Pancreas

The human Pancreas is a unique organ with a flat, leaf-like shape. It typically measures 15-22 cm long and weighs 50-125 grams. The Pancreas serves as an exocrine and endocrine function involving the secretion of digestive enzymes and the management of blood glucose levels. 

1.0What is the Pancreas?

The Pancreas serves a dual function within the body, functioning both as an endocrine gland—which produces essential hormones like insulin, glucagon, somatostatin, and pancreatic polypeptide—and as a digestive organ that releases pancreatic juice crucial for nutrient absorption and digestion in the small intestine. Positioned between the stomach and the duodenum (small intestine), the Pancreas connects to the common bile duct from the liver via a pancreatic duct, leading to hepatic pancreatic ampulla that opens into the duodenum. Comprising approximately 99% water, 0.5% inorganic salts, and 0.5% organic substances, the pancreatic juice is produced at about 1-1.5 litres daily. Due to the presence of bicarbonate ions, the fluid's high pH helps neutralize stomach acid, enabling effective enzymatic activity.

2.0Pancreas Structure

• The Pancreas is structured into three segments: the Head, body, and tail. The Head, located on the right side of the abdomen and attached to the duodenum via a small duct, is the gland's broadest part and consists of the Head proper and the uncinate process. The uncinate process extends backwards, encircling two major blood vessels—the superior mesenteric artery and vein. The tail, a slender tip, is positioned on the left side of the abdomen close to the spleen.
• The Pancreas comprises exocrine cells grouped into lobules (acini), separated by connective tissue. Embedded within the exocrine tissue are 1-2 million small endocrine clusters known as the islets of Langerhans, or pancreatic islets, making up about 1-2% of the pancreatic mass. Each islet is approximately 0.3 millimeters in diameter. The acinar cells, which can be spherical, grape-like, or tubular, contain a plentiful rough endoplasmic reticulum vital for extensive protein synthesis. The apical surface of these cells holds zymogen granules storing digestive enzymes, while the basolateral membrane is equipped with receptors that trigger enzyme secretion. These enzymes flow into the pancreatic duct, or duct of Wirsung, through small ducts originating from each acinar lobe, ultimately entering the duodenum via the ampulla of Vater.
• The islets of Langerhans contain four types of cells—Alpha (α) cells, Beta (β) cells, Delta (δ) cells, and PP cells. Together, these cells secrete five essential endocrine hormones: insulin, amylin, glucagon, somatostatin, and pancreatic polypeptide. These hormones are released into tiny capillaries surrounding each islet, playing crucial roles in regulating nutrient homeostasis and metabolism, including the uptake, storage, and release of metabolic fuels.

3.0Pancreatic Juice Function in Digestion

Your Pancreas produces natural juices known as pancreatic enzymes, which aid in the breakdown of foods. These fluids pass through the pancreatic ducts and discharge into the duodenum, the initial segment of the small intestine. Enzymes present in Pancreatic Juices are-

Role of  Trypsin - Trypsin, a proteolytic enzyme produced by the Pancreas, is initially secreted as an inactive precursor known as trypsinogen. Activation occurs when it encounters another enzyme called enterokinase. Once active, trypsin breaks down proteins, proteoses, and peptones into polypeptides and dipeptides.

Role of  Chymotrypsin - Chymotrypsin is a proteolytic enzyme that the Pancreas secretes in the inactive form known as chymotrypsinogen. It becomes active upon being activated by trypsin. Its function is comparable to trypsin, targeting native proteins, proteoses, and peptones to produce polypeptides and dipeptides. Additionally, chymotrypsin affects milk.

Role of  Carboxypeptidase  - This proteolytic enzyme is secreted by the Pancreas. Although it does not act on proteins, it effectively breaks down proteoses, peptones, and polypeptides into dipeptides and amino acids.

Role of Aminopeptidase - This enzyme, a proteolytic type, is produced by the Pancreas. It functions similarly to carboxypeptidase and targets proteoses, peptones, and polypeptides, breaking them down into dipeptides and amino acids.

Role of  Dipeptidase - This pancreatic enzyme targets dipeptides, breaking them down into amino acids.

Digestion of  Milk - Rennin and chymotrypsin are enzymes responsible for the digestion of milk. Rennin is produced by gastric glands, while chymotrypsin is secreted by the Pancreas. Their primary role is to coagulate milk, known as milk curdling. 

4.0Pancreas Function as Endocrine Gland

• The pancreatic islets, also known as islets of Langerhans, facilitate the endocrine function of the Pancreas. Named after Paul Langerhans, a German pathologist, these cell groups are dispersed throughout the pancreatic parenchyma.
• A typical human pancreas contains between 3.2 million - 14.8 million islets. Structurally, an islet typically features a core of beta cells encircled by alpha cells.
• Beta cells produce insulin, a peptide hormone that promotes glucose absorption in tissues.
• Alpha cells produce glucagon, which is also a peptide hormone that raises glucose levels by opposing insulin's effects.
• In healthy individuals, insulin and glucagon secretion production is regulated through negative feedback mechanisms.

Hormones produced by Pancreas

• Insulin helps to regulate high blood sugar levels by promoting glucose absorption and storage in fat, muscle, and liver cells. This stored glucose can later be converted back into energy when required insulin reduces blood sugar levels. 
• Glucagon prevents dangerously low blood sugar levels by prompting fat and muscle cells to release their glycogen stores and stimulating the liver to convert stored glycogen into glucose, increasing blood sugar levels.
• Somatostatin, produced by delta cells in the Pancreas, is released when the levels of other pancreatic hormones are excessively high. It aids in maintaining stable blood sugar levels and modulates hormone release within the digestive system.
• Pancreatic Polypeptide- It regulates secretory functions of Pancreas Gland.

5.0How Does the Pancreas help to Maintain Hormonal Levels in the Body?

• Insulin is produced when blood sugar (glucose) levels increase after a meal. It facilitates the transfer of glucose from the bloodstream into the body's cells, which lowers blood sugar levels. Once blood sugar levels normalize, the production of insulin decreases.
• Glucagon is produced when blood sugar (glucose) levels decrease below normal. Once sugar levels normalize, its production decreases.
• Somatostatin helps regulate blood sugar levels by inhibiting the production of insulin and glucagon. 

6.0Disorders of the Pancreas

• Acute Pancreatitis: This is a sudden inflammation of the pancreas that can cause severe abdominal pain, nausea, vomiting, and fever. It is often caused by gallstones or excessive alcohol consumption.
• Chronic Pancreatitis: This is a long-term inflammation that leads to permanent damage. Chronic pancreatitis is commonly associated with prolonged alcohol abuse, but it can also result from genetic mutations, autoimmune conditions, or other underlying diseases.
• Pancreatic cancer is one of the most aggressive forms of cancer, often diagnosed at an advanced stage due to its subtle early symptoms. Risk factors include smoking, chronic pancreatitis, diabetes, and family history. Symptoms can include jaundice, weight loss, and abdominal pain.
• Type 1 Diabetes: This is an autoimmune condition where the immune system attacks and destroys insulin-producing beta cells in the pancreas. Patients require lifelong insulin therapy.
• Type 2 Diabetes: This condition involves insulin resistance and eventual beta-cell dysfunction. It is often associated with obesity, physical inactivity, and genetic factors.