Brief Summary
This session by Dr. Anisha from Sri Chaitanya Educational Institutions covers key aspects of hematology, focusing on tissue fluid, its relation to lymph, and blood grouping. The session revises the components of blood (RBC, WBC, platelets), explains the formation and function of tissue fluid and lymph, and discusses ABO and Rh blood grouping systems, including transfusion reactions and incompatibilities.
- Tissue fluid is formed by filtration from blood capillaries and is also known as intercellular fluid.
- Lymph is formed when tissue fluid drains into lymphatic vessels and mixes with lymphocytes, fats, and fat-soluble vitamins.
- Karl Landsteiner discovered the ABO blood grouping system, and later the Rh typing was found out by Landsteiner and Weiner.
- Blood group incompatibility can lead to jaundice and acute renal failure due to the breakdown of RBCs.
Introduction
Dr. Anisha welcomes students to a new bridge course for NEET 2025 and 2027 aspirants. The session will cover hematology, specifically blood and blood cells, including blood coagulation and blood grouping. The discussion will address what happens when mismatched blood groups are mixed.
Components of Blood: A Quick Revision
The session starts with a quick revision of the components of blood, namely RBCs, WBCs, and platelets. The composition of RBCs, including the structure of hemoglobin, is discussed. While the detailed composition of WBCs is not covered in depth, it is mentioned that it will be addressed in future classes. The formation of platelets from megakaryocytes and the relative sizes of RBCs, WBCs, and platelets are also recapped.
Understanding Tissue Fluid
Tissue fluid, also known as intercellular fluid or lymph, is discussed. Arteries supply blood to tissues, and after the tissues utilize the oxygen and nutrients, carbon dioxide is produced. This CO2-loaded blood exits through venules, which join to form veins. The exchange of oxygen and carbon dioxide between blood and tissues is explained with diagrams.
Formation and Location of Tissue Fluid
Tissue fluid is found in the spaces between cells. As blood flows through capillaries, water, electrolytes, and small molecules filter out due to pressure. This fluid, accumulating between cells and tissues, is called tissue fluid or intercellular fluid. It contains water, electrolytes, amino acids, and glucose.
Tissue Fluid vs. Lymph
The difference between tissue fluid and lymph is explained. Excess tissue fluid drains into lymphatic vessels, mixing with lymphocytes (mostly WBCs), fats, and fat-soluble vitamins. This mixture is then called lymph, which is whitish or yellowish in color. Tissue fluid is essentially filtered blood in tissue spaces, while lymph is this fluid mixed with additional components in lymphatic vessels.
Key Differences Summarized
The key differences between tissue fluid and lymph are summarized in writing. Tissue fluid is formed when arteries branch into capillaries, and fluid containing water, electrolytes, and small molecules filters out into tissue spaces. When this tissue fluid drains into lymphatic vessels and mixes with WBCs (lymphocytes), fats, and fat-soluble vitamins, it becomes lymph. Lymph is essentially blood minus RBCs and platelets and is considered the "middle man" of the body.
Introduction to Blood Groups
The session transitions to the topic of blood groups. The importance of staying focused on studies is emphasized before starting the new topic.
ABO Blood Grouping System
Karl Landsteiner first discovered different types of blood in 1903. Mixing blood samples, he observed reactions that led to the discovery of the ABO blood grouping system. There are four types: A, B, AB, and O. These groups are named based on the presence of specific glycoproteins (carbohydrate and protein mixtures) on the surface of RBCs.
Glycoproteins and Blood Types
Blood group A has A-type glycoproteins, blood group B has B-type glycoproteins, and blood group AB has both A and B glycoproteins on the surface of their RBCs. Blood group O, derived from the German word "ohne" meaning zero or null, has no glycoproteins of this type on its surface.
Transfusion Reactions and Universal Donors
Transfusion reactions occur when incompatible blood types are mixed, leading to the destruction of RBCs by the recipient's immune system. A can donate to A and AB, B can donate to B and AB, and AB can only donate to AB. O can donate to all blood groups and is known as the universal donor because it has no surface components to trigger a reaction.
Rh Typing and the Rh Factor
Landsteiner and Weiner discovered the Rh typing system, named after the Rhesus monkey. The Rh factor, specifically the D type, is crucial for compatibility. Individuals are either Rh positive (have the D factor) or Rh negative (do not have the D factor). Rh-negative individuals can donate to Rh-positive individuals, but Rh-positive individuals cannot donate to Rh-negative individuals.
Blood Grouping Test Explained
The blood grouping test involves determining the ABO and Rh systems. Anti-A, anti-B, and anti-D chemicals (antibodies) are mixed with blood samples on a glass slide. Clumping (agglutination) indicates the presence of the corresponding antigen (A, B, or D). For example, clumping with anti-A indicates blood group A.
Understanding Agglutination Reactions
Blood grouping reactions are called agglutination or clumping reactions. If a blood sample clumps with anti-B, it is blood group B. If it clumps with both anti-A and anti-B, it is blood group AB. If there is no clumping with any, it is blood group O. The presence or absence of clumping with anti-D determines whether the blood is Rh positive or Rh negative.
Blood Group Incompatibility
Blood group incompatibility occurs when mismatched blood is transfused. The spleen is the graveyard of RBCs. When incompatible blood is given, the recipient's immune system destroys the foreign RBCs, breaking them down into heme and globin. The heme is converted to bilirubin and biliverdin in the liver, leading to jaundice (yellowing of the skin and eyes) and potentially acute renal failure.
Consequences of Incompatibility
In severe cases of blood group incompatibility, the large amount of bilirubin and biliverdin released into the bloodstream can cause jaundice and kidney failure. The person may experience shock and even death.
Review Questions
The session concludes with review questions to reinforce the concepts learned. Questions cover topics such as the characteristics of leukocytes, the site of RBC destruction, hemoglobin levels, the percentage of Rh-positive individuals, and blood group compatibility in emergencies.
Homework and Closing Remarks
A cross-matching exercise is assigned as homework. The session ends with a final question about blood clotting and a thank you to the students for their participation. Dr. Anisha encourages them to keep studying hard and have fun on the weekends.
