Female Reproductive System

Structure and Functions of the Female Reproductive System

Components of the Female Reproductive System

• What is female reproductive system?
• What is fertilization?

What are the components of the female reproductive system?

The female reproductive system:

Made up of the internal and external sex organs that function in human reproduction.

Female Reproductive System

The female reproductive system is immature at birth and develops to maturity at puberty to be able to produce gametes, and to carry a foetus to full term

Fertilization

Is the fusion/union of male and female gametes, during sexual reproduction, to form a zygote

The female reproductive system consists of the:

• Paired ovaries
• Fallopian tubes
• Single uterus
• Vagina

External genital structures

Egg cells (ova) are produced in the ovaries and travel through the fallopian tubes to the uterus.

The uterus is the site for the growth of the embryo-foetus

Structures and Functions of the Female Reproductive System

What are the structures and functions of the female reproductive system?

Ovaries

The ovaries are a pair of oval structures on either side of the uterus in the pelvic cavity Within an ovary are several hundred thousand primary follicles, which are present at birth.

Female Reproductive System

Each primary ovarian follicle contains an oocyte, a potential ovum or egg cell. Surrounding the oocyte are the follicle cells, which secrete estrogen.

Luteinizing hormone stimulates Graafian follicle (matured follicle) and cause ovulation

Ruptured follicle become corpus luteum and begins to secrete progesterone and oestrogen

Fallopian tubes

There are two fallopian tubes(oviducts) The lateral end of a fallopian tube encloses an ovary, and the medial end opens into the uterus.

The smooth muscles along it propels the ovum towards the uterus

The ovum is fertilized in the fallopian tube and swept to the uterus

Uterus

The uterus is shaped like an upside-down pear, superior to the urinary bladder and between the two ovaries in the pelvic cavity

Female Reproductive System

During pregnancy the uterus increases greatly in size, contains the placenta to nourish the embryo-foetus, and expels the baby at the end of gestation.

It is divided in to fundus (upper part), body (central part) and cervix (lower part)

Female Reproductive System

The myometrium is the smooth muscle layer during pregnancy these cells increase in size to accommodate the growing foetus and contract for labour and delivery at the end of pregnancy.

The lining of the uterus is the endometrium, forms the maternal portion of the placenta during pregnancy

Vagina

The vagina is a muscular tube that extends from the cervix to the vaginal orifice The vaginal opening is usually partially covered by a thin membrane called the hymen which ruptures after sexual intercourse

The functions of the vagina are to receive sperm from the penis during sexual intercourse,

• To provide the exit for menstrual blood flow, and

To become the birth canal at the end of pregnancy.

External genitals (Vulva)

• The external female genitalia includes:

Clitoris

Is a small mass of erectile tissue anterior to the urethral orifice. The only function of the clitoris is sensory. It responds to sexual stimulation.

Labia majora and minora

Are paired folds of skin which covers the urethra and vagina openings and prevent drying of their mucous membranes Bartholin‘s glands

They secrete lubricant which keep the vagina moist during sexual intercourse.

Oogenesis

How an egg cell is produced?

Oogenesis

It is the process of meiosis for egg cell formation; it begins in the ovaries and is also regulated by hormones.

Follicle stimulating hormone initiates the growth of ovarian follicles, each of which contains an oogonium, a stem cell for egg cell production

This hormone also stimulates the follicle cells to secrete estrogen, which promotes the maturation of the ovum.

For each primary oocyte that undergoes meiosis, only one functional egg cell is produced.

The other three cells produced are called polar bodies. They have no function, and will simply deteriorate.

A mature ovarian follicle actually contains the secondary oocyte; the second meiotic division will take place if and when the egg is fertilized.

Female Reproductive System

The production of ova begins at puberty (10 to 14years of age) and continues until menopause (45 to 55years of age), when the ovaries atrophy and no longer respond to pituitary hormones.

Female Reproductive System

Note; Oogenesis is the unequal cell division of which produces one to three polar bodies that later degrade, as well as a single haploid ovum, which is produced only if there is penetration of the secondary oocyte by a sperm cell.

Menstrual cycle

The menstrual cycle includes the activity of the hormones of the ovaries and anterior pituitary gland and the resultant changes in the ovaries (ovarian cycle) and uterus (uterine cycle).

Female Reproductive System

Involves four hormones which are FSH and LH from the anterior pituitary gland, estrogen from the ovarian follicle and progesterone from corpus luteum The cycle is described in three phases at an average of 28 days

Menstrual phase

• The loss of the functional layer of the endometrium is called menstruation or the menses.

Although this is actually the end of a menstrual cycle and a useful starting point.

The average time is 3-6 days

At this time, secretion of FSH is increasing, and several ovarian follicles begin to develop

2. Follicular phase

FSH stimulates growth of ovarian follicles and secretion of estrogen by the follicle cells.

The secretion of LH is also increasing, but more slowly.

Female Reproductive System

FSH and estrogen promote the growth and maturation of the ovum, and estrogen stimulates the growth of blood vessels in the endometrium to regenerate the functional layer.

This phase ends with ovulation, when a sharp increase in LH causes rupture of a mature ovarian follicle.

Ovulation phase

• Involves release of matured ovum from the ovaries
• Hormone responsible is luteinizing hormone

Known as heat period

The only time during menstrual cycle when a woman can get pregnant

3. Luteal phase

Under the influence of LH, the ruptured follicle becomes the corpus luteum and begins to secrete progesterone as well as estrogen.

Female Reproductive System

Progesterone stimulates further growth of blood vessels in the functional layer of the endometrium and promotes the storage of nutrients such as glycogen.

Female Reproductive System

As progesterone secretion increases, LH secretion decreases, and if the ovum is not fertilized, the secretion of progesterone also begins to decrease.

Without progesterone, the endometrium cannot be maintained and begins to slough off in menstruation.

FSH secretion begins to increase (as estrogen and progesterone decrease), and the cycle begins again.

Also secreted by the corpus luteum during a cycle are the hormones inhibin and relaxin.

Inhibits the secretion of FSH, and perhaps LH as well, from the anterior pituitary gland.

Female Reproductive System

Relaxin is believed to inhibit contractions of the myometrium (as does progesterone), which would help make implantation of the early embryo successful.

Key points

The female reproductive system consists of the paired ovaries and fallopian tubes, the single uterus and vagina, and the external genital structures During pregnancy, high levels of estrogen and progesterone prepare the glands for milk production.

Oogonia are the stem cell for egg cell production in oogenesis.

Evaluation

• What is female reproductive system?
• What are the structures of female reproductive system?
• What are the functions of the female reproductive system?

What is oogenesis?