Calcium

Question 1

What are the best sources of calcium?

Answer 1

milk and dairy

Question 2

Calitriol induces the synthesis of what 3 calcium transport proteins?

Answer 2

• TRPV6
• Calbindin D9K
• Vit D dependent calcium-ATPase

Question 3

What are the enhancers of calcium absorption?

Answer 3

• Vit D
• Lactose
• Sugar alcohols
• Protein (increases luminal acidity)

Question 4

Unabsorbed dietary fatty acids form what?

Answer 4

insoluble calcium soaps

Question 5

Calcium soaps can’t be absorbed and are excreted in the feces which leads to what?

Answer 5

steatorrhea

Question 6

What can diminish calcitriol production in the kidneys which reduces calcium absorption?

Answer 6

high plasma phosphorus

Question 7

What 3 hormones are involved in calcium homeostasis?

Answer 7

• parathyroid hormone (PTH)
• calcitriol
• calcitonin

Question 8

What stimulates PTH release from the parathryoid gland?

Answer 8

low plasma calcium

Question 9

What are the 3 ways PTH increases calcium concentrations?

Answer 9

1. increase osteoclasts activity in the bone
2. increase renal tubular absorption of Ca
3. increase synthesis of calcitriol by activating 1-hydroxylase

Question 10

How does PTH increase calcitriol synthesis?

Answer 10

activates 1-hydroxylase

Question 11

Calitriol increases the production of what 3 calcium absorption proteins in the enterocytes?

Answer 11

• TRPV6
• calbindin D9K
• Ca ATPase

Question 12

Calcitriol increases the production of what proteins in the kidney?

Answer 12

• TRPV5

- Calbindin D28K

Question 13

TRPV5 and Calbindin D28K promotes what?

Answer 13

increased renal tubular reabsorption of calcium

Question 14

When will parafollicular cells of the thyroid gland release calcitonin?

Answer 14

when plasma Ca is high

Question 15

What are the 2 functions of calcitonin?

Answer 15

1. inhibition of osteoclasts activity

2. reduce renal Ca absorption

Question 16

The extracellular Ca concentration can how many times greater than the intracellular?

Answer 16

10,000

Question 17

Thrombin binds calcium ions to what?

Answer 17

modified amino acids gamma-carboxyglutamate

Question 18

What initiates the skeletal or cardiac muscle cross bridging cycle?

Answer 18

Calcium from sarcoplasmic reticulum binds to Troponin C

Question 19

In smooth muscle calcium binds to what?

Answer 19

calmodulin

Question 20

Each calmodulin (two lobes) binds how many total calcium ions?

Answer 20

4

Question 21

Dietary protein promotes what, while simultaneously increasing what?

Answer 21

• promotes urinary calcium losses

- increases calcium absorption rates

Question 22

Diets high in phosphorus and low in calcium stimulate PTH and inhibits calcitriol, which causes what?

Answer 22

decrease bone calcium and decreased calcium absorption

Question 23

Calcium can diminish the absorption of what?

Answer 23

fatty acids

- this decreases the total and LDL cholesterol

Question 24

There is an inverse relationship between calcium and what vital sign?

Answer 24

blood pressure

- 600 mg or greater

Question 25

Populations with increased need for calcium include..

Answer 25

1. high phytate diets
2. fat malabsorption diseases
3. immobilization or antigravity environments
4. long-term use of thiazide diuretics

Question 26

High calcium diets suppress what?

Answer 26

1,25-dihydroxyvitamin D levels

- which if suppressed will reduce smooth muscle cell intracellular calcium, peripheral vascular resistance and thus BP.