Cartilage heals poorly and in many instances does not heal or recover at all after a severe injury. Why not?
What will be an ideal response?
Cartilage lacks blood vessels, because chondrocytes produce a substance that inhibits the formation of blood vessels. This limits nutrient and oxygen delivery. Furthermore, adult chondrocytes are terminally differentiated and can't divide so no more interstitial growth occurs. Both avascularity and lack of cell division combine to minimize cartilage healing.
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Which best describes the specific cause of Parkinson's disease?
A. Reduced ability of neurons in the substantia nigra to release dopamine B. Failure of serotonin receptors to bind with these neurohormones C. Hyperactivity of metabolic enzymes that degrade dopamine D. Natural tendency of basal nuclei to follow a daily recurring, oscillating cycle of rising and falling norepinephrine release E. Enhanced sensitivity of cholinergic receptors to acetylcholine
The ________ mechanism is the general tendency of vascular smooth muscle to contract when stretched
Fill in the blanks with correct word
Which of the following is not internal work?
a. energy required for active transport. b. energy required to pump blood. c. energy use to power skeletal muscle contractions for body movements d. energy used during synthetic reactions. e. energy used to maintain body posture.
Skin, hair, and nails belong to the ____ system
a. integumentary b. muscular c. digestive d. endocrine