SECOND TERM E-LEARNING NOTE
SUBJECT: BASIC SCIENCE
CLASS: JSS 1
WEEK ONE AND TWO DATE: …………….
TOPIC: REPRODUCTIVE SYSTEM
Reproductive System is a term applied to the group of plant or animal organs that are necessary for or that are accessory to the reproductive processes. Reproduction, process whereby all living organisms produce offspring. Reproduction is one of the essential functions of plants, animals, and single celled organisms, as necessary for the preservation of the species as eating is for the preservation of the individual.
The basic units of sexual reproduction are the male and female germ cells; this article deals with the organs within which the germ cells of animals mature and are stored, the organs through which they are transported in the process of producing a new individual, and accessory glandular organs.
Internal View of Male Reproductive System
The reproductive anatomy of the male human is largely external. Beginning at puberty, sperm are produced within seminiferous tubules of the testicles, a pair of glands that reside in a pouch called the scrotum. The external location of the scrotum keeps the temperature of sperm slightly below body temperature, which is necessary for their healthy development and survival. From each testicle, sperm migrate to a long, coiled tube known as the epididymis,
where they are stored for one to three weeks until they mature. Also located outside the body is the penis, the erectile organ responsible for the excretion of urine and the transfer of sperm to the vagina of the female. Just before ejaculation during sexual arousal, mature sperm travel from the epididymis, a coiled tube behind each testicle, through a long duct called the vas deferens. Sperm leave the body in semen, a fluid produced by the seminal vesicles.
There are two testes. Each is oval in shape and is housed in a wrinkle sac called scrotum which hangs out of the body behind the penis. The scrotum functions as a thermoregulator that protects the sperm from high temperature.
Primary sexual characteristics of women include the external genital (vulva) and the internal organs that make it possible for a woman to produce ova (eggs) and become pregnant. The vulva includes the mons pubis, the most visible part of the woman's external genitalia, which is the pad of fatty tissue that covers the pubic bone and is commonly covered by pubic hair; the outer labia, the large outer lips; and the inner labia, the smaller, hairless inner lips that run along the edge of the vaginal opening and often fold over to cover it. The inner labia come together in front to form the clitoral hood, which covers the clitoris, a sensitive organ that is very important to the woman's sexual response. The opening of the urethra, the tubular vessel through which urine passes, is located midway between the clitoris and the vaginal opening. The area where the outer labia join behind the vagina is called the frenlum of labia minora. The area of skin between the vaginal opening and the anus is the perineum. The hymen is a thin membrane that partially covers the vaginal opening. If the hymen is extensive and is still present at first intercourse, it may be broken or stretched as the penis enters the vagina and some bleeding and pain may occur, although more typically its presence is unnoticed. The presence or absence of a hymen is not a reliable indicator of virginity, although historically it was viewed as such.
The internal sex organs of the female consist of the vagina, uterus, fallopian tubes (or oviducts), and ovaries. The vagina is a flexible tube-shaped organ that is the passageway
between the uterus and the opening in the vulva. Because during birth the baby travels from the uterus through the vagina, the vagina is also known as the birth canal. The woman's menstrual flow comes out of the uterus and through the vagina. When a man and a woman engage in vaginal intercourse, the penis is inserted into the vagina.
The cervix is located at the bottom of the uterus and includes the opening between the vagina and the uterus. The uterus is a muscular organ that has an inner lining (endometrium) richly supplied with blood vessels and glands. During pregnancy, the uterus holds and nourishes the developing foetus. Although the uterus is normally about the size of a fist, during pregnancy it is capable of stretching to accommodate a fully developed foetus, which is typically about 50 cm (about 20 in) long and weighs about 3.5 kg (about 7.5 lbs). The uterine muscles also produce the strong contractions of labour.
At the top of the uterus are the pair of fallopian tubes that lead to the ovaries. The two ovaries produce eggs, or ova (the female sex cells that can become fertilized), and female sex hormones, primarily estrogens and progesterone. The fallopian tubes have finger like projections at the ends near the ovaries that sweep the egg into the fallopian tube after it is released from the ovaries. If sperm are present in the fallopian tube, fertilization (conception) may occur and the fertilized egg will be swept into the uterus by cilia (hair like projections inside the fallopian tube).
Precious seed BASIC SCIENCE FOR JUNIOR SECONDARY SCHOOLS BOOK PAGE 123-125
fallopian B. uterus C. endomentum C. fetus D. cilia
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