lecture 6 Flashcards

1
Q

bone is made of (6)

A

bone (osseous) tissue
cartilage
dense connective tissue
epithelial tissue
adipose tissue
nervous tissue

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2
Q

osteology

A

the study of bone structure

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3
Q

skeleton 6 main functions

A

supports body (framework)
protects internal organs
assists movement
assists mineral homeostasis
red blood cell production
store triglycerides

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4
Q

diaphysis

A

shaft of the bone

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5
Q

epiphysis

A

knobby ends of the bone

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6
Q

metaphysis

A

region between epiphysis and diaphysis. neck sort of thing

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7
Q

articular cartilage

A

reduced friction between joints, made of hyaline

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8
Q

periosteum

A

outer covering of the bones where tendons and ligaments attach

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9
Q

medullary cavity

A

hollow portion of diaphysis

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10
Q

endosteum

A

membrane that lines medullary cavity, made of 1 layer of osteocytes and thin connective tissue

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11
Q

% makeup of bone ECM

A

15 water, 30 collagen fibres, 55 mineral salts

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12
Q

calcification

A

harding of ECM

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13
Q

primary elements in bone

A

calcium first, then phosphorous

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14
Q

cells make up ____% of bone

A

2

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15
Q

4 cells in bone (o cell)

A

osteoprogenitor cells
osteoblasts
osteocytes
osterclasts

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16
Q

osteoprogenitor cells

A

stem cells of bone, located deep to the periosteum

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17
Q

osteoblasts

A

secrete collagen and other components of bone ECM. do not divide, once immobilized by its secretions, they become osteocytes

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18
Q

osteocytes

A

mature bone cells, do not divide or secrete, acquire nutrients and eliminate wastes

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19
Q

osteoclasts

A

catabolize bone, formed by 50 ish monocytes (WBCs), secrete lysosomal enzymes and acids, release minerals into blood
(bone resorption)

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20
Q

bone resorption

A

process done by osteoclasts where bone is catabolized or broken down and the minerals are released into the blood

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21
Q

where to find compact bone tissue

A

diaphysis of long bones
surrounding all bones (deep to periosteum)

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22
Q

where to find spongy bone tissue

A

inside epiphysis of long bones
inside flat bones (many of the axial skeleton)

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23
Q

structure of compact bone

A

strongest of bone tissues
resistant to mechanical stress
dense ECM
structural unit = osteons

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24
Q

bone remodeling

A

arrangement of osteons and trabeculae due to mechanical stress

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25
Q

types of lamellae

A

interstitial = old concentric from old osteons
concentric = rings around central canal
circumferential = surround long bone

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26
Q

interosteonic canals

A

provide passage for blood vessels and nerves
penetrates bone from periosteum to medullary cavity
travels between osteons

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27
Q

trabeculae structure

A

projections of bone tissue arranged alone areas of stress
surrounded by red bone marrow
is lighter that compact bone
supports and protects bone marrow
handles stress along multiple axes better then compact

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28
Q

periosteal arteries

A

nourish periosteum

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29
Q

nutrient artery

A

enters bone through nutrient foramen
penetrates diaphysis and branches into bone marrow

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30
Q

epiphyseal and metaphyseal arteries

A

nourish internal tissues of the epiphysis
branches of the nutrient artery

31
Q

functions of the blood supply in bone

A

bring nutrients (o2, cells, minerals, hormones), remove waste

32
Q

function of the nerve supply in bone

A

detect pain (respond before injury, regulate bone remodeling)

33
Q

ossification

A

formation of bones

34
Q

4 phases of life that require bone formation

A

development of embryonic skeleton
development during childhood and adolescence
during bone remodeling
during the repair of fractures

35
Q

intramembranous ossification

A

bone develops directly from mesenchymal tissue

36
Q

endochondral ossification

A

bone develops from a hyaline cartilage intermediate
forms most bones, including long bones

37
Q

intramembranous ossification steps

A
  1. formation of ossification centre
    - mesenchymal - osteoprogenitor - osteoblasts
  2. calcification of mineral salts secreted by osteoblasts
  3. formation of trabeculae in spongy tissue
    - CT between trabeculae becomes red marrow
  4. formation of periosteum
    - mesenchymal tissue surrounding trabeculae compacts and form the periosteum
38
Q

key points of intramembranous ossification (4)

A

bone forms directly from mesenchymal tissue
makes bone spongy and compact tissue
starts in the embryo
makes flat cranial bones and most facial bones

39
Q

endochondral ossification steps (6)

A
  1. mesenchymal cells differentiate into chrondroblasts
  2. chondroblasts secrete ECM to promote intersitial growth
  3. penetration of nutrient artery
  4. primary ossification extends to the ends of bones
  5. secondary ossification centre forms at epiphysis
  6. hyaline cartilage at joints become articular cartilage
40
Q

interstitial growth

A

growth in bone length

41
Q

appositional growth

A

growth in bone circumference

42
Q

step 1 of endochondral in detail

A

mesenchymal cells differential into chondroblasts

they secrete collagen to become hyaline cartilage, and forms the future diaphysis

43
Q

step 2 of endochondrial in detail

A

chondroblasts secrete ECM to promote interstitial growth

mature chondrocytes die and become lacunae

44
Q

step 3 endochondrial in detail

A

penetration of nutrient artery through the perichondrium

stimulates: osteoprogenitor cells to mature into osteoblasts and make trabeculae in the primary ossification centre, perichondrium compacting into periosteum, and hyaline cartilage to lose nutrients and disintegrate

45
Q

step 4 endochondrial in detail

A

primary ossification extends to the end of bone

osteoclasts digest some of the spongy bone, carving out the medullary cavity

46
Q

step 5 endochondrial in detail

A

secondary ossification centre forms at epiphysis

begins at birth

47
Q

step 6 endochondrial in detail

A

hyaline cartilage at joints becomes articular cartilage

cartilage remaining at metaphysis remains cartilage until adulthood (epiphyseal plate/line)

48
Q

interstitial growth zones (4)

A

zone of resting cartilage
zone of proliferating cartilage
zone of hypertrophic cartilage
zone of calcified cartilage

49
Q

zone of resting cartilage (3)

A

proximal to the epiphysis
does not divide
anchors epiphyseal plate to bone

50
Q

zone of proliferating cartilage (2)

A

contains actively dividing chondrocytes
contributes to interstitial growth

51
Q

zone of hypertrophic cartilage

A

contains mature chondrocytes
large cells arranged in columns

52
Q

zone of calcified cartilage

A

contains layers of dead chondrocytes
can be cleared by osteoclasts during bone remodeling
becomes “new diaphysis”

53
Q

appositional growth steps (4)

A
  1. periosteal cells become osteocytes, ridges of ECM form around periosteal vessels
  2. ridges fuse, old periosteum is now endosteum
  3. endosteal ostesblasts secrete ECM to create new concentric lamellae
  4. new circumferential lamellae are made by osteoblasts
54
Q

nutrient groups that affect bone growth (5)

A

calcium and phosphorus
vit D
vit C
vit K and B12
vit A

55
Q

what does calcium and phosphorus do for bone growth?

A

mineralize bone tissue ECM

56
Q

what does vit D do for bone growth?

A

promotes dietary calcium absorption

57
Q

what does vit C do for bone growth?

A

required for collagen synthesis

58
Q

what does vit K and B12 do for bone growth?

A

important for protein synthesis

59
Q

what does vit A do for bone growth?

A

stimulates osteoblast activity

60
Q

what hormones affect bone growth? (4)

A

human growth hormone
thyroid hormones (t3 and t4)
estrogen
test

61
Q

how does human growth hormone affect bone growth?

A

stimulates osteoblasts at epiphyseal plate and periosteum during childhood and before adulthood

62
Q

how does thyroid hormones t3 and t4 affect bone growth?

A

by stimulating osteoblasts

63
Q

how does estrogen affect bone growth?

A

it can inhibit or slow bone resorption by promoting apoptosis in osteoclasts

64
Q

three factors affecting bone growth

A

nutrition
hormones
exercise

65
Q

bone remodeling / when is it remodeled?

A

encompasses both bone resorption and bone deposition

bone is remodeled:
during growth
during and after injury
with changes to exercise and diet

66
Q

what happens during bone remodeling?

A

osteoclasts suction to bone and release enzymes and acids to catabolize bone and release minerals via transcytosis. osteoblasts then deposit bone along lines of mechanical stress

67
Q

calcium homeostasis feedback loop

A

stimulus - low calcium
sensor - parathyroid gland
control centre - nucleus of parathyroid gland
effector - kidneys and osteoclasts
response - increased calcium

osteoclasts will dissolve bone to release calcium into the blood, kidneys will make calcitriol to increase calcium absorption

68
Q

types of fractures

A

stress - can be microscopic and not damage surrounding tissue

compound - can be large and damage surrounding tissue

69
Q

reduction

A

the realigning of bones to initiate healing

closed reduction - occurs without surgery
open - skin is broken, occurs with surgical intervention

70
Q

bone repair phases (3)

A

reactive phase
reparative phase
remodeling phase

71
Q

reactive phase of bone repair

A

first phase

close like structure called fracture hematoma stops bleeding, inflammation bring immune cells to injury

lasts 4-6 weeks

72
Q

reparative phase of bone repair

A

second phase

formation of fibrocartilaginous callus made of collagen between fractured ends of bone, new blood vessels form

at the same time, osteoprogenitor cells secrete ECM to create new spongy bone and form bony callus

lasts 3-4 months

73
Q

bone remodeling phase

A

third phase

osteoclasts remove dead bone, compact bone replaces spongy tissue around fracture site and thickens at the fracture area

74
Q

osteoporosis

A

loss of bone density
higher levels of bone resorption than deposition
increased risk of fracture
affects elderly women more due to lower estrogen levels