1. The Human Endocrine System

2. Action of Steroid Hormones
Hormone diffuses through cell membrane of target cell
Hormone combines with receptor molecule
They move into the nucleus and attach to DNA
DNA activates a gene to produce a specific protein

3. Action of Steroid Hormones One Messenger system

4. Action of Protein Hormones
Hormone attaches to receptor on cell membrane of target cell
This causes cyclic AMP to be formed which acts as a messenger within the cell
Cyclic AMP activates enzymes in the cytoplasm which creates the desired hormonal effect

5. Action of Protein Hormones Two Messenger System

6. Negative Feedback
Is a type of control system that regulates hormone production
Works similar to a thermostat on your furnace
When the desired change is detected, the original action is inhibited

7. Negative Feedback

8. Endocrine Glands: Pituitary
Is often referred to as “master gland” because it controls the secretions of most of the other glands
Is located in the brain directly below the hypothalamus
Is composed of two lobes - the posterior lobe and the anterior lobe

9. hypothalamus
pituitary gland

10. Endocrine Glands: Thyroid
Is located in the neck just below the larynx and in front of the trachea.
Parathyroid glands consist of 4 tiny ovals embedded in the back of the thyroid gland. They regulate calcium and phosphate metabolism.

11. hypothalamus
pituitary gland
parathyroid
thyroid
thymus

12. Endocrine Glands: Adrenal
There is one adrenal gland sitting on top of each kidney.
Each adrenal gland is composed of an outer layer called the cortex and an inner layer called the medulla

13. hypothalamus
pituitary gland
parathyroid
thyroid
thymus
adrenal gland

14. Endocrine Glands: Pancreas
The pancreas has small clusters of hormone-secreting cells called islets of Langerhans
The hormones of the pancreas mainly control glucose levels in the body:
Beta cells produce insulin which causes body cells to take up glucose from the blood.
Alpha cells produce glucagon which causes the liver to store excess blood glucose as glycogen.

15. hypothalamus
pituitary gland
parathyroid
thyroid
thymus
adrenal gland
pancreas

16. Endocrine Glands: Gonads
Ovaries
Produce egg cells and release female sex hormones
Testes
Produce sperm cells and release male sex hormones

17. hypothalamus
pituitary gland
parathyroid
thyroid
thymus
adrenal gland
pancreas
ovaries
testes