Function of male reproductive organ, spermatogenesis and mechanism of erection and ejaculation.

A detailed Physiology of Male Reproductive Organs and the mechanism by which Erection and Ejaculation takes place.

1. Functions Of Male Reproductive Organs, Spermatogenesis and Mechanism Of Erection & Ejaculation . Saadiya Naeemi SBB Dewan University, Dewan Institute Of Rehabilitation Sciences .

2. I- Primary Sex Organ : Testis. II- Reproductive Tract : E pididymis. V as Deferens. S permatic cord. III- Accessory Sex Glands : Seminal vesicles. Prostate gland. Bulbourethral glands. IV- External Genitalia : Penis Components Of Male Reproductive System

3. An out pouching of loose skin & superficial fascia. The Left scrotum is slightly lower than the right. Functions: Houses & Protects the testis Regulates testicular temperature (no superficial fat ) It has thin skin with sparse hairs and sweat glands. Scrotum

4. The scrotum contains three major (paired) structures: Testis   – the site of sperm production. Epididymis   – situated at the head of each testicle. It functions as a storage reservoir for sperm. Spermatic cord   – a collection of muscle fibres, vessels, nerves and ducts that run to and from the testes . Scrotum

5. Paired almond-shape gonads that suspended in the scrotum by the spermatic cord. Its volume is about 20-25 ml. 4 - 5 cm long Weigh (10.5 – 14 g.). Functions: Spermatogenesis. Hormone production: (Androgens--testosterone) Testis or Testicle (singular), Testes (plural). Testes:

6. Fibrous septae extend from the capsule, divide the testis into a (200-300) -average 250- lobules. Each lobule contains, (1-3) seminiferous tubules. Seminiferous Tubules: (60 cm coiled tubule). They are the site of the spermatogenesis. They form the bulk of testicular tissue. Interstitial cells of Leydig secret Testosterone. Internal Structure of The Testis

7. Seminiferous Tubules: Maintain environment for spermatogonia by the basal lamina and the Sertoli cells Sertoli cells separate the lumen from the basal lamina and create a blood-testis barrier Creates three compartments Lumen – low glucose, high K + & steroid hormones Basal compartment – the baso - lateral side of the sertoli cells & containing the developing spermatogonia Interstitial fluid space – below the basal lamina and contains the Leydig cells Produce hormones/ paracrines From Sertoli cells From Leydig cells Internal Structure of The Testis

8. Seretoli Cells: Produce hormones & paracrines involved with control of hypothalamus-pituitary-gonad and the testes directly. Anti- M ü llerian Hormone (AMH) Secreted during embryogenesis Inhibin & activin Regulate FSH release from anterior pituitary inhibin decreases FSH release activin increases LH function & increases FSH release

9. Seretoli Cells: Androgen Binding Protein (ABP) Binds to testosterone and DHT( Dihydrotestosterone ), resulting in an increase in testicular testosterone levels Estradiols & Aromatase Support spermatogenesis GDNF ( glial derived neurotrophic factor) & ERM transcription factor Maintenance of the stem cell line

10. Leydig Cells: Produce androgens testosterone, androstenedione and dehydroepiandrosterone (DHEA) Increase spermatogenesis Influence secondary sexual characteristics Stimulated to produce androgens by luteinizing hormone (LH) FSH increases the response to LH by Leydig cells

11. Epididymis : A Single coiled tubule 6 Meters long. Located on the superior and posterior margins of the testis. It is divided into 3 parts: Head, Body and Tail. The Head receives ( rete testis) efferent ductules from the testis. The Tail is continuous with Vas Deferens.

12. Epididymis : Functions: 1. Secretes/absorbs the nourishing fluid. 2. Recycles damaged spermatozoa. 3. Stores spermatozoa Up to 2 weeks to allow for maturation.

13. Vas Defarans : A muscular tube 45 cm long. Carries sperms from the epididymis to pelvic cavity. It joins the duct of the seminal vesicle to form ejaculatory duct which opens in the prostatic urethra.

14. Accessory Glands: Seminal vesicle. Bulbourethral or Cooper’s glands. Prostate. Functions: 1. Secretion of seminal fluid. 2. Nourishing, activation of sperms. 3. Protection of sperms.

15. Accessory Glands: Seminal Fluid Components, Function and Location

16. Seminal Vesicle: Paired elongated glands. Secrete (60% of Semen)

17. Ejaculatory Ducts: Formed by the union of the lower end of the vas deferens and the duct of the seminal vesicle. Its length is about 2.5cm. The 2 ejaculatory ducts open into the prostatic urethr . They drain the seminal fluid into the prostatic urethra.

18. Prostate Glands: The Largest male accessory gland. It secretes enzymes which has the following functions : Aid in activating sperm motility Mucus degradation Neutralize female reproductive tract (Alkaline fluid )

19. Bulbourethral (Cooper’s) Gland : Small paired glands Located at the base of the penis. Secrete alkaline mucus for: Neutralization of urinary acids & Lubrication during sexual arousment . The bulbourethral glands contract during ejaculation. This is therefore a  sympathetic function, as opposed to the  parasympathetic control of erection .

20. Penis: Composed mainly of spongy tissue Becomes erect due to blood accumulation in its cylinders If relatively small when flaccid, likely to greatly expand when erect Enhanced at considerable risk The glans (head) has many nerve endings.

21. Muscles Of Penis: There are four muscles located in the root of the penis: Bulbospongiosus  (x2) associated with the bulb of the penis. It contracts to empty the spongy urethra of any residual semen and urine. The anterior fibres also aid in maintaining erection by increasing the pressure in the bulb of the penis. Ischiocavernosus  (x2) It contracts to force blood -this helps maintain erection .

22. Organs involved in the Production of Semen: Seminal Fluid/ : Volume of a typical ejaculation is 2.5 –5.0ml with a sperm count of 50 –150 million sperm (under 20 million sperm is considered infertile), fluid is slightly alkaline at pH 7.2 –7.7. Seminal Vesicles: Produce 60% of the volume of seminal fluid; SV’s produce an alkaline viscous fluid that contains: fructose, prostaglandins, and clotting proteins.

23. Organs involved in the Production of Semen: Prostate Gland : Produce 25% of the volume of seminal fluid; This fluid is a milky, slightly acidic fluid that contains citric acid (for ATP production), acid phosphatase along with several other enzymes ( prostate-specific antigen PSA, pepsinogen , and lysozyme Bulbo -urethral gland: produces alkaline mucus that help lubricate the urethra and the head of the penis Ampulla of ductus deferens : releases up to 150 million sperm cells

24. Spermatogenesis: The process by which sperm develop to become mature sperm, capable of fertilizing an ovum. Phases of spermatogenesis Proliferative: spermatogonia divide to replace their numbers; or produce daughter cells committed to becoming spermatocytes Type A spermatogonia . Meiotic : reduction division resulting in haploid spermatids Type B spermatogonia Spermiogenic : spermatids undergo changes to form mature spermatozoa. Entire process requires 64 days ( Ap spermatogonium  spermatozoon). Hormonal Regulation of Spermatogenesis Intratesticular Testosterone levels are 100 x greater than serum levels Testosterone will initiate & qualitatively maintain spermatogenesis in humans

25. Spermatogenesis: After ejaculation, the sperm can live for about 48 hours in the female reproductive tract. The sperm are released into the lumen of the seminiferous tubule and leave the testes. They then enter the epididymis where they undergo their final maturation and become capable of fertilizing a female gamete.

26. Mechanism Of Erection: An  erection  is a physiological phenomenon in which the penis becomes firmer, engorged and enlarged. erection is triggered by the parasympathetic division of the autonomic nervous system (ANS), causing nitric oxide (a vasodilator) levels to rise in the  trabecular  arteries and smooth muscle of the penis. The arteries dilate causing the penis to fill with blood; simultaneously the  ischiocavernosus  and  bulbospongiosus  muscles compress the veins of the corpora cavernosa restricting the egress and circulation of this blood. Erection subsides when parasympathetic activity reduces to baseline.

27. Mechanism Of Erection: As an autonomic nervous system response, an erection may result from a variety of stimuli, including sexual stimulation and sexual arousal. It is therefore not entirely under conscious control. Erections during sleep or upon waking up are known as nocturnal penile tumescence (NPT).

28. Mechanism Of Ejaculation: The process of ejaculation can be divided into two distinct phases: emission and expulsion. Emission: The initial step in emission commences with closure of the bladder neck due to sympathetic innervation . This action prevents the retrograde flow of ejaculate into the bladder. After bladder neck closure, secretion of fluid from the prostate, laden with acid phosphatase , citric acid, and zinc mixes with spermatozoa-rich fluid from the vas deferens in the prostatic urethra. Subsequent contribution of seminal vesicle fluid replete with fructose alkalinizes the final ejaculatory product.

29. Mechanism Of Ejaculation: Expulsion: The expulsion phase follows the emission phase. Relaxation of the external urinary sphincter (with a closed bladder neck) is followed by clonic contractions of the prostate, bulbospongiosus muscle, ischiocavernosus , levator ani , and transverse perineal muscles [6–8]. Through rhythmic contractions lasting 0.6–1.0 s with latency time of 0.7 s between, and a total mean duration of contraction lasting 4.2 s, semen is expelled from the urethra.

30. T H A N K Y O U