribution and excretion following K+ load?

Answer 20

for the first 6 hours there is an endocrine mediated movement of the ions into cells

slowly the renal excretion of excess potassium takes over in regulation

Question 21

what does an acute increase in potassium do to the pancreas?

Answer 21

it causes the secretion of insulin

Question 22

what does insulin do to potassium concentrations and how?

Answer 22

it affects the Na+/K+ ATPase and also the glucose/Na+ co-transporter which means that more sodium ions and glucose are pumped into the cells and therefore there is a greater concentration gradient for sodium ions to go out via the Na+/K+ ATPase - so more potassium comes in to the cell and out of the extracellular compartment

Question 23

why is it important to regulate the potassium concentration in the extracellular compartment?

Answer 23

doubling the extracellular potassium ion concentration leads to change in the membrane potential by -18mV - which is dangerous for the heart

Question 24

what does an an acute increase in potassium ions do to the adrenal glands?

Answer 24

It causes the secretion of epinephrine and aldosterone

Question 25

what does epinephrine do to potassium concentrations and how?

Answer 25

Epinephrine acts via the cAMP cascade to act on the Na+/K+ ATPase. It decrease potassium concentration by increasing uptake into the cell

Question 26

what does aldosterone do the potassium concentration and how?

Answer 26

Aldosterone acts within the cell to cause altered receptor expression? It decrease potassium concentration by increasing uptake into the cell

Question 27

FILL IN THE BLANKS:

when the potassium concentration ___creases by more than ______, insulin stimulates the ____________. Second messenger is not agreed upon, but likely to be a ______ ______

Answer 27

when the potassium concentration increases by more than 1mmol/l, insulin stimulates the Na-K ATPase pump. Second messenger is not agreed upon, but likely to be a protein kinase

Question 28

FILL IN THE BLANKS:

______ _______, such as salbutamol and terbutaline also stimulate the _____

Answer 28

Beta-2 agonists, such as salbutamol and terbutaline also stimulate the Na-K pump

Question 29

FILL IN THE BLANKS:

__________ is involved in the hour to hour regulation of the ______ pump

Answer 29

aldosterone is involved in the hour to hour regulation of the Na-K pump

Question 30

FILL IN THE BLANKS:

__________ adrenergic agonists such as ________ cause both hyper and hypokalaemia - initial ____ then _____

Answer 30

non selective adrenergic agonists such as adrenaline cause both hyper and hypokalaemia - initial hyper then hypo

Question 31

FILL IN THE BLANKS:

_____ alpha ______ cause _____kalaemia

Answer 31

selective alpha agonists cause hyperkalaemia

Question 32

FILL IN THE BLANKS:

______ beta2 _______ cause ______kalaemia

Answer 32

selective beta2 agonists cause hypokalaemia

Question 33

why and how does increased concentration of hydrogen ions cause hyperkalaemia?

Answer 33

Increased intracellular hydrogen ion concentration means that there is an increased efflux of the ion down the concentration gradient out of the cell through NHE. this means that there is an increased concentration of Na+ inside the cell as a result. Leading to increased activity of the Na-K ATPase which means that there is increased

Question 34

FILL IN THE BLANKS:

exercise causes the ______ of K+ from ______ cells (through ______ _______ K+ channel). Incomplete re-uptake of K+ by the Na pump during the __________ phase of the action potential leads to an ________ in the potassium concentration extracellularly

Answer 34

exercise causes the efflux of K+ from muscle cells (through delayed rectifier K+ channel). Incomplete re-uptake of K+ by the Na pump during the depolarisation phase of the action potential leads to an increase in the potassium concentration

Question 35

FILL IN THE BLANKS:

Hyperkalaemia in exercise is not dependent on _______. Patients with ________ disease still become hyperkalaemic

Answer 35

Hyperkalaemia in exercise is not dependent on acidosis. Patients with McArdles disease still become hyperkalaemic

Question 36

FILL IN THE BLANKS:

________ beta2 receptors slows down the Na-K pump and reuptake of the potassium ions by the _______ muscles

Answer 36

blocking beta2 receptors slows down the Na-K pump and reuptake of the potassium ions by the skeletal muscles

Question 37

FILL IN THE BLANKS:

Functional consequences of exercise induced hyperkalaemia

• skeletal muscle ________
• regulation of muscle blood _____
• regulation of ______ blood _______
• arterial chemoreceptor sensitivity
• myocardial stability

Answer 37

Functional consequences of exercise induced hyperkalaemia

• skeletal muscle fatigue
• regulation of muscle blood flow
• regulation of arterial blood pressure
• arterial chemoreceptor sensitivity
• myocardial stability

Question 38

FILL IN THE BLANKS:

Propranolol _______ exercise induced hyperkalaemia

Answer 38

Propranolol enhances exercise induced hyperkalaemia