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MC Bio 205 ch 25
reproductive system
| Question | Answer |
|---|---|
| cremaster muscle | associated with each testis is the -----, a series of small bands of skeletal muscle that descends as an extension of the internal oblique to surround the testes |
| seminiferous tubules | each of the 200-300 lobules in each testis contains 1 to 3 tightly coiled ----- that produce sperm |
| Leydig cells | L/spaces between seminiferous tubules | F/secrete testosterone |
| spermatogonia | stem cells that remain dormant during childhood and actively begin producing sperm at puberty |
| two major types of cell in the seminiferous tubules | spermatogenic cells and Sertoli cells |
| Sertoli cells | large cells in the seminiferous tubule | extend from the basement membrane to the lumen | F/form blood-testis barrier, which prevents immune response against sperm |
| how long does spermatogenesis take? | 65-75 days |
| major events in spermatogenesis | spermatogonia [diploid] undergo mitosis, forming primary spermatocytes [diploid] | meiosis I creates 2 secondary spermatocytes [haploid] | meiosis II creates 4 spermatids [haploid] | in spermiogenesis, those 4 become sperm |
| acrosome | L/a vesicle that covers the anterior two-thirds of the sperm nucleus | F/contains enzymes that help penetrate the oocyte |
| the head of the sperm | F/contains a nucleus with 23 highly condensed chromosomes |
| the middle piece of the sperm | F/contains mitochondria arranged in a spiral, which provide the energy (ATP) for locomotion |
| hormonal promotion of spermatogenesis | hypothalamus secretes gonadotropin-releasing h (GnRH) | anterior pit secretes luteinizing h (LH) and follicle-stimulating h (FSH) | LH stimulates Leydig cells to produce testosterone | FSH (w/test.) stimulates Sertoli cells to stimulate secretion of ABP |
| androgen-binding protein (ABP) | F/binds to testosterone in seminiferous tubules, keeping its concentration high | testosterone then stimulates the final steps of spermatogenesis |
| negative feedback + spermatogenesis | when enough sperm have been made, Sertoli cells release inhibin, which inhibits FSH secretion by anterior pit | when fewer sperm are in bank, inhibin production declines |
| male secondary sex characteristics | wide shoulders, narrow hips, facial and chest hair, thickening of the skin, enlargement of the larynx |
| sperm maturation | the process by which sperm acquire motility and the ability to fertilize a secondary oocyte | takes 14 days | occurs in the ductus epididymis |
| epididymis | a comma-shaped organ that lies along the posterior border of each testis | mostly contains ductus epididymis | sperm may remain viable here for several months |
| ductus deferens | aka vas deferens | this is what the ductus epididymis becomes at the point where its diameter increases and it becomes less coiled | stores sperm and conveys sperm from epididymis toward urethra |
| the spermatic cord | a supporting structure of the male reproductive system that ascends out of the scrotum | consists of the ductus deferens, the testicular artery, veins that drain the testes, autonomic nerves, lymphatic vessels, and the cremaster |
| ejaculatory duct | each ---- is about 2 cm long and is formed by the union of the duct from the seminal vesicle and the ampulla of the ductus deferens |
| the male urethra | passes through the prostate | three sections: prostatic, membranous, spongy (penile) |
| sequence of structures that sperm pass through | sperminiferous tubules, straight tubules, rete testis, efferent ducts, ductus epididymis, ductus deferens, ejaculatory duct, urethra |
| seminal vesicles | L/posterior to the base of the urinary bladder and anterior to the rectum | F/secrete alkaline fluid (60% of semen volume) that protects sperm from acidic vagina | fluid also contains fructose for ATP production, prostaglandins, clotting proteins |
| prostate | a single, donut-shaped gland inferior to the urinary bladder | secretes milky, slightly acidic fluid (25% of semen volume) that contains citric acid for ATP production, proteolytic enzymes, and seminalplasmin (an antibiotic) |
| bulbourethral glands | aka Cowper's glands | L/inferior to the prostate on either side of the membranous urethra | F/secrete alkaline fluid into urethra that protect sperm from acidic urine |
| avg number of sperm in a milliliter of semen | 50-150 million |
| F/semen | provides sperm with a transportation medium, nutrients, and protection from the acidic environment of the vagina |
| physiology of erection | parasympathetic fibers relax smooth muscle in the walls of aterieroles supplying erectile tissue | para. fibers also cause smooth muscle within erectile tissue to relax, thus widening blood sinuses | all of this compresses veins that drain the penis |
| physiology of ejaculation | a sympathetic reflex coordinated by the lumbar portion of the spinal cord |
| F/ovaries | produce gametes (secondary oocytes) | produce hormones (progesterone, estrogens, inhibin, and relaxin) |
| broad ligament | encloses ovaries and attaches them to the pelvic wall, where the ----- continues as the parietal peritoneum |
| ovarian ligament | anchors ovaries to the uterus |
| suspensory ligament | attaches ovaries laterally to the pelvic wall |
| oogonia | during fetal development, millions of diploid stem cells known as ----- differentiate within the ovaries |
| primary oocytes | during fetal development, a small proportion of the oogonia develop into larger cells called ----- that enter prophase of meiosis I before birth, but do not complete that phase until after puberty |
| primordial follicle | during their arrested stage of development, each primary oocyte is surrounded by a single layer of flat follicular cells, and the entire structure is called a ----- |
| the fates of primary oocytes | at birth, 200,000 to 2 million remain in each ovary | at puberty, approx 40,000 remain | around 400 will mature and ovulate during a woman's reproductive lifetime |
| primary follicles | each month after puberty, FSH and LH stimulate a few primordial follicles to grow into ----, which have multiple layers of follicular cells |
| zona pellucida | the clear glycoprotein layer between primary oocyte and granulosa cells |
| corona radiata | in secondary follicles, the innermost layer of granulosa cells becomes firmly attached to the zona pellucida and is now called the ---- |
| secondary follicle | middle phase of follicle maturation, during which the corona radiata and the antrum appear |
| mature (graafian) follicle | the final stage of follicle development, during which the primary oocyte completes meiosis I, forming a secondary oocyte and a first polar body |
| ovulation | at -----, the secondary oocyte is expelled into the pelvic cavity together with the first polar body and corona radiata |
| fertilization | if sperm are present in the uterine tube and one penetrates the secondary oocyte, meiosis II resumes | the secondary oocyte splits into two haploid cells of unequal size | the larger is the ovum, which unites with the sperm to form a zygote |
Created by:
dglenn34
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