Download - REPRODUCTIVE SYSTEM & HUMAN DEVELOPMENT. Male Reproductive System What do you already know?
Male reproductive system functions• Testes –
• Produce sperm in a process called spermatogenesis• Produce testosterone
Sperm are produced from puberty until the end of life, but fertility and sperm quality do decline with age.
Schizophrenia, autism, preterm birth and certain birth defects increase in dads over 35.
Testosterone
• Causes development of reproductive organs and secondary sexual characteristics (increased hair growth, thickening of bones, deepening of bones, and enlargement of muscles)
• Responsible for sex drive
• Supports sperm formation
Male reproductive system functions• epididymis –
• Storage and final site of maturation for sperm• Contracts during ejaculation to push sperm into ductus deferens
• Ductus deferens carries sperm to ejaculatory duct. The ejaculatory duct then joins the urethra.
Fun fact: Vasectomy involves severing the ductus deferens (aka vas deferens) so that sperm cannot be carried to the urethra, rendering a man infertile.
Accessory glands & semenThe accessory glands (seminal vesicles, prostate, and bulbourethal gland) produce most of the fluid that makes up semen.
• Seminal vesicles – produce fluid that nourishes and activates sperm• Prostate – produces fluid that activates sperm• Bulbourethal gland – produces fluid before ejaculation that reduces
acidity of urethra and acts as lubricant for sexual intercourse
Fun fact:
The prostate becomes enlarged in most men with age, making urination more difficult.
Prostate cancer second most common cancer in men (after skin), affecting 1 in 7 men.
External genitalia• The scrotum contains the testes and helps maintain optimal
temperatures for sperm production by hanging loosely (at high temps) or wrinkling up (at low temps).
• Erection occurs when the erectile tissue of the penis fills with blood, making the penis larger and rigid.
Fun fact:
Atherosclerosis is the #1 cause of ED
Female Reproductive System Functions• Ovaries
• Produce oocytes (eggs)• Produces estrogens
• develop female sexual characteristics• Establish menstrual cycle and supports growth of endometrium
• Produces progesterone• Establishes menstrual cycle• Supports pregnancy and milk production
Fun Fact: A woman is born with all the oocytes she will ever have, all paused at an early stage of development. Starting at puberty, several oocytes finish developing every month, with the ‘best’ of these rupturing through the ovary wall during ovulation
Female Reproductive System Functions• Uterine (Fallopian) tubes
• Beating of cilia within tubes carries the egg from the ovary to the uterus
• Not attached to ovary. Egg is pulled into uterine tubes by waving of fimbriae (hair-like projections of uterine tubes that partially surround ovary.
• Normal site of fertilization.
The egg is only viable for ~24 hours after ovulation, but it takes 3-4 days for it to reach the uterus.
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Female Reproductive System Functions• Uterus
• Receives & nourishes fertilized eggs to support pregnancy
• Normally size of pear• Endometrium is inner lining. This builds
up every month in order to allow implantation of fertilized egg, but sloughs off (menstruation) if zygote does not successfully implant and grow.
• Myometrium is muscular wall. • Cervix is the opening; prevents
premature birth. Opens fully to 10 cm diameter during earliest stages of labor.
Menstrual Cycle• Day 0 is first day of
menses
• Normal cycle varies from 22-34 days
• No matter what cycle length, ovulation occurs ~14 days prior to menstruation
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Pregnancy and Embryonic Development
• NOVA show (~50 min)
• Baby center short clips