High Yield Physiology Concepts

Question 1

Site of erythropoietin (EPO) production

Answer 1

Interstitial cells of the peritubular capillaries

Question 2

Active form of Vitamin D

Answer 2

1,25-dihydroxycholecalciferol (calcitriol)
1st hydroxylation happens in the liver (via 25-alpha hydroxylase)
2nd hydroxylation happens in the kidney (via 1-alpha hydroxylase)

Question 3

Contains vasa recta and has longer loops of Henle

Answer 3

Juxtamedullary nephrons (less common than cortical nephrons)

Question 4

Components of the juxtaglomerular apparatus

Answer 4

Macula densa (walls of the distal tubule; detects changes in BP)
JG cells (walls of the afferent arteriole; secretes renin)
Lacis cells (unknown function)

Question 5

Physiologic functions of renin

Answer 5

None

merely converts angiotensinogen from the liver to angiotensin I

Question 6

Physiologic function of angiotensin I

Answer 6

None

merely converted to angiotensin II due to ACE in the lungs

Question 7

Physiologic function of angiotensin II

Answer 7

Vasoconstricts afferent and efferent arteriole (efferent> afferent)
Systemic vasoconstriction
Stimulates thirst
Increases ADH, cortisol, epinephrine, norepinephrine and aldosterone

Question 8

Site of aldosterone production

Answer 8

Zona glomerulosa of the adrenal cortex

Question 9

Aldosterone actions

Answer 9

Increases Na+ reabsorption, K+ secretion, H+ secretion

Question 10

ADH actions

Answer 10

Insertion of aquaporins (QP-2) in the collecting ducts

Question 11

Triggers for ADH secretion

Answer 11

Increased plasma osmolarity
Decreased blood volume
Decreased blood pressure

Question 12

Increases GFR

Answer 12

Afferent arteriolar vasodilation

Moderate efferent arteriolar vasoconstriction

Question 13

Decreases GFR

Answer 13

Afferent arteriolar vasoconstriction
Efferent arteriolar vasodilation
Severe efferent arteriolar vasoconstriction

Question 14

Principal cells

Answer 14

Absorb Na+ and H2O and secrete K+

Question 15

Intercalated cells

Answer 15

Absorb K+ and secrete H+

Question 16

Tubuloglomerular feedback

Answer 16

Macula densa feedback
“Constant load delivered to the distal tubule”
Primary Mechanism for autoregulation of GFR

Question 17

Glomerotubular balance

Answer 17

“Percentage of solute reabsorbed is held constant”

Question 18

Substances with no transport maximum and renal threshold

Answer 18

Sodium and all passively transported solutes

Exhibits gradient-time transport

Question 19

Ascending limb of the Loop of Henle is permeable to

Answer 19

Solutes (Mnemonic: asinding limb is permeable to solutes)

Impermeable to water

Question 20

Descending limb of the Loop of Henle is permeable to

Answer 20

Water

Impermeable to solutes

Question 21

Normal pH in various fluid suites

Answer 21

Arterial blood: 7.4
Venous blood, interstitial blood: 7.35
Intracellular fluid: 6.0-7.4
Urine: 4.5-8.0
Gastric HCI: 0.8
Vaginal secretions: 3.5-4.5

Question 22

Acid-base abnormalities caused by diuretics

Answer 22

Metabolic acidosis: acetazolamide (Mnemonic: acidazolamide)

Metabolic: alkalosis: loop diuretics, thiazide diuretics

Question 23

Intact Nephron Hypothesis by Neil Bricker

Answer 23

Decreases in the number of functioning nephrons causes remaining nephrons to carry a larger burden of transport, synthetic function and regulatory function

Question 24

Bricker’s Trade-Off Hypothesis

Answer 24

Some physiologic adaptations to nephron loss also produce unintended clinical consequences

Question 25

Hyperfiltration Hypothesis by Barry Brenner

Answer 25

Some adaptations accelerate the deterioration of residual nephrons