Sex hormones in humans Revision Notes

Testosterone is the main male sex hormone produced primarily by the testes.

It causes physical changes such as growth of facial and body hair, deepening of the voice, and increased muscle mass.

Testosterone acts on target tissues to develop and maintain these male characteristics during puberty.

• Produced mainly by testes.
• Causes facial/body hair growth.
• Deepens voice and increases muscle mass.

Oestrogen is the main female sex hormone produced mainly by the ovaries.

It promotes breast development, widening of hips, and the start and regulation of menstrual cycles.

Oestrogen acts on specific tissues to bring about these female physical changes during puberty.

• Produced mainly by ovaries.
• Causes breast development and hip widening.
• Regulates menstrual cycle.

During puberty, levels of testosterone and oestrogen increase significantly.

These hormones coordinate the development of secondary sexual characteristics by acting on various organs and tissues.

They ensure the physical features typical of adult males and females develop properly and are maintained.

• Hormone levels rise during puberty.
• Hormones act on target tissues.
• Control development and maintenance of traits.

The ovaries undergo several changes during the menstrual cycle, including follicle development, ovulation, and corpus luteum formation.

• Follicles develop and mature in the ovaries.
• Ovulation occurs when a mature egg is released.
• The corpus luteum forms from the empty follicle post-ovulation.

The uterine lining, or endometrium, thickens and sheds in response to hormonal changes during the menstrual cycle.

• The lining thickens to prepare for a fertilized egg.
• If no fertilization occurs, the lining is shed during menstruation.

The menstrual cycle typically lasts about 28 days, influenced by hormones such as oestrogen and progesterone.

• Oestrogen promotes thickening of the uterine lining.
• Progesterone maintains the lining post-ovulation.

Oestrogen is primarily produced by the developing follicles in the ovaries before ovulation.

• Stimulates thickening of the uterine lining.
• Prepares the body for potential pregnancy.

After ovulation, progesterone is produced by the corpus luteum in the ovary.

• Maintains the uterine lining post-ovulation.
• Supports early pregnancy if fertilization occurs.

During pregnancy, the placenta takes over the production of both oestrogen and progesterone.

• Maintains the uterine lining throughout pregnancy.
• Supports fetal development.

FSH and LH are key hormones released by the pituitary gland that regulate the menstrual cycle.

• FSH stimulates the growth of ovarian follicles.
• LH surge triggers ovulation, releasing an egg.

Oestrogen and progesterone are crucial for preparing and maintaining the uterine lining.

• Oestrogen thickens the uterine lining before ovulation.
• Progesterone maintains the lining after ovulation.

If fertilization occurs, progesterone levels remain high to support the developing embryo.

• Prevents the breakdown of the uterine lining.
• Ensures a suitable environment for embryo development.