2 Renal Physiology refresher and Mendelian forms of HTN

Question 0

Effects of adding fluids

Answer 0

Hypotonic NaCl - Increases intracellular fluid more than extracellular
Isotonic NaCl- Increases extracellular fluid only
Hypertonic NaCl- increases extracellular shrinks intracellular compartmments

Question 1

Fluid distribution

Answer 1

2/3 intracellular.

280-300 mOsm/l

Question 2

Net filtration pressure

Answer 2

usually 10mmHg = 60(glomerular hydrostatic) - 18(bowmans capsule pressure) - 32 (glomerular oncotic pressure)

Question 3

Normal GFR

Answer 3

125 ml

Question 4

GFR

Answer 4

GFR= ultrafiltration coefficient (net filtration force)

Question 5

Relationship between GFR and MAP

Answer 5

No change in GFR with higher BP because of autoregulation.

• myogenic
• tubuloglomerular feedback

Question 6

Hormones that decrease GFR

Answer 6

NE, Epinephrine, Endothelin (all by increasing constriction)

Question 7

Hormone with no change in GFR/ prevention of decreasing GFR

Answer 7

ANGII (preferentially constricts efferent arteriole)

Question 8

Hormones/substances that increase GFR

Answer 8

Endothelal derived NO

Prostaglandins

Question 9

Filtration barrier

Answer 9

Fenestrations = 700 angstroms
Basement membrane= IV collagen, laminin, fibronectin (neg proteins)
Podocyte slit pores = 40-140 angstroms

Question 10

Solubility of proteins

Answer 10

Myoglobin (17kDa) .75

Albumin (69 kDa) .005

Question 11

Thin descending loop function

Answer 11

passive resorption of water 2/2 cortical medullary osmotic gradient

Question 12

Thin ascending limb function

Answer 12

Passive resorption of sodium and excretion of urea to dilute tubular fluid

Question 13

Thick ascending limb

Answer 13

• 25%sodium resorbed by NA/K/CL transporter
• Na resorbed in exchange for H+
• Sodium potassium ATP pump on interstitial side
• Chloride pore on interstitial side
• positive luminal fluid also pushes K, Na, MG, and Ca into interstitium via paracellular diffusion

Question 14

Furoseminde

Answer 14

Blocks NA, K, CL cotransporter

Question 15

Early distal tubule

Answer 15

• Paracellular Mg, Ca resorption
• NaCl cotransporter resption
• Na/K ATPase on interstitial side
• Cl channel on interstitial side

Question 16

Late distal tubule and collecting duct

Answer 16

• Resorbs Na, secretes K (via interstitial NA/K atpase and KC and ENaC on luminal side)
• aldosterone dependant
• ADH causes aquoporin translocation

Question 17

Medullary collecting duct

Answer 17

• Na resorption via NaK atpase and ENaC
• ADH aquoporin translocation
• Urea resorption in medullary collecting duct

Question 18

Aldosterone

Answer 18

^ NaK atpase activity

Question 19

ANP

Answer 19

Decreases NaCL resorption in distal tubule and collecting tubule and duct.

Question 20

ANGII

Answer 20

• Increases Na and H20 resorption in proximal tubule through NaK atpase on intertitial side and NaHCO3- cotransporter
• increases H secretion through NaH exchanger

MOST IMPORTANT FOR SODIUM RETENTION

Question 21

ADH

Answer 21

Increases H2O resorption from late distal tubule on

Question 22

PTH

Answer 22

Decreases proximal PO4 resorption

Increases CA++resorption in thick ascending and early distal tubule.

Question 23

AME (Apparent Mineralocorticoid Excess)

Answer 23

• Presentation: Low weight, FTT, early childhood severe hypotension, organ damage, renal failure
• Clinical S/S: Hypertension, hypokalemia, metabolic alkylosis, low plasma renin activity, low plasma aldosterone

Question 24

AME cause

Answer 24

*Deficiency in 11B HSD2 - converts cortisol into cortisone (resulting in high active cortisol concentrations and binding of cortisol to MR) Common on consanguineous relationships (kissing cousins)

Question 25

Liddle synddrome

Answer 25

*HTN, Hypokalemia, Metaboolic alkylosis, Low plasma renin activity, LOW PLASMA AND URINARY ALDOSTERONE.

Question 26

Liddle syndrome cause

Answer 26

*constituatively open ENaC | SCNN1G or SCNN1B gene mutations

Question 27

AME treatment

Answer 27

Condition usually recognized too late for treatment to be effective. Amiloride and Triamterene (block sodium channel) Spironolactone and Eplerenone (block MR) Dexamethasone (Block ACTH)

Question 28

Liddle Syndrome treatment

Answer 28

Amiloride and Triamterene (block sodium channel) | good prognosis with treatment

Question 29

Bartter syndrome

Answer 29

Early childhood presentation * Growth and mental retardation, polyuria, polydipsia, * HYPERCALCEMIA, hypokalemia, hyperreninemia,hyperaldosteronism, metabolic alkylosis, HYPOTENSION

Question 30

Gitelman Syndrome

Answer 30

Adolescent or adult presentation *cramping, fatigue, plyuria,noctura *HYPOMAGNESEMIA HYPOtension

Question 31

Barter and Gitelman causes

Answer 31

Autosomal recessive *NaCl resorption problems *RAS activation and hyperaldosteronism Bartter is NA/K/CL transporter in thick ascending Gitelman is NaCl transporter in distal tubule