Endocrine System

The endocrine system is comprised of glands that secrete hormones. These hormones affect every part of your body.

The main glands of the endocrine system are:

1. Pineal Gland
2. Adrenal Glands
3. Thyroid
4. Pituitary Gland
5. Thymus
6. Parathyroid

Other hormone producers include the: gonads, pancreas, hypothalamus, kidney, liver, stomach, intestine, and heart.

Hormones!

• Hormone- a chemical substance that is secreted  by cells in the endocrine system, that influences the activity of other cells.

Hormones are not secreted via ducts.  Instead, they are secreted directly into the interstitial fluid, and then diffuse into the bloodstream. Because of this dispersion method, hormones have a lag response, but the response it prolonged.

Some of the things that hormones affect are:

             Plasma membrane permeability,  protein synthesis, activation/deactivation of enzymes, secretory activities, and stimulation of mitosis.

Hormones are SPECIFIC! Each hormone binds to a specific receptor site on a specific target cell.

Control of Hormone Release: Hormone production happens in response to three (3) types of stimuli.

1. Humoral- Response to ion/nutrient levels in the blood. (i.e. Calcium homeostasis)
2. Neural- Response to a nervous system stimulus.
3. Hormonal- Hormones responding to the presence or absence of other hormones.

So we know what glands/organs/brain parts secrete hormones, but what gets rid of them?

• Degrading enzymes, kidneys, and the liver.