Human Reproductive System

The Reproductive System

You may find this unbelievable, but you began life as a single cell. This single cell was produced by the joining of two other cells. These other cells are the sperm and the egg, or ovum; (plural: ova).
The sperm is the male sex cell and the egg is the female sex cell. The joining of a sperm cell with an egg cell is called fertilization. Fertilization is an important part of reproduction, the process by which organisms produce more of their own kind. Sperm are produced in the male reproductive sys¬tem and eggs are produced in the female reproductive system.
A sperm cell has a head, a middle part, and a tail. Compared to the sperm, the egg is enormous. It is one of the largest cells in the body. The egg is so large that it can be seen with the unaided eye. Although the egg's shape and size differ from the sperm's, the cells share an important feature. Both cells contain thick, rod-like structures called chromosomes. Chromosomes pass on inherited characteristics from one generation of cells to the next.
Each cell of the human body, except the sex cells, contains 46 chromosomes. Each sex cell contains half this number, or 23 chromosomes. After fertilization, the fertilized egg contains 46 chromosomes. So a fertilized egg gets 23 chromosomes from the sperm and 23 chromosomes from the egg. The fertilized egg contains all of the information needed to produce a complete new human being.
The Male Reproductive System
The male gonads are the testes. The testes produce sperm cells, which are the male gametes, and the male sex hormone, testosterone. Testosterone is responsible for the secondary sex characteristics such as the body hair, muscle development, and deep voice characteristic of males. These traits usually appear during adolescence.
In the structure of the male reproductive system, there are two testes, which are located in a sac of skin that is outside the body wall. This sac, which is called the scrotum, keeps the temperature of the testes slightly lower than that of the rest of the body. The lower temperature is best for the production and storage of sperm.
Each testis consists of small, coiled tubes called the seminiferous tubules. There are 300 to 600 tubules in each testis. Immature sperm are produced in the seminiferous tubules. From there, the sperm pass to the epididymis, a storage area on the upper, rear part of the testis. The sperm remain in the epididymis until they are mature. They leave the epididymis through the vas deferens, a tube that leads upward from each testis into the lower part of the abdomen.

The two vas deferens join at the urethra, the passageway for the elimination of urine. In the human male, the urethra passes through the penis to the outside of the body. It is also the passageway through which sperm leave the body. As sperm enter the urethra, the seminal vesicles, Cowper's glands, and the prostate gland all secrete fluids into the urethra. The mixture of these fluids and the sperm is called semen. The semen pass through the urethra and reflex actions keep the outlet of the urinary bladder closed, thereby preventing urine from entering the urethra.

The Female Reproductive System

   The female gonads are the ovaries. The ovaries produce eggs, which are the female gametes, and also secrete the female sex hormone estrogen. Estrogen is responsible for the female secondary sex characteristics, such as development of the breasts, broadened pelvis, and pattern of fat distribution.
     These characteristics usually appear during adolescence. Estrogen also plays a large role in the menstrual cycle.
     The structure of the female reproductive system: The female has two ovaries, located deep in the lower part of the abdomen. They are about 4 centimeters long and 2 centimeters wide. Each ovary contains about 200,000 tiny egg sacs called follicles. Each follicle contains an imma¬ture egg. These immature eggs are already present at the time of birth. During the life of a female, no more than about 500 mature eggs are produced.
      When an egg matures, the follicle surrounding it ruptures, or bursts, and the egg is released at the surface of the ovary. This process is called ovulation.
 Ovulation first occurs at puberty, when the individual becomes sexually mature and capable of reproduction. There after ovulation occurs about once a month.
       Near each ovary, but not connected to it, is an oviduct, or Fallopian tube. The oviduct is a tube with a funnel-like opening. Ciliated cells lining the oviduct create a current that draws the released egg into the tube. The egg passes through the oviduct to the uterus, a thick-walled, muscular, pear-shaped organ. If sperm are present in the oviduct, the egg may be fertilized. If the egg is fertilized, it completes its development in the uterus. The narrow neck of the uterus is called the cervix. The cervix opens into the vagina, or birth canal, which leads to the outside of the body. At birth, the child leaves the mother's body through this passageway. In the human female, the urethra has its own opening and is completely separate from the reproductive system.

THE MENSTRUAL CYCLE
A mature female goes through monthly reproductive changes called the menstrual cycle. The menstrual cycle usually takes about 28 days but can be longer or shorter. It is controlled by hormones released by the pi¬tuitary gland and ovaries.
During the menstrual cycle, an egg matures inside an ovary. Usually just one egg matures in one ovary at a time. While this happens, the inside lining of the uterus devel¬ops extra blood vessels and grows thicker. The egg is then released from the ovary by a process called ovulation. Ovulation occurs on about day 14 of the menstrual cycle. The released egg enters an oviduct and travels toward the uterus. During this time, the lining of the uterus grows even thicker.
 If the egg is not fertilized, the menstrual cycle continues. Both the egg and lining of the uterus break down. Blood and cells from the uterus flow through out the body in the process of menstruation, The period of menstruation, or the menstrual period, lasts from 3 to 7 days. After menstruation ends, another egg begins to mature, and the entire cycle repeats itself.
     The menstrual cycle begins at puberty, which usually occurs in human females sometime between the ages of 10 and 14. The cycle ceases temporarily during pregnancy. It ceases permanently sometime in middle age, usually between the ages of 45 and 50. The permanent cessation of the menstrual cycle is called menopause.
Stages of Development
    Almost immediately after a zygote, or fertilized  is formed, a new human being begins to develop. The zygote divides into two cells. Then each of these cells divides again and again, and so on. Change and growth continue for approximately nine months or 280 days until birth. This time be¬tween fertilization and birth is called pregnancy.
    Human beings go through various stages of development before and after birth. Before birth, a single human cell develops into an embryo and then a fetus. After birth, humans pass through the stages of infancy, childhood, and adolescence to adulthood.

Development before Birth
As the zygote first begins to divide, the cells remain close together and give the appearance of a bunch of berries. By the time this berry-shaped group of cells reaches the uterus, the cells have di¬vided a few more times and look like a hollow ball of cells. During this early stage of development, and for the next eight weeks or so, the newly formed organism is called an embryo.
      Once the embryo enters the uterus, it attaches itself to the wall of the uterus. In the uterus, several membranes form around the embryo. A clear mem¬brane called the amnion forms a fluid-filled sac. This amniotic sac cushions and protects the developing baby. Another membrane forms the placenta. The placenta is made partly from tissue that develops from the embryo and partly

from tissue that makes up the wall of the uterus.
       The placenta is a kind of transfer station between the embryo and its mother. Both mother and embryo have separate circulatory systems and separate blood supplies. However, oxygen obtained by the mother's lungs and food from her digestive system pass through the placenta to the embryo. Wastes pass out of the embryo through the placenta and are eliminated by the mother. An embryo is connected to the placenta by a cord called an umbilical cord. The umbilical curd contains blood vessels that transport food, oxy¬gen, and wastes back and forth between the embryo and the placenta.
        After eight weeks, the embryo is called a fetus. A fetus has developed eyes, ears, cheeks, arms, and legs. After three months, it is easy to identify the fetus as a male or a female. During the last three months of pregnancy, the fetus gains more weight. A layer of fat develops under its skin. Hair may grow on its head. New brain cells are produced. By the end of the ninth month, the fetus is about 45 centimeters long and has a mass of about 3 kilograms.
    In recent years, methods have been developed allow doctors to study and even treat fetuses before they are born. One of these methods consists of drawing off a small amount of the fluid in which the fetus floats. The fluid contains cells from the fetus that. can be studied to determine its health, as well as many of its inherited characteristics. In an¬other process, sound waves that produce an image on a television screen are sent through the uterus of the mother. This procedure gives a detailed, moving image of the fetus. Sound pictures have been used to safely diagnose and treat fetuses with medical problems before they are born.
Birth
After about nine months of development and growth inside the uterus, a baby is ready to be born. Strong muscular contractions of the uterus begin to push the baby out of the uterus into the vagina. This process is called labor. As labor progresses, the contractions of the uterus become stronger and occur more frequently. Eventually the baby, still connected to the placenta by the umbilical cord, is forced out of the mother.

Sometimes more than one fetus develops in the uterus at the same time. Twins, triplets, and quadruplets are all ex¬amples of multiple fetuses.
 Multiple fetuses form in two ways. Sometimes a zygote or young embryo splits apart into several sections. Each section then develops into a fetus. Multiple fetuses formed this way are called identical fetuses because they develop from the same egg, fertilized by the same sperm. Identical fetuses usually share a placenta, have sep¬arate umbilical cords, and may or may not have separate amnions. Because identical fetuses develop from the same zygote. they look alike and are always the same sex.


      Sometimes both of a female's ovaries release an egg at the same time. Or one ovary releases several eggs at once. If each egg is fertilized, several zygotes are formed, and each develops into a fetus. Multiple fetuses formed this way are called fraternal fetuses because they come from different eggs fertilized by different sperm.  Fra¬ternal fetuses have separate placentas, umbilical cords, and amnions. Because fraternal fetuses develop from different zy¬gotes, they don't look exactly alike and can be different sexes.

THE APPLICATION OF REPRODUCTION PRINCIPLES IN FAMILY PLANNING

 Family planning is regulation method of birth or fertility that has purpose to reach healthy family, whether physical, mental, or social economical. Family planning also has purpose to control population growth rate.
 Family planning is done through the contraception method of temporary and permanent.
I. Temporary contraception method that is applied in family planning    consist     of      several methods, those are :
1)    Calendar system, that is the action of pregnancy prevention by avoiding sexual, contact when wife is undergoing fertile period.
2)    Condom wearing has purpose to block the entering of sperm into vagina so the fertilization process can be prevented
3)    The using of spermatic drugs (vagina pill) has purpose to destroy sperm that enters into vagina
4)    The wearing of spiral or contraception device in uterus.
5)    Hormonal contraception, is given in three forms those are pill, injection and implant.  

II. Permanent Contraception
Permanent contraception method is done through sterilization. This method is separated  into two kind, those are :
1.    Tubectomy, that is bonding or cutting of both tuba falopii
2.    Vasectomy, that is bonding or cutting of vas deferens

DISORDERS AND DISEASES IN HUMAN REPRODUCTIVE SYSTEM
1)    Pregnancy outside Womb
      Pregnancy outside Womb happens because fetus grown outside uterus, for example in tuba falopii, cervix or in peritonium
2)    Breast tumor and cancer
 Breast tumor can be fame, that is only elastic lump that can be erased through surgery,but it can have serious property if has become breast cancer.
3)    Vulvovaganitis
Vulvovaganitis is inflammation in vulva and vagina and often produces symptom of leucorrhea, that is discharging of white greenish liquid from vagina.This disease is the caused by bacteria (Gardnerela vaginalis) and Gonorrhoea chlamidia
4)    Impotent
      Impotent is inability of erection of sustaining erection in penis in normal sexual relationship.
5)    Gonorrhoea
 Gonorrhoea is an acute infection disease  that infeets mucilage membrane from urethra that is caused by Neissseria gonorrhoea
6)    Prostatitis
     Prostatitis is inflammation in prostate that is often accompanied with inflammation in urethra.
7)    Infertility
     Infertility is disability to produce heredity.
8)    Endometriosis
Endometriosis that is finding of endometrium tissue outside uterus such as in ovary, peritoneum,large intestine and urethra   
9)    Cervix cancer
This cancer is many founding woman of 40 – 55 years old, it often producing death if just found after advance period. 
10)    Syphilis
      Syphilis is can infective disease that is caused by Treponema pallidum