Question

Describe the composition of semen. Indicate the reproductive structures each component derives from, as well as the function(s) of each component. Indicate normal volume and numbers as appropriate. Also explain the autonomic regulation of male sexual response (erection and ejaculation).

Answer 1

1. Semen is composed of Spermatozoa ,Fructose ,amino acids, proteolytic enzymes,Immunoglobin,bicarbonate ion, mucoproteins .
2. Spermatozoa is derived from the seminiferous tubules present in the testis ,It is involved in the fertilisation of the egg in the female reproductive tract.
3. Fructose and amino acids are derived from the Seminal vesicles , they provide nutrient to the spermatozoa..Seminal vesicles secrete 60% of the semen volume.
4. Protelytic enzyme and bicarbonate ions are derived from the prostate gland which is required for the neutralisation of acidic environment in female reproductive tract to prevent the lysis of spermatozoa.Prostate gland contributes for 30% of the seminal secretion.
5. Mucuproteins are derived from the bulbourethral gland , It help in the lubrication of urethral passage and pe-nis during the copulation.Bulbourethral gland secrete about 5% of the semen secretion,

• Erection and Ejaculation is under the autonomic nervous system control.First the Erection mechanism initiates by Stimulus from parasympathetic innervation. Parasympathetic innervation causes the dilation of arteries in the pe-nis and relaxation of smooth muscles of pe-nis which help in expansion of sinusoidal spaces in pe-nis.As a result blood entering the pe-nis tissues increase and there is increase in the pressure and expansion of cavernous spaces resulting in completion of Erection mechanism.Then Ejaculation mechanism begins with both parasympathetic and sympathetic innervations.Parasympathetic innervation causes the release of seminal content form the accessory gland along with the spermatozoa from the vas deferens.and sympathetic innervation causes rapid rhythmic contraction of smooth muscle on pe-nis(bulbospongiosus and Ischicavernosus) leading to the Ejaculation of Semen.