6.2.2 Glands and Hormones

• Endocrine glands synthesise substances such as hormones and release them into the bloodstream
• Hormones are chemical substances that circulate in the bloodstream and only affect target organs
  • They are produced in large quantities and can be very powerful
  • They control ongoing internal functions and enable our bodies to react according to changes in the environment

Pituitary Gland 

• The pituitary gland is often referred to as the ‘master gland’ because it controls the production and release of other hormones from other glands in the endocrine system
  • It is controlled by the hypothalamus 
• The anterior lobe releases an adrenocortical trophic hormone (ACTH), which stimulates the adrenal cortex and the release of cortisol 
• The posterior lobe released oxytocin, which is responsible for uterus contractions during childbirth.
  • Oxytocin helps regulate our emotional responses and pro-social behaviours, including trust, empathy, and the processing of bonding cues

Pineal Gland

• This releases melatonin which is responsible for important biological rhythms, including the sleep-wake cycle
• It receives information from the environment about the light-dark cycle which influences the production and secretion of melatonin

Thyroid Gland

• This plays a role in controlling heart, muscle and digestive function, brain development and bone maintenance
• It releases thyroxine, which is responsible for regulating our metabolism through other organs like the liver and kidneys
• Our metabolism is involved in chemical processes of converting food into energy

Pancreas Gland

• This plays a signficant role in digestion by producing enzymes to break down food and hormones to help regulate blood-sugar levels and appetite
• The main hormone it produces is insulin
• Insulin helps your body break down carbohydrates to produce glucose, which we use for energy
• Without insulin, we cannot break down glucose properly, which can cause blood-sugar levels to rise and increase the risk of diabetes

Andrenal Gland

• The adrenal gland is divided into two parts, the adrenal medulla and adrenal cortex
• The adrenal medulla releases adrenaline and noradrenalin which play a key role in ‘fight or flight’ repsonse
• The adrenal cortex releases cortisol which stimulates the release of glucose while suppressing the immune system

Testes

• The testes release androgens, which include the main hormone testosterone
• Testosterone is responsible for the development of male sex characteristics during puberty, including muscle growth, fat distribution and sperm production

Ovaries

• The ovaries release oestrogen which controls the regulation of the female reproductive system, including the menstrual cycle and pregnancy