reproductive system science7
TRANSCRIPT
The Reproductive
System
• Reproduction is the process that continues life on earth
• Males and females each have structures specialized for their roles in reproduction
• The male reproductive system consists of both external and internal organs
• The main external (outside the body) organs are the penis and the scrotum
• The scrotum contains the testes, which produce the hormone testosterone
• The testes also produce male reproductive cells called sperm
• Each sperm consists of a head and a tail; the head contains hereditary information and the tail moves it
• Semen is the mixture of sperm and fluid that helps move reproductive cells through the urethra and out of the body
• The internal parts of the male reproductive system include:
• vas deferens, a long, muscular tube that travels from the epididymis (a long tube that rests on the back of each testicle) into the pelvic cavity.
• The vas deferens transports mature sperm to the urethra
• Female reproductive organs are internal
• Ovaries are the female reproductive organs that produce eggs, the female sex cells
- When a female is born, she already has all the cells that will become eggs
• Ovulation is a process in which an egg is released, about once every month. The two ovaries release eggs on alternating months
• The uterus is a muscular organ with thick, protective walls
• A fertilized egg develops in the uterus (aka womb)
• Fertilization is the joining of egg and sperm
• The cervix is the lower end of the uterus; it is directly connected to the birth canal (vagina)
• It is through the birth canal that a baby travels from the womb to the outside world.
• The menstrual cycle is the monthly cycle of changes in the female reproductive system.
• This cycle is controlled by hormones, which begin by developing eggs in the ovary.
• Hormones also cause the lining of the uterus to become thicker, in preparation for the possibility of protecting and nourishing a baby
• Ovulation occurs about 14 days before menstruation begins; once an egg is released, it must be fertilized within 24 hours or it begins to break down
• If the egg is not fertilized, the lining of the uterus breaks down. Blood and tissue cells are released in menstrual flow.
• The entire menstrual cycle averages 28 days, though this can vary
• The average age at which menstrual cycles begin is 12 or 13 years, though this can vary widely.
• The cycle continues until around age 50 or 51 (again, this varies). (these years between are called a woman’s reproductive years)
• Menopause occurs when both ovulation and menstrual periods end
• In years right before menopause, hormone production begins to shut down and changes in the cycle occur. This time is called perimenopause