Blood is a bodily fluid that allows the circulation of oxygen throughout the body while lymph helps in fighting against infections and removal of waste products.
|Components||RBCs, WBCs, Platelets, Plasma||WBCs, watery fluid|
|System||Circulatory system||Lymphatic system|
|Color||Red||Colorless, milky white|
|Purification||In kidneys||In lymph nodes|
|Proteins||Both diffusible and nondiffusible proteins||Only diffusible proteins|
|Clotting||More clotting ability||Less clotting ability|
|Flow||Circular motion (two way)||In a single direction|
|Functions||Supply of oxygen and nutrients, Removal of CO2 and waste material, maintenance of pH and water balance.||Transportation of infection frightening cells, phagocytosis, storage of lymphocytes|
|Diseases||Anemia, polycythemia, thalassemia||Lymphadenopathy, lymphedema, lymphoma|
What is Blood?
Blood is a special type of connective tissue. It is mesodermal in origin and is made up of two parts; cellular and non-cellular. Its cellular part constitutes about 45% while rest (55%) is the noncellular part which is plasma. Cellular part is made up of red blood cells (erythrocytes), white blood cells (leukocytes) and platelets. White blood cells are divided into two types; granular leukocytes and agranular leukocytes. Neutrophils, eosinophils, and basophils are granular leukocytes while lymphocytes and monocytes are agranular leukocytes. Plasma consists of a fluid part (water 91%) and a solid part (9%). Plasma contains organic and inorganic substances. Organic substances are proteins, enzymes, pigments, non-nitrogenous substances and non-protein nitrogenous substances. RBCs are red oxygen carrying hemoglobin containing, non-nucleated cells present in the blood. Hemoglobin is a red, oxygen carrying pigment present in RBCs. Red blood cells have an average life span of 120 days while 70-90 days in neonates. All types of blood cells are made in bone marrow especially in ribs, sternum, hips and vertebrae. The major function of blood in the body is the transport but it has important role in defense mechanism of the body. White blood cells are involved in defense mechanism against infectious diseases. Deficiency of blood is called anemia which is because of deficiency of red blood cells and hemoglobin while polycythemia is the opposite condition in which increased number of red blood cells are produced. In megaloblastic anemia, erythroblasts are large and odd shaped. There are two types of megaloblastic anemia, one is lack of vitamin B12 which is called pernicious anemia while second is caused by deficiency of folic acid. Sickle cell anemia is another type of anemia in which abnormal form of hemoglobin occurs because of inherited genetic defect. Thalassemia is a genetic disorder characterized by a diminished synthesis of globin chains of Hb. This disease occurs due to abnormalities of the genes that are responsible for the synthesis of the globin portion of the hemoglobin molecule.
What is Lymph?
Lymph has derived from Latin word “lympha” which means “connected to water”. Lymph is the fluid of lymphatic system. Lymph is made when the interstitial fluid is gathered through lymph capillaries. It is transported through larger lymphatic vessels to lymph nodes where waste materials are removed by lymphocytes, before emptying into the right or the left subclavian vein, where it mixes back with the blood. The composition of lymph changes as the blood and its surrounding cells continually exchange material with the interstitial fluid. It is similar to blood plasma which is fluid of extracellular matrix of blood. Lymph returns the proteins and extra interstitial fluid to the blood stream. Lymph also transports metastatic cancer cells. It transports fats from the digestive system to the blood with the help of chylomicrons. It also picks up bacteria and brings them to lymph nodes where they are destroyed. Although lymph has a composition as that of plasma, it differs slightly from plasma. Lymph that leaves lymph node has a greater number of lymphocytes. Lymph which has formed in the digestive system is rich in fats. The flow of the lymph in the thoracic duct in an average resting person almost 100 ml per hour and approximately 25 ml per hour in other lymph vessels. Total lymph flow in the body is approximately 4 to 5 liters per day. Which can be increased several folds in case of exercising. Thus it can be estimated that without lymphatic flow, a person would die within 24 hours. Spleen which is located above kidneys, is largest organ of lymphatic system. Most common diseases of lymphatic system are lymphadenopathy which is the enlargement of the lymph nodes, lymphedema which is due to swelling of lymph node and cancers of this system. Lymphoma is cancer of lymphatic system which results because of uncontrolled growth and multiplication of lymphocytes.
Blood vs. Lymph
- Blood is pumped by the heart, which is a powerful pumping muscular organ, throughout the body while lymph has not such pumping organ.
- Blood transports oxygen in the body while lymph removes waste material from the body.
- Damage to the blood can be seen with the naked eye while damage to lymph cannot be seen with naked eye.