The spleen is an organ present in all humans.
Similar in structure to a large lymph node, it acts primarily as a blood filter.
Thus life is possible after the spleen is removed.
The spleen plays important roles in regard to red blood cells and the immune system.
It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock and also recycles iron.
As a part of the mononuclear phagocyte system, it metabolizes hemoglobin removed from senescent erythrocytes.
The globin portion of hemoglobin is degraded to its constitutive amino acids and the heme portion is metabolized to bilirubin, which is removed in the liver.
The spleen synthesizes antibodies in its white pulp and removes antibody-coated bacteria and antibody-coated blood cells by way of blood and lymph node circulation
These monocytes, upon moving to injured tissue turn into dendritic cells and macrophages while promoting tissue healing.
The spleen is a center of activity of the reticuloendothelial system and can be considered analogous to a large lymph node as its absence causes a predisposition to certain infections.
In humans, the spleen is brownish in color and is located in the left upper quadrant of the abdomen.
The spleen is located in the upper left part of the abdomen under the ribcage.
It works as part of the lymphatic system to protect the body, clearing worn-out red blood cells and other foreign bodies from the bloodstream to help fight off infection
The spleen also helps the body fight infection.
The spleen contains lymphocytes and another kind of white blood cell called macrophages which engulf and destroy bacteria, dead tissue, and foreign matter and remove them from the blood passing through the spleen.
The spleen helps control the amount of blood and blood cells that circulate through the body and helps destroy damaged cells.
The spleen is part of the lymphatic system.
The Red Pulp has the function of mechanical filtration of red blood cells
The White pulp produces an active immune response through humoral and cell-mediated pathways
The spleen is composed of nodules, called Malpighian corpuscles.
These are composed of:
1. Lymphoid follicles rich in B-lymphocytes
2. Periarteriolar lymphoid sheaths (PALS) rich in T-lymphocytes
Other functions of the spleen are less prominent, especially in the healthy adult:
1. Production of opsonins, properdin, and tuftsin.
2. Creation of red blood cells.
While the bone marrow is the primary site of hematopoiesis in the adult, the spleen has important hematopoietic functions up until the fifth month of gestation.
After birth, erythropoietic functions cease, except in some hematologic disorders.
As a major lymphoid organ and a central player in the reticuloendothelial system, the spleen retains the ability to produce lymphocytes and, as such, remains a hematopoietic organ.
3. Storage of red blood cells, lymphocytes and other formed elements.
The red blood cells can be released when needed
In humans, up to a cup (236.5 ml) of red blood cells can be held in the spleen and released in cases of hypovolemia.
It can store platelets in case of an emergency.
Up to a quarter of lymphocytes can be stored in the spleen at any one time.
The spleen is enlarged for various reasons such as cancer specifically blood-based leukemias.
But in some cases, more serious diseases such as cancer can cause the spleen to expand.
Traumas such as a motor vehicle accident can cause rupture of the spleen.
This is a situation that requires immediate medical attention.
TABLE OF CONTENT
Introduction
Chapter 1 The Spleen
Chapter 2 Spleen Function
Chapter 3 The Immune system of the Spleen
Chapter 4 Protection of the Spleen
Chapter 5 The Spleen and Diseases
Epilogue
