Chat with AIExam 20: B--The Reproductive System
Describe the regulation of the ovarian and uterine cycles. Include all stages of each cycle in your answer.
(87) 
VerifiedThe ovarian cycle is under the influence of a variety of hormones. At the beginning of the cycle, FSH and LH from the pituitary gland stimulate oocyte development and follicle growth in the ovary; this is the follicular phase of the ovarian cycle. Estrogen secreted from the growing follicle also stimulates follicle growth and causes thickening of the endometrial lining; this is the proliferative phase of the uterine cycle. Elevated estrogen levels in the blood begin to inhibit FSH release from the pituitary, but LH levels continue to rise. About halfway through the cycle LH levels surge, causing the ovarian follicle to rupture and release a secondary oocyte. The ruptured follicle differentiates to form a corpus luteum that secretes progesterone; this begins the luteal phase of the ovarian cycle. Progesterone causes extensive thickening of the endometrial lining; this is the secretory phase of the uterine cycle. By about day 22, if fertilization does not occur the corpus luteum begins to degenerate and progesterone levels begin to decline. Around day 28 the endometrial lining detaches and menstruation begins; this is the menstrual phase of the uterine cycle. Low levels of estrogen and progesterone during this phase allow the pituitary to secrete more FSH and LH, and the cycles for the ovary and uterus repeat.
Describe the endocrine events that help maintain pregnancy after the blastocyst implants.
(68) VerifiedFertilization occurs around day 14 of the ovarian cycle when estrogen levels are the highest. After ovulation, the ovarian follicle becomes a corpus luteum and secretes progesterone, which stimulates thickening of the endometrium and is necessary for implantation of the developing embryo (blastocyst). About one week after fertilization, the blastocyst implants in the endometrium and the placenta develops. The placenta secretes estrogen, which helps maintain the endometrium, and human chorionic gonadotropin (hCG), which maintains the corpus luteum. The corpus luteum continues to secrete progesterone, which also prevents the endometrium from detaching from the uterine wall.
Summarize the current modes of contraception and their effectiveness.
(76) VerifiedMeans of contraception fall into three main methods. (A) Blockage of sperm transport to the ovum includes five techniques: (1) The rhythm method involves avoiding intercourse around the time of ovulation.
(2) Coitus interruptus involves withdrawal of the penis from the vagina before ejaculation.
(3) Chemical contraceptives destroy the sperm before they reach the secondary oocyte.
(4) Physical barriers, such as the condom, diaphragm, and cervical cap prevent movement of sperm into the uterus.
(5) Sterilization involves surgery that prevents the movement of sperm in men or in the oviduct. (B) Prevention of ovulation includes oral contraceptives (birth control pills), patches, and implanted contraceptives. All of these alter hormone levels and prevent ovulation. (C) Blockage of implantation involves preventing a developing embryo from implanting in the uterus. These include the intrauterine device (IUD) and "morning-after pills." The most effective contraceptive is implanted contraceptives and the IUD, followed in efficiency by oral contraceptives, barrier methods, chemical contraceptives, coitus interruptus, and the rhythm method.
Discuss the pros and cons of estrogen replacement therapy following menopause.
(66) 
Filters
- Essay(0)
- Multiple Choice(0)
- Short Answer(0)
- True False(0)
- Matching(0)