THE ENDOCRINE SYSTEM

Endocrine System Communication system that uses chemicals called hormones to send messages through the body. Works with the nervous system

Hormones Substance secreted into blood stream by a gland Acts on a target organ elsewhere in the body Alter cellular activity, so have ability to alter metabolic rate Classified as Steroids Proteins Brain controls secretion of endocrine glands which regulates function of internal organs

Endocrine Glands Secrete directly into the bloodstream Do not have ducts Hypothalamus Part of nervous system Regulates the pituitary gland Produces releasing and inhibiting hormones

Endocrine Glands 2. Pituitary Gland Located at base of brain Divided into 2 lobes Called the master gland

Endocrine Glands 3. Pineal Gland Located in centre of brain Secretes melatonin Sleep/awake hormone

Endocrine Glands 4. Thyroid Gland Just below larynx Has two lobes Secretes thyroxine and calcitonin

Endocrine Glands 5.Parathyroid Glands Four tiny glands in posterior wall of thyroid Secretes parathyroid hormone ( PTH )

Endocrine Glands 6.Thymus Upper thorax behind sternum Protects the body from infection Produces thymosin

Endocrine Glands 7. Pancreas Is both endocrine and exocrine gland Mainly a digestive gland Secretes insulin and glucagon from groups of cells called Islets of langerhans

Endocrine Glands 8. Adrenal Gland Attached to upper part of kidneys Secretes aldosterone which is involved in control of blood pressure Secretes cortisol enabling body to cope with stress Secretes DHEA which stimulates male secondary sexual characteristics Secretes adrenaline at times of emotional or physical stress

Endocrine Glands

Endocrine Glands 9. Gonads The sex glands Ovaries in female Testes in male Hormones excreted are progesterone, oestrogen and testosterone These hormones maintain the reproductive system and develop sexual characteristics

Endocrine Glands

Exocrine Glands Secrete their products into ducts which open onto a surface Examples are Sweat glands Salivary glands

Diabetes Mellitus Most common endocrine disease Caused by disturbance of hormonal control and level of glucose in blood Type 1 starts in childhood but can occur when older Autoimmune disease Person’s immune system destroys insulin produced by pancreas High level of glucose, ( hyperglycaemia ), causes person to have polyuria and thirst ( polydipsia ) Treated with insulin

Diabetes Mellitus Type 2 Usually appears at later age Often associated with obesity, can run in families Problem is lack of insulin Can be treated often with weight reduction and dietary changes Some people require medication