The Reproductive System

One of the most fascinating things about the human body is its reproductive system.  Its remarkable how a man and a woman can come together and create a tiny human being.  Without the different parts from each sex, it wouldn't be possible.  

The male is responsible for production of the sperm cells used to fertilize a females ovum, or egg.  The testes are the primary organs of the male reproductive system because they make the sperm and a hormone called testosterone which is responsible for the development of male secondary sex characteristics.  Each sperm cell has 3 parts. The head, which holds the nucleus and contains an enzyme that allows them to penetrate the ovum called acrosome. The midpiece, which gives the sperm the energy needed to move. Lastly, the tail propels it forward.

  

The internal accessory organs that go along with the testes in the male reproductive system are the epididymis, vas deferens, seminal vesicles, prostate gland, and bulbourethral glands.  All of these organs are connected and work together to get the sperm cells where they need to be in order to leave the male body.  It begins with the maturing of the sperm cells in the epididymis and then a tube (the vas deferens) carries them to the urethra.  The seminal vesicles secrete seminal fluid that sperm cells use to make energy and also stimulates muscular contractions in the female reproduction system in order to help propel sperm forward.  This mixture of sperm and fluid create semen.  The prostate gland also produces a milky fluid that helps to protect the sperm when they enter the female.  Both these products are released just before ejaculation.  

Males also have 2 external reproductive organs: the scrotum and the penis.  The scrotum is the pouch that holds the testes away from the body in order to keep the temperature about a degree lower so that the sperm can remain alive.  The penis is made up of erectile tissue that surrounds the urethra which runs through the penis.  Its functions are to deliver the semen and for urination.

Fun fact:  The total semen volume is between 1.5 and 5.0 mL per ejaculation with a sperm count between 40 to 250 million/mL.  Normal sperm count is 80+ million.

In the female reproductive system the ovaries are the primary female sex organ because they produce the female sex cells known as ova and the hormones estrogen and progesterone.  Most females have two ovaries.
Fun fact:  Unlike the fact that males continuously make sperm cells, females are born with the maximum number of oocytes (immature ovum) that she will ever produce.  

The internal accessory reproductive organs of a female consists of the fallopian tubes, uterus, and vagina.  The fallopian tubes grab and transport an ovum from the ovary.  The uterus is a muscular organ that receives a developing embryo and maintains it during development.  It consists of 3 layers: the endometrium, myometrium, and the perimetrium.  The vagina is the muscular organ that extends from the uterus to the outside of the body which allows the body to receive and erect penis during sexual intercourse so that sperm cells can fertilize an ovum.  

The cycle that the female reproductive system goes through is called a menstrual cycle.  It consists of a monthly "period" or bleeding due to shedding of the uterine lining.  This happens when a ovum has not been fertilized.  The first menstrual period is known as menarche.  When menstrual cycles cease, this is known as menopause.  

After sexual intercourse, sperm cells make their way to the ovum.  Even though many will reach the ovum, only one will actually unite with it.  Once united, enzymes are released to prevent other sperm from penetrating it.  The nucleus of each the sperm cell and ovum come together to make one that contains 46 chromosomes.  The product of this is called a zygote.  After about a day after a zygote is formed it begins mitosis.  During this process the zygote is implanted into the uterus wall and becomes an embryo.  

The embryonic period extends from the second week to the eighth week.  During this period, the placenta, amnion, umbilical cord, and yolk sac are formed along with most of the internal organs and external structures of the embryo.  The placenta allows nutrients and oxygen pass to the embryonic blood and waste products from the fetal blood to pass into the maternal blood. Amnion is the fluid that protects the embryo.  The umbilical cord exchanges oxygenated and deoxygenated blood to and from the placenta and embryo and the yolk sac makes new blood cells for the embryo as well as determine the sex cells of the baby. 

The fetal period picks up from the eighth week and ends at birth.  During this time, the offspring is called a fetus and growth is rapid.  All parts and organs of the fetus are formed and begin functioning.  The fetus gains weight and positions itself upside down for delivery.  

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The birth process ends pregnancy.  The cervix thins and softens. Contractions are regular and the amniotic sac ruptures either own its own or by a surgical puncture.  Once the cervix is dilated to about 10 cm, contractions and abdominal compressions (the pushing stage) force the fetus out of the vagina.  After birth, the placenta separates from the uterine wall and is expelled from the body.  If the fetus is not in the head down position a c-section may be required to remove the fetus from the body.  

The reproductive system in both male and female are completely different.  They are simple yet complicated.  When you put the two together you create life and a family!