Sunday, 17 July 2016

Blood

• Total circulating blood is 8% of total body weight
• Active bone marrow forming the blood cells is called red marrow and inactive marrow is called yellow marrow. Inactive marrow is filled with fats.
• 75% bone marrow belongs to white blood cells producing myloid series
• Neutrophils and monocytes are produced from single precursor. There are se[arate pools for proginators of megakaryocytes, lymphocytes, erythrocytes, eosinophils, and basophils
• Mast cells, kupffer cells, dendritic cells, osteoclasts and langerhans cells also originate from bone marrow
• Best source of hematopoitic stem cells is umbilical cord blood
• Average half life of nutrophils in circulation is 6 hours
• Nutrophils, eosinophols and basophills are collectively called granulocytes/polymorphonuclear cells
• Eosinophils are abundant in GIT and respiratory mucosa
• Mast cells are abundant in areas rich in connective tissue eg beneath epithelium
• Monocyte leave the circulation and become macrophages in tissues. They donot reenter the circulation.
• Pluripotent uncommitted stem cells become committed by the action of IL1, IL6 followed by IL3(I,3,6 commits the stem cells, kind of love guru )
• Cytokines are hormone like molecules that act generally in paracrine fashion
• IL1 increases slow wave sleep and reduces apetite
• Platelets don’t have nuclei.They have half life of 4 days and life span of 8 to 10 days..
Remember the above difference between life span n half life of platelets
• Splenectomy causes increase in circulation platelets.
• Cytoplasm of platelets contains actin, myosin, glycogen, lysosomes, and two types of granules
a. Dense granules: they have nonprotein substances. They contain serotoninand ADP
b. Alpha granules: contain clotting factors, PDGF
• Platelet production is controlled by colony stimulating factor and thrombopoitin. Thrombopoitin controls the maturation of megakaryocytes and is produced by kidney and liver.
• Osmotic fragility of RBC starts at 0.5% saline. Almost half the RBCs are lysed at 0.40 to 0.42% saline. Complete lysis occurs at 0.35% saline.
• 2.5 % hb in adults is HbA2
• Hb F has the ability to decrease the polymerization of deoxygenated HbS. Hydroxyurea causes HbF production and is used in treatment of HbS
• Blood group antigens are called aglutinogens
• Blood group antibodies are called agglutinins
• Blood group antigens are also present in salivery gland, saliva, kidney, pancrease, liver, lungs, testes, semen, and amniotic fluid
• A and B antigens are actually oligosaccharides that differ in their terminal suger. In RBCs they are mostly OLIGOSPHINGOLIPIDS and in other tissues they are glycoprotiens.(past MCQ)
• An antigen called H antigen is present in all RBCs in all individuals. In blood group A the A antigen is attached to H antigen, in blood group B the B antigen is attached to H antigen where as in blood group O no antign is attached to H antigen i.e terminal part of blood group O is H antigen(past MCQ). Blood group AB has both antigens at the terminal.
• Bilirubin rarely penetrates Blood brain barrier in adults. But in neonates and fetus the BBB is permeable to it an in erythroblastosis feotalis it causes KERNICTERUS
• If whole blood is allowed to clot and clot is removed, remaining is called serum. (plasma minus factor 2,5,8,fibrinogen is called serum)(past MCQ)
• Serum has high serotonin level due to breakdown of platelets.
• Thrombomodulin is produced by all endothelial cells except that of microcicculation of brain
• Thombin is procoagulant in circulation blood. It becomes anticoagulant when it binds to thrombomodulin
• Lymph has lower protein content than plasma..

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