1. The Endocrine System

2. Characteristics of Hormones
Chemical nature
Made of either proteins or steroids
Protein hormones cannot be delivered orally

3. Mechanism of hormone action
Cells that respond to specific hormones have receptor sites (target tissue)
Works like lock and key model
Receptors either on the surface (protein) or interior (steroid) of cell

4. Control of hormone action
Negative feedback mechanisms
Tropic hormones
Nervous stimulation

5. Endocrine Glands

6. Pituitary Gland Also called the hypophysis Consists of two regions:
Adenohypophysis
neurohypophysis

8. Hormones of the Adenohypophysis
Growth hormone (GH)
Thyroid-Stimulating Hormone (TSH)
Adenocorticotropic Hormone (ACTH)
Gonadotropic Hormone (LH, ICSH, & FSH)
Prolactin (PRL)

9. Hormones of the Neurohypophysis
Antidiuretic Hormone (ADH)
Oxytocin

10. Thyroid Gland
Thyroxine
Triiodothyronine
Calcitonin

11. Parathyroid Gland
Parathyroid Hormone (PTH)

12. Pancreas Both endocrine and exocrine
Islets of Langerhans – alpha and beta cells
Glucagon
Insulin

13. Adrenal Glands Located on top of kidneys
Composed of a cortex and medulla
Hormones of the cortex:
Mineralcorticoids (aldosterone)
Glucocorticoids (cortisol)
Gonadocorticoids (androgens and estrogens)
Hormones of the medulla:
Epinephrine
Norepinephrine

14. Gonads - Male Testes Produce group of hormones called androgens
Testosterone

15. Gonads - Female
Ovaries
Estrogens
Progesterone

16. Pineal Gland
Melatonin

17. Other Endocrine Glands
Thymus
Gastric mucosa
Small intestine mucosa
Atria of heart
Placenta