Human Reproductive System

The Human Reproductive System

• Male sperm cells are produced in the testes

• Female eggs are produced in the ovaries

• At about 8 weeks the developing organism is called an embryo

Male Reproductive System

Female Reproductive System

Human Gamete Production

Hormones Control Reproductive Cycles

• Hormones – act as messengers that influence other organs– Produced by glands and other secretory

organs– Create feedback systems – Sex of the embryo is determined by the

chromosomes, but the development into male or female is controlled by hormones

Menstrual Cycle

Estrogen and Progesterone

• Estrogen is secreted by the maturing follicle in the ovary– Causes increase in blood supply in the uterus and a

thickening of the lining– Increases for 14 days until the follicle bursts and the

ovum is released (ovulation)• Progesterone is secreted by the burst follicle (it

has become something called the corpus luteum)– Acts with estrogen to stimulate additional buildup of

the lining of the uterus in preparation for implantation of the egg

Estrogen and Progesterone

• If no fertilization takes place, the corpus luteum degenerates, the levels of progesterone and estrogen decrease and menstruation begins

• Menopause – the cessation of the menstrual cycle with advancing age between age 45 and 50

• The number of sperm a male produces also decreases with age

Birth Control

• Birth Control Pills – contain estrogen and progestin that inhibits the development of egg follicle in the ovaries (about 99% effective)– There is a male pill in developmental testing

• Hormonal implant under the skin (good for about 5 years)• IUD – prevents the fertilized egg from implanting in the

uterus• Preventing contact between sperm and egg

– Condoms– Diaphragms

• Sterilization– Vasectomy for males– Tubal ligation for females