What is the Difference Between Pancreas and Spleen

The main difference between the pancreas and spleen is that the pancreas is a wing-shaped gland that extends from the duodenum to the spleen whereas spleen is a fist-sized organ located in the left upper quadrant of the abdomen. Furthermore, the two functional regions of the pancreas are the acini and Islets of Langerhans while the two functional regions of the spleen are the red pulp and the white pulp. Moreover, the pancreas produces digestive enzymes, aiding in digestion and serves as an endocrine organ by producing hormones including insulin and glucagon while spleen filters blood and serves as one of the several secondary lymphoid organs of the body, allowing lymphoid organs to become functional.  

Pancreas and spleen are two functionally important organs of the human body found within the upper part of the abdomen. However, they are quite different in appearance, composition, and function. 

Key Areas Covered 

1. What is the Pancreas
     – Definition, Anatomy, Function
2. What is the Spleen
     – Definition, Anatomy, Function
3. What are the Similarities Between Pancreas and Spleen
     – Outline of Common Features
4. What is the Difference Between Pancreas and Spleen
     – Comparison of Key Differences

Key Terms 

Digestive Enzymes, Insulin, Pancreas, Secondary Lymphoid Organ, Spleen

What is the Pancreas 

The pancreas is the large, retroperitoneal organ located immediately behind the posterior wall of the lesser sac, on the floor of the supracolic compartment of the abdominal cavity. It is a flat, spongy, wing-shaped organ with a head, neck, body, and tail.  Moreover, pancreas serves as both exocrine and endocrine glands. Generally, 95% of the pancreatic tissue has an exocrine function, secreting digestive enzymes into the duodenum. The exocrine content of the pancreas is also responsible for the digestion of carbohydrates, proteins, and lipids while neutralizing the acidity from the stomach.

Figure 1: Pancreas

Furthermore, the cells with an endocrine function are arranged in clusters called acini. Acini are one of the two functional components of the pancreas, the second being the Islets of Langerhans. However, the Islets of Langerhans have an endocrine function, producing and secreting hormones responsible for the regulation of blood sugar levels. Basically, the three types f hormones produced in the pancreas are insulin, glucagon, and somatostatin.

What is the Spleen 

Spleen is the largest secondary lymphoid organ of the lymphatic system. It is located deep in the left hypochondrium, wedged between the gastric fundus, left hemidiaphragm and left kidney. The spleen is a fist-sized organ with the anatomical structure, resembling a large lymph node. It contains blood in its sinus rather than lymph in lymph nodes. Moreover, the spleen has a capsule, an outer layer, consisting of fibrous and elastic connective tissue. The two functional regions of the spleen are the red pulp and the white pulp separated by a marginal sinus.

Figure 2: Spleen

The main function of the red pulp is to mechanically filter red blood cells. Normally, it filters dead, aged or defected red blood cells from the circulation while recycling hemoglobin. In addition, red pulp stores over half of the total monocytes of the body, those responsible for moving into the injured tissues to promote tissue healing by becoming macrophages and dendritic cells. The main function of the white pulp is to generate an active immune response through humoral and cell-mediated immune pathways. Moreover, it is composed of Malpighian corpuscles, a type of nodules containing lymphoid follicles rich in B lymphocytes and periarteriolar lymphoid sheathes rich in T lymphocytes. Therefore, the white pulp removes antibody-coated blood cells while producing antibodies. 

Similarities Between Pancreas and Spleen 

• Pancreas and spleen are two organs located nearly in the upper part of the abdomen. 
• However, they differ in anatomy according to their function. 
• They also have a rich blood supply. 

Difference Between Pancreas and Spleen 

Definition 

Pancreas refers to a large gland behind the stomach, secreting digestive enzymes into the duodenum while spleen refers to an abdominal organ, involving in both production and removal of blood cells and forming a part of the immune system. 

Location 

The pancreas is located behind the stomach, extending from the duodenum to the spleen, while the spleen is located left to the stomach in contact with the tail of the spleen in the left upper part of the abdomen. 

Shape 

While the pancreas is a wing-shaped organ, the spleen is a fist-sized organ. 

Color 

The pancreas has a salmon color while the spleen has a purple color. 

Size 

Moreover, the pancreas is around 12-15 cm long while the spleen is around 7-14 cm long. 

Anatomy 

The pancreas has a head, neck, body, and a tail while spleen resembles a large lymph node. 

Functional Anatomy 

Furthermore, the pancreas is embedded with Islets of Langerhans and acini while the two functional areas of the spleen are the red pulp and white pulp.  

Blood Supply 

Superior and inferior pancreaticoduodenal arteries and tortuous splenic artery supply blood to the pancreas while splenic artery supplies blood to the spleen. 

Significance 

While the pancreas is an accessory digestive organ, the spleen is the largest secondary lymphoid organ. 

Mai Function 

The main function of the pancreas is to secrete digestive enzymes into the duodenum while the main function of the spleen is to filter blood. 

Other Functions 

In addition, the pancreas serves as an endocrine organ by secreting insulin and glucagon while spleen removes defected or dead red blood cells from the circulation. 

Clinical Significance

Impaired secretion of insulin by the pancreas causes diabetes while the enlarged spleen, ruptured spleen, sickle cell disease, and thrombocytopenia are the main clinical conditions of the spleen. 

Conclusion 

The pancreas is the wing-shaped organ which secretes digestive enzymes to the duodenum. It also extends up to the spleen. In addition, it secretes insulin and glucagon by serving as an endocrine organ. However, reduced insulin levels of the body cause diabetes. On the other hand, the spleen is the fist-sized organ, locating left to the stomach. Moreover, its structure resembles a large lymph node. Therefore, it is the largest secondary lymphoid organ responsible for filtering blood while clearing dead or defected red blood cells from the circulation. Hence, the main difference between the pancreas and spleen is their anatomy and function. 

References:

1. “The Pancreas and Its Functions.” COLUMBIA | SURGERY, Columbia University Irving Medical Center, Department of Surgery, New York, NY., Available Here.
2. Hoffman, Matthew. “The Spleen (Human Anatomy): Picture, Location, Function, and Related Conditions.” WebMD, WebMD, 18 May 2019, Available Here.

Image Courtesy:

1. “1820 The Pancreas” By OpenStax College – Anatomy & Physiology, Connexions Web site. (CC BY 3.0) via Commons Wikimedia   
2. “2208 Spleen” By OpenStax College – Anatomy & Physiology, Connexions Web site. (CC BY 3.0) via Commons Wikimedia   

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