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Flashcards in potassium and hydrogen Deck (24)
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1
Q

Potassium is a largely …… cation?

A

Intracellular.

2
Q

The major extracellular cation is?

A

Sodium.

3
Q

How much potassium is stored in cells?

A

95%. So 5% ECF but kept within tight limits to prevent cardiac problems.

4
Q

Intracellular potassium is needed for?

A

Cell growth (needed for enzyme function)

5
Q

Hyperkalaemia initially makes cells?

A

More excitable but also slows repolarisation of the cell if resting potential is greater than threshold potential.

6
Q

What are the sources of potassium?

A

Passive diffusion in SI.
Active transport it response to aldosterone in colon.
sometimes,
Haemolysis and muscle damage

7
Q

The kidneys remove what percentage of potassium? What percentage is removed by GIT?

A

90-95% is removed via kidneys.

5-10% by the GIT.

8
Q

The translocation from ECF to ICF

prevents?

A

life threatening hyperkalaemia until the kidneys can excrete the rest.

9
Q

Uptake of potassium into liver & muscle cells is

promoted by hormones?

A

Insulin & adrenaline (affects beta 2 ßç)

— Thereby increasing activity Na/K ATPase

10
Q

What situations promote the release of potassium from ICF?

A

Insulin deficiency, aldosterone deficiency, acidaemia, exercise and increased ECF osmolality.

11
Q

What happens K+ at the glomerulus?

A

It is freely filtered.

12
Q

How much K+ is reabsorped in PCT?

A

70%

13
Q

How much K+ is reabsorped in the ascending limb?

A

10-20%

14
Q

What happens to K+ in the distal nephron and collecting ducts?

A

Net reabsorption or secretion in
distal nephron. First part of collecting duct
DETERMINES RENAL EXCRETION
DEPENDING ON NEED

15
Q

What does high Na+ do to K+?

A

Leads to increased secretion of it.

16
Q

What are the effects of aldosterone deficiency?

A

Causes dimished Na+ reabsorption in the distal tubule therefore K+ from the blood is not pumped into tubular cells in exchange for Na+ so levels of K+ can rise dangerously high in the blood called hyperkalaemia. This is happens in a disease called Addisons/aldosterone deficiency.

17
Q

Aldosterone promotes?

A

Distal tubule Na+ reabsorption and K+ excretion into tubular lumen.

18
Q

ENaC stands for?

A

Epithelial sodium channel- amiloride sensitive

19
Q

What happens to K+ excretion in acidosis?

A

Decreases we need a more alkaline environment and loosing it would cause further acidosis.

20
Q

Aldosterone is secreted by?

A

zona glomerulosa of adrenal gland in response to high K+

21
Q

What stimulates and inhibits aldosterone release?

A

corticotrophin (ACTH) } stimulatory
angiotensin II (ANG II)
inhibitory
- Atrial Natriuretic Peptide (AN P)

22
Q

What does insulin do to K+?

A

Insulin is agonist for Na/k ATPase pump therefore K+ moves into cells.

23
Q

What species is prone to hyperkalaemic periodic paralysis (HYPP)?

A

The horse

24
Q

What type of cat is prone to hypokalaemic periodic paralysis?

A

Burmese cats.