The Reproductive System PDF

The Reproductive System GENERAL INFORMATION Gonads: – Produce gametes Males: Testes Females: Ovaries – Secrete hormones Males : Testosterone Females : Progesterone and estrogen Accessory organs: ducts, glands, and external genitalia Function: to produce offspring MALE SYSTEM Testes – Produce sperm S...

The Reproductive System GENERAL INFORMATION Gonads: – Produce gametes Males: Testes Females: Ovaries – Secrete hormones Males : Testosterone Females : Progesterone and estrogen Accessory organs: ducts, glands, and external genitalia Function: to produce offspring MALE SYSTEM Testes – Produce sperm Seminiferous tubules: “sperm factories” Cells – Spermatogenic cells: give rise to sperm – Interstitial cells: produce androgens testosterone OVERVIEW SCROTUM Scrotum: sac of skin and superficial fascia that hangs outside of the abdominopelvic cavity Viable sperm are not produced at body temperature - core body temperature is 37⁰C - sperm is abundantly produced at 34⁰C Scrotum helps maintain proper temperature – Cold = the testes are pulled closer to the pelvic floor – Warm = scrotal skin is flaccid and loose to increase surface area for cooling away from the trunk – Muscles: Dartos muscle: layer of smooth muscle that wrinkles the scrotal skin Cremaster muscle: bands of smooth muscle that arise from the internal oblique muscles SCROTUM AND THE TESTES EXTERNAL GENITALIA OF MALE Penis – Delivers sperm to the female reproductive tract External genitalia: – The penis and the scrotum that hang from the perineum ACCESSORY DUCTS - 1 - Epididymis Nonmotile, immature sperm leave testis & enter epididymis Epididymis muscles contract to expel swimming sperm during sexual stimulation and ejaculation ACCESSORY DUCTS - 2 – Ductus deferens (vas deferens): Runs upward as part of the spermatic cord from the epididymis through the inguinal canal into the pelvic cavity Its terminus expands to form the ampulla and joins the duct of the seminal vesicle to form the ejaculatory duct – Urethra: the terminal portion of the male duct system MALE REPRODUCTIVE SYSTEM - 1 MALE ACCESSORY SEX GLANDS – Seminal vesicles Yellowish, viscous fluid (Makes up approx. 60% of semen) Contains nutrients, clotting factors, prostaglandins Sperm and seminal fluid mix in ejaculatory duct before entering the urethra – Prostate gland Milky-white, slightly acidic Contains enzymes & citrate – Bulbourethral glands Thick, clear mucus Neutralizes acidic urine MALE REPRODUCTIVE SYSTEM - 2 SEMEN - 1 – White, milky, somewhat sticky – Mixture of Sperm (approx. 5%) Testicular fluid Accessory gland secretions – Transport medium for sperm – Nutrients for sperm Fructose: provides nearly all the fuel needed for sperm ATP synthesis SEMEN - 2 – Chemicals: Prostaglandins: – Stimulate reverse peristalsis of uterine tubes Relaxin & other enzymes: enhance sperm motility Seminalplasmin: prostate antibiotic protein to help prevent UTI in males Clotting factors : coagulate the semen just after it is ejaculated- makes it stick to walls of the vagina to prevent it from draining out Fibrinolysin: liquefies the sperm soon after to allow the sperm to swim – Slightly alkaline: to neutralize the acidic environment in the male urethra and the vagina- protecting the sperm – 2 – 5 mL of semen ejaculated 20 – 150 million sperm per milliliter SPERMATOGENESIS Begins at puberty and continues throughout life The process from a spermatogonia (the most immature male gamete) to a full spermatozoa (sperm) takes about 64 days A round of mitosis produces one cell that will continue through meiosis (a primary spermatocyte) and one that can be a feeder cell for future divisions Meiosis in the primary spermatocyte creates two secondary spermatocytes, each of which divides to form a spermatid The spermatid matures into a full spermatozoa (sperm) SPERM 100-300 million produced per day Head of the sperm has a nucleus and is covered by an acrosome (a cap) that contains lysozyme (enzymes that help the sperm penetrate) Midpiece of the sperm contains many mitochondria to produce energy The tail of the sperm is created by cytoskeleton and moves the sperm MALE SEXUAL RESPONSE - 1 Erection: -Penile erectile bodies are flooded with blood -Controlled by the parasympathetic nervous system -No sexual arousal = erectile tissue arterioles are constricted Ejaculation: Controlled by the sympathetic nervous system Impulses cause: 1. Bladder sphincter muscle constricts 2. Reproductive ducts and accessory glands contract 3. Semen in the urethra triggers a spinal reflex for the bulbospongiosus muscle to contract propelling semen Orgasm (climax): the entire ejaculatory event MALE SEXUAL RESPONSE - 2