18. ENDOCRINE GLANDS AND EXOCRINE GLANDS

18. ENDOCRINE GLANDS AND EXOCRINE GLANDS

• the body contains two kinds of glands: 

1. exocrine glands and 
2. endocrine glands. 

Exocrine glands (exo- outside) 

• secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ, or to the outer surface of the body. 
• Exocrine glands include 

1. sudoriferous (sweat), 
2. sebaceous (oil), 
3. mucous, and 
4. digestive glands.

Endocrine glands (endo- within) 

• secrete their products (hormones) into the interstitial fluid surrounding the secretory cells rather than into ducts. 
• From the interstitial fluid, hormones diffuse into blood capillaries and blood carries them to target cells throughout the body. 
• Because most hormones are required in very small amounts, circulating levels typically are low.

The endocrine glands include 

1. the pituitary,
2.  thyroid, 
3. parathyroid,
4. adrenal, and 
5. pineal glands 

•  In addition, several organs and tissues are not exclusively classified as endocrine glands but contain cells that secrete hormones. 
• These include the

1.  hypothalamus, 
2. thymus, 
3. pancreas, 
4. ovaries, 
5. testes,
6. kidneys, 
7. stomach, 
8. liver, 
9. small intestine, 
10. skin, 
11. heart, 
12. adipose tissue, and 
13. placenta. 

• Taken together, all endocrine glands and hormone-secreting cells constitute the endocrine system. 
• The science of the structure and function of the endocrine glands-and the diagnosis and treatment of disorders of the endocrine system is endocrinology ( endo- within; -crino to secrete; -logy study of).