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Anatomy
Ch 3 Male Repro
| Question | Answer |
|---|---|
| Male reproductive system | testes, ductal system, scrotum, penis,&accessory glands. |
| Internal structures | testes (produce sperm), ducts (transport sperm),& glands (produce male hormones&o r secretions). |
| external structures | penis& scrotum. area between scrotum& anus is called perineum. |
| Testes | Produce spermatozoa (sperm cells)&secrete sex hormones. |
| Testes (structure) | 2 almond-shaped gland, 1 on each side of scrotum. Sm., approx. 1.5 to 2 inches long& 1 inch wide & thick. Tissue layers,1 of which partitions into 250-300 lobules, cover each testis. Ea lobule contains functional units, called seminiferous tubules. |
| Seminferous tubules | Tightly convoluted. Comb length about half a mile! W/i, sperm cells are prod &mature. Betw tubules:sm clusters speclized endocrine cells, = interstitial cells, secrete testosterone/ androgens (m/hormones). Cells lining tubules produce sperm. |
| Ductal System | male reproductive organs have a system of ducts that store&transport sperm from testicles to urethra. se ducts include paired epididymides (singular: epididymis), ductus deferentia (singular: ductus deferens),& ejaculatory ducts. |
| Development of Sexual Characteristics | • Secretes hormones that initiate puberty• Maintains specific male characteristics• Secretes mucus, spermatic fluid,&o r substances |
| Reproduction | • Produces sperm• Passes genetic information to offspring• Participates in copulation&fertilization |
| Epididymis | Long, comma-shaped organ attachd posterior surface of testis. Tightly coiled tube is approx 20 feet long, but so tiny it can barely be seen w/ naked eye. Stores sperm cells. W/i epididymis, millions sperm cells in final stages of matur&gain motility. |
| cont. | Sperm cells are unable to fertilize an egg unless y mature in epididymis. Smooth muscles propel sperm into ductus deferens. |
| Ductus Deferens | sperm continue ir journey through a tube called vas deferens or ductus deferens, which is about 18 inches (45 cm) long. It transports sperm from epididymis to ejaculatory duct. |
| Ductus deferens | passes upward posterior to testis, n into abdominal cavity,&continues over top&down posterior surface of urinary bladder, into pelvic cavity. Peristaltic contractions propel sperm cells through ductus. |
| Each ductus deferens | joins a duct from seminal vesicles. se ducts, toge r with blood vessels, lymphatic vessels, nerves,&connective tissue coverings, make up spermatic cord. spermatic cord is covered with connective tissue. |
| Spermatic cord | passes through an opening in musc abdominal wall =inguinal canal. Normally inguinal canal firmly encloses spermatic cord as it passes through abdominal wall. It is a weak spot,&common site for herniation in men (inguinal hernia). |
| cont. | It is also site where testicles descend into scrotum before birth. |
| Ejaculatory Ducts | about 1 inch (2 cm) long. Each one originates where ampulla of ductus deferens joins duct from seminal vesicle. ejaculatory ducts empty into urethra. |
| cont. | ejaculatory ducts also receive secretions from prostate gland. ( semen, mixed with various secretions, is called ejaculatory fluid.) |
| Scrotum | Testes are enclosed in a saclike structure called scrotum, which is suspended behind base of penis. Supports&protects testes. External appearance of scrotum varies, depending on environmental conditions& contraction of its attached muscles. |
| cont. | muscles involuntarily contract&bring testicles closer to body as external temperature lowers. temperature of testes (35° C or 95° F) is lower than internal body temperature. This temperature is maintained to facilitate sperm production. |
| Penis | Cylindrical organ located immediately in front of scrotum. It is composed of three masses of cavernous(erectile) tissue, ea contains sm muscle, connective tissue,&blood sinuses (large vascular channels). |
| cont. | When bl flow thru sinuses is minimal,penis is soft&flaccid. At time of sex excitement, blood fill sinuses& penis becomes firm&erect. &capable of penetrating vagina to deposit sperm. During sexual intercourse, semen is propelled into vagina. |
| Route of sperm: | testes [seminiferous tubules] (produce sperm&male hormones, begin maturation of sperm cells) → epididymis (storage of sperm, final maturation of sperm, sperm bec motile) |
| cont. | → duct deferens (up past testis, to abdom, over top&down back of urin bladdr) → joins seminal vesi → ejac duct → thru prostate → thru inguin canal → urethra → expelld |
| Smooth cap of penis | is called glans penis&is covered by a fold of loose skin that forms hoodlike foreskin (prepuce). Surgical removal of this foreskin, called circumcision, is sometimes performed on male babies. |
| Urethra | w/i penis serves as common passagewy for urinary&repro systs. (Urine&ejaculatory fluid do not pass thru urethra simultaneously.) An involunt sphincter located at base of bladder automatically inhibits micturition (voiding) during semen ejaculation. |
| Accessory Glands-Seminal Vesicles | 2 seminal vesicls are convoluted, sac-shaped glands about 2 inches long, located posterior to urinary bladder. Secrete a sticky, alkaline, yellowish substance, |
| cont. | (Semen), wh serves as a fluid medium for sperm. Seminal vesicles secrete about 60% of all of a man's semen. secretion contains many nutrients, citric acid, coagulation proteins,&prostaglandins. |
| Prostate Gland | a doughnut-shaped muscular gland lying just below bladder. It surrounds neck of urethra as urethra emerges from bladder. glandular tissue adds an alkaline secretion to semen, |
| cont. | which increases sperm motility. muscular portion of prostate contracts during ejaculation to expel semen from urethra. |
| Bulbourethral Glands | Cowper's gland. locate below prostate. Sz of pea & secrete alkaline mucus in tiny duct & empties into urethra. Coats urethra to neutrz pH vagina to maintain sperm motility/viability |
| Sperm survive better | in an alkaline medium than in an acid medium. Alkalinity helps maintain sperm motility. A woman's vagina is acidic because of its normal flora (natural bacterial population). alkaline environment of seminal fluid helps to neutralize acidic vaginal pH |
| Hormonal Influences | Male repro sys develops dur childhood&adolescence. Not functional until hormones secreted dur puberty, stage of life during which repro organs bec fully funct. In boys, 12-16. |
| Hormones from hypothalamus | ,pituitary gland,& gonads influence repro sys. Before puberty (prepubescence), bl concentrations of androgens (male hormones)&estrogens (female hormones) are same in every person. |
| When a boy reaches puberty, | hypothalamus stimulates secretion of both interstitial cell-stimulating hormone (ICSH)&follicle-stimulating hormone (FSH) from anterior pituitary. As a result, organs of reproductive system (genitals) begin to funct,&secondary sex char appear |
| ICSH&FSH are | gonadotropic hormones. |
| In men, hormones | have two main effects: Stimulate gonads (sex glands) to secrete hormones.• FSH: stimulates formation of sperm. |
| Major androgen is testosterone. | ICSH stim prod of testost. Dur puberty, male glandular developmt becomes active. Boys begins to dev a beard&pubic&axillary hair. Increase in hair growth all over his body. Musculature develops. Voice deepens, broad shouldrs, narrow hips=2nd sex charac |
| Testosterone | also maintains functioning of male accessory organs&stimulates protein anabolism. As a result, a man has larger&stronger musculature than a woman. |
| System PhysiologySperm Cells&Spermatogenesis | Beginning when a male is around 13 years old&continuing throughout life, male gonads, stimulated by testosterone, form sperm cells. |
| sperm cell is male gamete, | one of two cells that must unite to initiate development of a new individual. This formation of mature&functional spermatozoa is called spermatogenesis. Normal spermatogenesis does not occur if testes are too warm or too cold (above or below 35° C [95° |
| Stem cells of sperm cell development are called spermatogonia. | Spermatogonia div by mitosis& then meiosis to form spermatocytes. Next form is spermatids, wh eventually dev into spermatozoa. Testes prod millions of spermatozoa ea day. It takes 2 mo for to mature until stored in ductus deferens |
| Sperm cells are highly specialized | &are made up of several divisions. Head= 23 chromos. Tip head, acrosome, contains enzymes wh dissolve tough cell wall of ovum. Body (middle piece) contains mitochondria, wh prov energy (locomotion). Flagellum propels w/whip tail. |
| After sperm&semen combine in ejaculatory duct | Semen (now also known as ejaculatory fluid) contains about 60 to 100 million sperm cells per milliliter. Semen with a sperm count of less than 10 to 20 million per milliliter may have difficulty fertilizing an ovum. |
| Amount of semen each man ejaculates | (expels fr body) varies 2-5 mL. After ejac into vagina, a sperm can surv 3 days. Of avg 250 million sperm cells ejac, only 100 surv to contact ovum in oviduct. In norm cond, only one sperm fertz ovum. |
| Sperm have 23 chromosomes | Sperm can live for a maximum of 3 days after ejaculation. |
| Copulation | Sexual intercourse or sexual union between a man&a woman is called copulation, intercourse, or coitus. man inserts his erect penis into vaginal canal&deposits semen containing sperm when he ejaculates. |
| male sex act is a complex series of reflexes consisting of several components: | Erection, secretion, emission,&ejac. Erection occurs when nervous impulses from spinal cord&brain cause vasodilation of arteries of penis. When arteries dilate, venous return is obstructed& cavernous tissue in penis becomes engorged with bl. |
| Secretions from male glands | Lubricate passageway for semen, as well as tip of penis. Emission is accumulation of sperm cells&secretions in urethra. |
| Ejaculation | is forceful expulsion of semen from ejaculatory ducts, through urethra. |
| Orgasm | is physical&emotional, pleasurable sensation that occurs at climax of sexual intercourse; in men it is accompanied by ejaculation of semen. |
| Secretions from male glands | lubricate passageway for semen, as well as tip of penis. Emission is accumulation of sperm cells&secretions in urethra. |
| Ejaculation | is forceful expulsion of semen from ejaculatory ducts, through urethra. |
| Orgasm | is physical&emotional, pleasurable sensation that occurs at climax of sexual intercourse; in men it is accompanied by ejaculation of semen. |
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