Bone Flashcards

1
Q

What type of tissue is bone?

A

specialized connective tissue

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2
Q

What are the support cells of bones?

A

osteoblasts and osteocytes

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3
Q

What are the non-mineralized organic matrix of collagen and GAGs?

A

osteoid

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4
Q

What are the inorganic mineral salts within matrix?

A

hydroxyapatite

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5
Q

What are the remodeling cells of bone?

A

osteoclast

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6
Q

What are the functions of bone?

A

-mechanical support
-locomotion
-protection
-metabolic reservoir of mineral salts

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7
Q

What type of bones are in limbs?

A

long bones

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8
Q

What is the shaft of long bones called?

A

diaphysis

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9
Q

Where is compact bone?

A

cortex

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10
Q

Where is spongy, cancellous/trabecular bone?

A

medullary cavity
-marrow

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11
Q

Where is red (hematopoietic) and yellow (fatty) bone marrow at?

A

medullary cavity

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12
Q

What are the ends of bones called and what are they made up of?

A

epiphyses
-spongey, cancellous/trabecular bone covered with hyaline articular cartilage

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13
Q

What are the flared regions between the epiphysis and diaphysis called?

A

metaphysis

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14
Q

Where is the epiphyseal plate?

A

metaphysis

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15
Q

What is an osteoid?

A

collagenous support tissue embedded in a GAG gel containing osteocalcin (binds calcium)
-has deposition of mineral salts to give bones rigidity and strength

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16
Q

What makes and maintains osteoids?

A

osteoblasts and osteocytes

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17
Q

What is woven bone?

A

haphazard organization of collagen fibers and is mechanically weak
-fast production of bone

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18
Q

What is lamellar bone?

A

regular, parallel alignment of collagen into sheets and is mechanically strong

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19
Q

What are the two major components of bones?

A

-outer cortical or compact bone
-inner trabecular or cancellous bone

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20
Q

What is the outer shell of the bone?

A

cortical bone
-resist deformation

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21
Q

What is the inner network of the bone?

A

trabecular network

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22
Q

What surrounds osteons?

A

concentric lamellae of compact bone with osteocytes

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23
Q

What acts as packing between adjacent Haversian systems?

A

interstitial bone lamellae

24
Q

What horizontally links osteons?

A

Volkmann’s canal

25
Q

What carries the blood vessels and nerves in osteons?

A

Volkmann’s canal

26
Q

How do osteocytes communicate with one another?

A

canaliculi

27
Q

What can cause abnormalities in bone architecture?

A

-damage to both cortical and trabecular bone due to fracture
-decreased cortical and trabecular bone due to osteoporosis
-destruction of trabecular bone due to cancer
-maldevelopment of bone

28
Q

What is the endosteum?

A

membrane lining the inner surface of the bony wall also identified as the lining membrane of the bone marrow cavity

29
Q

What does the endosteum line?

A

Haversian canals and all internal cavities of the bone

30
Q

What makes up the endosteum?

A

a layer of flattened osteoprogenitor cells and a type III collagenous fibers

31
Q

Which is thinner: endosteum or periosteum?

A

endosteum

32
Q

What are the two layers of the periosteum?

A

outer fibrous membrane and inner cellular layer

33
Q

What is the outer fibrous layer of periosteum?

A

irregular, dense connective tissue type with more collagenous matrix and fewer cells

34
Q

What is the inner cellular layer of periosteum?

A

made of osteoprogenitor cells
-also known as osteogenic layer
contains osteoblasts in young developing bones (in adults, osteoblasts may be absent unless required)
-rich in vascular structure and many blood vessels

35
Q

What are osteoprogenitor cells?

A

multipotent stem cells
-undergo mitotic division and differentiate into osteblasts

36
Q

What are Sharpey’s fibers?

A

parallel bundles of collagen fibers
-extend from periosteum or muscle tendon and insert into superficial layer of bone
-provide anchorage and support

37
Q

What are osteoblasts?

A

make osteoids and mineralized it by depositing hydroxyapatite
-only large and metabolically active when synthesizing/mineralizing
-polygonal, mesenchymal derived from osteoprogenitor cells
-basophilic due to organelles for making of large amounts of proteins and proteoglycans

38
Q

What are osteocytes?

A

inactive cells trapped within bone matrix

39
Q

What are osteoclasts?

A

multinucleate cells derived from monocytes
-reabsorb bone to release calcium and phosphate
-stimulated by parathyroid hormone in response to low serum calcium levels

40
Q

What allows osteoblasts to calcify?

A

secretion of matrix vesicles

41
Q

What is inside the matrix vesicles?

A

alkaline phosphatases
-cause precipitation of mineral salts in form of hydroxyapitate

42
Q

Where do osteoblasts mature into osteocytes?

A

lacunae

43
Q

What are the components of bone?

A

70% inorganic salts and 30% organic matrix

44
Q

What is the organic matrix?

A

> 90% type 1 collagen

45
Q

What GAGs are in the ground substance of bone?

A

hyaluronic acid, chondroitin sulfate, and keratan sulfate

46
Q

What are the non-collagenous organic molecules in bone?

A

-osteocalcin
-osteonectin
-sialoproteins

47
Q

What is osteocalcin?

A

binds intracellular Ca during mineralization

48
Q

What is osteonectin?

A

bridges/binds collagen and minerals

49
Q

What are sialoproteins

A

rich in sialic acid; concentrated in plasma

50
Q

What does bone have high affinity for?

A

heavy metals (Pb and Hg) and radioactive isotopes

51
Q

Where are osteoclasts normally found?

A

endosteal/periosteal surface in depressions called Howship’s lacunae or reabsorption bays

52
Q

How do osteoclasts function in Ca homeostasis?

A

produce organic acids and lysozymes that digest bone
-secreted into ECS by ruffled border

53
Q

What 2 antagonist hormones work to maintain calcium homeostasis?

A

parathyroid hormone and calcitonin

54
Q

What is parathyroid hormone?

A

secreted by parathyroid hormone
-stimulate osteoclast activity
-increase blood Ca levels and decrease renal excretion by kidneys

55
Q

What is calcitonin?

A

secreted by thyroid gland
-stimulate osteoblast activity
-inhibit osteoclasts
-decrease blood calcium levels

56
Q

What is somatotropin?

A

pituitary growth hormone
-stimulates growth in epiphyseal cartilage and bone
-decrease bone calcium
-oversecretion can lead to gigantism or acromegaly
-undersecretion leads to pituitary dwarfism