1. 8.1 Importance of the Endocrine System

2. Hormones
Hormones are chemical regulators produced by cells that affect cells in another part of the body.
Endocrine hormones are produced in glands and are secreted directly into the blood.
Involved in the regulation of development, growth and homeostasis.

3. Hormones Growth Hormone (GH) or Somatotropin (STH) Insulin
Regulates development of long bones.
Produced by pituitary gland.
Insulin
Regulates blood sugar by increasing permeability of cells to glucose.
Produced by beta cells of the islets of Langerhans in the pancreas.
Epinephrine (Adrenaline)
Produced during stress (“fight-or-flight response”).
Produced in the adrenal medulla.

4. Chemical Control Systems
Integration of nervous system and endocrine system to control organs and tissues.
Failure of one system results in compensation from the other.
Nervous system allows body to adjust quickly to changes in the environment.
Endocrine system allows control over a longer duration.

5. Chemical Control Systems
Hypothalamus regulates pituitary gland through nerve signals.
Endocrine glands, stimulated by the pituitary gland, secrete hormones that affect the nerve activity of the hypothalamus.

7. Chemical Signals: Steroid and Protein Hormones
Steroid Hormones
Made from cholesterol
Soluble in fat.
Includes sex hormones and cortisol.
Protein Hormones
Made from chains of amino acids.
Soluble in water.
Includes insulin and growth hormones.

8. Steroid Hormones

9. Protein Hormones

10. The Pituitary Gland

11. The Pituitary Gland Often referred to as the “master gland”.
Pituitary gland produces and stores hormones.
Hypothalamus stimulates release of hormones from pituitary gland.

12. The Pituitary Gland Consists of posterior and anterior lobe.
Posterior lobe stores and releases hormones produced by the hypothalamus.
Anterior lobe produces its own hormones and their release is regulated by the hypothalamus.

13. The Pituitary Gland Regulation of Hormone-Secretion
Hypothalamic hormones secreted from nerve ends travel through blood to the anterior pituitary.
Activates specific cells in the anterior pituitary, causing the release of pituitary hormones.

14. The Pituitary Gland Regulation of Hormone-Secretion
Two hypothalamic releasing factors inhibit secretion anterior pituitary hormones.
Dopamine inhibits secretion of prolactin (PRL).
Somatostatin inhibits secretion of somatotropin.

15. The Pituitary Gland
Certain regulator hormones stored in anterior pituitary.
Reproductive-stimulating hormones, growth-stimulating hormones, prolactin and ACTH.
Thyroid-stimulating hormone (TSH).
Stimulates thyroid to produce thyroxin.