Summary Introduction to the Endocrine system

Introduction to the Endocrine system
- Works with nervous system to maintain homeostasis
- Endocrine glands secrete hormones into body fluids
- Hormones diffuse into blood steam to act on specific target cells
- Exocrine glands – secrete products into ducts, outside the internal environment
- Endocrine glands – secrete hormones into blood body fluids to affect target cells
o Pituitary gland
o Thyroid gland
o Parathyroid glands
o Adrenal glands
o Pancreas
o Pineal gland
o Reproductive glands
o Kidneys
o Thymus gland
o Other glands – liver, heart etc.

A comparison between Nervous and Endocrine systems




Hormones action
Steroids
- Derived from cholesterol
- Lipid soluble -> Can pass though cell membrane easily
- Carried in the bloodstream
- Receptors are located inside the target cells
- Binds with DNA and activates specific genes
- E.g. Sex hormones

Non-steroids
- Amines, peptides, protein or glycoproteins -> produced from amino acid
- Combine with receptors in target cell membrane, receptors have a binding site and an
active site