The endocrine system is made up of a number of glands that secrete hormones (chemical messengers) directly into the bloodstream. Each hormone has a particular cell that it targets. #

Glands include the pancreas, pituitary gland and kidney.

The pancreas regulates blood sugar levels

The pituitary gland links the nervous system to the endocrine system. Produces many hormones that control different functions in the body

The Kidneyfilters waste products from the blood and reabsorbs useful substances

The pituitary

Secretes hormones into the blood to regulate many chemical reactions in the body.

It is a pea sized structure located at the base of the brain, just below the hypothalamus to which it is attached via nerve fibers.

It is split into 2 halves called lobes, each producing its own hormones

Anterior lobe

• growth hormone

• thyroid- stimulating hormone - metabolism

• adrenal - stimulating hormone - cortisone

• FSH - follicle stimulating hormone - ovaries and testes

• LH - luteinising hormone - stimulates the lining of the uterus/ stimulates testosterone

• prolactin - stimulate milk production after giving birth

Posterior lobe

• Oxytocin - stimulates uterus to contract during childbirth and milk production

• ADH - Antidiuretic hormone - increase absorption of water into the blood by the kidneys

The pancreas

It is an organ located in the abdomen. It plays an essential role in converting the food we eat into fuel for the body’s cells.

Functions of the pancreas

-Exocrine function = helps in digestion (making enzymes for the small intestine)

-Endocrine function = regulates blood sugar (makes hormones)

The pancreas produces 2 hormones insulin and glucagon

Insulin

-made in islet of Langerhans

-insulin - we take glucose into cells for energy

-stimulates liver to convert glucose into glycogen - stored in the liver

-made by beta cells

Glucagon

-made in islet of Langerhans

-stimulates the liver when glucose levels in the blood are low

-the glucose has gone so glucagon is released

-glycogen converted back into glucose

-made by alpha cells

Insulin turns glucose into glycogen (glycogenesis)

Glucagon breaks down glycogen to glucose (glycogenolysis)

The pancreas regulates blood glucose levels by a negative feedback mechanism

Blood Glucose

Glucose is essential for respiration, therefore it is important that the amount of glucose in the blood is kept at a fairly constant level.

Normal blood glucose concentration is around 90mg per 100cm^3, which is between 4 and 6 mmol/dm^3

Any deviation away from the normal range is detected by the alpha and beta cells in the islets of Langerhans. These cells release hormones, triggering an appropriate response (negative feedback)