Male Reproductive System PDF

The Male Reproductive System The male reproductive system has only one function, and all the organs of this system function together to complete this one task. This task is to produce the male half of the genetic code and deliver it into the female. Spermatogenesis, the production of the male half...

The Male Reproductive System The male reproductive system has only one function, and all the organs of this system function together to complete this one task. This task is to produce the male half of the genetic code and deliver it into the female. Spermatogenesis, the production of the male half of the genetic code, the sperm, will be the main focus of the physiology, but first we must look at the anatomy of the male reproductive system and the function of each organ. Male anatomy terms: Scrotum – Sac that holds testes. Testes – Male reproductive organs that actually perform spermatogenesis. Epididymis – tube where spermatozoa mature: 4 to 5 meters epididymis long. scrotum testis Vas deferens – storage area seminal vesicle for sperm from a few hours to 42 days. No loss of fertility during storage. Seminal vesicle – secretes a slightly alkaline mucus which contains fructose (food source for the sperm) and prostaglandin (a hormone that produces vas deferens uterine contractions). Ejaculatory duct – area where vas deferens and seminal vesicles empty during ejaculation. Prostate gland – where the ejaculatory duct passes through and meets the urethra. Contracts during ejaculation to empty secretions to the mix. Highly alkaline, ejaculatory prostate duct mucus secretion. gland Bulbourethral gland (Cowper’s gland) – urethra secretes a viscid, alkaline secretion that cleanses urethra and lubricates penis. Urethra – common tube from bladder and reproductive organs. Carries ejaculate out of the body. bulbourethral gland Penis – organ of ejaculate delivery. The shaft of the penis is composed of two types of “erectile tissue” called the corpus cavernosa and the corpus spongiosum. The corpus spongiosum enlarges at the distal end to form the glans penis. Semen – fluid ejaculated during the male sexual act. Contains about 120 million sperm/ml and 1 to 5ml are usually ejaculated per sexual act. It is a milky white, viscid fluid that is composed of sperm, and the secretions from the seminal vesicles, Prostate gland, and the bulbourethral glands. Its pH = 7.5. This pH allows the acid secretions of the vagina to be neutralized (pH of the vagina is between 3 and 4) to allow the sperm to exist at a pH of 6-6.5, which is the pH at which they are most mobile. So semen is sperm with food, acid neutralizers, and uterine contraction producers. Seminiferous tubules – tubes spermatogenesis in testes where sperm are formed and begin maturation. epididymis testis Vas deferens Cross section Seminiferous tubule The testicles or testes are the male reproductive organs responsible for the production of sperm cells through the process of spermatogenesis. This process starts at the age of about 13 and continues throughout a man’s life. Cells called spermatogonia (singular = spermatogonium), which are formed during fetal life, begin to pass through a sequence of stages that produce spermatozoa or mature sperm cells. The process of spermatogenesis is as follows: Spermatogonium – divides by mitosis. One daughter cell goes on to become a primary spermatocyte, the other divides again to form another spermatogonium and another primary spermatocyte, etc., etc. Primary Secondary spermatocyte spermatocyte Spermatid Sperm Chromosomes replicated Spermatogonium Primary spermatocyte Secondary spermatocyte Spermatid – immature sperm Spermatozoa – mature sperm cells Mitosis Meiosis I – the DNA was replicated, then is reduced. Meiosis II – DNA is reduced a second time. The process of division with chromosomal reduction is called meiosis. This process helps to reduce the normal complement of 23 pairs or 46 chromosomes to a simple complement of 23 chromosomes (diploid to haploid). This process of development takes about 74 days. The process also must occur at a body temperature about 3 to 5 degrees below that of normal body temperature. This is why the testes are located external to the body. Normal sperm production will produce about 120 million sperm per ml of semen. If the number drops below 20 million then functional infertility has occurred. Factors that can dramatically reduce sperm production: High temperature Alcohol – excessive X- Rays and chemotherapy Drugs – of various types A controversial question facing today’s new parents: Should baby boys be circumcised? Circumcise 1. To remove the prepuce (often called the foreskin of the penis) of a male. 2. To remove all or part of the clitoris, prepuce (often called the hood of the clitoris), and/or labia of a female.