The Anatomy of the Pancreas

Abstract 

The pancreas is a crucial organ, functioning both as an exocrine gland and an endocrine gland, of the endocrine and digestive system of vertebrates. In human beings, it is a tapered, elongated organ located behind the stomach in the abdominal cavity. It plays an indispensable role in the regulation of the blood’s glucose concentration by producing hormones such as insulin and glucagon. Moreover, it is responsible for the secretion of digestive enzymes including lipases, amylases and proteases, thus aiding in digestion. This article aims to provide an overview of the anatomy of the pancreas i.e. its structure. 

Introduction 

The pancreas is a crucial organ, functioning both as an exocrine gland and an endocrine gland. In human beings, it is a tapered, elongated organ located behind the stomach in the abdominal cavity. It plays an indispensable role in the regulation of the blood’s glucose concentration by producing hormones such as insulin and glucagon. Moreover, it is responsible for the secretion of digestive enzymes including lipases, amylases and proteases, thus aiding in digestion[1,3]. There are a plethora of disorders affecting the pancreas, the primary ones being pancreatitis, pancreatic cancer and precancerous conditions such as PanIN and IPMN[2,3]. Pancreatitis and Pancreatic cancer will be discussed below.

Pancreatitis can act as an acute condition; the pathogenesis of this occurs by the injury of the pancreatic duct or acinar. Subsequently, there is insufficient secretion of digestive enzymes, leading to autodigestion and inflammation of the organ. Chronic pancreatitis develops as a result of a continuous acute attack which results in inflammatory infiltrates and fibrosis within the pancreas[4].Furthermore, pancreatic cancer is a condition that arises when malignant cells grow, divide and spread in the organ. It refers to the carcinoma – a type of cancer that develops from epithelial cells – arising from the pancreatic duct. It is the fourth leading cause of cancer deaths in the United States[5]. 

Anatomy 

1. Division 

The pancreas is a retroperitoneal organ. It is a long, accessory digestive and endocrine gland situated on the posterior abdominal wall where it crosses the bodies of both the L1 and L2 vertebrae. Furthermore, it is located between the spleen and the small intestine’s duodenum. The pancreas is divided anatomically into 4 major parts and separate sections: the head, neck, body and tail. The head is encircled by the duodenum’s C loop and rests on the renal vein and inferior vena cava[6,7]. The splenic hilum  is reached by the pancreatic tail. The pancreas produces and secretes endocrine substances, specifically its hormones glucagon and insulin from the pancreatic islets of Langerhans, into the blood while the exocrine s pancreatic juice manufactured from the acinar cells passes through the main and auxiliary pancreatic duct into the duodenum[7].

Photo Credits: The Olive Laboratory

2. Types of Cells 

The pancreatic islets consist of four different types of cells, those being the alpha, beta, delta and pancreatic polypeptide cell. The alpha cells have a pivotal role in the endocrine function as they are responsible for production of glucagon and account for an estimated 20% of each islet. The beta cells also carry out the endocrine function as they synthesise insulin. They are a majority as 75% of each pancreatic islet comprises them. The delta cells, however, only make up 4% of each islet and secrete somatostatin - a peptide hormone. Finally, the pancreatic polypeptide (PP) are in the smallest minority - reckoning only 1% of the islets, but they play an important role nonetheless as they manufacture the pancreatic polypeptide hormone[6]. 

Conclusion 

The pancreas is a requisite organ functioning both as endocrine (ductless) and exocrine (secreting via a duct) gland. It is responsible for the synthesis and secretion of the pancreatic juice, a mixture consisting of water, bicarbonate, lipases, carbohydrases and proteases, into the small intestine’s duodenum via the pancreatic duct. The islets of Langerhans manufacture and secrete insulin and glucagon directly into the bloodstream. Because of its physiology, it is a crucial organ and its anatomical structure aids in its function.

Resources:

1. https://www.hopkinsmedicine.org/health/conditions-and-diseases/the-digestive-process-what-is-the-role-of-your-pancreas-in-digestion#:~:text=Your%20pancreas%20plays%20a%20big,down%20proteins%20in%20your%20diet.

2. https://columbiasurgery.org/pancreas/pancreas-and-its-functions

3. https://my.clevelandclinic.org/health/body/21743-pancreas

4. Pancreatitis - Nabeeha Mohy-ud-din; Suzanne Morrissey - https://www.ncbi.nlm.nih.gov/books/NBK538337/

5. Pancreatic Cancer - Yana Puckett; Karen Garfield - https://www.ncbi.nlm.nih.gov/books/NBK518996/

6. Anatomy and Physiology by Lindsay M. Biga, Staci Bronson, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Matern, Katie Morrison- Graham, Kristen Oja, Devon Quick, Jon Runyeon

Anatomy, Abdomen, and Pelvis, Pancreas - Saurabh S. Talathi; Ryan Zimmerman; Michael Young - https://www.ncbi.nlm.nih.gov/books/NBK532912/#:~:text=The%20pancreas%20is%20an%20extended,Langerhans)%20that%20enter%20the%20blood.