December of the penis. The third part
December 9, 2017The reproductive system is part of an individual’s body, in order for human existence to sustained.
The male and the female are formed and developed distinctively, which gives each system a distinctive job, but they also have some similarities. The male’s reproductive system function is to produced, maintained and transport sperm (Cleveland Clinic, 2017). The female’s reproductive system is to produce and stored ova and support an embryo that develops. Altogether both systems contain functional organs and hormones that work together to generate life.
When males go through their adolescent years, changes begin to occur physically and emotionally throughout their body. During puberty boys will develop a deeper voice and hair growth in the pubic area, armpits, legs, arms, and face. Testicles start to grow and increase, and their testes will then be able to produce sperm and a hormone called testosterone (Cleveland Clinic, 2017). The penis will increase in length, but not grow as much in width. Meanwhile, the prostate, the two seminal vesicles, and Cowper’s glands produce and discharge fluids that combine with the sperm to form semen. Sexual feelings and erections will also be developed. Erections occur when the penis is filled with blood and stretches in size and shape. Basically, when boys hit puberty from ages 9-14 they will be able to get a female pregnant.
The male reproductive system is mostly located outside the body. The structures that are involved are the penis, scrotum, and the testicles (Cleveland Clinic, 2017). The penis is the organ that is needed for sexual intercourse because it transports semen into the female vagina. The penis is composed of three parts, the roots which are connected to the wall of the abandoned, it connects the penis to the bone of the pelvis through several ligaments. The root is made up of 3 erectile tissues, the two crura and the bulb of the penis. The second part is the shaft known as the body, it is the part that extends out the body to the tip of the penis. The third part is the glans, which is the head of the penis and the tip is urethral which is open.
This openness lets semen and urine to come out. The glans is a delicate area with multiple nerve endings, so it is covered with a layer of loosened skin known as foreskin (Cleveland Clinic, 2017) , in order to protect its sensitivity. The scrotum is an organ made of skin that looks like a sac and hangs behind the penis. Its consist of 2 pouches that are alongside and each contains testes, one gland produces sperm and the other stores the sperm.
“The testes are organs that look oval and are about the size of an olive” (Cleveland Clinic, 2017). Their function is to make testosterone and produce sperm. The task of the scrotum is to keep “the testes at a constant temperature a little cooler than the body temperature” (Cleveland Clinic, 2017). If there was no control to maintain the sperm at a certain temperature, then it will eventually die.
The Epididymis is a long firmly coiled tube that rests along the backside of each testicle. (Cleveland Clinic, 2017) . In figure 1, the epididymis looks like it is bent on the back edge of each testis. It also consists of three categories, the head, body, and tail. The head stores sperm until it is ready to go through maturation.
The body is a long twisted tube where the sperm will then mature. The tail is joined to the deferent duct. Even though the epidermis looks like a small organ, it is actually long when expanded.
On the other side, the organs that are inside of the male reproductive system, are vas deferens, ejaculatory ducts, the urethra, seminal vesicles, prostate gland and the bulbourethral glands (Cleveland Clinic, 2017). Vas deferens is a big muscular tube that goes through the epididymis into the pelvic cavity and at the back of the bladder. Its job is to carry mature sperm to the urethra in order for ejaculation to occur. According to figure 1 we can see, Ejaculatory ducts are created by the joining of the vas deferens and the seminal vesicle.
The urethra attaches the urinary bladder to the penis. The urethra is a tube that has distinctive functions, it moves urine from the bladder to the outside of the body and ejaculates semen when an orgasm occurs in males (Cleveland Clinic, 2017). In this case, ” the flow of urine is blocked from the urethra, allowing only semen to be ejaculated” (Cleveland Clinic, 2017).
Figure 1, shows the seminal vesicles as a paired of organs that look like sacks. These sacks are connected to the vas deferens in the back of the bladder. These vesicles are important because they produce sugar known as fructose, needed to give energy and help the sperm move toward the egg. Therefore, the prostate gland adds more fluid to support the sperm and when a male ejaculates, the fluid along from other glands form semen, which is then expelled (Cleveland Clinic, 2017). Another type of gland is the bulbourethral, it also contributes to the addition of the fluid to the semen. Their responsibility is to create a fluid that is slippery and clear. The fluid helps to lubricate the urethra and prevent acidity due to urine (Cleveland Clinic, 2017).Now that the organ functions in the reproductive system were explained, what are the steps to create sperm?.
The formation of sperm is known as spermatogenesis (Freeman, 2017), during this process diploid cells called spermatogonia divide through mitosis while the resulting cells continue to work as spermatoni (Freeman, 2017). Others will also form into specialized cells that are primarily focused on developing the sperm. The specialized cells then form primary spermatocytes, in this case these cells go through meiosis I, which form the secondary spermatocytes that go through meiosis II (Freeman, 2017). At the end of this process four haploid cells are the results. The haploid cells will then mature into sperm . The task of “the sperm is to carry a haploid genome from the male through the female reproductive tract and fertilizing an egg” (Freeman, 2017).To get a closer look at the sperm cell the structure can be seen in Figure 2, it shows the head that holds the nucleus and an enzyme-filled structure known as the acrosome.
“The neck encloses a centriole that will combine with a centriole contributed by the egg to form a centrosome” (Freeman, 2017). In figure 2, we can see the middle piece is filled with mitochondria creating ATP, this is needed to power the movement of sperm. The last structure is the tail, it is made up of flagellum which is composed of microtubules and is surrendered by the plasma membrane. This makes it possible for the sperm to swim in directions (Freeman, 2017). The structure of the sperm is important because it carries functions that allow information to be transported to create a new individual.
On the other hand, most females hit puberty at the age of 12 years old (Freeman, 2017). This means their menstrual cycle has started and causes physical and emotional changes in the body due to hormone activity. The cycle can be different for every woman, but it usually lasts for 28 days long.
The menstrual cycle has 3 phases known as the follicular phase, the ovulatory phase, and the luteal phase (Cold et al., 2017). Follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone are involved in the cycle (Cold et al., 2017).The first phase is the Follicular, hormone LH and FSH are released from the brain traveling into the blood and to the ovaries. These hormones activate follicle, which starts maturing up to last 14 days. In meiosis I, primary oocytes are completed and ovulation begins when the follicle is finally mature, releasing secondary oocyte into the oviduct (Freeman, 2017). LH and FSH can also cause an increase in the female hormone estrogen by the ovaries.
When levels of follicle increase, it shuts down the production of follicle-stimulating hormones. This hormone can decrease the number of follicles that mature (Cold et al., 2017). During this time, the mature follicles suppress all the other follicles causing them to stop maturing and eventually die. The mature follicle will then continue to produce estrogen (Cold et al.
, 2017).As the follicle prepares for ovulation, this becomes the next menstrual period beginning two weeks later (Cold et al., 2017).
The increase of estrogen from the mature follicle will pull a powerful trigger in the amount of LH, produced by the brain.This trigger will lead the mature follicle to release its egg from the ovary. When theses egg are released they are captured at the end of the fallopian tube (Cold et al.
, 2017). There is also an increase in the thickness of mucus produced by the cervix. If sexual intercourse was to occur between the female and male, the thick mucus will capture the sperm providing it will nutrients and helping it move towards the egg for fertilization (Cold et al., 2017).After ovulation, the luteal phase begins and is 14 days long (Freeman, 2017). The LH causes the follicle to break and the eggs are released. The follicle then forms a new structure called the corpus luteum. This new structure releases the hormone called progesterone.
Progesterone then prepares the uterus for a fertilized egg to implant (Cold et al., 2017). If sexual intercourse occurs then the man’s sperm fertilizes the egg, it will then travel through the fallopian tube to implant in the uterus . This process is where the woman is now pregnant. “If the egg is not fertilized the corpus luteum degenerates, the progesterone level fall as the corpus luteum shrink” (Freeman, 2017). The drop of progesterone levels will cause the lining of the uterus to breaks down and shed and the next menstrual cycle will start and the cycle will then start again. With all the information discovered on the control of hormones in the menstrual cycle, scientist were able to develop and opened a research on birth control.
Researchers discovered that manipulating levels of progesterone and estradiol can prevent ovulation (Freeman, 2017). This research will help prevent pregnancies for couples who are not ready to have a baby, but in a safe way, also known as contraception. “Hormone-based contraceptive methods deliver synthetic versions of progesterone or of progesterone and estradiol” (Freeman, 2017). These hormones put an end to the release of GnRH, FSH, and LH through negative feedback (Freeman, 2017). Throughout history, the most common contraceptive method is birth pills (Freeman, 2017).
Most pills contain a mix of estrogen and progesterone, this combination blocks the release of eggs from the ovaries (Britannica Academic, Encyclopædia Britannica, 17 Jun. 2016). Other pills contain only progestogen, this causes a change in the mucus to block the sperm from moving further (Britannica Academic, Encyclopædia Britannica, 17 Jun. 2016). The intrauterine device, which I did not know existed is quite interesting. It is a small T-shaped structure that is inserted the uterus and secretes hormones to prevent sperm from fertilizing an egg .
All theses hormonal contraceptive methods prevent ovulation (Freeman, 2017). On the other hand female and male use condoms to prevent sperm from going inside the uterus. Overall, life would not exist without the male and female reproductive system