Blood Clotting Serum blood clot gel Fibrin traps

Blood Clotting • Serum + blood clot gel – Fibrin traps formed elements • Coagulation • Thrombosis • Embolus

Blood Clotting • Chemicals involved: – Ca 2+ – Inactive enzymes – Molecules from platelets – Molecules from damaged tissues • Requires Vitamin K and Ca 2+ – Uncontrolled bleeding

Blood Clotting 1. Formation of prothrombinase – Via 2 pathways 2. Conversion of prothrombin into thrombin by prothrombinase 3. Conversion of fibrinogen into fibrin by thrombin

Prothrombinase Formation • TF = thromboplastin (lipoproteins + phospholipids) • Clotting factor X = thrombokinase • Factor V = proaccelerin • Factor XII = Hagemen factor

Thrombin Formation

Fibrin Formation • Factor XIII = fibrinstabilizing factor • (also in plasma + platelets)

Positive Feedback of Thrombin • Accelerates prothrombinase formation (clotting factor V) • Activates platelets = reinforces aggregation

Clot Retraction • “Shrinking” of a blood clot • Platelets pull on fibrin threads = contract vessel • Permanent repair of the blood vessel – Fibroblasts form CT in ruptured area – New endothelial cells repair vessel lining – Fibrinolytic mechanisms break down clot

• Quick assigned reading • Read “Homeostatic Control Mechanisms” page 679 -680

Blood Topics 1. 2. 3. 4. 5. 6. 7. 8. Functions and Properties of Blood Components of Blood Cell Formation Red Blood Cells White Blood Cells Platelets Hemostasis Blood Groups and Blood Transfusion

Blood Groups • The ABO blood types and Rh system are based on antigen-antibody responses – 24 blood groups – 100 antigens

Blood Groups • “Self-antigens” are located on RBC plasma membranes • Blood grouping based on presence/absence of selfantigens

Blood Groups

ABO Cross Matching Recipient Donor A B AB O A B AB O

Rh Group • Rh+ = expression of Rh antigen • Rh- = no expression of Rh antigen • Most people are Rh+ • Most people do not have Anti-Rh antibodies. • If an Rh- person is exposed to Rh+ blood, they will produce Anti-Rh antibodies.

Donations • Universal donor = O • Universal receiver = AB+ • These terms are dangerous! • Cross-matching

Blood Transfusion • Principles of Transfusion • Hemolysis occurs if recipient’s blood plasma antibodies interact with donor’s antigens

Hemolytic Disease of the Newborn

Key Terms • Agglutinins = antibodies • Agglutinogens = antigens • Incompatibility between them = aggluntination

Review Questions 1. What are the functions of the cardiovascular system? § Rapidly transports nutrients, respiratory gases, regulatory substances, waste products, and cells within the body. 2. What are the main components of the cardiovascular system? § Blood, Heart, Blood Vessels 3. What are the main components of blood? § Plasma – mostly water § Formed elements – RBCs, WBCs, platelets

Review Questions 4. Where are blood cells manufactured? § Red bone marrow 5. Name three kinds of hemopoietic growth factors. § Erythopoietin (EPO) § Thrombopoietin § Cytokines 6. What are the main functions of a RBC? § Transport oxygen bound to hemoglobin

Review Questions 7. What is erythropoiesis? § Formation of RBC from pluripotent stem cells myeloid stem cells 8. Which parts of hemoglobin are recycled and reused? § Amino acids protein synthesis § Iron (Fe 3+) stored / used for new RBC formation 9. Which WBCs are agranular? § Lymphocytes and monocytes 10. Which WBC is normally the most prevalent? § Neutrophils

Review Questions 11. List three platelet functions § Form platelet plug § Promote vascular spasm § Promote blood clotting (cascade) 12. What are three steps of hemostasis? § Vascular spasm § Platelet plug formation § Blood clotting

Review Questions 13. What are three main steps of blood clotting? § Formation of prothrombinase § Conversion of prothrombin into thrombin by prothrombinase § Conversion of fibrinogen into fibrin by thrombin 14. Which antigen(s) and antibody(s) are found in type A blood? § Antigen A § Antibody anti-B