Understanding the functions of male reproductive system

Passage of Spermatozoa: Seminiferous tubule Reta testes Vasa efferentia Epididymis Vas deferensEjaculatory duct urethra outside of the body. Urethra:  In males, the urethra is the shared (common) terminal duct of the reproductive and urinary systems.  The urethra originates from the neck of the urinary bladder and extends through the penis to its external […]

Passage of Spermatozoa: Seminiferous tubule Reta testes Vasa efferentia Epididymis Vas deferensEjaculatory duct urethra outside of the body.

Urethra:
 In males, the urethra is the shared (common) terminal duct of the reproductive and urinary systems.
 The urethra originates from the neck of the urinary bladder and extends through the penis to its external opening called urethral meatus.
 The urethra provides an exit for urine & semen during ejaculation in males.

Penis:

 The penis and the scrotum constitute the male external genitalia.
 The penis serves as a urinal duct and also intermittent organ that transfers spermatozoa to the vagina of female.
 The human penis is made up of three columns of tissue;
 Two upper corpora cavernosa on the dorsal aspect and
 One corpus spongiosum on the ventral side.
 Skin and a subcutaneous layer enclose all three columns.
 The corpora cavernosa consist of special tissue with spaces that are filled with blood.
 They help in erection of the penis to facilitate insemination.
 The enlarged and bulbous end of penis called glans penis is covered by a loose fold of skin (foreskin) called prepuce.
 The urethra traverses the corpus spongiosum and its opening called urethral meatus lies at the tip of the glans penis.

Male accessary genital glands:

 The male accessory glands include paired seminal vesicles, a prostate gland & bulbourethral glands.

Seminal Vesicles:
 The seminal vesicles are a pair of simple tubular glands present posterior inferior to the urinary bladder in the pelvis.
 Each seminal vesicle opens into the corresponding vas deferens, where the vas deferens enters the prostate gland.
 The secretion of the seminal vesicles constitutes about 60 percent of the volume of seminal fluid.
 It is an alkaline, viscous fluid that contains fructose, proteins, citric acid, inorganic phosphorus, potassium, and prostaglandins.
 Once this fluid joins the sperm in the ejaculatory duct, fructose acts as the main energy source for the sperm outside the body.
 Prostaglandins are believed to aid fertilization by causing the mucous lining of the cervix to be more receptive to sperm as well as by aiding the movement of the sperm towards the ovum with peristaltic contractions, of the uterus and fallopian tubes, after coitus.

Prostate gland:

 Prostate gland is located directly beneath the urinary bladder.
 The gland surrounds the prostatic urethra and sends its secretions through several prostatic ducts.
 In man, the prostate contributes 15-30% of the semen.
 The fluid from the prostate is clear and slightly acidic.
 The prostatic secretion activates the spermatozoa and provides nutrition.

Bulbourethral Glands:

 Bulbourethral glands, also called Cowper’s glands, are located beneath the prostate gland at the beginning of the internal portion of the penis.
 They add an alkaline fluid to semen during the process of ejaculation.
 The fluid secreted by these glands lubricates the urethra.
 It is also thought to function as a flushing agent that washes out the acidic urinary residues that may remain in the urethra, before the semen is ejaculated.

Practice Bits:

1. The primary reproductive organs are

a. Testes & Penis
b. Vagina & penis
c. Prostateglands & mammary glands
d. Testes & ovaries
Answer: d

2. Before birth the testes descend into the scrotal sac from abdominal cavity passing through

a. Bidders canal
b. Inguinal canal
c. Eustachian canal
d. Ingluvial canal
Answer: b

3. Inhibin, a protein is secreted by

a. Leydig cells
b. Interstitial cells
c. Sertolicells
d. Germinal epithelial cells
Answer: c

4. The erection of penis occurs when the blood fills

a. Urethra
b. Tunica albuginea
c. Glanspenis
d. Blood spaces of penis
Answer: d

5. The gland secreting citric acid is

a. Seminal vesicle
b. Prostate glands
c. Bulbourethral gland
d. Perineal gland
Answer: a

6. The narrow middle part of epididymis is

a. Caput epididymis
b. Cauda epididymis
c. Corpus epididymis
d. Rete testes
Answer: b

By Dr. Modala Mallesh
Subject Expert
Palem, Nakrekal, Nalgonda
9989535675