control of water and electrolytes

Question 1

water is gained by which 2 methods?

Answer 1

• ingestion

- formed in metabolism

Question 2

water is lost by which 2 methods?

Answer 2

• excretion

- evaporation

Question 3

how much water does the average person gain and lose per day?

Answer 3

2400ml

Question 4

which hormone is the main control for water?

Answer 4

ADH

Question 5

how are sodium levels controlled?

Answer 5

• renin-angiotensin-aldosterone system

- atrial natriuretic hormone

Question 6

what does the renin-angiotensin-aldosterone system do?

Answer 6

• promote reabsorption of sodium and water in distal convoluted tubule

Question 7

what is angiotensin?

Answer 7

potent vasoconstrictor

Question 8

what does atrial natriuretic hormone do?

Answer 8

increase excretion of sodium and water

Question 9

which hormone has the opposite effect of atrial natriuretic hormone?

Answer 9

aldosterone

Question 10

which hormone regulates potassium levels?

Answer 10

aldosterone

Question 11

hypo secretion of ADH causes what condition?

Answer 11

diabetes insipidus

Question 12

hyper secretion of ADH results in what?

Answer 12

water retention

Question 13

what effect does increased ECF potassium have on nerve function?

Answer 13

depolarisation causing APs and prolonged refractory period

Question 14

how do potassium salts in toothpastes work to desensitises teeth?

Answer 14

• potassium ions diffuse along dentinal tubules raising potassium concentration at the inner end of the tubule
• this depolarises the nerve, sodium channels are inactivated, and prolonged refractory period is sustained