Hormones

Reproductive Hormones

The main male reproductive hormone is testosterone.

• Produced by the testes
• Stimulates sperm production

The main female reproductive hormone is oestrogen.

• Produced in the ovary
• Produces physical changes and is involved in the menstrual cycle

It begins with the lining of the uterus breaking down, and the woman has her period. The layer then builds up again, until ovulation (day 14) occurs- an egg is released from the ovary and moves to the uterus via the fallopian tube.

If a fertilised egg has not been embedded in the lining after 28 days, it begins to break down and the cycle continues.

The events of the cycle are controlled by four hormones.

1. Follicle stimulating hormone (FSH) causes the maturation of an egg in the ovary, within a structure called a follicle

• Produced in the pituitary gland
• Stimulates the ovaries to produce oestrogen

2. Oestrogen causes the lining of the uterus to grow again

• Produced in the ovaries
• Secreted as a result of FSH
• Stimulates the production of LH and inhibits the secretion of more FSH

3. Luteinising hormone (LH)

• Produced in the pituitary gland
• Produced as a result of the hormone oestrogen
• Its release results in ovulation

4. Progesterone

• Produced in the ovaries and secreted from the egg follicle.
• Maintains the lining of the uterus, and supports a pregnancy if the egg is fertilised
• Inhibits the release of both FSH and LH

Pituitary Gland:

Location: The base of the brain.

Hormones Produced:

Growth hormone: Stimulates growth and development.

ADH (antidiuretic hormone): Controls water balance in the body by affecting the kidneys.

TSH (thyroid-stimulating hormone): Stimulates the thyroid gland to produce thyroid hormones.

Target Organs: Kidneys, bones, muscles, and the thyroid gland.

Function: Known as the "master gland" because it controls many other glands in the endocrine system.

Thyroid Gland:

Location: In the neck, around the trachea.

Hormones Produced:

• Thyroxine: Regulates metabolism, heart rate, and temperature.

Target Organs: Most body cells.

Function: Controls the body's metabolism, growth, and energy usage.

Pancreas:

Location: Behind the stomach.

Hormones Produced:

• Insulin: Lowers blood glucose levels by allowing cells to take in glucose.
• Glucagon: Raises blood glucose levels by causing the liver to release stored glucose.

Target Organs: Liver, muscles, and fat cells.

Function: Regulates blood sugar levels, which is critical for maintaining energy balance in the body.

Adrenal Glands:

Location: On top of the kidneys.

Hormones Produced:

• Adrenaline: Prepares the body for "fight or flight" by increasing heart rate and boosting energy.
• Cortisol: Helps the body manage stress and control blood sugar levels.

Target Organs: Heart, blood vessels, liver, and muscles.

Function: Adrenaline prepares the body for emergency responses, while cortisol helps with long-term stress management.

Ovaries (in females):

Location: In the lower abdomen.

Hormones Produced:

• Oestrogen: Regulates the menstrual cycle and promotes the development of female secondary sexual characteristics.
• Progesterone: Prepares the uterus for pregnancy.

Target Organs: Uterus, breasts, and other reproductive organs.

Function: Controls the female reproductive system and plays a crucial role in pregnancy.

Testes (in males):

Location: In the scrotum.

Hormones Produced:

• Testosterone: Controls the development of male secondary sexual characteristics and sperm production.

Target Organs: Muscles, skin, bones, and reproductive organs.

Function: Regulates male reproductive functions and promotes muscle and bone growth.