Male and Female Reproductive Systems Structure and Functions

• Shumaila Asadullah

Human Reproduction

In this essay I am going to cover the structure and function of male and female reproductive system, how different organs of each reproductive system contribute to their functions. I am also going to include the brief explanation of menstruation cycle, what happens during the cycle and the hormones involved and four different phases of menstruation.

The male reproductive system is made up of organs and hormones that work together to insure reproduction. Their main function includes, production of sperm (male sex cell), production of male sex hormones called testosterone to maintain sex characteristics, production of seminal fluid (semen) to help sperm transportation. Testes are the primary sex organ and secondary ones are ducts, glands and penis.

Testes are also referred as testicles; they are suspended and protected in the scrotum just behind the penis. Scrotum is slightly cooler than the rest of the body because they are outside of the abdomen, this is important because testes make large number of sperms in cool condition. They are attached to the abdomen via a spermatic cord and cremaster muscle. Testes are made up of a large number of sperm tubules where sperms are made; this gives the testes a high production rate. Testes are responsible for the manufacturing of sperms and testosterone.

(Innerbody, 2013), (Roberts and Ingram, 2001),(Roberts, 1986), (Boyle and Senior, 2008)

As the sperms are produced, they move into a coiled tube called epididymis where sperms are also stored. They are thin tubules that are compactly coiled. Sperms move into the epididymis to mature (before travelling out of the body) then they move through the vas deferens, it is a muscular tube that carries sperms from the epididymis to abdominal cavity and to the ejaculatory duct. Before travelling out the urethra in the penis, an organ called seminal vesicle, stores and produces liquid that contains proteins and mucus that has alkaline properties that helps sperm to live in the acidic environment of the vagina. The prostate gland is made up of smooth muscles and secrets milky white liquid that has enzymes and chemicals to protect sperm during ejaculation.

The sperm and waste material (urine) from bladder travel from the urethra, Cowper’s Glands secrets a clear liquid in order to clean the urethra for sperm.

It is impossible to urinate and ejaculate at the same time.

(Innerbody, 2013), (Roberts and Ingram, 2001),(Roberts, 1986), (Boyle and Senior, 2008)

The female reproductive system is made up of the organs and hormones that work together to help human reproduce. Main function includes production of female sex hormones (oestrogen and progesterone) to maintain sex characteristics, nurture new life and production of female sex cells (eggs or ova). The female reproductive system is made up of internal and external (secondary) organs. The external organs include labia majora, they protect the other external organs in female, they are thick folds of skin (fleshy) and similar to the scrotum in males and contain sweat and oil secreting glands. Labia minora are positioned inside the labia majora, and surround the vaginal opening and urethra. Bartholin’s glands are found nearby the vaginal opening and secrets mucus. Clitoris contains several nerve endings and it is same as the penis and can become erect during intercourse.

(WebMD, 2014), (Cleveland Clinic, 2014)

Ovaries are primary sex organs in females. They are a pair of small glands situated on either side of the abdomen. They produce egg cells and also secrets female sex hormones oestrogen and progesterone. Each month through ovulation one of the ovaries sheds a mature egg into the fallopian tube. Fallopian tubes are narrow muscular tubes that are covered by finger like fimbriae which move near to the ovary during ovulation. Fertilization of an egg occurs in these tubes if it isn’t fertilised within a day or so egg will die. Fallopian tubes connect the ovaries to the uterus. Inside of these tubes cilia are presented that are smooth muscles and take ovum to the uterus.

(InnerBody, 2013), (WebMD, 2014), (Cleveland Clinic, 2014)

Uterus is like a bag with a thick muscular wall attached to the fallopian tubes and inferior part opens into the vagina. The inner lining is called endometerium; it sustains the embryo during pregnancy. The lining of endometerium breaks down during menstruation. It is also known as womb where the baby nourishes and develops. The lower end of the uterus is called cervix, a narrow muscular canal. When an egg is released from the ovary, watery mucus is secreted by the cervix that helps the sperm to swim towards the uterus. Cervix opens into the vagina. Vagina is a muscular tube that leads to the outside of the body. During the intercourse, the vaginal muscles relax and glands in it secrete lubricating mucus. It leads sperm to the uterus and fallopian tubes.

It is also referred as birth canal and during menstruation blood flows out through the same tube. Breasts are also part of female reproductive system as they contain mammary glands that secrete milk. Milk exits the body through the milk duct on its way to the nipples. During pregnancy, these glands active and stay activated until milk is no longer required.

(eschooltoday, 2014), (InnerBody, 2013), (WebMD, 2014), (Cleveland Clinic, 2014), (Roberts and Ingram, 2001), (Roberts, 1986), (Boyle and Senior, 2008)

Menstruation is a part of female reproductive system and the average length of this cycle are 28 days, it starts when a girl becomes sexually mature and the lining of the uterus breaks down and a small amount of blood passes out through the vagina. The cycle is divided into four phases.

Proliferative phase is when the hypothalamus releases Gonadotropin releasing hormones (GnRH) that triggers the anterior pituitary gland to secrete Follicle Stimulating Hormones (FSH). This hormone targets the ovaries, as the FSH level increases one of the follicles begins to grow and develops into a Graafian follicle, and secretes oestrogen until day 14, as the oestrogen levels rise, the endometrium wall begins to build.

(Roberts and Ingram, 2001), (Roberts, 1986),

In the ovulation phase, when the oestrogen level reaches the threshold level, it has a positive stimulating effect on pituitary gland and it releases Luteinising Hormones (LH); the increase level of LH causes ovulation. Ovulation occurs when the endometrium wall has built up because if the egg is fertilised it can implant on the thick endometrium wall. After the ovulation the cells of the follicle become the corpus luteum (yellow body).

In secretory phase, the corpus luteum secretes high level of oestrogen and progesterone. These increased levels of oestrogen and progesterone have inhibitory effect on pituitary gland that decreases the LH and FSH levels and keep them low, it also stops further follicles stimulation and maintain the thick endometrium wall for possible pregnancy. If pregnancy occurs, the embryo secretes Human Chorionic Gonadotropin (HCG) that maintains the corpus luteum to keep on secreting progesterone and no egg is released.

As the corpus luteum degenerates that stops producing oestrogen and progesterone and menstrual phase starts. This causes endometrium walls begins to break down and blood flows out through the vagina.

The drop level of these hormones also reduces the feedback inhibition of the hypothalamus and pituitary. This triggers secretion of FSH and LH which stimulates the development of a new follicle.

(Roberts and Ingram, 2001), (Roberts, 1986), (Boyle and Senior, 2008), (betterhealth, 2013), (womenshealth, 2012), (womenshealth.about.com, 2014)

I would include conclude this essay by adding, the male and female reproductive system are made up of different organs that contribute to their functions. Key functions of the male reproductive system are to produce male sex hormone (testosterone), male sex cells (sperm), whereas the main functions of female reproductive system are the production of female hormones (oestrogen and progesterone), production of female sex cells (eggs). Both reproductive systems include external and internal organs. Labia majora, labia minora and clitoris are the external organs in female reproductive system where Labia majora protects other external organs. In male penis and testicles are the external organs where testicles are protected by scrotum.

Menstruation is also a part of female reproductive system. Menstrual cycle starts when a girl becomes sexually mature. Internal reproductive organs are involves in menstruation such as ovaries, fallopian tubes, uterus and vagina.

Hormones such as Follicle Stimulating Hormones (FSH), Luteinising Hormones, oestrogen and progesterone are also involved in menstrual cycle. These hormones work through negative and positive feedback mechanism.

References:-

1. Betterhealth. (2013), Menstrual Cycle, [Online]. Available at: http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Menstrual_cycle?open, [Accessed on 16^th March 2014].
2. Boyle, M. and Senior, K. (2008). Biology 3^rd ed. London: HarperCollinsPublishers Limited.
3. Cleveland Clinic. (2014), The Female Reproductive System,[Online]. Available at: http://my.clevelandclinic.org/anatomy/female_reproductive_system/hic_the_female_reproductive_system.aspx [Accessed on 15^th March 2014].
4. Eschooltoday. (2014), Sexual reproduction. [Online]. Available at: http://www.eschooltoday.com/sexual-reproduction/the-female-reproductive-organ.html [Accessed on 15^th March 2014].
5. InnerBody. (2013), female Reproductive System. [Online].Available at: http://www.innerbody.com/image/repfov.html [Accessed on 15^th March 2014].
6. InnerBody. (2013), Male Reproductive System. [Online].Available at: http://www.innerbody.com/image/repmov.html [Accessed on 15^th March 2014].
7. M.B.V. Robert. (1986). Biology For Life 2^nd ed. London: Thomas Nelson and Sons Ltd.
8. Robert, M and Ingram, N. (2001). Biology 2^nd ed. London: Nelson Thornes Ltd.
9. Webmd. (2014), Sex and Relationship.[Online]. Available at: http://www.webmd.com/sex-relationships/guide/your-guide-female-reproductive-system [Accessed on 15^th March 2014].
10. Womenshealth. (2012), Menstruation and the menstrual cycle fact sheet, [Online]. Available at: http://www.womenshealth.gov/publications/our-publications/fact-sheet/menstruation.html [Accessed on 16^th March 2014].

Poster References:-

1. med.nyu.edu (2014), Fertilization and Implantation, [Online], Available at: http://www.med.nyu.edu/sti/contented35.html [Accessed on 22^nd March].
2. jabsom.hawaii.edu (2014), Development of the Placenta, [Online], Available at: http://www2.jabsom.hawaii.edu/PRCEHD/placenta_development.html, [Accessed on 22^nd March].
3. Medicinenet, (2014), Pregnancy, [Online], Available at: http://www.medicinenet.com/pregnancy/page4.htm#breast_changes [Accessed on 23^rd March].
4. Americanpregnancy, (2007), Breasts Changes During Pregnancy, [Online], Available at: http://americanpregnancy.org/pregnancyhealth/breastchanges.htm [Accessed on 23^rd March].
5. Healthline, (2014), Body Changes During Pregnancy, [Online], Available at: http://www.healthline.com/health/pregnancy/body-changes-infographic [Accessed on 23^rd March].
6. Americanpregnancy, (2007), Stages Of Childbirth:Stage 1, [Online], Available at: http://americanpregnancy.org/labornbirth/firststage.html [Accessed on 23^rd March].
7. parents.com, (2001), The Stages of Labor and Birth in a Vaginal Delivery, [Online], Available at: http://www.parents.com/pregnancy/giving-birth/labor-and-delivery/labor-childbirth-phases/?page=2 [Accessed on 23^rd March].
8. Babycenter, (2014), The Stages Of Labor, [Online], Available at: http://www.babycenter.com/stages-of-labor?page=6 [Accessed on 23^rd March].