control of water and electrolytes

Question 1

how is water gained by the body?

Answer 1

• water ingested in food and drinks
• water formed in metabolism

Question 2

how is water lost by the body?

Answer 2

• through excretion eg urine and faeces
• through evaporation eg sweat and expired air

Question 3

which factor within water balance is under homeostatic control?

Answer 3

urinary excretion

Question 4

renal function and anatomy

Answer 4

Glomerulus
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting ducts

Question 5

what is the glomerular filtration rate and what is its value?

Answer 5

estimates how much blood passes through the glomeruli (in kidneys) each minute
120ml/min

Question 6

what opposes the capillary hydrostatic blood pressure?

Answer 6

plasma protein oncotic pressure

Question 7

what is the proximal convoluted tubule?

Answer 7

a segment of the renal tubule responsible for the reabsorption and secretion of various solutes and water

Question 8

what occurs in the proximal convoluted tubule?

Answer 8

• obligatory reabsorption of 60-70% of glomerular filtrate
• secretion of H+
• active transport, facilitated diffusion

Question 9

what is the loop of henle?

Answer 9

long U-shaped portion of the proximal convoluted tubule that conducts urine

Question 10

what is important for concentration of urine?

Answer 10

loop of henle

Question 11

what occurs in the distal convoluted tubule?

Answer 11

Reabsorption of water, Na+, Cl–, Ca2+
Secretion of H+, K+

Question 12

what is the activity of the distal convoluted tubule controlled by?

Answer 12

hormones
- aldosterone
- atrial natriuretic hormone
- ADH
- parathyroid hormone

Question 13

what occurs in the collecting ducts?

Answer 13

water reabsorption under influence of ADH

Question 14

what regulates water and electrolytes?

Answer 14

Antidiuretic Hormone (ADH)
Renin-angiotensin-aldosterone
Atrial Natriuretic Hormone (ANH)

Question 15

what is another name for hormone ADH?

Answer 15

vasopressin

Question 16

where is ADH produced?

Answer 16

hypothalamus

Question 17

where is ADH released?

Answer 17

posterior pituitary gland

Question 18

where does ADH act?

Answer 18

on distal convoluted tubules (distal end) and collecting ducts to increase water permeability

Question 19

what increases ADH secretion?

Answer 19

• decreased extracellular fluid volume
• increased extracellular fluid osmolarity

Question 20

what are electrolytes?

Answer 20

ions present in intra/extra cellular fluid

Question 21

what controls electrolyte ion secretion?

Answer 21

kidneys (not only)

Question 22

how is renin-angiotensin-aldosterone system involved in Na+ control?

Answer 22

Promotes reabsorption of Na+ (and water) in DCT; exchange for K+, H+
Angiotensin is a potent vasoconstrictor

Question 23

how is atrial natriuretic hormone involved in control of Na+?

Answer 23

Increases excretion of Na+ (and water)
Opposite effects to aldosterone

Question 24

what regulates K+?

Answer 24

aldosterone

Question 25

what are the effects of hypo secretion of ADH?

Answer 25

• diabetes insipidus
• large volumes of insipid urine

Question 26

what are the effects of hyper secretion of ADH?

Answer 26

• syndrome of inappropriate ADH
• excess ADH leading to water retention

Question 27

K+ on nerve function