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MC Bio 205 ch 25

reproductive system

QuestionAnswer
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