Transcription
The human male reproductive system. Despite having the same main function, the male reproductive system has quite different parts compared to the female.
To start with, there are two ovoid testes in male humans. The testes lie in a pair of sacs which are pouched-like extensions of their skin between the thighs. These are called the scrotal sacs. The development of the sperms requires a temperature around 1 to 8.8° less than the body temperature. This means around 30° C. This is why the testes lie in the scrotal sacs outside the main body.
There is a spermatic cord that contains blood vessels at the upper end of each testes. Leading from the end of the testes is a narrow, much coiled tube, the epididymis. The testes produce sperms. The sperms may then be stored in an inactive form in the epididymis before entering the vas deferens or sperm duct. The sperm duct from each side passes into the abdominal cavity. It loops over the ureter of that side and finally opens into the urethra.
A gland called the seminal vesicle opens into each sperm duct at the base of the urinary bladder. Where the two sperm ducts join their urethra is the prostate gland. Beneath the prostate gland is the bulbourethral gland (Cowper's gland). The seminal vesicle, the prostate, and the bulbourethral gland secrete a slippery fluid that mixes with the sperms called seminal fluid or semen. The semen is an important fluid because it contains nutrients and enzymes which serve to nourish and protect the sperms and activate them so that they begin to swim.
The urethra is a tube that passes through the center of the penis to carry the semen to the exterior during ejaculation. The penis is an organ that contains erectile tissue with numerous blood spaces. When stimulated, the blood will fill the spaces and the penis will become erect and hard. Given enough stimulation, ejaculation or the release of the semen can happen.
Urine and semen will not pass through the urethra at the same time. This is due to a circular band of involuntary muscle called the internal urethral sphincter at the base of the urinary bladder that blocks urine from coming out or flux of semen from coming in during ejaculation.
The human sperm or spermatozoon has a head with a diameter of only about 2.5 micrometers. But exactly how small is a 2.5 micrometer? Compare it with the diameter of your hair, which is around 70 micrometers. Get the picture? You can fit 28 of these wiggly cells along the width of just a single hair.
Coming towards the composition of the sperm head, it contains a large nucleus that carries a haploid set of chromosomes, little cytoplasm, and an acrosome. The acrosome is a sac containing enzymes. The human sperm also includes a middle piece containing mitochondria to provide energy for the activity of the sperm and, of course, a tail or flagellum to enable the sperm to swim towards the egg. The enzymes can break down part of the egg membranes to let the sperm penetrate during fertilization.
Puberty. Puberty is the stage in the development of humans and other mammals when the sex organs mature and produce gametes for the first time. In humans, puberty takes place later in life as compared to other mammals. Puberty begins at the age of about 12 years for boys. However, there has been a recent increase in hitting puberty at a younger age because of the artificial food given to our kids. Testosterone is the male sex hormone made by the testes that is increased during puberty and is responsible for secondary sex characteristics.