Blood & Plasma are an important part of human.pptx

blood and plasma

1. B.Sc. III Semester Zoology System Physiology Unit 1: Blood cells and Plasma, Blood Coagulation and Blood Groups

2. Diagram showing the development of different blood cells from  hematopoietic stem cells  to mature cells

3. Mechanism of blood clotting When blood flows normally through blood vessels, the platelets are in their inactive state. Blood vessels are lined by cells called endothelial cells. When these cells are damaged due to injury, platelets are attracted to the site of damage. Endothelial cells are cells that form the thin, endothelial lining of blood vessels. This step is called adhesion, in which platelets adhere to the damaged portion of the blood vessel (Fig1). Once the platelets adhere at the site of damage, they become activated. Activated platelets release factors that attract more platelets, causing these platelets to adhere and be activated, too! All of the platelets aggregate together, eventually forming a temporary platelet plug that prevents the other components of the blood from freely leaking out of the damaged vessel, as shown in Figure 2.

4. Fig 1. A d iagram depicting a wounded blood vessel with a damaged wall, where platelets are attracted to the site of damage.

5. Figure 2 : A diagram depicting the formation of a platelet plug in the wall of a damaged blood vessel. The activated platelets release factors that attract more platelets to the site of damage.

6. The formation of the platelet plug triggers a cascade of biochemical reactions. The damaged blood vessels and the tissues surrounding blood vessels express the tissue factor, thromboplastin. This factor is responsible for converting a protein called prothrombin, which is produced by the liver, into thrombin, which is an active enzyme. This reaction takes place if calcium ions  (Ca)2+  are present. Blood also contains a protein called fibrinogen, which is produced by the liver and is soluble in blood plasma. When the enzyme thrombin is formed from prothrombin, it acts upon fibrinogen and converts it into fibrin, which is insoluble in blood plasma. The fibrin precipitates out of the blood as a network of microscopic fibers. The strands of fibrin formed in this way will reinforce the platelet plug by forming a net or a mesh, which traps red blood cells and more activated platelets. The fibrin, red blood cells, and platelets together form a stronger clot, effectively sealing the wall of the blood vessel and allowing it to heal, as shown in Figure 3.

7. Figure 3 : A diagram depicting the formation of a fibrin “net” that traps red blood cells and platelets and reinforces the platelet plug, forming the blood clot

8. Flow charts summarizing the steps involved in the process of blood clotting Figure 4 : A flowchart depicting the cascade of biochemical reactions involved in the process of blood clotting.

9. Blood clotting factors Factor I: Fibrinogen: Adhesive protein that aids in fibrin clot formation. Factor II: Prothrombin: Presence in the activated form and the main enzyme of coagulation Factor III: Tissue thromboplastin: Lipoprotein initiator of extrinsic pathway. Factor IV: Ionized calcium: Metal cation important in coagulation. Factor V: Proaccelerin or labile factor: Activation of prothrombin to thrombin. Factor VI: Stable factor: Initiates extrinsic pathway. Factor VII: Antihemophilic factor: Intrinsic activation factor. Factor VIII: Christmas factor: Enzyme for intrinsic activation. Factor IX: Stuart – Power factor: Forms prothrombinase complex. Factor X: Plasma thrombin antecedent: Activates intrinsic activator. Factor XI: Hegman factor: Activates antihemophilic factor. Factor XII: Fibrin stabilising factor: Cross links fibrin clot.

10. Blood Groups Blood Group System Karl Landsteiner, an Austrian scientist discovered the ABO blood group system in the year 1900. In his experiments, he mixed different blood types and noted that the plasma from certain blood type produced agglutinates or formed clusters which were caused by the absence of molecules on red blood cells and resulting in antibodies to defeat that molecule. He then made a note of the agglutination and divided the blood types into 4 different groups. For the discovery of ABO blood group, he was awarded the Nobel Prize. The blood grouping system is pivotal in blood transfusion. Our immune system recognizes another blood type as foreign and attacks it if introduced in the body causing a  transfusion reaction .  Any inappropriate match with the Rh and ABO blood types, causes the most serious and life-threatening transfusion reactions. Therefore, before blood transfusion, it is suggested to have a blood group checked.

11. ABO and Rh blood group In 1940 Landsteiner and Weiner discovered a different antigen in the blood of rhesus monkey which was later found to be present in the red blood cells of 85% human beings. Since the antigen was originally discovered in rhesus monkey, it was named the rhesus factor abbreviated to Rh and During the blood transfusion, the two most important group systems examined are the  ABO-system  and the  Rhesus system . The ABO blood group system consists of 4 types of blood group – A, B, AB, and O and is mainly based on the antigens and antibodies on red blood cells and in the plasma. Both antigens and antibodies are protein molecules in which antigens are present on the surface of Red Blood Cells and antibodies are present in the plasma which is involved in defending mechanisms. On the other hand, the Rh blood group system consists of 50 defined blood group antigens. In the Rh system, the most important antigens are D, C, c, E, and e. The ABO and Rh blood systems are discussed in detail below.

12. ABO blood Group system The basis of ABO grouping is of two antigens- Antigen A and Antigen B. The ABO grouping system is classified into four types based on the presence or absence of antigens on the red blood cells surface and plasma antibodies. Group A  – contains antigen A and antibody B. Group B  –contains antigen B and antibody A. Group AB  –contains both A and B antigen and no antibodies (neither A nor B). Group O  – contains neither A nor B antigen and both antibodies A and B. Blood group antibodies: The blood group antibodies belong to the serum globulins and may be divided into two broad classes: a) immune IgG, and b) naturally occurring, IgM

13. ABO blood group  antigens  present on  red blood cells  and  IgM   antibodies  present in the  serum

14. The ABO group system is important during blood donation or blood transfusion as mismatching of blood group can lead to clumping of red blood cells with various disorders. It is important for the  blood cells  to match while transfusing i.e. donor-recipient compatibility is necessary. For example, a person of blood group A can receive blood either from group A or O as there are no antibodies for A and O in blood group A. Rh Blood Group System In addition to the ABO blood grouping system, the other prominent one is the Rh blood group system. About two-thirds of the population contains the third antigen on the surface of their red blood cells known as  Rh factor  or  Rh antigen ; this decides whether the blood group is positive or negative. If the Rh factor is present, an individual is  rhesus positive  ( Rh+ve ); if an Rh factor is absent individual is  rhesus negative  (Rh- ve ) as they produce Rh antibodies. Therefore, compatibility between donor and individual is crucial in this case as well. About 15% human beings do not possess Rh antigen and called Rh negative. If the blood of a person containing Rh antigen is transfused into a person who lacks this antigen, recipient is said to be sensitized and the corresponding antibody (Rh antibody) will appear in his serum. Besides, red cells from a fetus carrying an antigen, inherited from its father but absent in mother may also produce the equivalent immune antibodies (IgG) by entering the maternal circulation through the placenta. No person is found to contain anti Rh bodies but an Rh- can develop if exposed to Rh antigen, blood transfusion with Rh + or Rh – woman who had borne Rh+ children.

15. Functional Anatomy of Heart, Cardiac Cycle, Cardiac Output and Electrocardiogram The  heart  is a muscular  organ  in most  animals . This organ pumps  blood  through the  blood vessels  of the  circulatory system . [1]  The pumped blood carries  oxygen  and  nutrients  to the body, while carrying  metabolic waste  such as  carbon dioxide  to the  lungs . In  humans , the heart is approximately the size of a closed  fist  and is located between the lungs, in the  middle compartment  of the  chest , called the mediastinum. In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right  atria  and lower left and right  ventricles . Commonly the right atrium and ventricle are referred together as the  right heart  and their left counterparts as the  left heart . Fish, in contrast, have two chambers, an atrium and a ventricle, while most reptiles have three chambers.

16. Different animal hearts

17. Structure of human heart

18. Structure of the Heart

19. The atrium and ventricle of the same side are Pulmonary artery and the aorta respectively are provided with the semilunar valves, the valves in the heart allows the flow of blood only in one direction, i.e. from the atria to ventricles and from ventricles to pulmonary artery or aorta. These valves prevent any backward flow.

20. Cardiac Cycle

21. Electrocardiogram: ECG

22. Nerve Supply The heart receives nerve signals from the  vagus nerve  and from nerves arising from the  sympathetic trunk . These nerves act to influence, but not control, the heart rate.  Sympathetic nerves  also influence the force of heart contraction. [35]  Signals that travel along these nerves arise from two paired  cardiovascular centres  in the  medulla oblongata . The vagus nerve of the  parasympathetic nervous system  acts to decrease the heart rate, and nerves from the  sympathetic trunk  act to increase the heart rate. [7]  These nerves form a network of nerves that lies over the heart called the  cardiac plexus . [7] [34]