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BIO 235 Chapter 5 > chapter 6 > Flashcards

chapter 6 Flashcards

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1
Q

bone

A

organ made up of several tissues working together: bone tissue, cartilage, dense connective tissue, epithelium, adipose tissue and nervous tissue

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2
Q

basic functions of skeletal muscle

A
  1. support
    2.protection
  2. assistance in movement
  3. blood cell production
  4. triglyceride storage
  5. mineral homeostasis
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3
Q

function: support

A

skeleton supports soft tissue and providing attachment points to the tendons of most skeletal muscle

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4
Q

function: protection

A

protects internal organs

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5
Q

function: assistance in movement

A

muscle attach to bone when they contract, they pull on bone to produce movement

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6
Q

function: blood cell production

A

red blood marrow produces RBC, WBC, and platelets in process called hemepoeisis. It consists of developing blood cells: adipocyte, fibroblast and macrophage within network of reticular fiber
-in fetus and some adult bone: hips, ribs, sternum, vertebrae, skull, femur, humerus
-older you get RBM turn yellow

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7
Q

function: triglycerides storage

A

yellow bone marrow consists mainly of adipose which stores triglycerides= potential chemical energy reserve

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8
Q

function: mineral homeostasis

A

-bone tissue males up 18% of weight, stores minerals (calcium and phosphorus) which help bone strength
-bone tissue stores 99% of body calcium
-on demand, bone releases minerals into the blood to maintain homeostasis and bring minerals to rest of the body

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9
Q

long bone

and what does it consist of

A

one that has greater length than width and consists of
-diaphysis
-epiphysis
-metaphyses
-articular cartilage
-periosteum
-medullary cavity
-endosteum

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10
Q

diaphysis

A

bone shaft, main portion

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11
Q

epiphysis

A

proximal and distal end of bone

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12
Q

metaphyses

A

-region between epiphysis and disphysis
-contain epiphyseal plate/ epiphyseal line

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13
Q

epiphyseal plate

A

layer of hyaline that allows disphysis to grow in length

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14
Q

epiphyseal line

A

when the bone length growth stops cartilage in epiphyseal plate is replaced by bone

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15
Q

articular cartilage

A

thin layer of hyaline cartilage covered the part of epiphysis where bone forms a joint with another bone
-reduces friction and absorbs shock
-repair of damage is limited due to lack of perichondrium and blood vessels

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16
Q

periosteum

what is it made of?
function
how does it attach?

what is it?

A

-tough connective tissue sheath and is associated with blood supply that surrounds bone surface where there is no articular cartilage
-composed of outer fibrous layer (irregular connective tissue) and inner osteogenic layer (cell)
-helps grow in thickness, not length
-protects bone, assists in fracture repair, nourish bone tissue, attachment point for tendons and ligament
-attaches to bone by perforating fibers (thick bundles of collagen extend from periosteum ito extracellular matrix)

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17
Q

medullary cavity

what is it?
function

A

-hollow, cylindrical space with diaphysis that contains yellow fatty bone marrow and blood vessels (in adults)
-minimizes weight of bone by reducing dense bone material where it is least needed
-long, tubular design provides max strength with min weight

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18
Q

endosteum

A

-thin membrane that line medullary cavity
-contains single layer of bone forming cells and small amount of connective tissue

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19
Q

what does the extracellular matrix consist of

A

15% water, 30% collagen, 55% crystallized mineral salts (calcium phosphate) and hydroxyapatite (calcium phosphate + calcium hydroxide)

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20
Q

calcification

A

minerals are deposited into framework formed by collagen fibers of extracellular matrix, they crystallize and tissue hardens
-initiated by bone building cells (osteoblasts)

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21
Q

bone hardness

A

depend on crystallized inorganic mineral salts

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22
Q

bone flexibility

A

depend on collagen fibers

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23
Q

4 types of cells present in bone tissue

A

1.Osteoprogenitor Cells
2.osteoblasts
3. osteocytes
4.osteoclasts

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24
Q

Osteoprogenitor cells

what is it
found where?

A

-unspecialized bone stem cells derived from mesenchyme
-only bone cells to undergo cell division= develop into osteoblasts
-found along inner portion of periosteum, in the endosteum and the canals with bone containing blood vessels

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25
Q

osteoblasts

A

-bone building cells
-synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix and initiate calcification
-surround themselves with extracellular matrix, trapped in secretion and become osteocytes

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26
Q

Osteocytes

what is it?
function

A

-mature bone cells, main cells in tissue
-maintain its daily metabolism such as exchange of nutrients and wastes in the blood
-does not undergo cell division

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27
Q

blast

A

secretes extracellular matrix

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28
Q

cytes

A

monitors and maintains tissue

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29
Q

osteoclasts

A

-huge cell derived from the fusion of as many as 50 monocytes and concentrated in endosteum
-osteoclasts plasma membrane is deeply folded into a ruffled border, here the cell releases lysomal enzymes and acid that digests the protein and minerals on the extracellular bone matrix

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30
Q

Compact bone tissue

A

-80% of skeleton
-contains few spaces, strongest form of bone
-found beneath periosteum, makes up bulk of diaphysis
-provides protection, support, and resists stress of weight and movement

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31
Q

what does compact bone consist of?

A

-osteon
-concentric lamellae
-lacunae
-canaliculi
-interstitial lamellae
-interosteonic canals
-circumferential lamellae

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32
Q

osteon

A

-consist of concentric lamellae arranged around osteonic canal
-aligned in same direction and are parallel to length of diaphysis which aids in helping resist break and fracture in long bone
-not static, change overtime based on physical demands

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33
Q

concentric lamellae

A

-are circular plates of mineralized extracellular matrix of increasing diameter, surrounding a small network of blood vessels and nerves located in central canal

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34
Q

lucunae

A

small spaces between concentric lamellae which contain osteocytes

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35
Q

canliculi

A

-come from all direction from lacunae which are filled with extracellular fluid, inside are finger like process of osteocytes
-connects lacunae with other central canals which forms connecting canals throughout the bone (route for nutrients and O2)

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36
Q

interstitial lamellae

A

-areas between neighbouring osteons, fragments of older osteons that have been partially destroyed during growth of rebuilding

37
Q

interosteonic canals

A

how blood verssels and nerves from the periosteum penetrate the compact bone

38
Q

circumferential lamellae

A

arranged the entire outer and inner circumference of the shaft pf the long bone, develop during initial bone formation

39
Q

internal circumferential lamellae

A

line medullary cavity

40
Q

external circumferential lamellae

A

deep to periosteum, connected by perforating fibers

41
Q

Spongy bone

what does it consist of?

A

-always located in interior bone
-consists of lamellae arranged in irregular pattern of thin collagens called trabeculae
-macroscopic spaces that are filled with RBM that produce blood cells and yellow bone tissue
-each trabeculae consists of concentric lamellae, osteocytes that lie in lacunae and canaliculi that radiate outward from lacunae
-in long bone it forms core of epiphysis
-always covered by layer of compact bone for protection
-located where less physical stress occurs

42
Q

how is spongy different than compact

A

-spongy is light
-trabeculae of spongy support and protect bone marrow (hip bone, ribs, sternum, vertebrae, proximal end of humerus and femur
-site of hemoposisis (cell production)

43
Q

periosteal arteries

A

-small arteries accompanied by nerves, enter diaphysis through many interosteonic canals and supply the periosteum and outer part pf compact bone

44
Q

nutrient artery

A

-near centre of diaphysis, passes though a hole in compact bone called nutrient foramen
-when entering medulla cavity it divides into proximal and distal branches
-branches supply inner part of compact bone in diaphysis and spongy and red bone marrow
- some bones have 1, some have multiple

45
Q

metaphyseal artery

A

enters the metaphysis pf a long bone and together with nutrient artery supply the red bone marrow and bone tissue of metaphyses

46
Q

epiphyseal arteries

A

enter the epiphysis of long bone and supply red bone marrow and bone tissue of epiphysis

47
Q

veins that carry blood away from the long bones are evident in 3 places

A
  1. nutrient veins (1 or 2)
  2. numerous epiphyseal veins and metaphyseal veins
  3. periosteal veins
48
Q

Nerves

A

accompany blood vessels that supply bones
-periosteum is rich in nerves
-sensitive to tearing and tension

49
Q

Ossification: 4 principals situations

A
  1. embryo and fetus
    2.growth of bone during infancy, childhood, adolescence until adult
  2. remodelling of bone
    4.repair of fractures
50
Q

bone formation in embryo and fetus

A

composed of mesenchyme in general shape of bone
cartilage formation and ossification occur 6 weeks

51
Q

bone formation in embryo and fetus 2 patterns

A
  1. intramembraneous ossification
  2. endochondrial ossification
52
Q

Intramembraneous ossification location

A

flat bone of skull, facial bones, mandible and medial clavicle

53
Q

Intramembraneous ossification steps

A
  1. development of ossification center
  2. calcification
  3. formation of trabeculae
  4. development of periosteum
54
Q

development of ossification center

A

-specific chemical message cause cells of the mesenchyme to cluster together and differentiate- first into osteoprogenitor cells the into osteoblasts (cluster site is ossification center)
-osteoblasts secrete organic extracellular matrix of bone until they are surrounded by it

55
Q

calcification

A

-secretion of matrix stops, cells (now osteocytes) lie in lacunae and extend their narrow cytoplasmic processes into canaliculi that radiate in all directions
-within a few days, calcium and other mineral salts and deposited and extracellular matrix hardens

56
Q

formation of trabeculae

A

-as bone extracellular matrix forms, it develops into trabeculae that fuse into one another to form spongy bone around network of blood vessels
-connective tissue associated the blood vessels in trabeculae differentiates into red bone marrow

57
Q

development of periosteum

A

-same time as trabeculae, the mesenchyme condenses at the periphery of the bone and develops into the periosteum
-thin layer of compact bone replaces the surface layer of spongy bone and spongy bone remains in center

58
Q

Endochondrial ossification steps

A
  1. development of cartilage model
  2. growth of cartilage
  3. development of primary ossification center
  4. development of medullary cavity
    5.development of secondary ossification center
  5. formation of articular cartilage and epiphyseal plate
59
Q

development of cartilage model

A

-on site where the bone is going to form, specific chemical messages cause the cells in the mesenchyme to crowd together in shape of future bone and the develop chondroblasts
-chondroblasts secrete cartilage extracellular matrix, producing a cartilage model of hyaline cartilage
-perichondrium develops around cartilage model

60
Q

growth of cartilage

A

-when chondroblasts become deeply buried in cartilage extracellular matrix they are called chondrocytes
-cell division of chondrocytes make bones grow longer and secretion of cartilage extracellular matrix
-interstitial growth and appositional growth
-chondrocytes in mid region increase in size and surrounding cartilage extracellular matrix calcify , others die because no nutrients as they die spaces left behind merge into small cavities

61
Q

interstitial growth

A

growth from within

62
Q

appositional growth

A

growth of cartilage in thickness due to deposition of extracellular matrix material on the cartilage surface by new chondroblasts that develop from the perichondrium

63
Q

development of primary ossification center

A

-proceeds inward from external surface of bone
-nutrient artery penetrate perichondrium and calcifying cartilage model through a nutrient foramen, stimulating osteoprogenitor cells in perichondrium to change into osteoblasts
-once perichondrium start to form bone, periosteal capillaries grow into disintegrating calcified cartilage, inducing growth of primary ossification centers
-osteoblast begin to deposit bone extracellular matrix over remnants of calcified cartilage forming spongy bone trabeculae

64
Q

development of medullary cavity

A

-during primary ossification center development, osteoclasts breakdown newly formed spongy bone trabeculae
-this leaves a cavity in diaphysis
-eventually most of the diaphysis wall will be compact bone

65
Q

development of secondary ossification center

A

-develops when branches of epiphyseal artery enter epiphysis
-similar to primary but spongy bone remains in the interior of epiphyses
-proceeds outward

66
Q

formation of articular cartilage and epiphyses (growth) plate

A

-hyaline cartilage that covers epiphyses become articular cartilage
-before adulthood, hyaline remains between diaphysis and epiphysis as growth plate

67
Q

growth in length involves 2 major events

A
  1. interstitial growth of cartilage on epiphyseal side of epiphyseal plate
  2. replacement of cartilage on diaphysial side of epiphyseal plate with bone by endochondrial ossification
68
Q

4 zones of epiphyseal plate

A
  1. zone of resting cartilage
  2. zone of proliferating cartilage
  3. zone of hypertrophic cartilage
  4. zone of calcified cartilage
69
Q

zone of resting cartilage

A

-layer nearest epiphysis
-consists of small, scattered chondrocytes
-anchor epiphyseal plate to epiphysis , do not function in bone growth

70
Q

zone of proliferating cartilage

A

-larger chondrocytes, stacked like coins
-undergo interstitial growth, they divide to replace those that died of diaphysis side

71
Q

zone of hypertrophic cartilage

A

-consists of large, mature chondrocytes arranged in columns

72
Q

zone of calcified cartilage

A

-few cells thick and consists of chondrocytes that are dead because extracellular matrix has calcified
-osteoclasts dissolve calcified cartilage and osteoblasts and capillaries invade area
-osteoblasts lay down bone extracellular matrix, replacing cartilage by endochondrial ossification

73
Q

growth in thickness step 1

A
  1. at bone surface, periosteal cells differentiate into osteoblasts (secretes collagen fibers and organic molecules to form extracellular matrix). Osteoblasts get surrounded by extracellular matrix and develop into osteocytes.
    -Process forms bone ridges on both sides of periosteal blood vessel
    -ridges slowly enlarge and create groove for periosteal blood vessels
74
Q

growth in thickness step 2

A

-ridges fold together and fuse
-the groove becomes a tunnel that encloses the blood vessel
-periosteum is now the endosteum that lines the tunnel
-

75
Q

growth in thickness step 3

A

-osteoblasts in endosteum deposit bone extracellular matrix, forming new concentric lamellae
-formation of additional concentric lamellae proceeds inward toward peristeal blood vessel
-tunnel fill in and new osteon is created

76
Q

growth in thickness step 4

A

-as osteon is forming, osteoblasts under the periosteum deposit new circumferential lamellae which increases the thickness
-as additional periosteal blood vessels become enclosed step 1 continues

77
Q

Remodelling bone involves

A

replacing old bone tissue
1. bone resorption
2. bone deposition

78
Q

what is remodelling triggered by?

A

-exercise
-sedentary lifestyle
-change in diet
-injury

79
Q

what % of bone mass is being remodelled

A

5%

80
Q

benefits of bone remodelling

A

-grow thicker and stronger
-change shape to provide support
-more resistant to fracture

81
Q

bone resorption

A

removal of minerals and collagen fibers from bone through osteoclasts

82
Q

bone deposition

A

-addition of minerals and collagen from osteoblasts

83
Q

resorption process

A

-osteoclasts attach tightly to bone surface at the endosteum or periosteum and form leak proof seal at edge of ruffled border
-then releases protein digesting lysosomal enzymes into sealed pocket which dissolves bone minerals
-osteoclasts carve small tunnel in old bone
-degraded bone protein and extracellular matrix minerals enter osteoclasts by endocytosis, cross in vesicles then undergo exocytosis on other side
-interstitial fluid products diffuse into blood capillaries
-once absorbed, osteoclasts depart and osteoblasts move in to rebuild

84
Q

factors affecting bone growth and remodelling

A
  1. minerals
    -large amount of calcium and phosphorus and small amount of magnesium, floride and manganese
  2. vitamins
    -vit A stims osteoblasts
    -vit C synthesizes collagen
    -vit D increases absorption of calcium in food
  3. hormones
    -insulin like growth factor stim osteoblasts, promote cell division at growth plate and periosteum and enhance synthesis of proteins
    -thyroid hormone (t3 and T4) stim osteoblasts
    insulin synthesizes bone proteins
    -sex hormones growth spurts, stops growth of epiphyseal plate , increases osteoblast,
    -estrogen slows resorption by promoting apoptosis of osteoclasts
85
Q

Bone’s role in calcium homeostasis

A

-bone is calcium reservoir
-maintain level of calcium in blood by controlling rate of calcium resorption from bone into blood and calcium deposition from blood to bone
-helps buffer blood Ca2 level into blood plasma (using osteoclasts) when the level lower and absorbing calcium (using osteoblasts) when level rises
-Ca2 exchange is regulated by parathyroid gland, it increases blood Ca 2 level

86
Q

calcitrol

A

hormone that promotes absorption of calcium from food

87
Q

calcitonin

A

inhibits activity of osteoclasts, speeds blood Ca 2 uptake by bone and accelerates Ca2 deposition into bones

88
Q

calcium homeostasis negative feed back system

-controlled condition
-receptor
-input
-control centre
-output
-effecto

A

-stimulus disrupts homeostasis by decreasing
-controlled condition: blood calcium level Ca2
-receptor: parathyroid gland cells
-input: detect lowered Ca2 concentration which increases production of cyclic AMP
-control center: parathyroid hormone gene
-output: when gene is turned on which increases release of PTH
-effector: osteoclasts increase bone resorption, kidneys retain Ca2 in blood and excrete phosphate and produce calcitrol
-response: increase blood Ca2 level
return to homeostasis when response brings blood Ca2 level to normal

BIO 235 Chapter 5 (3 decks)

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