6.1 Female Reproductive System

The female reproductive system

It is a system that produces ova (egg cells), provides an environment for fertilisation and foetal development, and secretes vital hormones.

Ovary

Organs in females that produce eggs and hormones like oestrogen and progesterone.

Feature of Ovaries

• Almond-shaped organs located on either side of the uterus

• Contain structures called follicles

Role of the ovaries

• They make eggs and hormones like; Oestrogen and progesterone.

• The hold undeveloped or immature eggs.

• They release an egg into the fallopian tube as part of a woman’s cycle.

• They help regulate the menstrual cycle

Ova

Undeveloped eggs

Follicles

Small sacs in the ovaries, filled with fluid that contain an immature/undeveloped egg.

Immature egg

Oocyte

Another name for ‘Mature egg’

Ovum

Ovum

The female reproductive cell, also known as an egg cell, which can be fertilised by a sperm

Ovulation

When an egg is released

Fertilisation

The process by which a sperm cell joins with an egg cell to form a zygote

Implantation

The stage where a fertilised egg attaches itself to the lining of the uterus and begins to grow.

Zygote

A fertilised egg cell

Fallopian Tubes

• They are two bilateral tubes which connect the ovaries to the uterus.

• Also known as the oviduct

Functions/Feature of the Fallopian Tubes

• They are responsible for transporting the egg from the ovary to the uterus.

• They are covered in small hairs (cilia) which help move the egg along.

• This where fertilisation occurs if a sperm meets the egg.

Cilia

Microscopic, hair-like cellular organelles, found all along the internal lining of the fallopian tube.

Fimbria

• Macroscopic, finger-like structures located at the end of the fallopian tube closest to the ovaries.

• Their primary function is to catch the egg

• They do this by draping over the ovary and performing a sweeping motion during ovulation

Uterus

Also known as the womb, is a hollow shaped muscular bag, where a fetus or baby grows.

Functions of the Uterus

• It protects and nurtures the developing foetus until it is ready to be born.

• It provides physical protection by having muscular walls.

• The strong muscular walls are also needed to push the baby out through the vagina, during birth.

Lining of the uterus

• Also known as endometrium, sheds and thickens as part of the menstrual cycle.

• Where an egg will be implanted.

Foetus

The baby developing in the uterus. It is known as the foetus from nine weeks after conception until birth.

Birth Canal

The passage through the pelvic bones that the baby passes through to be born. It is made up of the uterus, cervix and vagina which form a continuous tube through the pelvis.

Cervix

A strong ring of muscle at the lower part of the uterus, that opens into the vagina.

Function of the Cervix

• It helps protect the uterus from bacteria and infections by acting as a barrier.

• It is also responsible for producing mucus that changes during the menstrual cycle, to either help or prevent sperm from entering the uterus.

• During childbirth, the cervix expands about 4 inches, so that the body can travel from the uterus, through the vagina and into the world.

Vagina

A tube that connects the uterus to the outside of the body-(vaginal opening).

Features of a Vagina

• Folds of skin called the labia, meet at the entrance of the vagina from the vulva.

• Urine passes through the urethra, which opens into the vulva but this is seperate from the vagina.

Functions of a Vagina

• During sexual intercourse it allows an entrance point for the penis, so that the sperm can be released as close to the uterus as possible.

• During birth, it expands and lengthens with the uterus to form the birth canal.

• It contains strong, powerful muscles, to help the baby to be pushed to the outside.

Menstrual Cycle

The monthly cycle in which the uterine changes, to prepare for possible pregnancy via hormones and physiology

Characteristics of the menstrual cycle

• Girls begin their periods around the age of 12 and continue till menopause around the age of 50

• They cycle lasts around 28 days

The Menstrual Cycle: Key Phases

1. Menstrual Phase: Days 1-5

2. Follicular Phase: Days 1-13

3. Ovulation: Day 14

4. Luteal Phase: Days 15-28

The Menstrual Cycle Phases in detail

1. Menstrual Phase (Day 1-5)
   — Shedding of the uterine lining
   — Causes menstrual bleeding (3-5 days typically)
   — This phase is triggered by a drop in oestrogen and progesterone
   
   

2. Follicular Phase (Day 1-13)
   — Overlaps with the menstrual phase
   — The pituitary gland produces FSH, which stimulates ovarian follicles
   — As the follicles mature, they start the secretion of oestrogen
   — One follicle matures into a dominant follicle
   — Oestrogen levels begin to rise, causing endometrium to start rebuilding
   
   

3. Ovulation (Day 14)
   — The dominant follicle ruptures to release the mature egg from ovary
   — Triggered by a surge in LH, produced by the pituitary gland
   — Egg survives - 24 hours for fertilisation
   — Most fertile period of the cycle
   
   

4. Luteal Phase (Day 15-28)
   — Ruptured follicle forms corpus luteum
   — Which starts the secretion of progesterone that maintains the uterine lining
   — If fertilisation does not occur, corpus luteum degenerates and is reabsorbed
   — This stops the production of progesterone
   — This sudden decline of progesterone starts the process of menstruation

What would happen in the Menstrual Cycle Phase, if fertilisation was to occur

• Ovulation (Day 14)
  — The dominant follicle ruptures to release the mature egg from ovary
  — Triggered by a surge in LH, produced by the pituitary gland
  — Once the egg is released, the fimbria use their finger like structures to waft the egg from the ovary into the fallopian tube, also known as the oviduct.
  — The egg starts its journey down the fallopian tube
  — Egg survives - 24 hours for fertilisation
  — If sperm is present in the fallopian tube, the egg is fertilised to form a zygote
  — This cell then begins multiplying as they travel towards the uterus
  — Most fertile period of the cycle

• Luteal Phase (Day 15-28)
  — Ruptured follicle forms corpus luteum
  — Which starts the secretion of progesterone that maintains the uterine lining
  — The progesterone starts the nourishment of the thickening endometrium, making it ready for the embedding of an embryo
  
  

• If the egg is fertilised and cells multiply
  — The egg embeds into the lining of the womb and the developing placenta produces another hormone (hCG) that stops menstruation
  — It is this hormone that is detected in pregnancy

Corpus Luteum

• It is yellow in colour

• The ruptured follicle or ‘egg shell’, from which the egg was released

• Starts the production of progesterone during the menstrual cycle

Hormone

A chemical messenger produced by glands that regulates processes in the body, including reproduction.

The Key Hormones involved in the Menstrual Cycle

FSH, Oestrogen, LH, Progesterone

FSH

• Follicle-Stimulating Hormone

• Stimulates follicle growth in the ovary

Oestrogen

Rebuilds and thickens the uterine lining

LH

• Luteinising Hormone

• The sudden surge triggers ovulation; the release of a mature egg

Progesterone

• Secreted by the corpus luteum

• Maintains the uterine lining

• Inhibits the release of FSH and LH to prevent any new follicles from maturing while the body waits to see if fertilisation was successful

Menopause

Marks the end of monthly menstruation and is officially confirmed after 12 months without a period.

Features of Menopause

• It occurs due to a reduction in oestrogen and progesterone, causing ovulation to stop.

• As a result of ovulation stopping, fertility ceases.

• It typically occurs between the ages of 45 and 55.