Bone Physiology

Question 1

Functions of the skeletal system

Answer 1

1. protect organs
2. support
3. movement (mm attatchment)
4. red blood cell production: hemopoesis=storage of red bone marrow
5. Ca homeostasis–important for mm cont and calcification of bone
6. triglyceride storage (yellow bone marrow)

Question 2

Parts of Long Bone

Answer 2

1. diaphysis-long tube, 80% of bone tissue
2. epiphyses-ends
3. metaphysis-contains epiphyseal plate/line
4. articular/hyaline cartilage-absorbs shock and reduces friction
5. Periosteum-connective tissue around bone
6. endosteum-connective tissue lining medullary cavity. contains osteoblasts, osteoclasts, and osteogenic cells
7. medullary cavity-hollow tube containing yellow bone marrow

Question 3

osteogenesis imperfecta

Answer 3

genetic defect in genes that produce collagen

Question 4

Spongy bone

Answer 4

consist of trabeculae: a lattice of lamelle containing lacunae and caniliculi

Question 5

Interstitial Bone Growth

Answer 5

I. zone of resting cartilage: chondrocytes anchor epiphyseal plate to epiphysis
II. zone of proliferating cartilage-chondrocytes divide and stack
III. zone of hypertrophic cartilage-chondrocytes grow and mature
IV. zone of calcified cartilage-osteoblasts lay down ECM around chondrocytes, they die and leave Haversian canal

Question 6

appositional growth

Answer 6

growth in width, occurs under the periostium-osteoblasts lay down ECM and osteon forms in spaces

Question 7

blood supply to bone

Answer 7

1. nutrient artery
2. metaphyseal artery
3. epiphyseal artery

Question 8

gigantism
dwarfism
acromegaly

Answer 8

• too much HGH during childhood
• too little HGH during childhood
• excess HGH during adulthood, causes bones to get thicker and wider

Question 9

What factors influence bone remodeling?

Answer 9

• diet: Vitamin C (for synthesis of collagen), Vitamin A (for osteoblast activity), Vitamin D (for absorption of Ca) and Ca (for mm contraction)
• load/stress (skeleton, too little space)

Question 10

How does the body compensate when there is too much and too little Ca in the bloodstream?

Answer 10

• too little activates parathyroid hormone, which increases osteoclast activity and decreases Ca loss in urine and stimulates formation of calcitriol (form of vitamin D which is important for Ca reabsorption
• too much activates calcitonin, which decreases osteoclast activity

Question 11

Osteoporosis

Answer 11

• thinning of bones, decrease in overall bone mass
• affects women more than men because women have lower bone mass and menopause leads to a decrease in estrogen
• drug therapies are hormone replacement and biophosphonates (which decrease osteoclast activity)