Endocrine system

• Components of the endocrine system

  • Hypothalamus
  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenals
  • Ovaries
  • Testes
  • Pancreas
• Hypothalamus

  Located in the brain, responsible for control of body temperature, water balance (osmoregulation) and secretion of hormones via the pituitary gland
• Hypothalamus

  Responsible for control of most of the homeostatic mechanisms that regulate the internal environment of the body - either directly e.g ADH or by controlling other endocrine glands via releasing hormones
• Pituitary

  Located in the brain and divided into anterior and posterior lobes, the anterior lobe produces its hormones but the hypothalamus produces releasing factors that stimulate it to secrete these hormones e.g Growth hormone, Thyroid stimulating hormone (TSH), the posterior lobe stores hormones produced in the hypothalamus which are oxytocin and ADH
• Thyroid

  Located in the anterior part of the neck, responsible for regulation of metabolic rate
• Metabolism

  Describes all the chemical reactions that take place in the body
• Metabolic rate

  The rate at which energy stored in food is transferred by all metabolic reactions that take place in the body
• Parathyroid

  The parathyroids work together with the thyroid to regulate the levels of calcium in the body, PTH (Parathyroid hormone) is secreted by the parathyroid and increases the concentration of calcium ions in the blood while calcitonin secreted by the thyroid lowers the concentration of calcium ions in the blood
• Adrenals

  Located on top of the kidneys, the Adrenal Medulla produces the hormone adrenaline that prepares the body to respond to threat or danger - known as 'the fight or flight' response, the Adrenal cortex produces several steroid hormones involved with the regulation of different aspects of metabolism such as carbohydrate and mineral ions
• Ovaries

  Located in the pelvic region, produce the hormones oestrogen and progesterone, involved with release of egg cells, regulation of menstrual cycle and maintenance of pregnancy (progesterone)
• Testes

  The testes are two small organs found in the scrotum and have dual function: Production of sperm cells and Secretion of male sex hormones e.g testosterone
• Pancreas

  The pancreas has endocrine and exocrine (release substances through ducts e.g digestive juices) functions, produce the hormones insulin and glucagon respectively, these are the hormones responsible for the regulation of the blood glucose level
• Gland

  • Thyroid
  • Adrenal
  • Ovaries
  • Testes
  • Stomach
  • Pituitary
• Hormone

  • Thyroxine
  • Glucocorticoids (Cortisol)
  • Oestrogens
  • Testosterone
  • Gastin
  • Growth hormone
  • Follicle Stimulating Hormone (FSH)
  • Insulin
  • Glucagon
• Thyroxine

  Helps to regulate cell metabolism and the body's energy levels
• Glucocorticoids (Cortisol)


  Secreted in response to stress, help with the production of glucose
• Oestrogens


  Responsible for the development of female secondary sex characteristic such as uterine and breast development
• Testosterone

  Responsible for growth and increase of bones and muscles strength
• Gastin

  Acts on the stomach to support mucosal growth, gastric motility and hydrochloric acid (HCl)secretion
• Growth hormone

  Affects many target cells throughout the body by stimulating their growth, repair, and reproduction
• Follicle Stimulating Hormone (FSH)

  Stimulates the follicle cells of the gonads to produce gametes—ova in females and sperm in males
• Mechanism of blood glucose level control

  1. The pancreas is an endocrine gland that secretes insulin which is a hormone that aids in the absorption of glucose

  2. Glucose receptors are found in different tissues e.g the skeletal muscle, are sensitive to insulin thereby aid in the entrance of glucose into and available for the muscle cell

  3. Disruption in this endocrine signalling due to lack of production of insulin or lack of sensitivity of the receptors, result to accumulation of glucose outside of the cells, inability of cells to receive the glucose which will be converted to energy and resulting to symptoms of diabetes mellitus
• Functions of the endocrine system:

  • Regulation of growth and development.
  • Regulation of the reproductive system.
  • Homeostasis - regulation of the internal environment of the body.
• There are 2 types of hormones according to their chemical structure:

  1. Steroid derived hormones

                       -  Sex hormones which regulate the reproductive system e.g oestrogen, progesterone, testosterone.

             - Corticosteroid hormones that regulate carbohydrate metabolism

                and mineral ions. E.g Cortisol and aldosterone.

  1. Amino-acid derived hormones

  • Other hormones e.g Growth hormone.