Female Reproductive System

How Do Organism Reproduce of Class 10

The female reproductive system is designed to carry out several functions. It produces the female egg cells necessary for reproduction, called the ova or oocytes. The system is designed to transport the ova to the site of fertilization.Conception, the fertilization of an egg by a sperm, normally occurs in the fallopian tubes. The next step for the fertilized egg is to implant into the walls of the uterus, beginning the initial stages ofpregnancy. If fertilization and/or implantation does not take place, the system is designed to menstruate (the monthly shedding of the uterine lining). In addition, the female reproductive system produces female sex hormones that maintains the reproductive cycle.

It is more complex as compared to that of males. It consists of a pair of ovaries, a pair of fallopian tubes, uterus and vagina.

Ovaries: They are the primary sex organs located in the lower part of the abdominal cavity near kidney. Each ovary is connected by a ligament to the uterus. It produces gametes (eggs) and hormones like estrogen and progesterone. Ovary is composed of ovarian follicles. Each follicle contains a large ovum (egg) surrounded by many layers of follicle cells.

When a girl is born, the ovaries already contain thousands of immature eggs. At puberty some of these eggs start maturing. One egg is produced every month by one of the ovaries. The release of egg from the ovary is called ovulation. It is caused by increase in turgidity aided by contraction of unstriped muscle fibres around the follicles. The force of ejection carries the egg to the fallopian tube. In women each measures about 3 cm × 2 cm × 1 cm and surrounded by the fold of peritoneum.

Ovaries produce ova and secrete female sex hormones, oestrogen and progesterone. The process of formation of egg in the ovary is known as oogenesis.

Fallopian tubes:These are narrow tubes that are attached to the upper part of the uterus and serve as tunnels for the ova (egg cells) to travel from the ovaries to the uterus. Conception, the fertilization of an egg by a sperm, normally occurs in the fallopian tubes. The fertilized egg then moves to the uterus, where it implants into the lining of the uterine wall.

Uterus (womb):It is a large (8 cm × 5 cm × 2 cm) hollow muscular, highly vascular and pear shaped structure present is the pelvis between the bladder and rectum. It is formed of three parts :

  • Fundus :It is upper dome shaped part above the opening of follopion tubes.
  • Body or corpus :It is middle and main part of uterus. Its wall is formed of outer peritoneal layer called perimetrium; middle muscular mucosa or myometrium of smooth muscle fibres and inner highly vascular and glandular mucosa or endometrium.
  • Carvix :It is lower narrow part which opens in body of uterus by internal osand in vegina below by external os.
  • Functions. It is the site of foetal growth during pregnancy. It also takes part in placenta formation and expelling of the baby during parturition.
  • Vagina: The vagina is a large, median elastic muscular tube. It is adapted to receive the male penis during copulation. The vagina is also called “birth canal”. It allows the passage of baby at the time of child birth.

Human-female reproduction

Reproductive system (Female)

Gland:

  • Bartholin's gland: It secretes a clear, viscous fluid under sexual excitement.
  • The fluid serves as a lubricant during copulation or mating.

Menstrual Cycle:

menstrual

  • It is a cyclic phase of the flow of blood with mucus and tissues etc. from the uterus of a woman at monthly intervals.
  • It occurs on average of 28 days interval.
  • It starts at the age of 12-14 years and stops at 45 - 50 years of life.
  • This cycle stops during pregnancy.
  • The menstrual cycle consists of following phases:

(i) Bleeding or menstrual phase:

  • It is the first stage of menstrual cycle.
  •  Its duration is of 5 days but normally bleeding is found for 2 - 3 days.
  •  In this stage hormones oestrogen, progesterone, follicle stimulating hormone and luteinizing hormone are found in minimum quantity
  •  Total 100 ml, of blood flows in a complete bleeding phase.

(ii) Proliferative phase:

  •  In this phase F.S.H stimulates development and maturation of graffian follicles.
  •  In this phase oestrogen level rises which leads to formation of new endometrium.
  •  It lasts for about 10 - 14 days. Thinnest endometrium is found in this phase.
  •  It is also called as follicular phase.

Ovulation phase:

  • At this phase ovulation occurs.
  •  Ovulation occurs in the presence of FSH and LH.
  •  Thickest endometrium found in this stage.
  •  It also lasts for about 14 days.

(iv) Secretory phase: In this stage both oestrogen and progesterone levels are high.

  •  If fertilization takes place, this stage extends till to the parturition (giving birth to a child).
  •  If fertilization does not take place, this stage completes on 28th day of menstrual cycle.
  •  The commencement of menstruation at puberty is called as menarche.
  •  It's stoppage around the age of 50 years is called as menopause.
  •  The period between menarche and menopause is the reproductive phase in human female.

(b) Oogenesis:

Oogenesis is a process of formation of ovum. The ovum is a rounded, non-motile cell. Its size varies in different animals depending upon the amount of yolk in it.

Ovum consists of two types of coverings:

(i) Inner thin, transparent, non-cellular covering called as zonapellucida. It is composed of protein and sugars. It is secreted by follicle cells.

(ii) Outer thick covering is called as corona radiata.

 

 

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