Bone

Question 1

What type of tissue is bone?

Answer 1

specialized connective tissue

Question 2

What are the support cells of bones?

Answer 2

osteoblasts and osteocytes

Question 3

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

Answer 3

osteoid

Question 4

What are the inorganic mineral salts within matrix?

Answer 4

hydroxyapatite

Question 5

What are the remodeling cells of bone?

Answer 5

osteoclast

Question 6

What are the functions of bone?

Answer 6

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

Question 7

What type of bones are in limbs?

Answer 7

long bones

Question 8

What is the shaft of long bones called?

Answer 8

diaphysis

Question 9

Where is compact bone?

Answer 9

cortex

Question 10

Where is spongy, cancellous/trabecular bone?

Answer 10

medullary cavity
-marrow

Question 11

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

Answer 11

medullary cavity

Question 12

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

Answer 12

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

Question 13

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

Answer 13

metaphysis

Question 14

Where is the epiphyseal plate?

Answer 14

metaphysis

Question 15

What is an osteoid?

Answer 15

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

Question 16

What makes and maintains osteoids?

Answer 16

osteoblasts and osteocytes

Question 17

What is woven bone?

Answer 17

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

Question 18

What is lamellar bone?

Answer 18

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

Question 19

What are the two major components of bones?

Answer 19

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

Question 20

What is the outer shell of the bone?

Answer 20

cortical bone
-resist deformation

Question 21

What is the inner network of the bone?

Answer 21

trabecular network

Question 22

What surrounds osteons?

Answer 22

concentric lamellae of compact bone with osteocytes

Question 23

What acts as packing between adjacent Haversian systems?

Answer 23

interstitial bone lamellae

Question 24

What horizontally links osteons?

Answer 24

Volkmann’s canal

Question 25

What carries the blood vessels and nerves in osteons?

Answer 25

Volkmann's canal

Question 26

How do osteocytes communicate with one another?

Answer 26

canaliculi

Question 27

What can cause abnormalities in bone architecture?

Answer 27

-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

Question 28

What is the endosteum?

Answer 28

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

Question 29

What does the endosteum line?

Answer 29

Haversian canals and all internal cavities of the bone

Question 30

What makes up the endosteum?

Answer 30

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

Question 31

Which is thinner: endosteum or periosteum?

Answer 31

endosteum

Question 32

What are the two layers of the periosteum?

Answer 32

outer fibrous membrane and inner cellular layer

Question 33

What is the outer fibrous layer of periosteum?

Answer 33

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

Question 34

What is the inner cellular layer of periosteum?

Answer 34

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

Question 35

What are osteoprogenitor cells?

Answer 35

multipotent stem cells -undergo mitotic division and differentiate into osteblasts

Question 36

What are Sharpey's fibers?

Answer 36

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

Question 37

What are osteoblasts?

Answer 37

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

Question 38

What are osteocytes?

Answer 38

inactive cells trapped within bone matrix

Question 39

What are osteoclasts?

Answer 39

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

Question 40

What allows osteoblasts to calcify?

Answer 40

secretion of matrix vesicles

Question 41

What is inside the matrix vesicles?

Answer 41

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

Question 42

Where do osteoblasts mature into osteocytes?

Answer 42

lacunae

Question 43

What are the components of bone?

Answer 43

70% inorganic salts and 30% organic matrix

Question 44

What is the organic matrix?

Answer 44

>90% type 1 collagen

Question 45

What GAGs are in the ground substance of bone?

Answer 45

hyaluronic acid, chondroitin sulfate, and keratan sulfate

Question 46

What are the non-collagenous organic molecules in bone?

Answer 46

-osteocalcin -osteonectin -sialoproteins

Question 47

What is osteocalcin?

Answer 47

binds intracellular Ca during mineralization

Question 48

What is osteonectin?

Answer 48

bridges/binds collagen and minerals

Question 49

What are sialoproteins

Answer 49

rich in sialic acid; concentrated in plasma

Question 50

What does bone have high affinity for?

Answer 50

heavy metals (Pb and Hg) and radioactive isotopes

Question 51

Where are osteoclasts normally found?

Answer 51

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

Question 52

How do osteoclasts function in Ca homeostasis?

Answer 52

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

Question 53

What 2 antagonist hormones work to maintain calcium homeostasis?

Answer 53

parathyroid hormone and calcitonin

Question 54

What is parathyroid hormone?

Answer 54

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

Question 55

What is calcitonin?

Answer 55

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

Question 56

What is somatotropin?

Answer 56

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