1. The male reproductive system

2.  Humans have 2 types of gametes:  Males have sperm – small, motile, many  Females have eggs – large, non-motile, few  Male and female reproductive systems are designed to maximize chance of fertilization

3. Sperm production and maturation: Testes (spermatogenesis and testosterone)  Inside scrotum  Begin development inside abdomen, only descending into scrotum in the last 2 months of gestation  Contain seminiferous tubules – sperm cells are made here (spermatogenesis)  Sertoli cells nourish sperm cells

5.  Acrosome contains enzymes that allow sperm to penetrate egg  Head has DNA and nucleus  The tail is also called a flagellum (for swimming)

6. Interstitial cells: lie between seminiferous tubules  Produce androgens (male hormones) (mainly testosterone)  Testosterone involved in spermatogenesis, and maturation of testes and penis at puberty

7. Brain break  Why does it take 300 million sperm to fertilize one egg?

8. Because they won't stop to ask directions.

9. Epididymis  Where sperm mature  Tightly coiled tubule (about 20 ft long)  Just outside each testis  Believed that some defective cells are destroyed here by the immune system

10. Transport: ductus deferens (vas deferens)  Joined to epididymis  Goes from testes, through inguinal canal and into abdomen to the urethra  What they cut in a vasectomy to sterilize a man  A hernia is what happens when inguinal canal gets stretched and a bit of intestine squishes through. Can get painful and sometimes strangulated (circulation cut off)

11. Seminal fluids  Three glands contribute to seminal fluid for sperm to swim in  Seminal fluid + sperm = semen  1: Prostate gland: alkaline fluid to protect sperm while in the female  2: seminal vesicles: sugar solution for energy  Prostoglandins: cause contractions of female reproductive muscles  3: Cowper’s glands: lubricating fluid

12. Penis  Copulatory organ  Has enlarged end (glans penis) covered in foreskin at birth (gets “smegma” if you don’t clean under it)  Can be removed by circumcision  Contains urethra, which is path taken by sperm during intercourse  During erection, sphincter from bladder closed off so no entry of urine  Penis fills with blood (in blood sinuses) and becomes erect  Impotency: inability to get an errection (sometimes psychological, sometimes hormone imbalance)  Deposits 150 – 300 million sperm outside cervix of female

13. Ejaculation  Process by which semen leaves a man’s body via the penis  Path of sperm:  Epididymis  vas deferens  (seminal fluid comes form the 3 glands)  urethra  vagina