Pancreas



 What enzymes are secreted by the pancreas 



Pancreas:

The pancreas comprises the head, neck, body and tail.It weights about 60 grams. It is about 2.5. centimetres wide 12 to 15 centimetres long, located posterior to the stomach in the abdominal cavity.The main pancreatic duct (= duct of Wirsung) opens into the hepatopancreatic ampulla.An accessory pancreatic duct( = duct of Santorin) is also present in the pancreas and opens directly into the duodenum.Internally pancreas consists of two parts: exocrine in the pancreas and opens directly into the duodenum.Internally pancreas consists of two parts:





(1) Exocrine part: It consists of rounded lobules ( acini) that secrete an alkaline pancreatic juice with pH 8.4. About 500 __ 800 ml of pancreatic juic is secreted per day and is carried by the main pancreatic duct into the duodenum through the hepatopancreatic ampulla.The accessory pancreatic duct directly pours the pancreatic juice into the duodenum.The pancreatic juice contains sodium  bicarbonate, three preoenzymes;


(i)Tryosinogen, 

(ii) Chymotrypsinogen 

(iii) Procarboxypeptidase

(iv) Pancreatic amylase

(v) Lipase 

(vi) Elastase,

(vii) DNAase

(viii) RNA ase


The pancreatic juice helps in the digestion of starch, proteins, nucleic acids and fats.The pancreas secretes several enzymes that aid in digestion. These enzymes include:

 1: Pancreatic Amylase: This enzyme helps break down complex carbohydrates (starches) into smaller sugars.

2: Trypsinogen:This inactive form of trypsin is produced by the pancreas and is activated into trypsin in the small intestine. Trypsin is responsible for digesting proteins.

 3: Chymotrypsinogen:Similar to trypsinogen, chymotrypsinogen is also an inactive enzyme that is converted into active chymotrypsin in the small intestine. Chymotrypsin aids in protein digestion.

 4): Lipase:Pancreatic lipase breaks down fats (triglycerides) into fatty acids and glycerol, facilitating fat digestion and absorption.

5: Ribonuclease(RNAase): This enzyme helps break down ribonucleic acid (RNA) into smaller components.

 6: Deoxyribose (DNAase):DNAase breaks down deoxyribonucleic acid (DNA) into smaller fragments.

7; Elastase:This enzyme is involved in the digestion of elastin, a protein found in connective tissues.



(2) Endocrine part :It consists of groups of islets of Langerhans. The human pancreas has about one million islets. They are most numerous in the tail of the pancreas. Each islet of Langerhans consists of the following types of cell which secrete hormones to be passed into the circulating blood. 

(a) Alpha cells (=œ_ cells). These cells are more numerous towards the periphery of the islet and constitute 15% of the islet of Langerhans. They produce glucagon hormone which converts glycogen into glucose in the liver.

(b) Beta cells ( =ß_ cells). These cells  constitute 65% of the islet of Langerhans. They produce insulin hormone which convert glucose into glycogen in the liver and muscles. Deficiency of insulin causes diabetes mellitus. 

(c) Deltas cells ( =ò_ cells).These cells constitute 5% of the  islet of Langerhans. They secrete somatostatin ( SS) hormone which inhibits the secretion of glucagon by alpha cells and to a lesser extent secretion of insulin by beta cells. It also inhibits the secretion of growth hormone from the anterior lobe of pituitary gland. 

(D) Pancreatic polypeptide cells ( =PP cells of F_ cells). The PP cells constitute 15%. These cells secrete pancreatic polypeptide ( PP) which inhibits the release of pancreatic juice. 
Both samoatostatin and pancreatic polypeptide are relatively newly discovered hormone of the pancreas, and both are still being studied. Two important disorders of the pancreas are as follows. 


(i) Diabetes mellitus ( Hyperglycemia): The most common endocrine disorder of the pancreas is the diabetes melitus, now recognized to exist in two forms__ insulin _ dependent and non_ insulin_ dependent. The insulin _ dependent diabetes  mellitus ( IDDM) is caused by a failure of the Beta_ cells to produce adequate amounts of insulin while the non_ insulin _ dependent diabetes mellitus ( NIDDM) appears to involve failure of insulin to facilitate the movement of glucose into cells.


(ii) Hypoglycemia occurs when the blood glucose level falls below normal. Theoretically, it may be caused by an excess of insulin, a deficiency of glucagon, or  failure of the secretion of the two hormones to completely regulate the blood sugar.



(e) Insulin: 
(i) It is antagonistic to glucagon.

(ii) It promotes protein synthesis in tissue from amino acids.

(iii) Insulin reduce from proteins. It is an 
anabolic hormone.

(iv) It increases the synthesis of fat in the adipose tissue from fatty acids.

(v) Insulin reduces the breakdown and oxidation of fat. Sulphur is essential for the formation of insulin. 

These enzymes are released into the small intestine as part of pancreatic juice, where they play vital roles in breaking down carbohydrates, proteins, fats, and nucleic acids for proper digestion and absorption of nutrients.


















































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