Renal Regulation of Water and Acid-Base Balance

Question 1

Equation for osmolarity

Answer 1

concentration x no of dissociated particles

units Osm/L or mOsm/l

Question 2

List examples of unregulated water loss.

Answer 2

sweat
faeces
vomit
water evaporating from resp lining and skin

Question 3

List an example of regulated water loss.

Answer 3

urine production

Question 4

What percentage of water is reabsorbed in the proximal convoluted tubule?

Answer 4

67%

Question 5

What condition is required for water to be reabsorbed into the loop of Henle and collecting duct?

Answer 5

medullary interstitium must be hyperosmotic to provide a gradient

Question 6

By what mechanism does the loop of Henle concentrate urine?

Answer 6

countercurrent multiplication

Question 7

urea recycling

Answer 7

SLIDE

Question 8

Amino acid length of ADH

Answer 8

9

Question 9

another name for ADH?

Answer 9

vasopressin

Question 10

main function of ADH

Answer 10

promote water reabsorption from collecting duct

Question 11

where is ADH produced?

Answer 11

hypothalamus

neurons in supraoptic and paraventricular nuclei

Question 12

where is ADH stored?

Answer 12

posterior pituitary

Question 13

how are changes in plasma osmolarity detected?

Answer 13

osmoreceptors in hypothalamus

Question 14

normal plasma osmolarity in a healthy adult?

Answer 14

275-290 mOsm/kg

Question 15

What % change is required for detection by baroreceptors?

Answer 15

5-10

Question 16

stimulatory factors that influence ADH production and release

Answer 16

^ plasma osmolarity
decreased BP
hypovolaemia
nausea
angiotensin II
nicotine

Question 17

inhibitory factors that influence ADH production and release

Answer 17

decreased plasma osmolarity
hypervolemia
^ BP
ethanol
atrial natruiretic peptide

Question 18

mechanism of action of ADH

Answer 18

ADH acts on a G-protein coupled receptor > (adenylate cyclase > cAMP > pkA) > ^transcription + insertion Aquaporin–2 channels to apical membrane of the DCT + CD > ^ permeability to water > water moves out of nephron > into blood stream

Question 19

list examples of ADH-related clinical disorders

Answer 19

central diabetes insipidus
nephrogenic diabetes insipidus
syndrome of inappropriate ADH secretion

Question 20

cause of central diabetes insipidus

Answer 20

decreased/negligent production and release of ADH

Question 21

clinical features of central diabetes insipidus

Answer 21

polyuria

polydipsia

Question 22

treatment for central diabetes insipidus

Answer 22

external ADH

Question 23

cause for SIADH

Answer 23

increased production and release of ADH

Question 24

clinical features of SIADH

Answer 24

hyperosmolar urine
hypervolemia
hyponatremia

Question 25

treatment for SIADH

Answer 25

non-peptide inhibitor of ADH receptor (conivaptan & tolvaptan)

Question 26

cause of nephrogenic diabetes insipidus

Answer 26

less/mutant AQP2 | mutant V2 receptor

Question 27

symptoms of nephrogenic diabetes insipidus

Answer 27

polyuria | polydipsia

Question 28

treatment for nephrogenic diabtes insipidus

Answer 28

thiazide diuretics and NSAIDs

Question 29

role of kidneys in acid base balance

Answer 29

secretion and excretion of H+ reabsorption of HCO3- production of new HCO3-

Question 30

what enzyme catalyses the reaction between CO2 and H20?

Answer 30

carbonic anhydrase

Question 31

majority of HCO3- is reabsorbed where?

Answer 31

PCT

Question 32

how is HCO3- reabsorbed in PCT?

Answer 32

CO2 diffuses in > catalysed by carbonic anhydrase with H20 > H+ + HCO3- > via NA+ - HCO3- symporter to blood stream

Question 33

function of alpha intercalated cell

Answer 33

HCO3- reabsorption & H+ secretion

Question 34

function of beta intercalated cell

Answer 34

HCO3- secretion & H+ reabsorption

Question 35

production of NEW bicarbonate ion in the PCT

Answer 35

glutamine broken down into 2NH4+ and A2- > A2- to 2HCO3- > absorbed into blood NH4+ removed via Na+ antiporter or NH3 removed over membrane and H+ via Na+ antiporter

Question 36

production of NEW bicarbonate ion in the DCT + CD

Answer 36

in alpha intercalated cell | water + CO2 > H+ + HCO3- > transported via Cl- - HCO3- antiporter

Question 37

characteristics of metabolic acidosis

Answer 37

decreased HCO3- | decreased pH

Question 38

characteristics of metabolic alkalosis

Answer 38

increased HCO3- | increased pH

Question 39

characteristics of respiratory acidosis

Answer 39

increased pCO2 | decreased pH

Question 40

characteristics of respiratory alkalosis

Answer 40

decreased pCO2 | increased pH

Question 41

compensatory response for metabolic acidosis

Answer 41

increased ventilation to blow off CO2 | ^ [HCO3-] reabsorption and production

Question 42

compensatory response for metabolic alkalosis

Answer 42

decreased ventilation | ^ [HCO3-] excretion

Question 43

compensatory response for acute respiratory acidosis

Answer 43

intracellular buffering

Question 44

compensatory response for chronic respiratory acidosis

Answer 44

^ [HCO3-] reabsorption and production

Question 45

compensatory response for acute respiratory alkalosis

Answer 45

intracellular buffering

Question 46

compensatory response for chronic respiratory alkalosis

Answer 46

decreased [HCO3-] reabsorption and production