Blood Typing

BLOOD CLOTTING Blood clots naturally when there is a disturbance, such as blood vessels being damaged. Platelets, that have irregular shapes, respond to chemicals (e.g., collagen). Platelet response: Increase in size, become more irregularly shaped, become sticky and adhere to fibers in blood vessel walls = platelet plug. May be enough to plug a small vessel.

Clotting in Larger Vessels Relies on a cascade of events involving 13 clotting factors. Simplified version: animationanimation 4 parts: platelets (cell fragments) clotting factors (special proteins) including fibrin(mesh-like) red and white blood cells

Cascade of Events Tear in blood vessel  platelets become activated, become sticky, stick to tear and form a platelet plug. Clotting factors become activated and add to plug. Chemicals from tissues combine with Ca++ in blood and convert prothrombin to thrombin. Thrombin causes fibrinogen (soluble clotting factor) to fibrin (insluble). Fibrin forms mesh to catch cells (RBCs, WBCs)

Karl Lansteiner Discovered “factors” in blood. Labeled one related set A and B. Labeled another set D. Labeled a third set M and N. There are about 100 sets.

Antigens Determine Blood Type

Antibodies to the “opposite” blood type are naturally made

Coagulation (agglutination/clumping) and hemolysis occurs if an antigen comes in contact with its antibody

Although similar in result, the clotting due to antigens has a different mechanism than clotting due to blood vessel tears.

Blood Types Among U.S. Population O+37.4%O = 44 % O-6.6% A-6.3%A = 42 % A+35.7% B+8.5% B = 10 % B-1.5% AB+3.4%AB = 4 % AB-0.6%

Quiz Yourself r/119/images/blood_typing_photos. htm