1. Target cells are the specific cells that are affected by a hormone.
2. A second messenger is an intracellular molecule that amplifies the signal of a first messenger.
3. A prostaglandin is a lipid that regulates the activity of cells that are in close proximity to its site of production.
4. Hormones are molecules that are secreted in small amounts, circulate in the bloodstream, and affect distant target cells.
1. d 2. c 3. a 4. c 5. c
1. A first messenger binds to cell surface receptors and stimulates production of a second messenger that is located within the target cell.
2. Hormones are transported in the bloodstream.
3. No; they have ducts and secrete sweat, not hormones. 4. It depends on the enzymes and other proteins that c-AMP activates to change the function of the cell.
STRUCTURES AND FUNCTIONS
1. Anti-C antibody prevents the hormone’s action.
2. No; the fact that three of the antibodies do not alter the hormone’s action is evidence that it is not simply the binding of an antibody that disrupts the action of the hormone.
3. Segment C is probably the receptor binding portion of the hormone.
1. Hypothyroidism results from a thyroid-hormone deficiency, but hypoglycemia results from excessive insulin. 2. Epinephrine and norepinephrine are both secreted from the medulla of the adrenal glands.
3. Releasing hormones are produced by the hypothalamus and control the secretion of luteinizing hormone. 4. Neurosecretory cells of the hypothalamus produce oxytocin and antidiuretic hormone.
5. Estrogen, progesterone, and testosterone are all steroid sex hormones secreted by the gonads.
1. d 2. a 3. c 4. d 5. b
1. No; the hypothalamus is a structure of the nervous system that regulates the pituitary gland.
2. The thyroid glands secrete calcitonin, which lowers blood levels of calcium, and the parathyroid glands secrete parathyroid hormone, which raises