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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
(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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- Winter '13