3. Endocrine System Overview Glands: Major organs of the endocrine system Glands make hormones – Hormones: chemical signals Hormones move through bloodstream Hormone binds to cell receptor Target cells produce proteins target cell hormone receptor not a target cell bloodstream

4. There are steroid hormones and nonsteroid hormones. –Steroid hormones enter the cell. –Nonsteroid hormones do not enter the cell. Steroid hormone diffuses through the cell membrane Steroid hormone binds to a receptor within the cell. The hormone and receptor enter the nucleus and bind to DNA Steroid hormone causes DNA to make proteins. Nonsteroid hormone binds to receptor on the cell membrane. Receptor stimulates a second messenger with in the cell. Second messenger starts a series of chemical reactions in the cytoplasm. Second messenger reactions activate enzymes. Steroid hormone receptor nucleus DNA proteins Non-steroid hormone receptor second messenger Chemical reactions activated enzymes

5. HYPOTHALAMUS PITUITARYTHYROID THYMUS ADRENAL GLANDS PANCREAS FEMALE GONADS :OVARIES MALE GONADS : TESTES Major Glands All the below create hormones Hypothalamus – Stimulates the pituitary gland to release hormones – Controls growth, reproduction, body temp Pituitary gland – Controls cell growth and [H2O] in blood – Stimulates other glands Thyroid gland – Regulates metabolism, growth, development Thymus – Allows WBCs to mature to fight infection Adrenal Glands – Controls “fight or flight” response – Increases breathing, alertness, blood pressure – Epinephrine Pancreas – Controls glucose level in blood – Insulin, glucagon Gonads: influence sexual development – Testes (males): testosterone – Ovaries: Estrogen, progesterone

6. Releasing hormones stimulate other glands to produce hormones. –allow glands to communicate with one another –are used in temperature regulation

7. Hormonal imbalances can cause severe illness. Abnormal hormone levels affect homeostasis. Hormonal imbalances might be treated with surgery or medicine. Steroids, a pituitary tumor, or some prescription drugs can make the pituitary overactive and indirectly cause problems.

8. hypothalamus Pituitary gland Thyroid thymus Adrenal glands pancreas ovaries testes