Module 5

Question 1

What is a flat bones shape and purpose?

Answer 1

Thin and curved; protects internal organs form compressive forces (Example: Sternum)

Question 2

What is a long bones shape and function?

Answer 2

cylinder-shaped bone that is longer than it is wide; functions as a lever (Ex. Femur)

Question 3

What is an irregular bones shape and function?

Answer 3

bone of complex shape; protects internal organs form compressive forces

Ex: vertebrae

Question 4

What is a sesamoid bones shape and purpose?

Answer 4

small, round bone embedded in a tendon; protects the tendon from compressive forces

Ex: patella

Question 5

What is a short bones shape and purpose?

Answer 5

cube-shaped bone that is approximately equal in length, width, and thickness; provides limited motion

Ex: cuneiform

Question 6

Diaphysis of long bones

Answer 6

tubular shaft that runs between the proximal and distal ends of a long bone

Question 7

Epiphysis

Answer 7

wide section at each end of a long bone; filled with spongy bone and red marrow

Question 7

Epiphyseal plate (growth plate)

Answer 7

sheet of hyaline cartilage in the metaphysis of an immature bone; replaced by bone tissue as the organ grows in length

Question 8

Periosteum

Answer 8

fibrous membrane covering the outer surface of bone and continuous with ligaments

Question 9

Spongy (cancellous) bone

Answer 9

trabeculated osseous tissue that supports shifts in weight distribution

Question 10

Trabeculae

Answer 10

sections of the lattice-like matrix in spongy bone

Question 11

Compact (cortical) bone

Answer 11

dense osseous tissue that can withstand compressive forces

Question 12

Endosteum

Answer 12

delicate membranous lining of a bone’s medullary cavity

Question 13

Medullary cavity

Answer 13

hollow region of the diaphysis; filled with yellow marrow

Question 14

Lacunae

Answer 14

spaces in a bone that house an osteocyte

Question 15

Osteon (harversian system)

Answer 15

basic structural unit of compact bone; made of concentric layers of calcified matrix

Question 16

Articular cartilage

Answer 16

thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber

Question 17

Where is an osteogenic cell (stem cell) located and what is its purpose?

Answer 17

undifferentiated and develop into osteoblasts; located in endosteum, cellular layer of periosteum

Question 18

What is an osteoblasts purpose and where is it located?

Answer 18

forms/deposit bone matrix; located in endosteum, cellular layer of periosteum, growing portions of bone

Blasts Build

Question 19

What is an osteocytes purpose and where is it located?

Answer 19

maintains bone tissue; entrapped in matrix

Question 20

What is an osteocytes purpose and where is it located?

Answer 20

develop from different cell lineage and act to reabsorb bone; located in endosteum, cellular layer of periosteum, at sites of old, injured, or unneeded bone

Clasts Chew

Question 21

What is intramembranous ossification?

Answer 21

compact and spongy bone develops directly from sheets of mesenchymal cells (flat bones of the face, most of the cranial bones, and the clavicles)

Question 22

What is endochondral ossification?

Answer 22

bone develops by replacing hyaline cartilage

Question 23

Is endochondral ossification or intramembranous ossification longer?

Answer 23

Endochondral

Question 23

Reserve zone

Answer 23

region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix

Question 23

What are the four layers of bone growth?

Answer 23

1. Reserve zone 2. Proliferation zone 3. Zone of maturation and hypertrophy 4. Zone of calcified matrix

Question 24

Proliferation zone

Answer 24

contains stacks of slightly larger chondrocytes

Question 25

Zone of maturation and hypertrophy

Answer 25

older and larger

Question 26

Zone of calcified matrix

Answer 26

zone closest to the diaphysis, are dead because the matrix around them has calcified, restricting nutrient diffusion

Question 27

Transverse fracture

Answer 27

occurs straight across the long axis of a bone

Question 27

Oblique

Answer 27

occurs at an angle that is not 90 degrees

Question 28

Spiral fracture

Answer 28

bone segments are pulled apart as a result of a twisting motion

Question 29

Open (compound) fracture

Answer 29

a fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection

Question 29

Impacted fracture

Answer 29

one fragment is driven into the other, usually as a result of compression

Question 29

Comminuted fracture

Answer 29

several breaks result in many small pieces between two large segments

Question 29

Greenstick fracture

Answer 29

a partial fracture in which only one side of the bone is broken, often occurs in the young

Question 30

Closed (simple) fracture

Answer 30

a fracture in which the skin remains intact

Question 31

What are the 6 phases of bone remodeling/healing process?

Answer 31

1. Quiescent phase 2. Activation phase 3. Reabsorption phase 4. Reversal phase 5. Formation phase 6. Mineralization phase

Question 32

What is happening during the quiescent phase of bone remodeling?

Answer 32

Bone is at rest

Question 33

What is happening at the activation phase of bone remodeling?

Answer 33

retraction of bone lining cells (mature osteoblasts) and digestion of endosteal membrane by collagenase. Recruitment and activation of osteoclasts to initiate bone resorption

Question 34

What is happening at the resorption phase of bone remodeling?

Answer 34

osteoclasts begin to dissolve mineral material and decompose osteoid matrix. Approx 2-4 weeks during each remodeling cycle

Question 35

What is happening at the reversal phase of bone remodeling?

Answer 35

bone resorption transition to bone formation. Mononuclear cells (monocytes, osteocytes, preosteoblasts) recruited to begin new bone formation

Question 36

What is happening during the formation phase of bone remodeling?

Answer 36

osteoblasts release and synthesize new osteoid matrix

Question 37

What is happening at the mineralization phase of bone remodeling?

Answer 37

new matrix is mineralized with calcium and phosphorous. Quiescent phase begin again.

Question 38

How do genetic factors impact bone remodeling?

Answer 38

60-80% of bone mass is genetically determined.

Question 39

How do mechanical factors impact bone remodeling?

Answer 39

Load, stress, PA

Question 40

How does vascularization impact bone remodeling?

Answer 40

Supplies blood, oxygen and nutrients

Question 41

How do nutritional factors impact bone remodeling?

Answer 41

Calcium, caffeine, alcohol, excess salt

Question 42

How do Thyroid hormones affect bone remodeling?

Answer 42

stimulate bone resorption and formation *e.g. bone loss in hyperthyroidism*

Question 43

Parathyroid hormone

Answer 43

controls homeostasis of calcium. PTH stimulate bone resorption by RANKL. Intermittent doses of PTH would stimulate bone formation

Question 44

Calcitonin effects on bone remodeling

Answer 44

inhibitor of bone resorption by reducing number and activity of osteoclasts

Question 45

Calcitriol effects on bone remodeling

Answer 45

intestinal absorption of calcium and phosphate, favors bone mineralization

Question 46

Androgens effects on bone remodeling

Answer 46

anabolic effect on bone by stimulation of osteoblasts

Question 47

Estrogens effects on bone remodeling

Answer 47

favor bone formation by increasing number and function of osteoblasts and reduce resorption