The humans use sexual mode of reproduction. The reproductive systems in human beings become functional or start functioning at a definite age called puberty. In complex multicellular organisms like human beings there are special reproductive organs to make sperms and eggs; to bring together sperms and eggs for fertilization; and for the growth and development of zygote in to a baby.
But before describing all this in human reproductive system, we will first understand the meaning of the term ‘puberty’.
Sometimes it becomes difficult to tell from appearance that whether the child is male or female having the same body shape in small age. A time of rapid growth and body changes starts in the early teens which make the girl appear different and also behave differently. These changes start earlier in girls than in boys. Time between childhood and adulthood is called ‘adolescence’. At this age production of male and female ‘sex hormones’ in the bodies of boys and girls increases and causes wide ranging changes in their bodies. The testes in boys and ovaries in girls make different hormones. So, they develop in different ways. Ultimately boys and girls become sexually mature and their reproductive system start functioning.
The age at which the sex hormones or gametes begin to be produced and the boy and girl become sexually mature or able to reproduce is called puberty.
Generally boys attain puberty at the age of 13 to 14 years while girls from 10 to 12 years. On attaining puberty, the male gonads testes start producing male gametes called sperms and the female gonads ovaries start producing female gametes called ova or eggs. With this male and female gonads also secrete sex hormones with the onset of puberty.
The testes produce the male sex hormone called testosterone, and the ovaries produce two female sex hormones, oestrogen and progesterone. The sex hormones plays important role in the process of reproduction because they make the reproductive organs to mature and start functioning. Puberty is the age at which the reproductive organs reach maturity and secondary sexual characteristics develop.
The various changes that occur in boys at puberty are: Hair grows under armpits and in pubic regions (genital area) between the thighs. Hairs also grow on other parts of the body like chest and face (moustache, beard etc.). Body becomes more muscular due to the development of muscles. The voice deepens or cracks. Chest and shoulders broaden. The penis and testes become larger. The testes start to make sperms. Feelings and sexual drives associated with adulthood begin to develop. All these changes in boys are brought about by the male sex hormones ‘testosterone’ made in testes.
The various changes which occur in girls at puberty are: Hair grows under armpits and pubic region (This change is same as in boys). Mammary glands or breasts develop and enlarge. The hips broaden. Extra fat is deposited in various parts of the body like hips and thighs. Fallopian tubes, uterus and vagina enlarge. Ovaries start to release eggs. Menstruation start. Feelings and sexual drives associated with adulthood begin to develop. All these changes in girls are brought about by the female sex hormones ‘oestrogen’ and ‘progesterone’ made in ovaries.
The Male Reproductive System
The human male reproductive system consists of the following organs: Testes, Scrotum, Epididymis, Vas deferens or Sperm duct, Seminal Vesicles, Prostrate gland and Penis.
The male reproductive system in humans
Testes are the oval shaped organs which lie outside the abdominal cavity of a man. A man has two testes. Testes are the primary reproductive organs in man or males. The function of testes is to make the male sex cells or male gametes called sperms and also to make the male sex hormone called testosterone. The testes of a man make the sex gametes or sperms from the puberty onwards, throughout his life. The testes of a man lie in small muscular pouch called scrotum, outside the abdominal cavity. The testes are outside the abdominal cavity of the body and not deep inside the body because the sperm formation requires a lower temperature than the normal body temperature. Being, outside the abdominal cavity, the temperature of scrotum is about 3 degree Celsius lower than the temperature inside the body. In this way, the testes provide an optimal temperature for the formation of sperms.
The sperms from the testes come out and go in to a coiled tube called epididymis. The sperms get stored temporarily in epididymis. From epididymis, the sperms are carried by a long tube called Vas Deferens or sperm duct which joins with another tube called urethra coming from the bladder. Along the path of vas deferens, the glands called seminal vesicles and prostrate gland add their secretions to sperms so that the sperms are now in a liquid. This liquid plus the sperms it contains is called semen which is a thick liquid. The secretions of seminal vesicles and prostrate gland provide nutrition to the sperms and also make their further transport easier. Urethra forms a common passage for sperms and urine. Urethra carries the sperms to an organ called penis which opens outside the body. The penis passes the sperms from the man’s body in to vagina in the woman’s body during mating for the purpose of reproduction.