Dec 20, 2015
Reproductive Anatomy of the Human Male. External:
- penis - scrotum
Internal: - gonads- accessory sex glands and ducts.
Human reproduction involves intricate anatomy and complex behavior
External structure of the penis:
glans penis
prepuce (foreskin)
There is no verifiable health benefit to circumcision.
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.
urethra
Testes are the male gonads. seminiferous tubules- form sperm Leydig cells (interstitial cells)- produce
androgens (ex. Testosterone, ABP).
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.
Semen Seminal fluid is thick, yellowish, and
alkaline. It contains mucus, fructose, a coagulating
enzyme, ascorbic acid, and prostaglandins.
Accessory glands:
1.seminal vesicle
2.prostate gland
3.bulbourethral gland
Seminal Vesicle
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
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 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.
Ejaculation
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.
Ejaculate
spermatogonium
1º spermatocyte
2º spermatocyte
Spermatids
Sertoli/sustenacular cell
Spermatozoa
Interstitial cells
Seminiferous Tubules
Hormones Involved in Spermatogenesis
• Gonadotropin Releasing Hormone (GnRH)• Follicle Stimulating Hormone (FSH)• Interstitial Cell Stimulating Hormone (ICSH=LH)• Testosterone• Inhibin• ABP
HypothalamusHypothalamusHypothalamusHypothalamus
Anterior Anterior PituitaryPituitaryAnterior Anterior PituitaryPituitary
GnRHGnRH
FSHFSHICSHICSH
Hormonal Control of
Spermatogenesis
Interstitial CellsInterstitial CellsInterstitial CellsInterstitial Cells
ICSHICSH
TestosteroneTestosterone
Hormonal Control of Spermatogenesis
Sertoli CellsSertoli CellsSertoli CellsSertoli Cells
TestosteroneTestosterone
SpermatogenesisSpermatogenesis
FSHFSH
InhibinInhibin
Hormonal Control of Spermatogenesis
Feedback Inhibition
InhibinInhibinActs on anterior pituitaryActs on anterior pituitaryInhibits FSH productionInhibits FSH production
TestosteroneTestosteroneActs on hypothalamusActs on hypothalamusInhibits GnRH productionInhibits GnRH production
Hormonal Control of Spermatogenesis
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
cervix
vagina
uterine tube
Ovary
uterus
Bladder
urethra
clitoris
l. minora
l. majora
Female Reproductive System
Internal reproductive:
• Vagina• Cervix• Fallopian tube
(uterian tube/oviducts)• Fimbrae• Ovary• Uterus
- Endometrium- Myometrium- Perimetrium
cervixvagina
fimbriae
uterine tube
ovary
uterus
endometrium
myometrium
perimetrium
OogenesisOvary- 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• The 2ndary oocyte travels down the uterine
tube to the uterus.• If fertilized by sperm, it will produce a zygote
Ovum in uterine tube
Hormones Involved in the Female Reproductive Cycle
• Gonadotropin Releasing Hormone (GnRH)Gonadotropin Releasing Hormone (GnRH)• Follicle Stimulating Hormone (FSH)Follicle Stimulating Hormone (FSH)• Luteinizing Hormone (LH)Luteinizing Hormone (LH)• EstrogenEstrogen• ProgesteroneProgesterone• InhibinInhibin• RelaxinRelaxin
HypothalamusHypothalamusHypothalamusHypothalamus
Anterior PituitaryAnterior PituitaryAnterior PituitaryAnterior Pituitary
GnRHGnRH
FSHFSHLHLH
Female Hormonal Cycle
Follicle CellsFollicle CellsFollicle CellsFollicle Cells
LHLH
EstrogenEstrogen
FSHFSH
Female Hormonal Cycle
Some Other Effects of Some Other Effects of EstrogenEstrogen
• breast development• external genitalia growth• bone growth• fat deposition• Increase protein anabolism• Decrease blood cholesterol• Facilitate calcium uptake• Promotes hydration of skin• Feminizes brain
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
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 glands.
INQUIRYINQUIRY
1. Where are sperm cells formed within the testes?
2. What portion of the sperm contains 23 chromosomes?
3. What 3 accessory glands produce seminal fluid?
4. What is the term for the primary human sex organs?
5. What structure is formed following ovulation?
6. What hormones are produced from the corpus luteum?
7. List several effective means for preventing conception.