A&PII Final ExamMale Reproductive System1) The parasympathetic nervous system stimulates an increase in Nitric Oxide causing relaxation and vasodilation of arterioles so erectile bodies fill with blood resulting in an erection. (PNS=point)The sympathetic nervous system stimulates spinal reflex causing contraction of ducts, glands, and bulbospongiosus muscles and constriction of the bladder resulting in the propulsion of semen from the male duct system aka ejaculation. (SNS=shoot) 2) The testes serve two distinct physiological roles: endocrine and exocrine. Exocrine function is the production of mature sperm (spermatogenesis) involving seminiferous epithelium and Sertoli cells. Exocrine function is the production of androgens (steroidogenesis) involving interstitial compartment and Leydig cells.3) Spermatogenesis takes place in the seminiferous tubules of the testes and produces sperm. It begins at about 14 years old and makes ~4 million sperm every day. There are 3 phases of spermatogenesis:I. Proliferative Phasei. There are 3 types of spermatogonia: Type Ad (dark/dense chromatin), Type Ap (pale/less dense chromatin), and Type Bii. Type Ad gives rise to a Type Ap as well as generating more Type Ad for future generations of sperm. Type Ap then gives rise to Type B.II. Meiotic Phasei. Meiosis I: Type B spermatogonia divide by mitosis into primary spermatocytes and replicated chromosomes seek out a partner. After Meiosis I, each daughter cell has 2 copies and the number of chromosomes is cut in half from 46 to 23.1. Crossing-over occurs during Meiosis I causing portions of nonsister chromatids to exchange places resulting in two recombinant chromatids with separate gametes.ii. Meiosis II: further division but the same number of chromosomes (23)III. Spermiogenic Phase is the differentiation of a spermatid into a sperm through 4 steps:i. Golgi Phase: tail filament appearsii. Cap Phase: head cap appears from acrosomal granuleiii. Acrosome Phase: nucleus and head cap elongate and acrosomal granule differentiates to form acrosomeiv. Maturation Phase: cell completes differentiation to become a mature spermSpermatogonia initiate a new cycle every 16 days and there are 4 total cycles= 64 daysi. 1st: Type A gives rise to Type Bii. 2nd: Primary spermatocytes of 1st cycle formiii. 3rd: Spermatids of first cycle appeariv. 4th: Spermatogenesis completed; spermiation beginsOnce sperm are released into lumen, another 10 days is required for movement to epididymis = 74 days.Sperm is then stored in the epididymis4) The hypothalamus releases GnRH to the pituitary gland, stimulating the production of FSH and LH. FSH binds to receptors in Sertoli cells circulating down through seminiferous tubules initiating sperm production and also increasing ABP. FSH also increases the number of LH receptors on Leydig cells. LH binds to Leydig cells stimulating testosterone production. Testosterone assists in sperm production and inhibits the pituitary gland while inhibin inhibits the hypothalamus.5) Sperm migration through the epididymis takes 10-16 days meaning 90 days total for mature sperm to appear in ejaculate. Sperm is stored in cauda epididymis and vas deferens but NOT in seminal vesicles. Maturational changes are that the sperm acquire the capacity for motility in epididymis. Elimination of aged sperm occurs through phagocytosis. Ejaculate consists of seminal plasma (secretions from accessory sex glands) and semen (combination of seminal plasma and sperm).Order of ejaculation: Cowper’s/Littre prostate ampulla and epididymis seminal vesicles (sperm may be present in first portion)I. Cowper’s gland is about .1-.2 ml or 5% of ejaculate. It is clear fluid rich in microproteins that lubricates the distal urethra. It may contain small amounts of spermII. Prostate gland is about .5 ml or 15-30% of ejaculate containing citric acid, acid phosphate, calcium, and zinc. It liquefies the ejaculate. Prostate-specific antigen (PSA) helps to activate sperm motality. (no sperm)III. Seminal Vesicles are about 2-2.5 ml or 45-80% of ejaculate rich in fructose and prostaglandins. It contains enzymes which cause coagulation of ejaculation. The absence of fructose is used to diagnose an absence of vas deferens (in the epididymis). (most sperm)Female Reproductive System1) In the fetal period oogenesis produces female sex cells. Oogonia (stem cells) divided by mitosis are transformed into primary oocytes. Primary oocytes begin meiosis but most don’t complete it. Oogonia peak at 20 weeks and then undergo meiosis when the number greatly diminishes. Oogonia are present in fetus between weeks 5-30.Mother cellMitosisPrimary oocytesMeiosis Ifirst polar body (meiosis II may or may not occur) and secondary oocytes (meiosis II completed only if sperm penetration occurs)polar bodies, secondary polar bodies, ovumOogenesis begins 6-8 weeks reaching 6-7 million oogonia by 16-20 weeks (maximal oogonial content of gonad).Store of oocytes becomes depleted 50 years laterWomen will have all the eggs she will need by 20 weeks in the womb.Having children over 35-40 years old could cause abnormalities2) The Ovarian Cycle:a. Follicular Phase: the period of follicular growth; days 1-14FSH (follicle stimulating hormone) develops about 20 follicles at the beginning of each cycle but only one develops and the rest undergo atresia (degeneration). The developing follicle has enough estrogen to be maintained due to theca and granulose cells on the follicle.- “Two Cell Theory”: LH induces androstenedione synthesis in theca cells. Driven by FSH stimulus, granulosa cells process androstenedione into estrone which is further converted to estradiol1. Basically, theca cells make androgens which are transferred to granulosa cells to make estrogenb. Midcycle: when ovulation occurs; 14 daysDevelopment of estrogen making follicleSurge in LH correlates with ovulationThe release of prostaglandins allows the egg to come out and upon release the release of the egg, the corpus luteum (required for pregnancy) is formed which makes progesterone. Progesterone must be present for pregnancy to be maintainedc. Luteal Phase: period of corpus luteum activity; days 14-28After ovulation, the ruptured follicle collapses and forms the corpus luteum which secretes estrogen and progesterone. If pregnancy does NOT occur, the corpus luteum degenerates in 10 days. If pregnancy DOES occur, the corpus luteum produces hormones until the placenta takes over
View Full Document
Unlocking...