LECTURE 1 bone (connective tissue type)

Question 1

functions of bone tissue (5)

Answer 1

support, protect, mineral storage, movement, blood-cell formation

Question 2

bone tissue componants

Answer 2

well vascularized, collagen fibers, periosteum, endosteum, formed from cartilage (through endochondralossification)

Question 3

bone tissue cells (3)

Answer 3

osteoblasts, osteocytes, osteoclasts

Question 4

osteoblasts

Answer 4

secrete organic part of bone matrix

Question 5

osteocytes

Answer 5

mature bone cells (in lacunae) that maintain bone matrix

Question 6

osteoclasts

Answer 6

degrade and reabsorb bone (release into blood stream)

Question 7

periosteum

Answer 7

external layer of CT that surrounds bone, outer is dense irregular CT, inner is osteoblasts and osteoclasts, maintains and repairs but can also break down bone

Question 8

endosteum

Answer 8

internal layer of CT that lines cavities and covers trabeculae, contains osteoblasts and osteoclasts, never in cartilage

Question 9

types of bone tissue (2)

Answer 9

compact bone, spongy bone (two organizations of bone tissue made up of same materials - matrix, cells, fibers)

Question 10

compact bone

Answer 10

dense, thick, strong, hard; external, superficial layer; functions: protection and weight bearing; osteon/Haversian system

Question 11

osteon/Haversian system

Answer 11

parallel to the long axis of the bone; groups of concentric tubules; lamella: layer of bone matrix where all fibers run in same direction; adjacent lamella fibers run in opposite directions; Haversian (central) canal runs through center of osteon, contains blood vessels and nerves, connected to each other by perforating (Volkman) canals; interstitial lamellae fills spaces and forms periphery (outside osteon, inside bone)

Question 12

spongy bone

Answer 12

aka cancellous bone; internal/deep layer; function: holding bone marrow, less weight bearing; trabeculae

Question 13

trabeculae

Answer 13

small, needle-like pieces of bone form honeycomb (aka spicuoles); each made of several layers of lamellae and osteocytes; covered by endosteum; no canal for vessels (no need with open space); spaces filled with bone marrow

Question 14

shapes of bones (4)

Answer 14

flat (skull, sternum, clavicle), irregular (pelvis, vertebrae), short (carpals, patella), long (femur, phalanges, metacarpals, humerus)

Question 15

anatomy of a long bone

Answer 15

diaphysis, 2 epiphyses, periosteum, endosteum

Question 16

diaphysis of long bone

Answer 16

centrally elongated, medullary cavity (holds yellow bone marrow), nutrient artery and vein

Question 17

2 epiphyses of long bone

Answer 17

on each end, epiphyseal plates/lines (for growth) made of hyaline carilage, epiphyseal artery and vein

Question 18

periosteum of long bone

Answer 18

does not cover epiphyses

Question 19

endosteum of long bone

Answer 19

covers trabeculae of spongy bone, lines medullary cavity of long bones

Question 20

types of bone formation (2)

Answer 20

intramembranous ossification, endochondral ossification

Question 21

intramembranous ossification

Answer 21

osteoblasts in membrane secrete osteoid that mineralizes

Question 22

endochondral ossification

Answer 22

begins with a cartilage model, cartilage calcifies, medullary cavity is formed by action of osteoclasts, epiphyses grow and eventually calcify (epiphyseal plates remain cartilage for up to 20 years), when cartilage cells die they all become bone and become epiphyseal line (no more growth)

Question 23

growth of bones

Answer 23

lengthening of bones: epiphyseal plates enlarge by chondroblasts, matrix calcifies, bone tissue replaces cartilage on diaphysis side; appositional growth: widening of bone, bone tissue added on surface by osteoblasts of periosteum, medullary cavity maintained by osteoclasts

Question 24

remodeling of bones

Answer 24

due to mechanical stress on bones their tissue needs to be replaced, ideally osteoclasts (breakdown bone) and osteoblasts (create new bone) work at same rate