Renal Endocrine

Question 1

is the principal circulating form of vitamin D.

Answer 1

25-hydroxycholecalciferol

Question 2

The enzyme is responsible for the hydroxylation step necessary to produce 1,25-(OH)2-cholecalciferol from 25-hydroxycholecalciferol.

Answer 2

1-alpha-hydroxylase

Question 3

Vitamin D3, which can be acquired from milk in the diet, is known as .

Answer 3

CHOLECALCIFEROL

Question 4

When it comes to new bone, the role of vitamin D is to promote .

Answer 4

Mineralization

Question 5

The major actions of 1,25-dihydroxycholecalciferol are on the , kidneys and bones.

Answer 5

INTESTINE
KIDNEY
BONES

Question 6

25-hydroxycholecalciferol is bound to a/an in plasma.

Answer 6

alpha-globulin

Question 7

25-hydroxycholecalciferol is physiologically (active/inactive) .

Answer 7

INACTIVE

Question 8

On the intestine, 1,25-dihydroxycholecalciferol increases calcium and phosphate absorption, by inducing the synthesis of a vitamin D-dependent calcium-binding protein known as .

Answer 8

Calbindin D-28k

Question 9

The second major regulator of calcium and phosphate metabolism (after parathyroid hormone) is .

Answer 9

Vitamin D

Question 10

The enzyme 1-alpha-hydroxylase is (stimulated/inhibited) by low concentrations of calcium and phosphate.

Answer 10

STIMULATED

Question 11

In the kidneys 25-hydroxycholecalciferol can be hydroxylated at the carbon-1 position to the active form known as .

Answer 11

1,25-(OH)2D3 (calcitriol).

Question 12

1,25-dihydroxycholecalciferol action on the kidney is to stimulate calcium (and/but not) phosphate absorption.

Answer 12

AND

Question 13

Vitamin D is a (polypeptide/steroid) hormone

Answer 13

Steroid

Question 14

Cholecalciferol is produced in the skin from in the presence of ultraviolet light, and also acquired from the diet.

Answer 14

7-dehydrocholesterol

Question 15

The action of vitamin D is to (increase/decrease) both calcium and phosphate concentrations in plasma

Answer 15

INCREASE

Question 16

The hydroxylation of cholecalciferol is regulated by (positive/negative) feedback mechanisms.

Answer 16

Negative

Question 17

Cholecalciferol is hydroxylated in the liver to form

Answer 17

25-hydroxycholecalciferol.

Question 18

Calbindin D-28K is the calcium-binding protein induced by in the intestine.

Answer 18

Calcitriol

Question 19

Decreased plasma calcium and _____ concentration stimulate the enzyme 1-alpha-hydroxylase.

Answer 19

phosphate

Question 20

In bone, 1,25-dihydroxycholecalciferol acts together with to stimulate osteoclast activity and bone resorption.

Answer 20

PTH

Question 21

The enzyme 1-alpha-hydroxylase is stimulated by (hormone) .

Answer 21

PTH

Question 22

Cholecalciferol is physiologically (active/inactive)

Answer 22

INACTIVE

Question 23

Vitamin D increases the plasma concentration of calcium (and/but not of) phosphate.

Answer 23

AND

Question 24

Low concentrations of and phosphate stimulate the enzyme 1-alpha-hydroxylase.

Answer 24

Calcium

Question 25

Vitamin D2, which can be acquired from plant foods in the diet, is known as .

Answer 25

Ergocalciferol

Question 26

When hypoxia occurs there is increased production of , which is the first step in erythropoietin synthesis.

Answer 26

Hypoxia-Inducible factor 1 alpha

Question 27

Decreased function of renal tissue results in decreased erythropoietin synthesis, which can cause .

Answer 27

ANEMIA

Question 28

Hypoxia-inducible factor 1-alpha acts on fibroblasts in the renal cortex and medulla to cause synthesis of for erythropoietin.

Answer 28

mRNA

Question 29

When the oxygen content of arterial blood is (increased/decreased) , the kidney is signalled to produce more erythropoietin.

Answer 29

DECREASED

Question 30

is a treatment option for anemia of chronic renal failure.

Answer 30

Recombinant EPO

Question 31

The are the ideal site for erythropoietin synthesis because they can determine whether the decreased oxygen delivery is due to decreased blood flow or decreased oxygen content of arterial blood.

Answer 31

KIDNEYS

Question 32

Erythropoietin acts to induce differentiation of .

Answer 32

PROERTHYTOBLASTS