Human Reproduction

• Diagram of the penis

  
• A gonad is an organ that produces sex cells in animals.
• The temperature of the scrotum is kept at 35 degrees Celsius which allows meiosis to occur to produce sperm.
• Testes consist of tubules that are lined with diploid sperm-producing cells. Meiosis occurs in these cells to produce haploid sperm cells.
• The epididymis are located outside the testes. Sperm mature and are stored in the epididymis.
• Sperm ducts are also known as the vans deferens. The duct carries sperm to the urethra.
• Seminal vesicles, prostate gland, and Cowper's glands all produce a liquid known as seminal fluid.
• Ejaculation is the release of semen from the penis.
• Structure of a sperm.

  
• The flagellum of a sperm allows it to swim.
• Follicle Stimulating Hormone causes sperm-producing cells in the testes to divide by meiosis to form new sperm. Luteinizing hormone stimulates the testes to produce testosterone.
• Male infertility can be caused by smoking, alcohol abuse, and marijuana.
• Diagram of the female reproductive system.

  A) Fallopian tube

  B) ovary

  C) uterus

  D) vagina

  E) bladder

  
• The ovary produces the eggs and female hormones.
• Funnels at the tip of each fallopian tube catch the egg after it is released from the ovary. The egg is moved along the tube by cilia and peristalsis.
• This lining of the uterus thickens each month with cells and blood vessels to nourish the embryo. The inner lining is called the endometrium.
• Oestrogen and progesterone are the female hormones
• Once meiosis is complete in the ovary the egg is surrounded within a structure called the Graafian follicle. When mature the follicle forms a swelling on the outside of the ovary. It bursts at ovulation to release the egg​. After ovulation the follicle becomes the Corpus luteum (yellow body). ​ This secretes the hormone progesterone.
• The menstrual cycle is a 28 day sequence of events that produces an egg and prepares the body for pregnancy.​
• Ovulation occurs on day 14 of the menstrual cycle.
• Insemination is the release of sperm into the female
• If an egg is present it releases chemicals to attract the sperm this is called chemotaxis.
• Fertilization occurs in the fallopian tube.
• Implantation occurs 6-9 days after fertilization. By this time the zygote has grown into an embryo. A membrane called the amnion develops around the embryo. This secretes amniotic fluid which will surround the developing embryo and act as a shock absorber.
• After implantation, the embryo forms an outer membrane called a chorion. This chorion develops projections (chorionic villi) which, together with the blood vessels of the mother in the endometrium, form the placenta.
• The umbilical cord connects the placenta with the embryo. It contains blood vessels which circulate blood between the embryo and the placenta​
• Diagram of the placenta

  A) mothers blood

  B) placenta

  C) chorion

  D) embryo

  E) amnion

  F) amniotic fluid

  G) umbilical cord

  H) embryo's blood

  
• Immediately before birth, the placenta stops making progesterone. The walls of the uterus begin to contract as a result.​ The pituitary gland releases the hormone called oxytocin. This causes further contractions of the uterus. ​Labour has now begun.
• In the first stage of labor, the contraction of the uterus pushes the fetus towards the cervix. This causes the cervix to dilate. The contractions cause the amnion to break releasing the amniotic fluid through the vagina. 
• In the second stage of labor, the fetus passes through the cervix and the birth canal head first. The umbilical cord is tied and cut. This leaves a scar that will eventually become the navel.
• In the third stage of labor, the baby is born and the uterus contracts to expel the placenta.
• Lactation is the secretion of milk from the mammary glands.
• Milk production is triggered by the release of prolactin by the pituitary gland.
• Birth control refers to the methods employed to limit the number of children that are born.
• Removing the possibility of conception is called contraception.
• An example of mechanical contraception would be using condoms.
• An example of chemical contraception would be the pill, which prevents the release of an egg by inhibiting the release of oestrogen.
• An example of surgical contraception would be a vasectomy or tubal ligation.
• Natural contraception is not having sexual intercourse during the fertile period of the menstrual cycle 
• In-vitro Fertilization is a method of treating infertility. It involves removing eggs from an ovary andfertilising them outside the body