Exam 3: Calcium Balance Flashcards Preview

Zak, Physiology 2 > Exam 3: Calcium Balance > Flashcards

Flashcards in Exam 3: Calcium Balance Deck (40):
1

Increases in _____ cause progressive depression of the nervous system.

Calcium

2

Decreases in _____ cause the nervous system to become more excited.

Calcium

3

What percentage of calcium is in the extracellular fluid?

0.1%

4

What percentage of calcium is in the cells and organelles?

1%

5

What percentage of calcium is in the bones?

~99%

6

85% of _____ is stored in bones.

Phosphate

7

T/F: Hypocalcemia causes nervous system excitement and tetany & seizures.

True

8

Tetany occurs when calcium falls from normal level of _____ to about _____.

9.5 mg/dl
6 mg/dl

9

_____ promotes calcium absorption by the intestines so that about _____ of ingested calcium is absorbed.

Vitamin D
35%

10

What percentage of daily intake of calcium is excreted?

~90%

11

About how much of the ingested calcium is excreted in the urine daily?

100 mg/day

12

_____ can greatly increase phosphate excretion

PTH

13

What is an inhibitor of hydroxyapatite?

Pyrophosphate

14

T/F: Bone may secrete a pyrophosphate inhibitor to allow hydroxyapatite precipitation.

True

15

The precipitation of calcium along the collagen fibers forms _____ _____.

Hydroxyapatite crystals

16

What form does some calcium salt remain in to be rapidly absorbed when needed in the extracellular fluid?

Amorphous form

17

T/F: Calcium concentrations return to normal within 12 hours of removal or addition of intravenous calcium.

False, within 30 minutes

18

What 3 hormones control calcium balance?

Vitamin D
PTH
Calcitonin

19

What causes intestines, kidneys, & bones to increase absorption of calcium and phosphate?

Vitamin D

20

Where are vitamin D receptors mainly located?

Nuclei of target cells

21

Calbindin (in intestinal epithelial cells) functions to...?

Transport calcium into the cell cytoplasm

22

T/F: Vitamin D always promotes bone calcification.

False, only in smaller quantities

23

Excess _____ causes rapid absorption of calcium salts from the bones.

PTH

24

Excess of _____ results in hypercalcemia.

PTH

25

Which phase of PTH results from activation of already existing bone cells to promote calcium and phosphate absorption?

Rapid phase

26

Which phase of PTH results from proliferation of the osteoclasts & reabsorption of bone itself, not merely absorption of the calcium phosphate salts?

Slower phase

27

T/F: Osteoclasts have membrane receptor proteins for PTH.

False, do not

28

Administration of _____ causes rapid loss of phosphate in the urine & increases renal tubular reabsorption of calcium.

PTH

29

What would cause the urine to eventually deplete the extracellular fluid & bones of calcium?

Loss of PTH activity of kidneys

30

Rickets, pregnancy, & lactation are conditions that do what?

Decrease calcium ion concentration

31

Excess calcium in diet, increased vitamin D, & bone absorption by disease are conditions that do what?

Increase calcium ion concentration

32

Calcitonin is secreted by what?

Thyroid gland

33

Calcitonin tends to _____ plasma calcium concentration.

Decrease

34

What is synthesized and secreted by parafollicular cells?

Calcitonin

35

When parathyroid glands are removed, calcium level in the blood _____ & blood phosphate concentration may _____.

Falls
Double

36

What is an abnormality of the parathyroid glands that affects the actual gland?

Primary hyperparathyroidism

37

What is a compensation for hypocalcemia caused by vitamin D deficiency leading to osteomalacia?

Secondary hyperparathyroidism

38

What is usually in children and results from calcium or phosphate deficiency in the extracellular fluid, caused by a lack of vitamin D?

Rickets

39

What is caused by lack of physical stress on the bones, malnutrition, lack of vitamin C, old age, Cushing's, and lack of estrogn?

Osteopororsis

40

T/F: Osteoporosis is due to diminished osteoblastic activity and diminished organic bone martix.

True