Physiology and Anatomy 1

The endocrine system includes gland which secrete hormones into the blood stream. It regulated the metabolism and development of most body cells and body systems through feedback mechanisms

Hormones are chemical messenger molecules that are made by cells in one part of the body and causes changes in cells in another part of the body. 

Hormones are released by glands or specialized cells into the blood circulation

1. Endocrine: Hormones are released into the blood and bind to distant target cells
2. Paracrine: Hormones act locally by diffusion from its source to target cells in the neighborhood
3. Autocrine: Cells secrete a hormone that binds to autocrine receptors on that same cell leading to changes in the cell 

They are synthesized in the rough ER of the endocrine system as large proteins and then form smaller pro-hormones in the ER. Enzymes then cleave the pro-hormones to smaller, activ hormones and inactiv fragments. The vesicles are stored within the cytoplasma. The hormones are released when the secretory vesicles fuse with the cell membrane

Oxytocin, Insulin, Glucagon

• Coding of several hormones by one gene 
• Depending on the posttranlational precessing, different hormones may be produced from the same precursor in different tissues

• Proteins with carbohydrate chains
• Major effect of the carbohydrate connection is that it increases the biological half life considerably 
• Glycoprotein have a half life of hours instead of minutes

Glucocorticoids, Mineralcorticoids, Sex steroids