Islets of langerhans

It contains good idea of islets of langerhans in general .

1. PANCREAS (ISLETS OF LANGERHANS )

2. Pancreas : The pancreas is an organ of the digestive system and heterocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland.It is located in the C-shaped structure of duodenum from L1 to L3 vertebrae.

3. Origin : As part of embryonic development, the pancreas forms as two buds from the foregut, an embryonic tube that is a precursor to the gastrointestinal tract. It is therefore of endodermal origin. It is formed from dorsal and ventral pancreatic buds .

4. PANCREAS (HETEROCRINE GLAND) Acinar Cells Islet of langerhans -Exocrine part -Endocrine part (Hormones) -Produces enzymes for d igestion. α -cells β -cells 𝛿 -cells (Glucagon) (Insulin (Somatostatin) and amylin)

5. There are about 3 million islets distributed in the form of density routes throughout the pancreas of a healthy adult human, each of which measures an average of about 0.1 mm (109 µm) in diameter. Each is separated from the surrounding pancreatic tissue by a thin fibrous connective tissue capsule which is continuous with the fibrous connective tissue . It consists of following types of cells: Alpha cells producing glucagon (20% of total islet cells) Beta cells producing insulin and amylin (≈70%) Delta cells producing somatostatin (<10 %) PP cells (gamma cells or F cells) producing pancreatic polypeptide (<5%)

6. It consists of following types of cells : -Alpha cells producing glucagon (20% of total islet cells ) -Beta cells producing insulin and amylin (≈70 %) -Delta cells producing somatostatin (<10 %) -PP cells (gamma cells or F cells) producing pancreatic polypeptid e (<5%)

7. Insulin -Discovered by Banting and Best. -The insulin mRNA is translated as a single precursor called preproinsulin , and removal of its signal peptide during insertion into the endoplasmic reticulum generates proinsuline which is further converted to insulin and diffuses into blood when needed . -It is secreted when there is high blood glucose level.

8. ACTIONS OF INSULIN - Stimulates the uptake of glucose. - Increased fat synthesis – insulin forces fat cells to take in blood glucose, which is converted into triglycerides . -Decreased lipolysis . -Induce glycogen synthesis – When glucose levels are high, insulin induces the formation of glycogen (Glycogenesis) by the activation of the hexokinase enzyme, which adds a phosphate group in glucose, thus resulting in a molecule that cannot exit the cell.

9. - Decreased gluconeogenesis and glycogenolysis . -Decreased proteolysis .

10. GLUCAGON - It is antagonistic hormone of insulin i.e. its action is opposite of insulin. -It is derived from the precursor proglucagon which is at first derived as preproglucagon from ribosomes. -It is secreted when there is low blood glucose level.

11. ACTION OF GLUCAGON -Glucagon generally elevates the concentration of glucose in the blood by promoting gluconeogenesis and glycogenolysis . -Glucagon also decreases fatty acid synthesis in adipose tissue and the liver, as well as promoting lipolysis in these tissues.

12. SOMATOSTATIN – It inhibits the function of insulin and glucagon in pancrease . AMYLIN - Amylin is a peptide hormone that is cosecreted with insulin from the pancreatic β-cell and is thus deficient in diabetic people. It inhibits glucagon secretion, delays gastric emptying, and acts as a satiety agent. Amylin replacement could therefore possibly improve glycemic control in some people with diabetes.

13. DISORDERS - Diabetes mellitus, a heterogeneous disorder, is the most common disease of the endocrine pancreas. -It is caused due to decreased function of insulin in the body which results in excess blood glucose level .It is of two types: A . Type 1 Diabetes : It is an autoimmune condition. It happens when your body attacks your pancreas  with antibodies. The organ is damaged and doesn't make insulin . It mostly occurs in children.

14. B . Type 2 Diabetes: Pancreas usually creates some insulin. But either it’s not enough or your body doesn’t use it like it should.  Insulin resistance , when your cells don’t respond to insulin, usually happens in fat, liver, and muscle cells. It occurs mostly in adults. Symptoms: Increased thirst , Frequent urination , Extreme hunger , Fatigue , Unexplained weight loss , Delay in wound healing , etc.

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