Question

What are the major components of seminal plasma?

Answer 1

Seminal plasma is also called as semen. Semen is a mixture of sperms and seminal fluid, which is the liquid portion of semen that consists of secretions of the seminiferous tubules, seminal vesicles, prostate gland and bulbourethral glands. The average volume of seminal plasma in an ejaculation is 2.5 - 5 ml, with a sperm count (concentration) of 200 to 300 million sperms.

Complete answer: The seminal plasma contains secretion of following glands :-
1.Seminal vesicles: These are paired, tubular, coiled glands situated behind the bladder. They secrete viscous fluid which constitutes the main part of the ejaculate. Seminal fluid contains fructose, citric acid, inositol and prostaglandins.
2.Prostate gland: The prostate gland is a chestnut shaped gland and is a collection of 30-40 tubuloalveolar glands which lie at the base of the bladder and surrounds the first part of the urethra. it contributes an alkaline component to the semen. (Although, the alkalinisation of semen is primarily accomplished through secretion from the seminal vesicles.) The alkaline secretions of prostate gland help the sperms to become active and counteract any adverse effects that the urine may have on the sperms. The prostatic fluid provides a characteristic odour to the seminal fluid. Prostate gland secretes citrate ions, calcium, phosphate ions and profibrinolysin.
Prostatitis : Inflammation of prostate gland.
3.Bulbourethral glands or Cowper's glands: The two bulbourethral glands are pea sized structures lying adjacent to the urethra at the base of penis. They secrete a viscous mucus which acts as a lubricant.The duct system, accessory glands and penis are secondary male sex organs. Their growth, maintenance and functions are promoted by testosterone, secreted by Leydig cells. On the other hand, the growth, maintenance and functions of seminiferous tubules and Leydig cells are regulated respectively by FSH and ICSH of anterior pituitary.

Note: Semen or seminal plasma has a slightly alkaline pH of 7.2-7.7, due to the higher pH and larger volume of fluid from the seminal vesicles. The prostatic secretion gives seminal plasma a milky appearance whereas the fluids from the seminal vesicles and bulbourethral glands give it a sticky consistency. Seminal plasma provides sperms with transportation medium and nutrients. It neutralizes the hostile acidic environment of the male urethra (due to presence of urine) and the female vagina.