Hormonal Control of Calcium and Phosphate Metabolism Flashcards Preview

Phys: Endocrine > Hormonal Control of Calcium and Phosphate Metabolism > Flashcards

Flashcards in Hormonal Control of Calcium and Phosphate Metabolism Deck (28):
1

What functions does calcium participate in?

1. Nerve function
2. Muscle contraction
3. Blood clotting
4. Bone and teeth

2

what functions does phosphate participate in?

1. ATP
2. Biological buffer
3. DNA

3

Where is most calcium stored?

Bone

4

Where is most phosphorous stored?

Intracellularly and bone

5

How is phosphate brought into the body?

Diet

6

How is phosphate excreted?

Urine

7

What 3 hormones regulate calcium?

1. PTH
2. 1,25 Dihydroxycholecalciferol: calcitriol
3. Calcitonin

8

What cells release PTH?

Chief cells of the parathyroid

9

When is PTH released? What does it do?

1. When calcium levels are low (below 8.5 mg/dL), detected by the parathyroid gland
2. PTH secreted into the blood
3. PTH reaches target organs
A. osteoclasts resorb bone
B. Kidney retains Calcium and promotes activation of an inactive form of vitamin D to an active form of vitamin D
C. Small intestine increases absorption of more calcium under the influence of calcitriol
4. Calcium Levels rise and inhibit PTH

10

What coenzyme helps facilitate absorption of calcium and phosphate in the intestine?

1. Vitamin D

11

Where is vitamin D activated?

1. Formation and hydroxylation of vitamin D3. 25-Hydroxylation takes place in the liver, and the other hydroxylations (1, 25-hydroxy D3) occur primarily in the kidneys.

12

What are the sources of vitamin D?

1. Sun
2. Diet and supplementation of D3 and D2

13

Where is calcitonin produced?

Produced by parafollicular cells of thyroid gland

14

What is the stimulus for calcitonin release?

Secreted in response to increased plasma calcium levels above 11 mg/dL for adults

15

What is the function of calcitonin?

1. Lowers circulating plasma calcium and phosphate levels
A. Inhibits bone resorption
B. Increases Ca excretion

16

Define hyperparathyroidism

1. Excessive PTH secretion that results in:
A. Increased plasma calcium level
B. Decreased plasma phosphate level

17

Why is hypercalcemia a problem?

1. Excess Ca enters cells
2. Results in decreased membrane excitability
3. Effects cardiac muscle & nervous system
A. bradycardia, shortened Qt interval
B. Fatigue, confusion, decreased LOC
C. Constipation, anorexia

18

What can cause primary hyperparathyroidism?

Parathyoid adenoma

19

What can cause secondary hyperparathyroidism?

Vitamin D deficiency or CRF

20

What are the sxs of hypercalcemia?

Bones, stones, thrones, abdominal groans, psychiatric moans, with fatigue overtones

21

What does (hypoparathyroidism) deficiency of PTH result in?

1. Decreased plasma calcium level
2. Increased plasma phosphate level

22

Why is hypocalcemia a problem?

1. Disturbances in cell membrane potential
2. Results in cardiac & neuromuscular irritability

23

What are the sxs of hypocalcemia?

1. CATS
A. Convulsions
B. Arrhythmias
C. Tetany
D. Stridor & spasms

2. Parathesias
A. Lips, tongue, fingers & feet
3. Pos Chovstek’s Sign
4. Pos Trousseau Sign

24

When does hypocalcemia occur?

Following thyroid or parathyroid surgery

25

What causes RIckets disease and osteomalacia?

1. Caused by insufficient Vitamin D
A. Results in inadequate calcium and phosphate for bone mineralization

26

What are the sxs of childhood rickets?

1. Stunted growth
2. Severe bow-legged

27

What are the sxs of adult osteomalacia?

1. bone malformation
2. Fractures

28

What is renal riscket's disease?

1. Limited production of Vitamin D due to kidneys damage
A. PTH cannot convert 25 hydroxycalciferol to active 1,25 dihydroxycholecalciferol