blood groups and clotting dn8 viv rolfe
DESCRIPTION
Blood Groups and Clotting DN8 Viv Rolfe. Summary. Blood transfusion History of transfusions and what they are used for. ABO blood group system. Rhesus blood group system. Mechanisms of blood clotting. Why give blood?. Why give blood? Because it saves lives. How it is used?. - PowerPoint PPT PresentationTRANSCRIPT
Blood Groups andClotting
DN8
Viv Rolfe
Summary
• Blood transfusion– History of transfusions and what they are
used for.– ABO blood group system.– Rhesus blood group system.
• Mechanisms of blood clotting
Why give blood?
Why give blood? Because it saves lives.
0
5
10
15
20
25
Percent
Blood Use
General surgery
General medical
Cardiothoracic
Orthopedics
Blood diseases
Casualty
Renal
Neonates
Intensive care
How it is used?
•Whole blood - in extreme emergencies of huge blood loss.
•Red cells - anaemia, burn victims, cancer, sickle cell disease.
•Platelets - bone marrow failure, leukaemia patients, chemotherapy.
•Fresh plasma - blood loss after childbirth, major surgery.
•Processed plasma - e.g. factor VIII for treatment of haemophilia.
Blood Typing
Blood types must be matched for donation to be successful.
Blood Typing
• Many different ways of classifying blood.• Easily tested for using commercially available kits.
– ABO/Rhesus both based on the types of ANTIGEN and
ANTIBODY in the blood.
Antigen and Antibody
ANTIGENA molecule on the
surface of foreign cells (bacteria, viruses)and our own cells(blood, immune)
ANTIBODYAn immunoglobulin protein secreted byour immune system
to bind to (and combat) antigen.
ABO System
Based on the types of
1. Antigen markers on red blood cells.2. Antibodies in the plasma.
What are the 4 types?
What type are you?
UK Distribution
• A = 42%
• B = 8%
• AB = 4%
• O = 46%
A antigens B antigens Both Neither
ABO Types of Antigen
ABO Types of Antibody
Blood Transfusions-Donation of red blood cells
Type A blood CAN BE GIVEN to a Type A patient.(B to B, AB to AB and O to O).
A A
Anti-B
A
DONOR RECIPIENT
•Type A blood CAN’T BE GIVEN to a Type B patient.•Donated red cells are attacked by recipient’s anti-A antibody in their plasma.
Anti-A
A B
DONOR RECIPIENT
O can be given to EVERYONE(universal donor)
OA B
AB
O
O cells have no ANTIGEN
AB can receive from EVERYONE(universal recipient)
O
A
B
AB
AB
Incompatibility
• Reacting cells clump together or AGGLUTINATE.
• Can block capillaries stopping the blood flow.• Red blood cells finally rupture -
HAEMOLYSIS - releasing HAEMOGLOBIN which is toxic.
• Can cause kidney damage and shock (loss of blood to vital organs) and can be fatal.
ABO Interactions
Blood Type Compatible donor
Incompatible donor
A A, O B, AB
B B, O A, AB
AB A, B, AB, O None
O O A, B, AB
Universalrecipient
Universaldonor
Need the same
donor or O
Summary
A
AB
B
O
Rhesus System
1. First identified in Rhesus monkeys.
2. Based on the Rhesus antigen on red blood cells.
• Rh + people have Rh antigen (85% UK population)• RH - don’t (15% population) BUT CAN DEVELOP
ANTIBODY IF EXPOSED TO RH+.
So What?
• Complications can occur during pregnancy. A Rh- mother with Rh+ baby are at risk….
• Rh- mothers can destroy the baby's blood if this is the 2nd or 3rd pregnancy.
• The baby may have to receive a blood transfusion immediately after birth.
http://nobelprize.org/medicine/educational/landsteiner/index.html
HAEMOSTASIS stopping bleeding
Haemostasis
• Important to stop haemorrhage.
• Must remain localised.
• 3 stages:
1. Vascular spasm
2. Platelet plug formation
3. Blood coagulation (clotting)
1 Vascular Spasm
• Blood vessels contract.
• Reduces blood loss for up to 30 minutes.
http://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/m1/s7/trm1s7_3.htm
2 Platelet Plug Formation
• Plug to prevent blood loss in small vessels.
Serotonin (5-HT) causes vasoconstriction.Thromboxane A2 causes further platelet aggregation.
Platelets release chemicals
3 Blood Coagulation
• Blood thickens forming a gel/clotto prevent loss.
• Vitamin K essential for blood clotting.
• Chemical reactions for blood clotting are very complex and involve CLOTTING FACTORS.
Prothrombin activator
Extrinsic pathway Intrinsic pathwayOccurs in seconds.Triggered by enzymes “outside” the blood.FACTOR 3 and 7
Occurs in minutes.Chain reaction triggered“within” the blood.FACTOR 11 and 12
Prothrombin Thrombin
Dense Fibrin Threads
FACTOR 13
FACTOR 10
Fibrin
And afterwards…
• Fibrin clot retracts pulling the damagededges together.
• The blood clot dissolves.
Problems - Thrombosis
• Clot forms in a blood vessel e.g. deep vein thrombosis in legs.
• Can cut off oxygen supply causing tissue damage.
• Some might dislodge forming an EMBOLUS which can block smaller vessels in the brain or lungs (pulmonary embolism).
Anticoagulants
Warfarin - prevents prothrombin formation
Heparin - inactivates thrombin
Streptokinase - dissolves clots “clot buster”