2.2 Reabsorption

Question 1

mechanism of glucose reabsorption in nephron

Answer 1

secondary active transport, energy from transport of Na+ down its gradient

Question 2

where is majority of glucose reabsorbed?

Answer 2

PCT

Question 3

Tm

Answer 3

maximum tubular resorptive capacity for a solute

Question 4

what happens to any glucose not reabsorbed in PCT?

Answer 4

stays in nephron and excreted as urine

Question 5

limit for glycosuria

Answer 5

10mmol/L

Question 6

why is glycosuria common in pregnancy?

Answer 6

Tm for glucose falls

Question 7

normal plasma conc of amino acids

Answer 7

2.5-3.5mmol/L

Question 8

mechanism of amino acid reabsorption. how easy is it to filter AAs through glomerulus?

Answer 8

-secondary active transport in PCT, symport with Na+
energy from ATPase
-easily filters through glomerulus

Question 9

is amino acid reabsorption Tm limited?

Answer 9

yes

Question 10

aetiology of central diabetes insipidus

Answer 10

impaired ADH synthesis/secretion by hypothalamus, due to damage
-brain injury
-tumour
-sarcoidosis/TB
-aneurysm
-meningitis

Question 11

treatment for central diabetes insidious

Answer 11

ADH (desmopressin)

-injections
-nasal spray

Question 12

aetiology of nephrogenic diabetes insipidus

Answer 12

-mutations in gene coding for V2 recptors
-chronic pylonephritis
-polycystic kidneys
-lithium drugs

Question 13

what is nephrogenic diabetes insipidus?

Answer 13

acquired insensitivity of kidney to ADH, water inadequately reabsorbed from collecting ducts, normal plasma ADH

Question 14

treatment of nephrogenic diabetes insipidus

Answer 14

none, thiazides can help Na+ excretion

Question 15

in which parts of nephron can reabsorption be controlled?

Answer 15

DCT, collecting duct

Question 16

SIADH

Answer 16

-excessive ADH release from Posterior pituitary gland, or tumour
-dilution hyponatraemia (too much water reabsorbed), not enough Na+ in plasma
-increased total body fluid