Reproductive system

Body cells vs. sex cells/gametes

• Body cells (ex: muscle, bone, skin): contain complete set of genetic material as a result of mitotic cellular division

• Gametes/sex cells: contain half the amount of genetic material (as a result of meiotic division) and when united, recombine to create a full set of genetic material (for formation of a zygote)

  • Male gametes: sperm

  • Female gametes: ova (egg cells)

Gonads (definition, function)

• Main reproductive organs/glands (testes and ovaries)

  • As organs: responsible for the production of gametes/sex cells (sperm and ova)

  • As glands: responsible for secreting sex hormones directly into the bloodstream (testosterone, estrogen, progesterone)

Where is sperm produced?

Testes

Where are the testes held and why?

Scrotal sac/scrotum, which is external to maintain cooler temperatures for maturation

Epididymis (location and function)

Long tightly coiled tube on the back of each testicle, responsible for storing and maturing sperm

Vans deferens (location and function)

Muscular tube behind each testicle that connects to the epididymis; responsible for transferring mature sperm to the urethra via the ejaculatory duct (connected with the seminal vesicle)

How and where does sperm become semen?

After passing through the vas deferens, the seminal vesicle, prostate gland, and bulbourethral glands add nutrients, protection, and lubricating fluid to the sperm, creating semen that is then ejaculated

What is the path of an egg in the female reproductive system?

• Ovaries (gonads) produce and store eggs/ova (gametes) until they mature

• After maturing, an egg moves through the fallopian tube towards the uterus

• Fertilization occurs in the fallopian tube, creating a zygote

• If fertilization doesn’t occur, the egg passes into the uterus where it’s absorbed into the uterine lining and eventually shed

What is a zygote?

A eukaryotic, diploid (complete genetic material) cell formed when an egg and sperm combine in the fallopian tube

What is a blastocyst?

A hollow, multicellular cell that forms in the uterine cavity ~5 days after a zygote is created/fertilization; it then implants into the endometrial lining and after ~10 weeks develops into a fetus

What are the main hormones (3) involved with the reproductive system/development of sex characteristics and where are they produced?

• Gonadotropin-releasing hormone/GnRH

  • Produced by the hypothalamus

  • Tells the pituitary to create FSH and LH

• Follicle-stimulating hormone/FSH

  • Produced by the pituitary

  • Stimulates sperm production (in the testes) and stimulates production of ovarian follicles which secrete estrogen

• Luteinizing hormone/LH

  • Produced by the pituitary

  • Stimulates production of testosterone and stimulates the ovulation process, causing the ruptured follicle to produce progesterone

FSH & LH during the menstrual cycle

• FSH: stimulates growth and maturation of ovarian follicles/eggs in the ovaries (primes the egg), stimulates production of estrogen early in cycle

• LH: triggers ovulation (releases the egg from the ovary), turns leftover follicle into the corpus luteum which produces progesterone (to support potential pregnancy)