Bone Physiology

Question 1

osteology

Answer 1

study of bones

Question 2

skeletal system

Answer 2

composed of bones, cartilage and ligaments joined to form framework for body

Question 3

functions of skeletal system

Answer 3

support, protection, movement, electrolyte balance, acid-base balance, blood formation, hormone secretion

Question 4

osseous tissue

Answer 4

connective tissue in which matrix is hardened by deposition of calcium phosphate and other minerals

Question 5

types of bone

Answer 5

flat, long and short/irregular

Question 6

bone make up

Answer 6

compact/dense/cortical bone, marrow cavity, spongy bone

Question 7

diaphysis

Answer 7

shaft of long bone

Question 8

epiphysis

Answer 8

expanded head at each end

Question 9

articular cartilage

Answer 9

hyaline cartilage that covers bones where they meet each other

Question 10

nutrient foramina

Answer 10

minute holes where blood vessels penetrate bone

Question 11

periosteum

Answer 11

sheath that covers bone

Question 12

osteogenic cells

Answer 12

stem cells that develop from embryonic mesenchyme then give rise to most other bone types

Question 13

osteoblasts

Answer 13

bone forming, synthesize organic matter of bone and promotes its mineralization
- process of osteogenesis

Question 14

osteocytes

Answer 14

former osteoblasts that became embedded in the matrix they deposited
- 90-95% of bone cells

Question 15

osteoclasts

Answer 15

bone - dissolving cells on bone surfaces
- process of osteolysis

Question 16

Matrix

Answer 16

stony matter that surrounds the osteocytes and lacunae
- 1/3 organic, 2/3 inorganic matter

Question 17

bone marrow

Answer 17

soft tissue that occupies marrow cavity of a long bone

Question 18

red bone marrow

Answer 18

fills nearly every bone in a child, hematopoietic tissue that produces blood cells

Question 19

yellow bone marrow

Answer 19

replaces most red marrow in adults, very fatty

Question 20

ossification

Answer 20

formation of bone by osteogenesis that begins with embryonic mesenchyme

Question 21

intramembranous ossification

Answer 21

produces flat bone of skull, most of clavicle and parts of mandible
steps: 1. deposition of osteoid tissue into mesenchyme
2. calcification of osteoid tissue and entrapment of osteocytes
3. honeycomb of spongy bone with developing periosteum
4. filling of pace to form compact bone at surface and spongy bone in middle

Question 22

endochondral ossification

Answer 22

process where bone developed from hyaline cartilage
1. formation of primary ossification center (diaphysis), bony collar and periosteum
2. vascular invasion, formation of primary marrow cavity and appearance of secondary ossification center
3. bone at birth with enlarged primary marrow cavity and appearance of secondary marrow cavity in one epiphysis
4. bone of child with epiphyseal plate at distal end
5. adult bone with single marrow cavity and closed epiphyseal plate

Question 23

zone of reserve cartilage

Answer 23

resting hyaline cartilage with no sign of transformation into bone

Question 24

some of cell proliferation

Answer 24

chondrocytes multiplying and lining up in rows of small flattened lacunae

Question 25

zone of cell hypertrophy

Answer 25

cessation of mitosis, enlargement of chondrocytes and thinning of lacuna walls

Question 26

zone of calcification

Answer 26

temporary calcification of cartilage matrix between columns of lacunae

Question 27

zone of bone deposition

Answer 27

breakdown of lacuna walls-leaving open channels, death of chondrocytes, bone deposition by osteoblasts, forming trabecular of spongy bone

Question 28

oppositional growth

Answer 28

deposition of new tissue at the surface - allows bone to continually grow in diameter and thickness

Question 29

wolfs law of bone

Answer 29

architecture of bone is determined by mechanical stresses place upon it and bone adapts to withstand it

Question 30

mineralization

Answer 30

crystallization process in which calcium, phosphate and other ions are taken from blood and deposited in bone tissue

Question 31

mineral resorption

Answer 31

process of dissolving bone

Question 32

hypocalcemia

Answer 32

calcium deficiency, causes excessive excitability of nervous system

Question 33

hypercalcemia

Answer 33

calcium excess, nerve and muscle cells are less excitable

Question 34

calcitriol

Answer 34

form of vitamin D produced by skin, liver and kidneys - behaves as hormone, raises blood calcium concentrate, increases calcium absorption by small intestine and from skeleton an promotes reabsorption by kidneys

Question 35

calcitonin

Answer 35

produced by parafollicular cells of thyroid gland and secreted when blood calcium is too high

Question 36

osteoclast inhibition

Answer 36

after secretion reduces osteoclast activity up to 70%os

Question 37

osteoblast stimulation

Answer 37

w/in one hour, increases number and activity of osteoblasts

Question 38

parathyroid hormone

Answer 38

secreted by parathyroid glands when blood calcium is low