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THE MALE REPRODUCTIVE SYSTEM. Structure and Function. In males, the reproductive cells are called sperm. The functions of the male reproductive system are to produce sex hormones, to produce and store sperm, and to deliver sperm to the female reproductive system.
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Structure and Function • In males, the reproductive cells are called sperm. • The functions of the male reproductive system are to produce sex hormones, to produce and store sperm, and to deliver sperm to the female reproductive system. • There, a sperm call may join with an egg in a process called fertilization.
Testes • The two oval shaped reproductive glands are called the testes. • The testes have two major functions- the production of testosterone and the production of sperm. • The sex hormone testosterone affects the production of sperm and signals physical changes at puberty, such as the growth of facial hair.
Penis • The penis is the external sexual organ through which sperm leave the body. • The tip of the penis is covered with loose skin, called the foreskin. • In some males, the foreskin is removed shortly after birth. • This surgical procedure is known as circumcision and is usually based on cultural or religious practices.
Sperm Production • Once a male reaches puberty, millions of sperm are produced in his testes each day. • Sperm production begins when the hypothalamus signals the pituitary gland to release two hormones- LH and FSH. • Sperm production continues throughout adulthood.
The Pathway of Sperm • Sperm are produced in the testes. They mature and store in the epididymis. • Sperm travel through the vas deferens to the seminal vesicles. • Seminal vesicles add a fluid that provides a source of energy for the active sperm. • The prostate gland adds a fluid that protects the sperm. • The bulbourethral glands add a fluid that protects the sperm from the acidic conditions if the urethra. • The mixture is called semen.
Release of Sperm • The ejection of semen from the penis is called ejaculation. • Ejaculation occurs when muscles in the male reproductive system and at the base of the bladder contract, forcing semen through the urethra. • Several million sperm cells are released during one ejaculation.
Release of Sperm • Sperm stored in the male reproductive system eventually break down and are disposed of. • Ejaculation can occur when the penis is at an erect stage. An erection is a condition in which the penis becomes larger and stiffer as chambers in the penis fill with blood. • An erection does not need to result in ejaculation.
Release of Sperm • It is common for teenage males to experience a nocturnal emission, or “wet dream,” which is an erection and ejaculation during sleep. • They are normal and may happen frequently. • It is also normal not to experience nocturnal emissions.
The Female Reproductive System • Eggs or ova (single) are the reproductive cells. • The functions of the reproductive system are to produce sex hormones, to produce eggs, and to produce a nourishing environment in which a fertilized egg can develop into a baby.
Ovaries • Glands in which the eggs are produced are called the ovaries. • Located a few inches below the waist, one on each side of the body and they are about the size of an almond. • Two important functions: they produce sex hormones estrogen and progesterone, and they release mature egg cells.
Ovaries • The sex hormone estrogen activates certain physical changes at puberty, such as breast development, and controls the maturation of eggs. • Progesterone activates changes to a woman’s reproductive system before and during pregnancy. • When a girl is born, each ovary contains hundred of thousand of immature eggs. • The eggs begin to mature once a girl reaches puberty. • One of the ovaries releases a ripened egg about once every month in a process called ovulation.
Fallopian Tubes • Two fallopian tubes- passageways that carry eggs away from the ovaries. • This is where fertilization usually occurs.
Uterus • A hollow, muscular, pear shaped organ. • Where the fertilized egg can develop and grow. • Several layers of tissue and a rich supply of blood that protect and nourish the developing baby. • The narrow base of the uterus is called the cervix. When a baby is ready to be born, the cervix expands to allow the baby to pass through.
Vagina • The vagina, or birth canal, is a hollow passage leading from the uterus to the outside of the body. • Sperm enter a female’s body through the vagina. • During childbirth the baby passes out of the mother’s body through the vagina. • The walls are very elastic which allows it to expand dramatically.
The Menstrual Cycle • The process of producing one mature egg after another each month. • An ovary releases a mature egg. The egg travels to the uterus. If the egg is not fertilized, the uterus lining is shed and a new cycle begins.
Factors Affecting the Menstrual Cycle • Average menstrual cycle is 28 days- can be 21-35 for other individuals. • Days 1-4 the uterine lining is shed during menstruation. • 5-13 An egg matures in one of the ovaries, and the uterine lining thickens. • 14-15 The ovary releases the mature egg during ovulation.
Menstrual Cycle • 16-22 The egg travels through the fallopian tubes to the uterus, and the uterine lining continues to thicken. • 23-28 The unfertilized egg enter the uterus. • In general, a menstrual period lasts about 3-5 days.
