Physiology

Question 1

What are the 2 stimuli for ADH release

Answer 1

hypothalamic osmoreceptors

left atrial stretch receptors

Question 2

when is aldosterone secreted?

Answer 2

in response to increased potassium and decreased sodium in the blood
activation of RAAS

Question 3

what does atrial natriuretic peptide promote?

Answer 3

excretion of sodium

Question 4

what cells release renin?

Answer 4

granular cells

Question 5

tracer used to measure
total body water (TBW)?
ECF?
plasma?

Answer 5

TBW - 3H2O
ECF - inulin
plasma - labelled albumin

Question 6

is there always more Na and Cl outside or inside the cell?

Answer 6

always more Na and Cl outside the cell

always more K inside the cell

Question 7

what is the osmotic conc of ECF? ICF?

Answer 7

both the same - 300mosmol/l

Question 8

what is the most common type of nephron in the human body? what type of urine do they produce?
capillary feature?

Answer 8

cortical
they produce dilute urine
peritubular network of capillaries

Question 9

juxtamedullary nephrons
short or long loop of henle?
capillary feature?

Answer 9

long loop of hence

single capillary called the vasorectum

Question 10

how is GFR calculated?

Answer 10

filtration coefficient (how ‘holey’ the membrane is) x net filtration pressure

Question 11

what are the 2 types of auto-regulation in the kidney?

Answer 11

myogenic - if vascular smooth muscle is stretched, it contracts
tubuloglomerular feedback - if more NaCl is flowing through the tubule it is sensed and constriction of the afferent arterioles occurs

Question 12

what is used to measure renal plasma flow?

Answer 12

para amino hippuric acid

Question 13

what is filtration fraction?

Answer 13

the fraction of plasma flowing through the glomeruli that is filtered into the tubules

Question 14

equation for plasma clearance

Answer 14

rate of excretion of x / plasma conc of x

Question 15

is clearance of reabsorbed/secreted substance constant once transport maximum has been reached?

Answer 15

no

Question 16

does blood osmolality of the vast recta rise or fall as it dips into the medulla?

Answer 16

blood osmolality rises as it dips into the medulla and falls again as it rises back up

Question 17

what are the three sources of H+ ions

Answer 17

1. the largest is carbonic acid formation
2. inorganic acids produced during breakdown of nutrients
3. organic acids resulting from metabolism i.e. lactic acid

Question 18

when bicarbonate is low, what do secreted hydrogen ions combine with? what is the max amount that can be secreted per day?

Answer 18

phosphate - the next most plentiful buffer

max amount secreted per day = 40 mmol

Question 19

what happens if acidosis persists and all filtered phosphate has combined

Answer 19

the kidneys use ammonia to create new bicarb

Question 20

what is the normal plasma pH, bicarb and arterial PCO2

Answer 20

plasma pH - about 7.4
bicarb - about 25
arterial PCO2 - about 40

Question 21

what is the pH proportional to ?

Answer 21

conc of bicarb / conc of CO2

Question 22

what is used if its essential to get accurate assessment of GFR?

Answer 22

51Cr-EDTA clearance

Question 23

where is the sodium chloride co transporter? what is it blocked by?

Answer 23

in the distal tubule

blocked by thiazide diuretics

Question 24

where is the sodium potassium exchanger? what blocks it?

Answer 24

in the collecting duct

blocked by K sparing diuretics e.g. spironolactone

Question 25

how do anions enter at the basolateral membrane?

Answer 25

either by diffusion or exchange for alpha-KG via OATs

Question 26

at the apical membrane, how do anions enter the lumen?

Answer 26

via MRP2 or OAT4

Question 27

how do cations enter the lumen at the apical membrane?

Answer 27

via either MRP1 or oc+/H+ anti porters

Question 28

what is the indirect result of loop diuretics? what is this beneficial in?

Answer 28

venodilation | beneficial in acute pulmonary oedema

Question 29

how do loop diuretics enter the nephron?

Answer 29

by OAT

Question 30

what do loop diuretics cause loss of?

Answer 30

potassium

Question 31

side effects of loop diuretics

Answer 31

hypomagnesia and hypocalcaemia increased toxicity of digoxin and class 3 antidysarrhythmic drugs e.g. amiodarone metabolic alkalosis hyperuricaemia

Question 32

Do thiazides cause hypocalcaemia?

Answer 32

no they increase reabsorption of Ca2+

Question 33

adverse effects of thiazide diuretics

Answer 33

``` hypokalaemia hypomagnesia metabolic alkalosis hyperuricaemia male sexual dysfunction if used at high dose impaired glucose tolerance ```

Question 34

how do potassium sparing diuretics work?

Answer 34

they block the apical sodium potassium channel causing decreased sodium reabsorption and decreased potassium secretion >> sodium loss, potassium gain

Question 35

``` Osmotic diuretics example how are they given what part of the nephron do they act on effect when are they used ```

Answer 35

mannitol given IV bc they're extremely polar act on proximal tubule they hold onto water and cause decreased sodium reabsorption used in prevention of acute hypovolaemic renal failure and acutely raised IOP and ICP

Question 36

what channel does aldosterone activate? where?

Answer 36

ENAC at the apical membrane

Question 37

what receptors does ADH act on ? where? | what does this cause

Answer 37

vasopressin receptors at the basolateral membrane | causes aquaporins to be inserted onto the apical membrane which water diffuses in across

Question 38

diabetes insipidus difference between neurogenic and nephrogenic? treatment of each?

Answer 38

``` neurogenic = lack of vasopressin secretion from the posterior pituitary. treated with desmopressin nephrogenic = inability of nephron to respond to vasopressin. usually x linked recessive mutation in the v2 receptor gene. no current treatment ```

Question 39

what drugs cause water loss without accompanying sodium?

Answer 39

aquaretics "vaptans"

Question 40

when are aquaretics of value?

Answer 40

in hypervolaemic hyponatraemia

Question 41

example of a SGLT2 inhibitor

Answer 41

canagliflozin

Question 42

where to SGLT2 inhibitors work?

Answer 42

proximal tubule