ENDOCRINE SYSTEM

Hormones

• Chemical messengers• Enter directly into the bloodstream• Regulate and integrate body functions• Play role in body’s metabolism and

growth

Endocrine Glands

• Are ductless glands• Consists of cells that produce internal

secretions called hormones

How The Endocrine System Works

• Cells of endocrine glands secrete hormones into the extracellular fluid

• Hormones enter the capillaries through diffusion and secrete directly into the bloodstream (plasma part of the blood)

• Through blood circulation, these hormones can be distributed all over our body

The Endocrine Glands• Pituitary Gland• Pineal Gland• Thyroid Gland• Parathyroid Gland• Thymus• Adrenal Glands• Pancreas• Gonads

Pituitary Gland

• Small gland about the size of a corn at the base of the brain

• Connected to the hypothalamus by a stalk• Master gland• Secretes hormones like Growth Hormone

(GH) & Thyroid Stimulating Hormone (TSH)- GH Influences body size and growth- TSH influences the thyroid gland to release

its thyroxine.

Pineal Gland

• Pear-shaped structure at the back of the base of the brain

• Behind the junction of the spinal cord and brain tissue

• Smaller than a pea• SECRETES: MELATONIN

- influences the biological rhythm of an organism.

Thyroid Gland

• Large gland below the larynx at the base of the neck

• Regulation of metabolism related to growth

• Secretes: Thyroxine- It influences the rate of metabolism

and physical development.

Parathyroid Glands

• Four small glands at the back of the thyroid gland

• Secretes: Parathyroid Hormone (PTH)• Control and maintain plasma

concentration of calcium and phosphorus

Thymus

• Located above the heart and under the breast bone

• SECRETES: Thymosin that promotes maturation of the immune system

• Lymphocytes are also produced by this gland

• Vital in the defense against body diseases

Adrenal Glands

• Two glands located on top of each kidney• Two parts: adrenal cortex and medulla

– Adrenal cortex SECRETES cortin, responsible for the control of fat, carbohydrates, protein metabolism

– Medulla SECRETES epinephrine/adrenalin which are the glands of emergency. The adrenaline is released during emergency situations or when the body is stressed.

Pancreas

• Large gland located below and behind the stomach

• Consists of cells called ISLETS OF LANGERHANS that SECRETE Insulin and Glucagon– Insulin decreases blood sugar level– Glucagon increases blood sugar level

Gonads

• Sex glands (Ovaries and Testes)• Control development of secondary sex

characteristics that change from childhood to adulthood

• Ovaries (located at the pelvis)– Secrete Estrogen and Progesterone

• Testes (below the pelvis)– Secrete Testosterone