Essay q’s ex 2

question

Describe the sliding filament theory. Discuss changes to the sarcomere, myofilaments, and Z discs in your essay
answer

When a muscle contracts, thick and thin filaments aside move past each other. The Z discs in one sarcomere move closer together. The sarcomere narrows or shortens in length. Thick filaments and thin filaments maintain their length.
question

Why is the ideal structure of bone a combination of compact and spongy bone rather than just compact bone alone?
answer

Because compact bone specifically forms the solid external walls of bone. The structure of spongy bone provides great resistance to stresses in different directions by distributing the stress throughout the entire structure.
question

Sex hormones help regulate bone cell activity. Considering this, why is osteoporosis more common in older women than older men?
answer

Women have less bone mass than men. Women begin losing bone mass earlier and faster in life. Postmenopausal women no longer produce significant amounts estrogen, which help protect against osteoporosis by stimulating bone growth.
question

Why are diarthrosis joints considered the least stable?
answer

Diarthrosis is the joint that has the most mobility, more mobile a joint is the less stable it is.
question

Although smooth muscle cells have thick and thin filaments, they do not have striations. Why not?
answer

Smooth muscle is not organized into sarcomeres. Z discs are not present in smooth muscle cells instead the thin filaments are attached to dense bodies by elements of the cytokskeleton.

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