Lect Assign Week Five

Chapter 7
7.1
1. Describe three or more functions of the skeletal system other than supporting the body and protecting some of the internal organs.
Bones along with muscles allow the body to move
Blood vessels are made in certain types of bones
Bones are able to store calcium as well as mineral phosphorus
7.2
2. What cell synthesizes the organic matrix of bone? What is the organic matrix of bone composed of?
Osteoblasts synthesize the organic matrix of bone. The organic matrix of bone is composed of collagen, glycosaminoglycan, proteoglycans, and glycoproteins
3. What is the inorganic matrix of bone composed of?
Composed of calcium, phosphorus, bicarbonate, citrate, magnesium, potassium, sodium, and hydroxide ions
4. What two organelles do you think are especially prominent in osteoblasts? (Hint: Consider the major substances that osteoblasts synthesize)
Mitochondrion and Golgi apparatus
5. Explain how each the organic material and inorganic material of bone is important to the integrity of bone function. (Hint: What do each component provide to help in proper bone health?)
Organic: Collagen is the flexibility to the matrix. Mineral components give the matrix compression-weight bearing-strength
Inorganic: gives rigidity and hardness to the bone
6. Describe rickets and osteogenesis perfecta compared to normal bone health.
Rickets- soft, bendable bones causing skeletal deformities and frequent fractures.
Osteogenesis imperfecta- bones break easily-brittle bone disease-lack of protein in the bone
7. What are the two kinds of bone marrow? What does hemopoietic tissue mean? Which type of bone marrow fits this description?
Yellow marrow and red marrow
Red marrow- hemopoietic tissue- tissue produces red and white blood cells
7.3
8. Describe how a cartilage model is transformed into a long bone in endochondral ossification.
Mesenchyme is developed into hyaline cartilage. The perichondrium that covers the mesenchyme produces chondrocytes. Chondrocytes are then inflated and die. Chondrocytes are no longer produced. Perichondrium now produces osteoblasts. Osteoclasts are now present in the blood creating the primary marrow cavity. Osteoblasts deposit layers of bone to thicken shaft. Secondary centers of ossification begin in the epiphysis at each end with invasion by blood vessels
9. Describe the five zones of a metaphysis and the major distinctions between them.
1. Zone of reserve cartilage- consisting of hyaline cartilage with chondrocytes. No signs of bone transformation
2. Zone of cell proliferation- chondrocytes are multiplied and arranged in columns of flattened lacunae
3. Zone of hypertrophy- chondrocytes begin hypertrophy. Thin walls of matrix between lacunae
4. Zone of classification- cartilage is temporarily calcified by mineral deposits in the matrix between columns of lacunae
5. Zone of bone deposition- walls between lacunae are broken down, chondrocytes are dead. Blood vessels and marrow invade each longitudinal channel in which osteoblasts then line up along and concentric lamellae of matrix is deposited. Temporary calcified cartilage is dissolved
10. How does Wolff's law explain some of the structural differences between the bones of a young child and the bones of a young adult? Explain using the law in your reasoning.
Change in form and function of a bone leads to change in internal structure. The bone adapt to withstand mechanical stresses placed upon it. When children exercise before initial growth spurt at puberty, the size of the child’s long bone cross-sections are modified-additional bone on the endosteal surface. In young adults, new endosteal bone is actively deposited. Basically, exercising increases bone mineral density
11. Deeper Insight 7.2: Explain what is achondroplastic dwarfism and what is its cause.
Anchondroplastic dwarfism is short statue with normal sized torso and short limbs. In childhood, the long bones of the limbs no longer grow
Causes: cartilage does not convert to bone as normal. In DNA replication, FGFR3 gene is mutated
7.4
12. Describe the role of collagen and seed crystals in bone mineralization.
Fibers of the collagen are layed for which the matrix can be hardened by encrusted minerals. Seed crystals come from the first few crystals and wait for additional minerals from tissue fluid so the matrix can be calcified completely
13. What positive feedback process can you recognize in bone deposition? Explain.
More calcium and phosphate are attracted from the first few crystals made
14. What is the role of the enzyme acid phosphatase in mineral resorption? Explain. What cell produces and secretes this enzyme?
Cathepsin k is an enzyme that can function in highly acidic environments. Its role is collagen digestion of the bone matrix. Secreted by the cell osteoclast
15. Explain why it is important to regulate blood calcium concentration within such a narrow range.
The movement of calcium ions can cause problems such as over-excited neurons due to too much calcium and they will send unneeded electrical signals and causes muscle tremors
16. Explain the role of the skeleton as a calcium reservoir in regulating blood calcium levels, including the antagonistic role that PTH and calcitonin play in maintaining homeostasis.
PTH is secreted when blood calcium levels are low. Works to raise the levels by stimulating osteoclasts to break apart bone to be released back into the bloodstream.
The thyroid gland secretes calcitonin to lower calcium blood levels when they get too high-slows down the breaking of the bone, also increases excretion of calcium in urine
17. Deeper Insight 7.3: Explain the role of the urinary, respiratory, and skeletal systems in maintaining the body’s pH.
Skeletal system- dissolve bone and release calcium carbonate into circulation
Urinary system- maintain red blood cell count within the body and the pH levels
Respiratory system- supply oxygen to circulatory system and removes wastes from metabolic process helps maintain pH levels
18. How is vitamin D synthesized, and what effect does it have on blood calcium concentration?
Vitamin D is synthesized by the action of the skin, kidneys, and liver. Lack of vitamin D- difficult for the body to obtain calcium from the diet. Adequate vitamin D promotes calcium absorption in the gut and maintains blood calcium concentrations
19. What are the bodily functions of phosphate? How do calcitriol and parathyroid hormone affect blood phosphate levels?
Helps body maintain pH balance and regulate vitamin D levels; helps kidneys filter out waste products
Calcitriol raises phosphate levels by intestinal absorption
Parathyroid hormone lowers phosphate levels by urinary exertion
20. Explain the effects of dietary vitamins A, C, and D on bone metabolism.
Vitamin A- glycosaminoglycan synthesis
Vitamin C- collagen synthesis; growth of bone; repair fractures
Vitamin D- integrity of the skeleton and prevention of rickets, osteomalacia, and osteoporosis
21. What are the effects of cortisol, estrogen, testosterone, growth hormone, insulin, and thyroid hormone on bone metabolism?
Cortisol- inhibits osteoclast activity
Estrogen- stimulates osteoblasts
Thyroid hormone- bone growth, enhances growth hormone
Insulin- bone formation
Growth hormone- bone elongation, increases intestinal Ca2+ absorption
7.5
22. Name and describe four types of bone fractures.
Stress fracture- break to a bone caused by abnormal trauma-fall
Pathological fracture- bone cancer cause the bone to break
Nondisplaced fracture- bone is cracked into separate pieces but properly alignment remains
Displaced fracture- one piece is shifted out of alignment
23. Why would osteomyelitis be more likely to occur in an open fracture than in a closed fracture? Explain.
Osteomyelitis- bone infection caused by bacteria that can infect the bone by spreading from open wounds (open fracture)