Anatomy and Physiology Answer Key

Used properly the chance of fertilization is almost

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Unformatted text preview: uteum. (b) Progesterone and estrogens. (a) Estrogen (high levels) and oxytocin. (b) Any two of: • Declining progesterone levels. • Loss of placental competency (placenta deteriorates). • High estrogen levels increasing uterine sensitivity to oxytocin. • Peak in oxytocin. • The physiological state of fetus (release of stress hormones etc.) is now known to play a major part in labor onset also. 3. The placenta secretes hormones that are important in maintaining the pregnancy and preparing the breasts for lactation. 1. 5. 6. (a) In the case of labor, positive feedback between oxytocin and uterine contraction accelerates the physiological processes that bring about delivery of the infant. Oxytocin causes uterine contraction and stretching of the cervix, which causes more release of oxytocin and so on until the delivery, after which stretching of the cervix ceases and the positive feedback loop is ended. (b) Positive feedback is also important in lactation and milk letdown. Suckling stimulates the secretion of prolactin (milk production) and oxytocin (milk let down). The more the infant suckles, the more these hormones are produced. This mechanism is important for maintaining lactation and inducing greater milk production, especially during periods of infant growth. (a) Antibodies are used to detect the presence of the hormone (HCG) produced by the placenta in pregnancy. The antibodies are produced against the glycoprotein hormone and bind them to form a complex, which is captured and immobilized by capture antibodies to create a color change in the test window. (a) Drugs may induce release of FSH from the pituitary so that development of ova is stimulated. (b) Some drugs contain FSH and/or LH and directly induce the development and release of many ova. 2. (a) Where the fallopian tubes are blocked. (b) Where the ovaries are not functioning normally (a donor egg may be necessary). 3. Risk associated with fertility drugs: Multiple pregnancy (twins or triplets). These involve a higher risk of ea...
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