What are the primary functions of saliva, and how is salivary secretion controlled?
What will be an ideal response?
Answer: Saliva functions to moisten the food, which helps dissolve food for chemosensation. Adding water and mucous to the food also helps it slide down. There are enzymes for the digestion of carbohydrates and lipids; although these accomplish very little digestion of food as they have little time to act (the acidity of the stomach inhibits them), they free some monosaccharides and fatty acids that can be sensed by the mouth. Saliva contains bacterial-killing lysozyme. Finally, saliva protects the teeth and bacteria on the teeth and gums from extremes of pH from food. Saliva is always secreted at a slow rate, and salivary secretion can be greatly increased by parasympathetic nervous activation in response to the smell, sight or thought of food, as well as by sensations of food being in the mouth.
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The hormone __________________ causes increased reabsorption of sodium (and the water that follows) and secretion of potassium from the later segments of the renal tubule.
Fill in the blank(s) with the appropriate word(s).
Because the kidneys are so important for water balance, the plasma membranes of kidney cells have many permanent aquaporins.
Answer the following statement true (T) or false (F)
The highest density of lymph nodes can be found ________.
A. in the arms and legs B. in the brain C. at the locations where lymphatic collecting vessels converge D. in the intestines
Carbon monoxide bonds to hemoglobin more effectively than does oxygen.
Answer the following statement true (T) or false (F)