Reproduction Part-3

Human Reproductive System

  • The female and male reproductive systems in humans differ remarkably from one another.
  •  Testes are the main reproductive structure in males where sperms (male gametes) are produced, and ovum (female gamete) is produced inside the ovary.

Male Reproductive System

Testes

  • The main reproductive organ in males is a pair of testes.
  • They are present in scrotal sacs outside the body and contain seminiferous tubules as the structural and functional unit.
  • Leydig cells or interstitial cells present in between the seminiferous tubules secrete the hormone testosterone.
  • Male sex cells, sperms, are produced by seminiferous tubules and mature in the epididymis.
  • Function-Regulate production of sperms and bring change at puberty.

Vas deferens

  • A single vas deferens carries sperm from the respective testis up to the urethra.

Urethera

  • The urethra acts as a common passage for semen and urine.

Associated Gland

  • The prostate gland and the seminal vesicles are glands of the reproductive system which make semen and nourish the sperm.
  • They produce different secretions which provide nutrition as well as medium for locomotion to the sperms.
  • The secretions of the three glands along with the sperms are known as semen.
  • Penis, having the urethra passing through it, is called a copulatory organ.

Female Reproductive System

  • The main reproductive organ in a female is a pair of ovaries.
  • They produce the female sex cells called eggs or ova and also produce female sex hormones called estrogen and progesterone.
  • The uterus, oviducts, and vagina are the accessory reproductive organs in human females.
  • The uterus is the site of fetal development, and the vagina receives sperm from the male.
  • Ovum is carried from the ovaries to the uterus through a pair of oviducts.
  • Function of Fallopian tube- Site of fertilization between the male and the female gametes and formation of the zygote early embryo.
  • Function of uterus- The embryo formed in the fallopian tube comes down and gets attached to the endometrium (implantation) and develops for the next nine months till the baby is delivered.
  • Vagina: The uterus opens into the vagina through the cervix. The vagina is a muscular tube through which the baby is delivered at the end of nine months. It also serves as the canal for receiving the semen at the time of copulation.

 

Fertilization

  • Humans reproduce sexually.
  • The female produces eggs, while the male produces sperms.
  • When the sperm fuses with the egg, it forms a zygote that gives rise to a new progeny.

Menstrual Cycle

Menstruation

  • Menstruation is the cyclical process in which the ovum is released from the ovary and removed from the body when fertilisation does not happen.
  • As the ovum releases itself from the body during menstruation, the uterus's blood-rich endometrium also disintegrates.
  • Two pituitary hormones, LH and FSH, and two ovarian hormones, estrogen and progesterone, all have their roles in menstruation.
  • In humans, the cycle repeats every 28 days.

Reproductive Health

  • Reproductive health deals with the prevention of STDs and unwanted pregnancy. Understanding the reproductive system is also a part of reproductive health awareness.

Contraceptives devices

  • Contraceptives are devices that prevent unwanted pregnancy and help avoid STDs.
  • Contraceptives can be of various types such as mechanical barriers, hormonal/chemical methods, surgical methods, etc.

 

Mechanical methods: These are used to prevent the passage of semen to the fallopian tube:

(i) Condoms: Condoms are thin rubber tubes worn over the penis before sexual intercourse. It is one of the most effective methods of contraception. It stops the semen from entering the female tract preventing pregnancy. It also avoids the possibility of contracting STDs.

 (ii) Diaphragm: It is a thin rubber fixed over a flexible metal ring which is fitted over the cervix in a woman’s body by a doctor. They stop the entry of semen inside the female tract and thus prevent pregnancy.

(iii) Intra Uterine Contraceptive Device (IUCD) or loop: It is inserted in the uterus and its insertion causes certain secretion which prevents the implantation of the embryo in the uterine wall.

Chemical methods

  • Use of spermicides: These are strong sperm-killing chemicals available in the form of creams, jellies etc. which are injected into the vagina just before copulation.
  • Oral contraceptive pills: These are hormonal pills which prevent ovulation but do not stop menstruation. They change the level of hormones in the body that prevents the release of the ovum from the ovaries.

Surgical methods

  • Vasectomy: It involves cutting and ligating the vas deferens in males.
  • Tubectomy: It involves cutting and ligating Reproductive organs the fallopian tubes in females.
  • Medical termination of pregnancy (MTP) or abortions is carried out to eliminate the developing embryo. This practice can, however, be misused to carry out female foeticide which involves the killing of the female foetus. It should be avoided at all cost as it disturbs the male-female ratio in a population.