main points lecture 6 part 2

Question 1

what is ossification

Answer 1

process of forming new bone

Question 2

under what four conditions does ossification occur

Answer 2

formation in late stage embryo
growth until adulthood
remodeling of bone
fracture repair

Question 3

steps of intra-membranous ossification

Answer 3

mesenchymal cells develop into osteoblasts in a fibrous membrane

Question 4

what bones are made by intra-membranous ossification

Answer 4

flat bones of the skull, mandible, and clavicle

Question 5

what type of bone is made by intra-membranous ossification

Answer 5

spongy bone

Question 6

steps of endochondral ossification

Answer 6

primary ossification center, bone collar
cartilage calcifies and develops cavities
spongy bone forms
secondary ossification centers form in the epiphyses

Question 7

what bones are made by endochondral ossification

Answer 7

long bones

Question 8

what type of cartilage is used in endochondral ossification

Answer 8

hyaline cartilage

Question 9

cartilaginous remnants found on bones produced by endochondral ossification

Answer 9

hyaline cartilage in the epiphyseal growth plate and articular cartialges

Question 10

what type of bone growth is longitudinal growth

Answer 10

endochondral ossification

Question 11

what does longitudinal growth require

Answer 11

the presence of epiphyseal cartilage

Question 12

five zones within epiphyseal growth plate

Answer 12

resting (quiescent) zone
proliferation (growth) zone
hypertrophic zone
calcification zone
ossification (osteogenic) zone

Question 13

resting (quiescent) zone characteristic

Answer 13

relatively inactive

Question 14

proliferation (growth) zone characteristic

Answer 14

rapidly dividing by pushing epiphysis away from diaphysis

Question 15

hypertrophic zone characterstic

Answer 15

older chondrocyte enlarge

Question 16

calcification zone characteristics

Answer 16

matrix calcifies, cartilage cells die, blood vessels invade

Question 17

ossification zone characteristics

Answer 17

new bone forms

Question 18

what happens to the epiphyseal growth plate toward the end of puberty

Answer 18

thins and is replaced by bone, bones lengthening decreases, bones of epiphysis and diaphysis fuse

Question 19

differences in timing for males and females

Answer 19

males 21
females 18

Question 20

how can bone growth plate be affected if epiphyseal growth plate is damaged

Answer 20

stunts bone growth, might cause uneven limb size

Question 21

what type of bone growth is appositional bone growth

Answer 21

sideways, thickening of bones

Question 22

does appositional bone growth end with puberty?

Answer 22

no

Question 23

where is most of new bone matrix laid down during appositional bone growth

Answer 23

periosteum

Question 24

where is most of old bone matrix dissolved during appositional bone growth

Answer 24

endosteum

Question 25

discuss rate of resorption vs. deposition in appositional bone growth

Answer 25

must be balanced but usually more building up than breaking down to allow for thickening

Question 26

essential minerals for bone growth and remodeling

Answer 26

calcium, phosphorous, magnesium, fluoride, manganese

Question 27

what vitamins are necessary for bone growth and remodeling

Answer 27

vitamin A,C, D, K, B12

Question 28

vitamin A importance

Answer 28

activity of osteoblasts

Question 29

vitamin C importance

Answer 29

synthesis of collagen

Question 30

Vitamin D importance

Answer 30

promotes absorption of calcium from foods in the GI tract

Question 31

Vitamin K and B12 importance

Answer 31

synthesis of bone proteins

Question 32

what occurs with low vit D and/or calcium deficiency

Answer 32

children - rickets adults - osteomalacia

Question 33

what hormones are necessary for bone growth in children

Answer 33

human growth hormone, and growth factors necessary to stimulate osteoblasts, promote cell division at the epiphyseal plate. enhance protein synthesis

Question 34

what hormones are necessary for bone growth and remodeling in adolescents and adults

Answer 34

thyroid hormones - ensures bone proportions sex hormones - growth spurt in adolescence

Question 35

negative feedback for calcium

Answer 35

parathyroid hormone removes calcium from bone when blood calcium is too low

Question 36

What is PTH, where is it made, what are the results

Answer 36

parathyroid hormone produced in parathyroid glands removes calcium from bone regardless of bone integrity

Question 37

what is calcitonin, where is it made, what are the results

Answer 37

produced by parafollicular cells of thyroid gland high doses lower blood calcium levels temporarily

Question 38

what hormone is primarily responsible for day to day regulation of bone remodeling

Answer 38

PTH parathyroid hormone

Question 39

what causes the release of PTH

Answer 39

low blood calcium levels

Question 40

how and on what does PTH work

Answer 40

stimulates osteoclastic activity and raises blood serum calcium levels stimulates reabsorption of calcium ions in kidney

Question 41

result of PTH release

Answer 41

increase blood calcium levels

Question 42

what hormone contributes to daily remodeling to a lesser extent

Answer 42

calcitonin, hGH, and sex hormones

Question 42

what hormone contributes to daily remodeling to a lesser extent. how they work, what is result

Answer 42

calcitonin, hGH, and sex hormones stimulate osteoblastic activity and lower serum calcium level

Question 43

how is bone remodeling affected by stress and lack of stress

Answer 43

bones thicken where they are stressed the most due to mechanical and gravitational forces

Question 44

what aspect of bone remodeling do hormones control

Answer 44

if necessary and when necessary

Question 45

what aspect of bone remodeling do mechanical/ gravitational forces control

Answer 45

where remodeling is necessary

Question 46

how are fractures acquired in youth and elderly

Answer 46

youth - trauma elderly - weakness due to thinning

Question 47

fracture classifications - position

Answer 47

non-diplaced - bones aligned displaced - bones out of alignment

Question 48

fracture classification - completeness of break

Answer 48

complete - all the way incomplete - not all the way

Question 49

fracture classification - skin penetration

Answer 49

compound (open) - penetrated simple (closed) - non penetrated

Question 50

four other ways fracture are classified

Answer 50

location of fracture, external appearance, nature of break, eponym (name of someone)

Question 51

how are fractures treated

Answer 51

reduction - realignment of broken bones immobilization - cast or traction

Question 52

steps of fracture repair

Answer 52

hematoma formation fibrocartilaginous callus forms - about a week bony callus forms - about two months bone remodeling - several months

Question 53

two principle effects of aging on bone

Answer 53

loss of bone - loss of calcium brittleness - decrease of collagen fibers and protein synthesis

Question 54

concentrations of sex hormones change as we reach later years

Answer 54

drop in hormone levels women drop in estrogen is more significant than male drop in testosterone

Question 55

what is osteoporosis

Answer 55

bone resorption outpaces bone deposition

Question 56

what causes osteoporosis in youth

Answer 56

depletion of calcium from the body

Question 57

what causes osteoporosis in aging and elderly

Answer 57

sex hormone changes

Question 58

what bones are highly susceptible to osteoporotic fractures and why

Answer 58

spongy bone of spinal column and neck of femur

Question 59

additional risk factors for osteopororisis

Answer 59

petite body, insufficient exercise, poor diet in calcium and protein smoking hormone related conditions - hyperthyroidism, low blood TSH, diabetes mellitus, low hGH and IGH production immobility males with prostate cancer taking androgen suppressing medication