Calcium Homeostasis

Question 1

what is the normal range for blood calcium?

Answer 1

9-11 (or 8.5-10.5) mg/100mL

Question 2

hypocalcemia causes chief cells of the parathyroid gland to release ____

Answer 2

parathyroid hormone (PTH)

Question 3

target organs of PTH

Answer 3

bone
kidney

Question 4

PTH action on bone

Answer 4

increases osteoclasts

Question 5

what is the effect of PTH on calcium & phosphate absorption in the kidney?

Answer 5

increase Ca absorption
decrease phosphate absorption
(increases phosphate in urine by phosphate buffer system)

Question 6

PTH in the kidney causes formation of…

Answer 6

1,25 (OH)2 vitamin D3
AKA 1,25 (OH)2 cholecalciferol
AKA calcitriol

Question 7

what is the effect of calcitriol?

Answer 7

increases Ca and Phosphorus absorption from intestines

Question 8

hypercalcemia causes parafollicular cells of the thyroid gland to release ____

Answer 8

calcitonin

Question 9

target organs of calcitonin

Answer 9

bone
kidney

Question 10

action of calcitonin on bone

Answer 10

increases osteoblasts

Question 11

action of calcitonin on kidney

Answer 11

decrease Ca absorption
increase phosphate absorption

Question 12

the kidney impacts absorption of Ca and phosphorus from the intestines in response to…

Answer 12

PTH (low Ca or high phosphorus in blood)

Question 13

PTH turns on the enzyme ____ and converts…

Answer 13

1-a hydroxylase
25 hydroxycholecalciferol -> 1,25 dihydroxycholecalciferol (vitamin D3 /calcitriol)

Question 14

what increases the rate of excretion of Ca ions by the kidney?

Answer 14

decrease in plasma level of PTH

Question 15

secretion of PTH is stimulated by ____

Answer 15

hypocalcemia

Question 16

function of ____ is increased by elevated PTH concentration

Answer 16

osteoclasts

Question 17

what is the mechanism of weightlifting increasing bone mass?

Answer 17

mechanical stress on bones increases osteoblast activity

Question 18

exposure to UV light directly facilitates…

Answer 18

conversion of cholesterol to 25-hydroxycholicalciferol

Question 19

a patient with renal failure and high vitamin D3 is unable to form…

Answer 19

1,25-dihydroxycholecalciferol in the kidneys

Question 20

what are 2 ways for the body to get vitamin D3?

Answer 20

1. diet
2. UV light exposure (7-dehydrocholesterol -> vitamin D3/cholecalciferol)

Question 21

in the liver, cholesterol is converted to ____

Answer 21

7-dehydrocholesterol

Question 22

Elevation of serum calcium concentration would cause the release of ____

Answer 22

Calcitonin