Reproduction in human beings

How Do Organism Reproduce of Class 10

The reproduction organs in human beings become functional after attaining sexual maturity. In males, sexual maturity is attained at a age of 13 – 14 years. In females, it is attained at an age of 12 – 13 years. This age is known as the age of puberty. During sexual maturity, hormonal changes take place in males and females, and under the influence of these hormones secondary sexual characteristics are developed.

Secondary sexual characteristics in males include deepening of voice, widening of shoulders, appearance of beard and moustaches, growth of axillary and pubic hair, enlargement of external genital organs and formation of sperms.

Secondary sexual characteristics in females include growth of axillary and pubic hair, widening of pelvis and hip, enlargement of breasts and initiation of the menstrual cycle.

Male Reproductive System

The male reproductive system consists of the two following organs – a pair of testes, a pair of epididymis, a pair of vasa deferentia, urethra, penis and accessary glands.

Reproduction in human beings

Male Reproductive System

Male reproductive system comprises of following parts:

(i) Testis (ii) Scrotum (iii) Vasa efferentia

(iv) Epididymis (v) Vas deferens (vi) Ejaculatory duct

(vii) Urethra (viii) Accessory sex glands (ix) Penis

Testis:

Testes are one pair of small sized oval shaped 4 to 5 cm long, pinkish coloured primary sex organ of male.These are present in a thin pouch made up of skin and connective tissue called scrotal sac or scrotum hanging from lower abdominal wall between the leg.Scrotal sac acts as thermoregulator and it keep the testicular temperature 2°C lower than body temperature. This temperature is suitable for development of sperms. Each testis is externally covered by a white fibrous capsule, the tunica albuginea which is produced inside the testis as fibrous septa. The septa divide the testis into a number of testicular lobes.Each lobule has one to three convoluted seminiferous tubules.The combined length of all seminiferous tubules is about 200–400 metres. Between the seminiferous tubules connective tissue are found.In this connective tissue interstitial cells also called Leydig cells are present as clumps.These cells secrete the male sex hormone, testosterone. This hormone regulates the maintenance of primary and secondary sexual charateristics in males.

EPIDIDYMIS

  • Epididymis is very coiled long tube of 6m. It is commonly known as store house of sperms.
  • Storage and activation of sperms take place here. Its secretion also contributes to seminal fluid. Sperm can be seen for 10 Hr. to 10 days in it.
  • If there is no ejaculation for longer time the sperms get absorbed by its wall.

Vasa deffrentia

  • Each epididymis continues from its lower end as a vas deferens.
  • It enters into abdominal cavity through inguinal canal, forms loop round the uretor and joins the duct of a seminal vesicles to form an ejaculatory duct. The ejaculatory duct opens into the urethra.
  • Near its end the vasa deferens is enlarged to form a spindle like ampulla for the temporary storage of sperm.
  • It is cut or tied off as the birth-control measure called vasectomy.

Urethra

It arises from the urinary bladder and joins the ejaculatory duct to form urinogenital canal as it carries urine, sperm and secretion of seminal vesicles postrate and cowper’s gland.

Urethra is 20 cm long, passes through the penis and it is differentiated into prostatic part (2.5 cm) membranous part (2.5 cm) and penile part (15.0 cm). Finally it opens at tip of penis.

In male it is the common pathway for release of urine and seminal fluid.

Penis: It is a long and thick muscular organ made up of mostly erectile tissue. It opens outside the body. It passes the sperms from the man’s body into the vagina of the women’s body during mating.

Human-male reproduction

Accessory sex glands

  1. Seminal vesicles: These are elongated coiled sacs. They secrete seminal fluid that contains sugar fructose. It provides energy to the spermatozoa.

SEMEN

  • Sperms and secretion of accesory glands collectively known as seminal fluid or semen.
  • It is milky, semi-solid in nature having particular smell.
  • pH – 7.35 – 7.5, specific gravity – 1.028
  • The secretion has many functions as –
  • Provide fluid medium to sperms
  • Nourish and activate sperms.
  • Facilitate the sexual act by lubricating the reproduction tract of the female.

(ii) Prostate gland: This gland surrounds the first portion of urethra. It secretes a fluid containing citrate and enzymes that nourish and activates the spermatozoa that swim.

SPERMATOZOA

  • Human sperm lives for many weeks in gonoduct but, once ejaculated it survives only for 24 to 48 hrs.
  • The sperms are released in millions. In one ejaculation about 200,000,000 (2 × 108) sperms are discharged. Sperm move with the speed of 2 mm/minute in female tract.
  • Structurally, a human sperm has three main parts – head, neck and tail. The tip of a sperm is covered by a cap-like structure, acrosome, which helps the sperm to penetrate inside the egg during fertilization.

Talk to Our counsellor