Spleen

The spleen is an <a href="/facts/Organ_(biology)/FUYsLaxz">organ</a> found in almost all <a href="/facts/Vertebrate/tT54FSTT">vertebrates</a>. Similar in structure to a large <a href="/facts/Lymph_node/vkwfcQjH">lymph node</a>, it acts primarily as a <a href="/facts/Blood/03zEulkj">blood</a> filter.
The spleen plays important roles in regard to <a href="/facts/Red_blood_cell/Kggpq8Jh">red blood cells</a> (erythrocytes) and the <a href="/facts/Immune_system/HRCTf1pb">immune system</a>. It removes old red blood cells and holds a reserve of blood, which can be valuable in case of <a href="/facts/Shock_(circulatory)/aIKGDS0e">hemorrhagic shock</a>, and also <a href="/facts/Human_iron_metabolism/Ecr983cT">recycles iron</a>. As a part of the <a href="/facts/Mononuclear_phagocyte_system/G2SLM6k0">mononuclear phagocyte system</a>, it metabolizes <a href="/facts/Hemoglobin/RsD1MzYA">hemoglobin</a> removed from <a href="/facts/Senescent/AHmBEpe8">senescent</a> red blood cells. The <a href="/facts/Globin/NvpSKo7k">globin</a> portion of hemoglobin is degraded to its constitutive <a href="/facts/Amino_acid/WDxYwBny">amino acids</a>, and the <a href="/facts/Heme/fRhyJAAb">heme</a> portion is metabolized to <a href="/facts/Bilirubin/HCHyCjkt">bilirubin</a>, which is removed in the <a href="/facts/Liver/Rtp4Fk2b">liver</a>.
The spleen houses <a href="/facts/Antibody/MX8pdTdP">antibody</a>-producing lymphocytes in its <a href="/facts/White_pulp/7hDasAwl">white pulp</a> and <a href="/facts/Monocytes/FW4NNMKM">monocytes</a> which remove antibody-coated bacteria and antibody-coated blood cells by way of blood and <a href="/facts/Lymph_node/vkwfcQjH">lymph node</a> circulation. These monocytes, upon moving to injured tissue (such as the <a href="/facts/Heart/fF4KSGdk">heart</a> after <a href="/facts/Myocardial_infarction/xoGw0qcG">myocardial infarction</a>), turn into <a href="/facts/Dendritic_cell/19KBuKFK">dendritic cells</a> and <a href="/facts/Macrophage/z7hkQu3o">macrophages</a> while promoting tissue healing. The spleen is a center of activity of the <a href="/facts/Mononuclear_phagocyte_system/G2SLM6k0">mononuclear phagocyte system</a> and is analogous to a large lymph node, as its absence causes a predisposition to certain <a href="/facts/Infection/182XrncP">infections</a>.
In humans, the spleen is purple in color and is in the <a href="/facts/Quadrant_(anatomy)/9hYKDQ72">left upper quadrant</a> of the <a href="/facts/Abdomen/HcTzDFL0">abdomen</a>. The surgical process to remove the spleen is known as a <a href="/facts/Splenectomy/oFGhehpQ">splenectomy</a>.

Spleen open-in-new

Spleen