Male Reproductive System

Human reproduction involves intricate anatomy and complex behavior Reproductive Anatomy of the Human Male. External: - penis - scrotum Internal: - gonads - accessory sex glands and ducts.

Male Reproductive System

The engorgement of the penis with blood causes an erection. The penis is composed of three layers of spongy erectile tissue. During sexual arousal the erectile tissue fills with blood from arteries. The resultant increased pressure seals off the veins that drain the penis. The engorgement of the penis with blood causes an erection.

External structure of the penis: glans penis prepuce (foreskin) There is no verifiable health benefit to circumcision.

Male Reproductive System

Male Reproductive System

Ejaculation/Review What is the anatomy of the penis? The penis is made up of: Two chambers called the corpora cavernosa, which run the length of the organ and contain a maze of blood vessels shaped like cavernous spaces (like a sponge) The urethra, or channel for urine and sperm, which runs along the underside of the corpora cavernosa Erectile tissue, which surrounds the urethra, two main arteries and several veins and nerves The shaft, the longest part of the penis The head (glans), which is at the end of the shaft The meatus, or opening at the tip of the head where urine and semen are discharged

How an erection occurs How does an erection occur? When the blood vessels of the corpora cavernosa relax and open up, blood rushes in through the cavernosus arteries to fill them. The blood then gets trapped under high pressure, creating an erection. An erection begins with sensory and mental stimulation. During sexual arousal, nerve messages begin to stimulate the penis. Impulses from the brain and local nerves cause the muscles of the corpora cavernosa to relax, allowing blood to flow in and fill the open spaces. The blood creates pressure in the corpora cavernosa, making the penis expand and creating an erection. The tunica albuginea (the membrane surrounding the corpora cavernosa), helps to trap the blood in the corpora cavernosa, sustaining the erection. Erection is reversed when muscles in the penis contract, stopping the inflow of blood and opening outflow channels.

Testes are located in the scrotum, outside the body cavity. This keeps testicular temperature cooler than the body cavity. The testes develop in the body cavity and descend into the scrotum just before birth.

Testes

Testes are the male gonads. seminiferous tubules- form sperm Leydig cells (interstitial cells)- produce androgens (ex. Testosterone, ABP).

Sperm Pathway Membranous urethra Prostatic urethra

seminal vesicle prostate gland bulbourethral gland Semen Seminal fluid is thick, yellowish, and alkaline. It contains mucus, fructose, a coagulating enzyme, ascorbic acid, and prostaglandins. Accessory glands: seminal vesicle prostate gland bulbourethral gland

Contains fructose, asorbic acid, coagulating enzyme, prostaglandin Seminal vesicle: A pair of glands that secrete a liquid component of semen into the vas deferens. Secretion is alkaline Contains fructose, asorbic acid, coagulating enzyme, prostaglandin Seminal Vesicle

Prostate gland: Location- surrounds and opens into the urethra where it leaves the bladder. Secretion- slightly alkaline fluid that activates the sperm and prevents them from sticking together Prostate problems are common in males over 40. Prostate cancer is one of the most common cancers in men. Prostate

Bulbourethral gland (Cowper’s gland): Location- paired glands that lie beneath the prostate Secretion- a thick, clear alkaline mucous that drains into the membranous urethra. Function- It acts to wash residual urine out of the urethra when ejaculating semen-- raises pH; neutralizes acidity of urine. Bulbourethral gland

Ejaculation Ejaculation propels sperm from the epididymis to the vas deferens. The vas deferens run from the scrotum and behind the urinary bladder. Here each vas deferens joins with a duct from the seminal vesicle to form an ejaculatory duct. The ejaculatory ducts open into the urethra. The urethra drains both the excretory and reproductive systems.

Ejaculate A male usually ejaculates about 2 – 5 mL of semen; each milliliter containing about 50 – 130 million sperm. Bulbourethral fluid also carries some sperm released before ejaculation. This is one of the reasons why the withdrawal method of birth control has a high failure rate.

Ejaculation How does ejaculation occur? Sexual stimulation and friction provide the impulses that are delivered to the spinal cord and into the brain. Ejaculation is a reflex action controlled by the central nervous system. It is triggered when the sexual act reaches a critical level of excitement. It has two phases. In the first phase, the vas deferens (the tubes that store and transport sperm from the testes) contract to squeeze the sperm toward the base of the penis and the prostate gland and seminal vesicles release secretions to make semen. At this stage, the ejaculation is unstoppable. In the second phase, muscles at the base of penis contract every 0.8 seconds and force the semen out of the penis in up to 5 spurts.

Spermatogenesis

Mature Spermatozoa acrosome head nucleus tail mitochondria

Seminiferous Tubules

Seminiferous Tubules spermatozoa Sertoli cell spermatids 2º spermatocyte 1º spermatocyte spermatogonium

Sperm Maturation & Development

Hormones Involved in Spermatogenesis Gonadotropin Releasing Hormone (GnRH) Follicle Stimulating Hormone (FSH) Interstitial Cell Stimulating Hormone (ICSH=LH) Testosterone Inhibin ABP

Hormonal Control of Spermatogenesis Hypothalamus GnRH Anterior Pituitary ICSH FSH

Hormonal Control of Spermatogenesis ICSH Interstitial Cells Testosterone

Hormonal Control of Spermatogenesis FSH Testosterone Sertoli Cells Spermatogenesis Inhibin

Hormonal Control of Spermatogenesis Feedback Inhibition Inhibin Acts on anterior pituitary Inhibits FSH production Testosterone Acts on hypothalamus Inhibits GnRH production

Some Other Effects of Testosterone muscle and bone growth facial and pubic hair growth thickening of vocal cords growth of pharyngeal cartilage hair follicle effects stimulates sebaceous glands Increased BMR

Vasectomy

Circumcision foreskin glans penis urethral opening sutures shaft corona

Circumcision

Male Circumcision (Mayo Clinic) Circumcision is a religious or cultural ritual for many Jewish and Islamic families, as well as certain aboriginal tribes in Africa and Australia. Circumcision can also be a matter of family tradition, personal hygiene or preventive health care. Sometimes there's a medical need for circumcision, such as when the foreskin is too tight to be pulled back (retracted) over the glans. In other cases, particularly in certain parts of Africa, circumcision is recommended for older boys or men to reduce the risk of certain sexually transmitted infections. The American Academy of Pediatrics (AAP) says the benefits of circumcision outweigh the risks. However, the AAP doesn't recommend routine circumcision for all male newborns. The AAP leaves the circumcision decision up to parents — and supports use of anesthetics for infants who have the procedure. Circumcision might have various health benefits, including: Easier hygiene. Circumcision makes it simpler to wash the penis. Washing beneath the foreskin of an uncircumcised penis is generally easy, however. Decreased risk of urinary tract infections. The overall risk of urinary tract infections in males is low, but these infections are more common in uncircumcised males. Severe infections early in life can lead to kidney problems later on. Decreased risk of sexually transmitted infections. Circumcised men might have a lower risk of certain sexually transmitted infections, including HIV. Still, safe sexual practices remain essential. Prevention of penile problems. Occasionally, the foreskin on an uncircumcised penis can be difficult or impossible to retract (phimosis). This can lead to inflammation of the foreskin or head of the penis.

Circumcision Easier hygiene. Circumcision makes it simpler to wash the penis. Washing beneath the foreskin of an uncircumcised penis is generally easy, however. Decreased risk of urinary tract infections. The overall risk of urinary tract infections in males is low, but these infections are more common in uncircumcised males. Severe infections early in life can lead to kidney problems later on. Decreased risk of sexually transmitted infections. Circumcised men might have a lower risk of certain sexually transmitted infections, including HIV. Still, safe sexual practices remain essential. Prevention of penile problems. Occasionally, the foreskin on an uncircumcised penis can be difficult or impossible to retract (phimosis). This can lead to inflammation of the foreskin or head of the penis.

Circumcision Decreased risk of sexually transmitted infections. Circumcised men might have a lower risk of certain sexually transmitted infections, including HIV. Still, safe sexual practices remain essential. Prevention of penile problems. Occasionally, the foreskin on an uncircumcised penis can be difficult or impossible to retract (phimosis). This can lead to inflammation of the foreskin or head of the penis. Decreased risk of penile cancer. Although cancer of the penis is rare, it's less common in circumcised men. In addition, cervical cancer is less common in the female sexual partners of circumcised men. Circumcision might not be an option if certain blood-clotting disorders are present. In addition, circumcision might not be appropriate for premature babies who still require medical care in the hospital nursery. Circumcision doesn't affect fertility, nor is circumcision generally thought to enhance or detract from sexual pleasure for men or their partners.

Female Reproductive System

Effects of Estrogen breast development external genitalia growth bone growth fat deposition Increase protein anabolism Decrease blood cholesterol Facilitate calcium uptake Promotes hydration of skin Feminizes brain

Female Reproductive System uterine tube ovary fimbriae uterus cervix bladder vagina urethra clitoris l. minora l. majora

Internal reproductive: Vagina Cervix Fallopian tube (uterian tube/oviducts) Fimbrae Ovary Uterus Endometrium Myometrium Perimetrium uterus uterine tube ovary endometrium fimbriae myometrium perimetrium cervix vagina

Fimbrae & Fallopian Tube

Oogenesis in the Ovary

Oogenesis Ovary- contains 400,000 oocytes; release about 500 in a lifetime Ovary- under influence of FSH. The follicles mature every 28 days Primary follicle produces estrogens And primary oocyte completes its 1st division produces 2ndary oocyte and polar body

Oogenesis Aprox 1/2 way through the 28 day cycle the follicle reaches the mature Vesticular or Graffian follicle stage.

Oogenesis Estrogen levels rise and release LH and FSH and triggers ovulation.

Oogenesis The 2ndary oocyte travels down the uterine tube to the uterus. If fertilized by sperm, it will produce a zygote Ovum in uterine tube

Ectopic Pregnancy

Ovarian Cyst

Endometriosis In some women, endometrial tissue grows outside the uterus. Growths may form on the ovaries, fallopian tubes, bladder, intestines, and other parts of the body. When it's time for your period, these clumps break down, but the tissue has no way to leave the body. While this is rarely dangerous, it can cause pain and produce scar tissue that may make it tough to get pregnant. There are treatments for endometriosis, but there is no cure.

Oogenesis

Hormones Involved in the Female Reproductive Cycle Gonadotropin Releasing Hormone (GnRH) Follicle Stimulating Hormone (FSH) Luteinizing Hormone (LH) Estrogen Progesterone Inhibin Relaxin

Female Hormonal Cycle Hypothalamus GnRH Anterior Pituitary LH FSH

Female Hormonal Cycle FSH LH Follicle Cells Estrogen

The Uterine Cycle

Hormone Fluctuation

Menopause: cessation of ovarian and menstrual cycles. Usually occurs between ages 46 and 54. Due to ovaries decreased responsiveness to gonadotropins. Menopause affects: changes in sexual desire triggers mood swings causes debilitating hot flashes may lead to bone and heart problems short-term memory loss insomnia

Milk drains into a series of ducts opening at the nipple. Mammary glands. Are present in both males and females. Are not a component of the reproductive system. Contain epithelial tissue that secrete milk. Milk drains into a series of ducts opening at the nipple.

Mammary Gland

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INQUIRY Where are sperm cells formed within the testes? What portion of the sperm contains 23 chromosomes? What 3 accessory glands produce seminal fluid? What is the term for the primary human sex organs? What structure is formed following ovulation? 6. What hormones are produced from the corpus luteum? 7. List several effective means for preventing conception.