renal control of acid-base status and renal endocrinology

Question 1

how does the kidney retain water

Answer 1

through antidiuretic hormone AKA vasopressin

Question 2

ADH: created in? acts on? effect?

Answer 2

• created in the posterior pituitary
• acts on the collecting ducts and distal renal tubule
• effect: resorption of water

Question 3

how does the kidney regulate calcium and phosphorous?

Answer 3

parathyroid hormone

Question 4

parathyroid hormone: created in? acts on? effect?

Answer 4

• created in the parathyroid gland
• acts on the kidney (distal tubules), bones, intestines
• effect is net absorption of calcium and excretion of phosphorus

Question 5

what is parathyroid hormone related peptide (PTHrp)

Answer 5

occasionally expressed in a variety of types of neoplasia - acts just like PTH!

Question 6

how does the kidney retain sodium

Answer 6

through aldosterone

Question 7

aldosterone: created in? acts on? effect?

Answer 7

• created in the zona glomerulosa cells of the adrenal cortex
• acts on the cortical collecting tubule/distal tubules
• effect is sodium reabsorption and potassium excretion in distal tubules (also important acid-base regulation)

Question 8

what are the stimuli for aldosterone

Answer 8

• increased blood potassium concentration
• angiotensin II

Question 9

what does aldosterone stimulate

Answer 9

• the sodium potassium ATPase pump on the basolateral membrane of the cortical collecting tubules
• also the hydrogen ion excretion from the collecting tubules

Question 10

how does the kidney retain sodium

Answer 10

angiotensin II

Question 11

angiotensin II: created in? acts on? effect?

Answer 11

• created in the liver (angiotensinogen -> AT I (renin) -> ATII (ACE in the lungs) -> kidney
• acts on the proximal tubules, loops of henle, and distal tubules and collecting tubules, efferent arterioles
• effect: robust conservation of sodium and water from the renal tubules

Question 12

what is the body’s most powerful sodium retaining hormone

Answer 12

angiotensin II

Question 13

angiotensin II is increased when:

Answer 13

there is excessive loss of extracellular fluid volume or low blood pressure events

Question 14

angiotensin II stimulates ____ secretion which in turn increases sodium resorption

Answer 14

aldosterone

Question 15

angiotensin II constricts the efferent arterioles and this reduces:

Answer 15

peritubular capillary hydrostatic pressure which increases net tubular reabsorption from proximal tubules

Question 16

what does the macula densa sense

Answer 16

decreases in NaCl

Question 17

what does the juxtaglomerular cells sense

Answer 17

decrease in blood pressure

Question 18

how does the heart affect the kidney’s regulation of blood pressure

Answer 18

atrial natriuretic peptide (ANP)

Question 19

ANP: created in? acts on? effect?

Answer 19

• created in the atrial myocardium
• acts on the kidney
• effect is increase sodium excretion

Question 20

ANP is stimulated by:

Answer 20

high blood volume in the atria

Question 21

release of ANP causes:

Answer 21

• direct decrease in sodium reabsorption in the distal tubules
• inhibition of renin production by the juxtaglomerular cells, leading to all the downstream affects of decreased angiotensin II

Question 22

which of the following hormones has effects that increase sodium resorption in the blood?

• aldosterone
• angiotensin II
• vasopressin
• ANP
• PTH

Answer 22

aldosterone and angiotensin II

Question 23

what is the general systemic effect of increasing your blood sodium

Answer 23

increase in blood pressure

Question 24

regulation of H+ in the blood by:

Answer 24

• secretion of H+
• reabsorption, creation, secretion of HCO3-

Question 25

what is the net effect of cellular mechanisms of acid-base control

Answer 25

for every H+ that is secreted into the lumen, 1 HCO3- is absorbed

Question 26

what are the two big urinary buffers

Answer 26

• ammonia buffer
• phosphate buffer

Question 27

what is the outcome of ammonia buffer

Answer 27

H+ bound to NH3 constitutes a net GAIN of HCO3-

Question 28

what occurs in alkalosis

Answer 28

• tubular secretion of H+ is reduced to a level that is too low to achieve complete HCO3- resorption
• enabling the kidneys to excrete HCO3- into the urine
• no excess H+ is available to combine to with the nonbicarbonate buffers, so no additional bicarb is made and resorbed wither

Question 29

what occurs in acidosis

Answer 29

• tubular secretion is sufficient to resorb the filtered HCO3-, with extra left over to bind with the nonbicarbonate budders - ammonia excretion

Question 30

stimulus for increased H+ secretions are:

Answer 30

• increased PCO2 (respiratory acidosis)
• increased H+ in the blood
• aldosterone

Question 31

paradoxial aciduria

Answer 31

low potassium

• decreased K intake
• metabolic alkalosis - causes the shift of potassium out of the blood and into the cells (left displaced abomasum)
• effect of aldosterone - potassium wasting (hypovolemia)

(aciduria in the face of alkalosis)