Calcium Balance

Question 1

What are the effects of hypercalcemia?

Answer 1

progressive depression of the nervous system

constipation and lack of appetite

Question 2

What does a decrease in calcium concentration cause?

Answer 2

nervous system is more excited

Question 3

What percent of of total body calcium is in the extracellular fluid?

Answer 3

0.1%

Question 4

What percent is in the cells and organelles?

Answer 4

1%

Question 5

Where is the majority of calcium stored?

Answer 5

in the bones

Question 6

What percent of phosphate is stored in the bones?

Answer 6

85%

Question 7

What percent of phosphate is stored in the cells?

Answer 7

14-15%

Question 8

What percent of phosphate is stored in extracellular fluid?

Answer 8

less than 1%

Question 9

How is inorganic phosphate in the plasma?

Answer 9

HPO4 and H2PO4

Question 10

T/F Large changes in the level of phosphate in the ECF do not cause major immediate effects on the body

Answer 10

T

Question 11

T/F Slight changes in extracellular calcium does not cause extreme immediate physiological effects

Answer 11

F, does cause extreme effects

Question 12

How does the body react to hypocalcemia

Answer 12

causes nervous system excitement and tetany

Question 13

Why does the nervous system become more excitable

Answer 13

increased neuronal membrane permeability to sodium

Question 14

Why does hypocalcemia cause seizures?

Answer 14

first sign is tetany in the hand

Question 15

When does tetany occur?

Answer 15

hypocalcemia

lethal amouth in 4mg/dl

Question 16

What are the usual rates of intake for calcium each day

Answer 16

1000mg/day

Question 17

What effect does vitamin D have on calcium absorption?

Answer 17

increases

Question 18

What happens to calcium when it isn’t absorbed?

Answer 18

excreted in feces (250mg/day- 90% of daily intake)

Question 19

How much calcium is excreted in urine?

Answer 19

10% - 100mg/day

Question 20

What percent of plasma calcium is bound to plasma proteins?

Answer 20

41%

Question 21

What percent of calcium do the renal tubules reabsorb?

Answer 21

99%

Question 22

What is the purpose of exchangeable calcium?

Answer 22

rapid buffering mechanism (goes back to normal in about 30 minutes)

Question 23

How does vitamin D increase calcium absorption?

Answer 23

by intestines, kidneys, and bones to absorb calcium into ECF and contribute to feedback regulation

Question 24

Where are vitamin D receptors in most cells?

Answer 24

nuclei of target cells

Question 25

What are the characteristics of vitamin D receptors

Answer 25

Have hormones binding and DNA binding

Question 26

What is calbindin?

Answer 26

calcium-binding protein in intestinal epitheial cells | help transport calcium into the cell cytoplasm

Question 27

How does 1,25 dihydrocycholecalciferol promote calcium absoprtion

Answer 27

1. calcium stimulated ATPase in brush border | 2. alkaline phosphatase

Question 28

What is the affect of extreme quantities of vitamin D?

Answer 28

absorption of bone

Question 29

What happens when vitamin D is in small quantities?

Answer 29

bone calcification

Question 30

What happens if there is excess PTH?

Answer 30

rapid absorption of calcium salts from bones

Question 31

What does hypofunction of PTH glands cause?

Answer 31

hypocalcemia and tetany

Question 32

What is the process of synthesis of PTH?

Answer 32

Location- ER and gogi | preprohormone --> prohormones --> hormone

Question 33

What occurs during the rapid phase of PTH?

Answer 33

begins in minutes- activation of already existing bones to promote Ca and phosphate absorption

Question 34

What occurs during the slower phase of PTH?

Answer 34

begins in days or weeks | through proliferation of osteoclasts, reabsorption of bone itself

Question 35

T/F osteoclasts have membrane receptor proteins for PTH?

Answer 35

F- they do not

Question 36

What is the major secondary signal in osteoclasts to activate preosteoclast cells?

Answer 36

osteoprotegerin ligand

Question 37

What are the two stages of the osteoclastic system?

Answer 37

1. Immediate activation of osteoclasts | 2. Formation of new osteoclasts

Question 38

What affect does PTH have on renal calcium reabsorption?

Answer 38

rapid loss phosphate in urine | increase renal tubular reabsorption

Question 39

What are three conditions that decrease calcium ion concentration?

Answer 39

1. Rickets 2. Pregnancy 3. Lactation

Question 40

What conditions increase calcium ion concentration above normal?

Answer 40

- excess calcium in diet - increased vitamin D in diet - bone absoprtion

Question 41

What are the characteristics of calcitonin?

Answer 41

- peptide hormone - decreases calcium concentration - secreted by thyroid gland

Question 42

Where is calcitonin synthesized?

Answer 42

parafollicular cells (C cells)

Question 43

What is occurring during Paget disease?

Answer 43

osteoclastic activity is greatly accelerated | calcitonin is more potent

Question 44

When does hypoparathyroidism occur?

Answer 44

when PT glands dont secrete enough PTH osteoclasts become totally inactive signs of tetany- spasms can obstruct respiration

Question 45

What is primary hyperthyroidism?

Answer 45

abnormality of parathyroid gland cause excess PTH | *more prevalent in women

Question 46

What is secondary hyperthyroidism?

Answer 46

High levels of PTH | Can be cause by vitamin D deficiency

Question 47

Aldosterone is the major mineralocorticoid and is secreted by which of the following regions of the adrenal cortex?

Answer 47

Zona glomerulosa

Question 48

Coritsol secretion is controlled by which of the following factors?

Answer 48

ACTH

Question 49

Which of the following is not a characteristic of lack of aldosterone?

Answer 49

hypernateremia

Question 50

Adrenal diabetes may occur due to excess of which of the following

Answer 50

Glucocorticoids

Question 51

Addisons disease is due to a deificiency in what?

Answer 51

GLucocorticoids and mineralocorticoids