Anatomy and Physiology Answer Key

A capacitation changes in the surface of the sperm

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Unformatted text preview: etrium. These villi contain the capillaries that connect the fetal arteries and vein. The blood vessels of the mother and fetus are in close proximity, forming a complex network that allows for the exchange of nutrients, respiratory gases, wastes. 2. (a) They cross the placenta and are taken up by the fetus. The fetus does not have the capacity to filter out toxins. Any substance capable of diffusing into the fetal capillaries does so. (b) CO diffuses across the placenta into the fetal capillaries and occupies the fetal hemoglobin, reducing the oxygen carrying capacity of fetal blood and causing oxygen deprivation. Contraception (page 222) 1. Combined oral contraceptive pills utilize the normal negative feedback mechanisms operating in the menstrual cycle. By providing an artificially high level of reproductive hormones (estrogen and progesterone), they prevent release of the pituitary hormones (FSH and LH) that induce follicle development and ovulation. 2. OCPs suppress follicle development and ovulation whereas the mini-pill does not affect the normal cycle of egg production and release; it merely thickens cervical mucus and prevents sperm entry, and prevents endometrial thickening. 3. OCPs offer effective contraception because they work either by preventing ovulation, or by providing an effective natural barrier to sperm entry at the cervix. Used properly, the chance of fertilization is almost nil. (a) Fetal arteries: Deoxygenated and containing nitrogenous wastes. (b) Fetal vein: Oxygenated and containing nutrients. 3. (b) Home tests are quick, simple to use, and avoid a doctor's visit for something that is not an illness. Users must ensure they do not perform the test too early in the pregnancy, when the levels of HCG are too low to enable detection. The Hormones of Pregnancy (page 220) Anatomy and Physiology 1. 2. (a) The placenta does not develop fully until three months or so into the pregnancy. Before this, the progesterone to maintain the endometrium must come from the corpus l...
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