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.…show more content… Cell D secretion is increased because it is unable to detect hormone secreted by Cell M. In response to the increased levels of Cell D hormones, Cell M secretions increase.
1. Semen contains sperm and the secretions of three exocrine glands-the seminal vesicles, the bulbourethral glands, and the prostate gland.
2. The testes are the gamete-producing organs of the male reproductive system.
3. Ejaculation is the forceful expulsion of semen from the penis.
4. Seminiferous tubules are the specialized compartments of the testes in which sperm are produced.
5. Sperm complete development within each epididymis, which is closely attached to each testis.
1. c 2. c 3. c 4. c 5. d
1. Sperm move from the seminiferous tubules to the epididymis, through the vas deferens and urethra, and out of the penis.
2. Semen is composed of sperm and secretions from three exocrine glands-the seminal vesicles, bulbourethral glands, and the prostate gland.
3. Seminiferous tubules are located in the testes- the vas deferens is not; there is more than one seminiferous tubule-there is only one vas deferens; seminiferous tubules have meiotic cells in their walls-the vas deferens does not; and the vas deferens has abundant smooth muscle cells in its wall-seminiferous tubules do not.
4. The sperm’s flagellum enables it to swim to an egg, and its head contains digestive enzymes that help it penetrate the egg’s outer layers.