BELLWORK• Write these objectives in your notebook:

• SWBAT explain hemostasis

• SWBAT define antigen, antibody, and explain how this relates to blood types

BLOOD

HEMOSTASIS AND BLOOD TYPES

HEMOSTASIS• Stoppage of blood flow when a blood vessel breaks

• Three phases:

1. Platelet plug formation: platelets become sticky and pile up to form a “plug”

2. Vascular spasms: narrow blood vessel to decrease blood loss

3. 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

DONORS• Universal Donor: (who can donate to ANYBODY)

• Universal recipient: (who can receive from ANYBODY)

O-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