Bellwork Write these objectives in your notebook: SWBAT explain hemostasis SWBAT define antigen, antibody, and explain how this relates to blood types
Hemostasis and Blood Types
hemostasis Stoppage of blood flow when a blood vessel breaks Three phases: Platelet plug formation: platelets become sticky and pile up to form a “plug” Vascular spasms: narrow blood vessel to decrease blood loss Coagulation: basis of a clot
Blood clotting Usually clots within 3-6 minutes Clot stays until tissue regenerates
Bad clotting Can be deadly if it happens in heart or brain Thrombus Clot inside blood vessel Embolus A thrombus that breaks away and floats in blood stream
Blood loss When you lose blood, your body usually compensates by making more Losing 15-30% of total blood will make you pale and weak Losing 30%+ can cause shock and be fatal
Treating blood loss May require a blood transfusion Blood collected from a donor, and mixed with anticoagulant (prevents clotting) If refrigerated, can be stored up to 35 days
Antigens & antibodies Antigen: protein within plasma membrane of RBC Your body thinks its foreign, and releases antibodies as a defense Antibody: Substances produced by body to provide immunity against antigen
Antigens & antibodies When antibodies bind to antigens, the cells clump together – agglutination Clumps clog vessels, depriving tissues of oxygen Foreign RBCs rupture, freeing hemoglobin which may block tubules in kidney and cause kidney failure
Blood groups Over 30 common RBC antigens ABO and Rh groups cause the most severe transfusion reactions Blood groups are based on which antigens a person has
ABO Blood groups
Rh Most Americans are Rh+ (carry Rh antigen on RBCs) If a Rh- person is given Rh+ blood, immune system will start producing antibodies Eventually RBCs will rupture
O- AB+ Donors Universal Donor: (who can donate to ANYBODY) Universal recipient: (who can receive from ANYBODY) AB+
Testing for blood group In the lab: Mix a sample of the patient’s blood with 2 serums: antibody-A and antibody-B to determine blood type Crossmatch: Sample of patients blood with serum from donor Sample of donor blood with patient serum