The endocrine system notes

Endocrine or exocrine
Endocrine gland = secreted hormones directly into blood- no duct
Exocrine gland = secretes molecules into duct, exocrine cells are called acinar cells – found in clusters around pancreatic duct which goes to the duodenum.
Other examples of exocrine glands: salivary glands, lacrimal glands and mammary glands.
Hormones

Functions of adrenal glands
Found above kidneys- there are 2 of them
Each divided into medulla (inner region) and cortex region (outer region)

The regulation of blood glucose
The pancreas
Involved in both endocrine and exocrine functions.
How is blood glucose concentration regulated?
Secretion of enzymes
Manufacture and release of digestive enzymes – exocrine function
Cells are found in small groups surrounding tiny tubules into which they secrete the enzymes.
Tubules joint to make up pancreatic duct which carries enzymes into part of small intestine.
Enzymes: amylase – a carbohydrase and trypsinogen – an inactive protease.
Secretion of hormones: pancreas as an endocrine gland
Islets of Langerhans contain alpha and beta cells; they also have a good blood supply for transporting hormones. α-cells :make and secrete glucagon β-cells: make and secrete insulin

If blood glucose too high
1. high conc. of glucose in blood detected by beta cells
2. beta cells secrete insulin into the blood
3. insulin travels to all target cells and tissues
4. these target cells have specific receptors in the membrane where the insulin can bind
5. When insulin binds to a complementary receptor a hormone, receptor complex is formed.
6. This activates adenyl cyclise inside the cell which converts ATP into cAMP
7. cAMP activates enzyme controlled reactions
8. more glucose channels placed in cell surface membrane
9. more glucose enters the cells
10. glucose is converted into glycogen for storage ( glycogenesis)
11. more glucose is converted into fats
12. more glucose is used for respiration

If glucose drops too low
1. low conc. detected by alpha cells
2. they secrete glucagon
3. its target cells are hepatocytes which possess specific receptors for glucagon
4. as a result glycogenolysis occurs – glycogen is