Calcium + Bone Homeostasis

Question 1

Thyroid hormone play what kind of role in growth?

Answer 1

1. permissive

2. direct in nervous system development

Question 2

need what for bone growth?

Answer 2

calcium and protein

Question 3

where does hydroxyapatite bind to in bone?

Answer 3

collagen fiber lattice

Question 4

vascular supply of bone?

Answer 4

very vascular

Question 5

outer bone is called? purpose?

Answer 5

compact or cortical bone for strength

Question 6

spongy bone called? filled with?

Answer 6

trabecular bone, open, cell-filled spaces

Question 7

osteoblasts are modified?

Answer 7

fibroblasts

Question 8

osteoblasts produce what?

Answer 8

enzymes and osteoid to allow hydroapatite to bind

Question 9

2 other factors aid in bone deposition in osteoblasts:

Answer 9

osteocalcin

osteonectin

Question 10

site of bone growth?

Answer 10

epiphyseal plate

Question 11

shaft of long bone called?

Answer 11

diaphyses

Question 12

ends of long bones called?

Answer 12

epiphyses

Question 13

Chondrocytes’ role in bone growth?

Answer 13

near epiphysis, make collagen, continuously dividing column, disintegrate leaving spaces where osteoblasts can deposit hydroxyapatite

Question 14

when osteoblasts aren’t active, they are called?

Answer 14

osteocytes

Question 15

describe osteoclasts histologically

Answer 15

large mobile multinucleate cells from hematopoietic stem cells

Question 16

osteoclasts secrete

Answer 16

acid and protease to dissolve calcified matrix and collagen support

Question 17

3 organs involves in Calcium metabolism and control are?

Answer 17

bones
kidney
intestines

Question 18

3 Calcium metabolism and control hormones?

Answer 18

PTH
Vitamin D3 (calcitriol)
Calcitonin

Question 19

Calcium and cell adhesions?

Answer 19

important in tight junctions

Question 20

how much %calcium is found in:
Bone
ECF
ICF

Answer 20

Bone: 99%
ECF: 0.1%
ICF: 0.9% (signalling)

Question 21

most calcium lost where?

Answer 21

urine

Question 22

where in kidney is calcium reabsorbed?

Answer 22

distal nephron

Question 23

need parathyroid glands?

Answer 23

essential for life

Question 24

what does PTH do to plasma calcium and phosphate?

Answer 24

increase plasma calcium

decrease plasma phosphate

Question 25

PTH receptors in bone?

Answer 25

Nope. works via paracrine osteoprotegerins (OPG) and RANKL

Question 26

PTH action on kidney?

Answer 26

reabsorb calcium | excrete phosphate

Question 27

PTH actions on intestine?

Answer 27

indirectly increases resorption via Vitamin D activation

Question 28

PTH peptide or steroid?

Answer 28

peptide

Question 29

PTH stored?

Answer 29

Nope

Question 30

onset of PTH on: kidney osteoclasts Intestinal absorption

Answer 30

kidney: minutes osteoclasts: 1-2 hours Intestinal absorption: 1-2 days

Question 31

when is calcitonin released?

Answer 31

only with extreme hypercalcemia

Question 32

calcitonin peptide or steroid?

Answer 32

peptide

Question 33

calcitonin affect intestine?

Answer 33

Nope. only bone and kidney

Question 34

calcitonin is possibly protective during?

Answer 34

pregnancy and lactation

Question 35

how to activate vitamin D? does what?

Answer 35

1. sunlight to make Vitamin D3 2. liver - add hydroxyl 3. kidney - add hydroxyl 4. activated and promotes intestinal absorption of Ca2+ and PO43-

Question 36

Vitamin D3 peptide or steroid?

Answer 36

steroid

Question 37

what 3 things stims Vitamin D3?

Answer 37

1. low calcium 2. indirectly via PTH 3. prolactin

Question 38

Vitamin D3 target organ and target in cell?

Answer 38

intestine bone kidney nuclear target

Question 39

What is the endogenour precursor to vitamin D3?

Answer 39

7- dehydrocholesterol

Question 40

what stops long bone growth?

Answer 40

estrogen

Question 41

phosphate movements vs. calcium movements are?

Answer 41

paralleled

Question 42

What happens to phosphate with: PTH: Vitamin D3:

Answer 42

PTH: promotes excretion in kidneys, and resorption in bone | Vitamin D3: enhances absorption in intestines

Question 43

usual cause of PTH hypersecretion?

Answer 43

tumour

Question 44

usual cause of PTH hyposecretion?

Answer 44

inadvertent parathyroidectomy

Question 45

Vitamin D deficiency leads to what?

Answer 45

poor intestinal calcium absorption Rickets - kids Osteomalacia - adults

Question 46

osteoporosis high in what conditions?

Answer 46

``` post-menopausal women cushing's alcoholism malnutrition inactivity ```

Question 47

preventable ris factors for osteoporosis:

Answer 47

dietary calcium exercise smoking