Biology · Body Fluids and Circulation · NEET
| Colour | Red | Colourless / pale |
| RBCs | Present (haemoglobin) | Absent |
| Platelets | Present | Absent |
| WBCs | All types present | Mainly lymphocytes |
| Oxygen transport | Main carrier (via RBC) | Little / none |
| Main function | Transport of O2, CO2, nutrients | Fat transport (lacteals) + immunity |
| Proteins | More plasma proteins | Fewer proteins |
| Flows in | Blood vessels | Lymphatic vessels |
Blood looks red because it has red blood cells (RBCs) that contain the red pigment haemoglobin. Lymph does NOT have RBCs, so there is no haemoglobin and no red colour. That is why lymph is a colourless (or pale) fluid. NEET often asks this one-line reason directly.
No. Oxygen is carried by haemoglobin inside RBCs. Since lymph has no RBCs, it carries very little or no oxygen. Blood is the main oxygen-transport fluid. Lymph mainly transports fats (absorbed by lacteals in intestinal villi), plus nutrients, hormones and lymphocytes for immunity.
Plasma is the fluid part of blood, inside blood vessels. When plasma leaks out of blood capillaries into the spaces between cells, it becomes tissue fluid (interstitial fluid). This tissue fluid has the same mineral distribution as plasma but less protein. When the lymphatic vessels collect this tissue fluid, it is called lymph. So: plasma (in blood) to tissue fluid (around cells) to lymph (in lymphatic vessels).
Lymph forms from tissue fluid, which is plasma that filtered out of capillaries. Large formed elements like RBCs and platelets, and large plasma proteins, mostly stay behind in the blood vessels and do not leak out easily. So lymph ends up with lymphocytes but no RBCs, no platelets, and fewer plasma proteins than blood.
Clotting mainly needs platelets and certain plasma clotting factors, so lymph clots very slowly or poorly compared to blood. Lymph contains specialised lymphocytes (a type of WBC) that are responsible for immune responses. NCERT states lymph is a colourless fluid containing lymphocytes.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Blood is specifically called a fluid (special) connective tissue in NCERT. Lymph is described as a body fluid / tissue fluid that helps in transport and immunity. For NEET, remember 'blood = fluid connective tissue' as the exam-safe statement.
Lymph is the main carrier of fats absorbed from the intestine. Fats enter special lymph vessels called lacteals in the intestinal villi. Lymph also carries nutrients, hormones and lymphocytes.
An elaborate network of lymphatic vessels collects tissue fluid as lymph and drains it back into the major veins. So lymph ultimately returns to the blood circulation.
Lymph mainly contains lymphocytes, which are responsible for the body's immune responses. It does not contain RBCs or platelets.
Tissue fluid (which becomes lymph) has the same mineral distribution as plasma. The big difference is fewer proteins and the absence of RBCs and platelets in lymph.
