The endocrine system communicates through hormones secreted by various glands to control body functions. The major glands include the hypothalamus and pituitary gland in the brain, the thyroid and parathyroid glands in the neck, the adrenal glands on the kidneys, the pineal gland in the brain, and cells in the pancreas and reproductive organs. Hormones regulate processes like metabolism, growth, mood, stress response, and calcium levels without connecting ducts by circulating in the bloodstream to target tissues.

1. The Endocrine System

2. Endocrine System
• System that “communicates” to control body
functions
• Uses chemicals called hormones
• Hormones come from glands
• Unlike digestive glands, these glands are ductless
*If they are ductless, how do they “communicate”
with the body?

3. Major Glands of the Endocrine System
• hypothalamus
• pituitary
• thyroid
• parathyroid glands
• adrenal glands
• pineal gland
• pancreas*
• reproductive organs (gonads)

4. Hypothalamus
• found in the brain, lower central part
• regulation of satiety, metabolism and body
temperature
• regulates the pituitary gland
– somatostatin: stops release of growth hormone

5. Pituitary Gland
• found below the
hypothalamus, pea-sized
• “most important gland of
the endocrine system”
• produces a vast number
hormones
• ex: growth hormone, TSH,
ACTH, LH, FSH, prolactin
• ex: vasopressin, oxytocin

6. Thyroid Gland
• found in the lower front
part of the neck
• regulates body
metabolism
• maintains normal blood
pressure, heart rate,
digestion

7. Parathyroid glands
• pair of glands adjacent
to the thyroid gland
• regulates calcium in
bone and blood

8. Adrenal glands
• found on top of your kidneys
• adrenal cortex and adrenal medulla
• outer: corticosteroids – regulate metabolism,
salt and water balance
• inner: catecholamines – deals with physical
and emotional stress (ex: adrenaline)

9. Pineal body
• regulates circadian rhythm
• SAD (seasonal affective disorder)

10. Pancreas
• has both exocrine and endocrine function
• “communicates” with the liver by hormones
• islets of Langerhans
– insulin 
– glucagon 

11. Homework
• Pheromones
• Sex hormones
– androgens
– estrogens