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Definition -It is defined as the red colour fluid that circulates through vascular system of humans and other vertebrates and carries oxygen and various other nutrients to all parts of the body. Blood is fluid connective tissue, and it is called the fluid of life. Properties of blood →
- Color: It is red in color. Arterial blood is scarlet red due to more oxygen content whereas the venous blood is purple due to less oxygen content
- Volume: In a normal adult the volume of blood is 5L
- Reaction and pH: blood is alkaline in nature& its pH in normal conditions is 7.
- Specific gravity: of total blood -> 1, 092 to 1, 001 of blood cells -> 1, 092 to 1. 101 of plasma -1. 022 to 1. 026
- viscosity: blood is 5 times more viscous than water due to red blood cells and plasma proteins. Blood composition: blood contains cells which are called formed elements and the liquid portion known as plasma. → BLOOD CELLS Three types of cells are present: 1 )RBC or erythrocytes 2 )WBC or leucocyte 3 )Platelets or thrombocytes Hematocrit value : is the volume of RBC in blood expressed in percentage, also called packed cell volume.
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→ If blood is collected in a hematocrit tube with a suitable anticoagulant and centrifuge it for 30mins at 3000rpm then we see red blood cells settled at the boltan which make up 45% of blood, clear plasma is present at top making 55% of blood& a thin white Buffy layer is present between them which are the WBC and platelets agitated by centrifugation PLASMA → it is straw-colored clear liquid which is 91-92% water and 8-9% of solids which can be organic (Albumin, globulin) or inorganic (Na, K, Fe)and some gases (oxygen, carbon dioxide) Serum → is the clear fluid that oozes out from blood clot. Blood clots due to conversion of fibrinogen to fibrin. Serum is different from plasma only by the absence of fibrinogen. serum= Plasma - Fibrinogen BLOOD VOLUME → average volume of blood in a human is 5L and in a new born baby it is 150mL.Blood volume is about 8% of total body weight in a normal adult male weighing 70 kgs. In females it is slightly less, about 4.5L VARIATIONS OF BLOOD VOLUME → Physiological variations - 1 )Age: Blood volume increases with age. At birth or 24 hours after it is 80mL/kg for an adult which is about is year old it is 70 mL/kg. 2 )Sex: In males the blood volume is slightly more compared to females because of increased erythropoietic activity, body weight and surface area of the body. In females is less due to loss of blood through menstruation 3 )surface area of body: directly proportional 4 )Body weight: directly proportional 5 )Atmospheric temperature: cold-reduces BV warm-increases BV
functions of blood → 1 )Nutritive function : digested food is absorbed by gastrointestinal tract and carries it to other body parts by blood. 2 )Respiratory function : Blood carries oxygen to all parts of the body from lungs 3 )Excretory function : Blood carries waste products from cells and CO2 from all parts of the body to the excretory organs 4 )water balance 5 )Acid-base balance regulation : acts as a buffer 6 )Transport of hormones lenzymes : hormones which are secreted by ductless glands Endocrine are carried to target cell by blood. 7 )Body temp. maintenance : balance between heat loss and heat gain in the body. 8 )storage functions : acts as a readymade source for nutrients in cases of starvation 9 )Defense mechanism : Blood has WBCs.
→ RBCs or erythrocytes are the non-nucleated formed elements of Blood that appear red in color due to the presence of haemoglobin in it. → the normal RBC count ranges from 4 to 5. 5 mil/cu mm of blood. In males it is 5 mil/ cu mm and in females it is 4.5mil/ cu mm. → The normal life span of RBC is about 120 days, after which they are destroyed in reticuloendothelial system. Shape: the shape of RBC is biconcave or dumbbell shaped, that is, it is thinner in the middle and periphery portion is thicker. This structure has its own mechanical and functional advantages such as:
- Minimal tension is exerted on the surface/membrane when volume alters.
- It makes it easies for them to squeeze into the blood vessels without any damage.
- It makes diffusion of oxygen and other substances rapid and equal into the interior of the cell.
- This structure provides a large surface area for absorption or removal of substances. Normal size - diameter: 7. 2 M (6. 91 to 7. 1M) thickness: periphery 2. 2M and central IM surface area: 120 sqM volume: 85 m M to 90 cuM. → the RBC is non-nucleated and also does not have other cell organelles present in it such as Golgi apparatus or mitochondria. Due to the absence of mitochondria, energy is produced by glycolytic process. PROPERTIES →
- ROULEAUX FORMATION: When blood is taken out from blood vessels the RBCs pile up on one other like a stack of coins this is called rouleaux formation and it is promoted by plasma proteins such as fibrinogen and globulin.
- SPECIFIC GRAVITY: It is 1.092 to 1. 101
- PACKED CELL VOLUME: or hematocrit volume is volume of RBC expressed in percentage. It is 45% normally with plasma being 55%.
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functions →
- Transport of oxygen to lungs: oxygen combines with haemoglobin and gives rise to oxyhemoglobin. 97% of oxygen is transported throughout the body in this form.
- Transport of carbon-dioxide from lungs: the carbon-dioxide combines with hemoglobin and gives carbhemoglobin
- Buffer action in blood: hemoglobin acts as a good buffer. It regulates hydrogen ion concentration in the blood and hence plays a vital role in acid-base balance.
- Blood group determination: RBC carries the antigen and Rh factor which helps in determination of blood group. Variation in number of red blood cells- PHYSIOLOGICAL VARIATIONS → increase in number of RBC is called polycythemia. It occurs in both pathological and physiological conditions. In physiological conditions it is called physiological polycythemia and the conditions are marginal and temporary. It occurs in the following conditions:
- Age: in infants the RBC count is 8 to 10 mill/cu mm of blood. After birth in about 10 days the RBC count decreases. which causes excessive hemoglobin release and liberation of bilirubin which causes physiological jaundice 2 to 3 days after birth. It lasts for a few days.
- Sex: Before puberty and after menopause the number of RBCs is same in females and males but during reproductive period of females it decreases slightly.
- Muscular activities: causes increase in count due to mild hypoxia which increases sympathetic activity secretion of adrenaline by adrenal medulla which causes squeezing of spleen which in turn releases RBC in blood.
- Altitude: people which live 10, 000 feet above sea level have a higher RBC count due to less supply of oxygen: hypoxia.
- After meals: RBC count increases after meals.
- Emotional condition: Anxiety causes an increase in RBC count due to sympathetic activity and contraction of spleen. Due to increased metabolic activity.
- Environmental conditions: temperature increases RBC count. B. Decrease in RBC count:
- High barometric pressure: such as in deep sea, due to high oxygen tension RBC count decreases
- Sleep: all activities reduce during sleep.
- Pregnancy: During pregnancy RBC count reduces as ECF volume increases which increases plasma volume resulting in hemodilation. PATHOLOGICAL VARIATIONS → the RBC count increases to 7 mil/cu mm of blood. There are two types of polycythemia. Primary polycythemia: polycythemia vera The RBC count reaches 14 mil /cu mm of blood and is accompanied by increase in WBC count to about 24, 000. It is caused by malignancy in red bone marrow. Secondary polycythemia: it occurs due to disease in same other organ, such as:
- Repeated mild hemorrhages
- Chemical poisoning
- Ayerza's disease: hypertrophy of right ventricle and obstruction of blood to the lungs.
- Respiratory disease like emphysema
- Congenital heart disease
- Chronic carbon monoxide poisoning These cause hypoxia which stimulates release of erythropoietin Anemia: decrease in RBC count
Leukokpoiesis: development and maturation of leukocytes White blood cells or leukocytes are the colourless cellular elements of blood. Unlike RBC they have a nucleus and no fixed shape. WBC is larger in size but less in number in comparison to RBC, but still as important as it is. WBC plays a vital role in the defense mechanism of the body. on the basis of presence of granules WBC is classified - Neutrophils - » They are also called polymorphonuclear leukocytes as they have multi-lobed nucleus with the lobes varying from 1 to 6. → They have very fine or small granules which on staining with leishman's stain (has acidic eosin and basic methylene blue) take up the stain equally resulting in violet color → Neutrophils are ameboid and phagocytic in nature. → Their diameter is from 10 to 12 FUNCTIONS:
- Alongside monocytes, they provide the first line of defense against invading organism
- Move by diapadesis to the injured tissue by means of chemotaxis.
- They perform phagocytosis and engulf invading organisms
WHILE BLIND DELL
WBC V V Granulocytes Agranulocytes a (^). Neutrophils :^ take^ up both^ acidic^ basic^ stain^ a. Monocytes b. Eosinophils :^ take^ up^ only^ acidic^ stain^ b.^ Lymphocytes C. (^) Basophils :^ take^ up^ only^ basic^ stain M
Eosinophils » They have coarse granules which stain pink, orange with eosin. → They usually have a bilobed nucleus which is spectacle shaped. The nucleus is rarely trilobed. → The diameter is tran about 10 to 14 FUNCTIONS:
- Plays a role in defense mechanism by acting against parasitic infections and allergies.
- Responsible in detoxification, disintegration and removal of foreign proteins.
- Secrete cytotoxic substances which destroy invading species Basophils - » They have coarse granules that stain purple blue with methylene blue. → They nucleus is bilobed and the diameter is 8 to 10 FUNCTIONS:
- Involved in healing process and hypercentivity reactions.
- Basophils release histamine and heparin from their granules Monocytes » they do not have any granules, and are the largest leukocytes, with diameter 11 to 18 → The nucleus is round, oval, bean shaped or kidney shaped. It can either be present in the centre of the cell or be pushed to one side with large amount of cytoplasm visible. → Nucleus can also be horseshoe shaped. FUNCTIONS:
- They are motile and phagocytic, hence provide first line of defense along with neutrophils.
- They are precursors of macrophages. The mature monocyte stay in blood for a few hours after which they enter cells and form macrophages. Ex: Kupfers cells in lives, alveolas in lungs and macrophages in spleen. M M Wh
- Leukemia -it is a type of blood cancer caused by genetic mutation in DNA of bone marrow which causes increased production of immature and abnormal leukocytes. The leukocyte count reaches 10, 00, 000 /cu mm LIFE SPAN OF WBC -the life span of WBCs is not fixed, it varies with demand in body and their function. PROPERTIES →
- Diapedesis: It is the properties of WBCs to squeeze through narrow blood vessels.
- Phagocytosis: Monocytes and Neutrophils engulf foreign bodies by means of phagocytosis.
- Chemotaxis: the property of attraction of WBCs to injured tissues by the chemical substances released at site of injury. The site releases chemoattractants
- Ameboid movement: Neutrophils, monocytes and lymphocytes show amebic movement characterized by protrusion of cytoplasm. FUNCTIONS : Plays a vital role in bodies defense mechanism by protecting it from foreign bodies by either destroying or inactivating them. PUS and PUS CELS -It is the white yellowish formed at the infected tissue. They are the dead WBCS killed by toxins produced by bacteria during battle along with bacteria, serum, allular debris and foreign bodies. FACTORS NECESSARY FOR LEUKOPOIESIS → Leukopoiesis is influenced by hematopoietic growth factors and colony-stimulating factors. CSF → are proteins that cause formation of colony-stimulating blastocyst. Such as:
- Monocyte-CSF (M-CSF): produced by monocyte and endothelial cells
- Granulocyte -CSF(G-CSF): produced by monocyte and endothelial cells
- Granulocyte -Monocyte -CSF(GM-CSF): produced by monocyte, endothelial cells and T lymphocytes.
Stem cells → PLURIPOTENT STEM^ CELLS 2 * lymphoid colony-forming stene cell^ blastocyte I ~ Colony-forming (^) colony-forming unit lymphoblast unit^ -^ E^ (RBC) -^ m^ (platelets) ~ colony-forming unit-am lymphocyte (^) V MYELOBLAST ↓ PROMYCLOCYTE MONOBLAST ~ ~^ - BaSOPHIL NEUTROPHIL^ Eosinophil^ Premonocyte myelocyte MYCLOCYTE^ myelocyte^ ~ monocyte
- (^) v Basophil NEUTROPHIL ~ EOsiNOPHIL metamyelocyte meramyelocyte^ metamyelocyte V ~
Basophil NEUTROPHIL^ Eosinophil
→ The A blood group has two subgroups A, A2, hence AB also has 2 subgroups A1B and A2B. PRINCIPLE of BLOOD Typing → Agglutination: means the collection of separate particles like RBCs into clumps or masses. Agglutination occurs when a antigen is mixed with its corresponding antibody called isoagglutinin. REQUISITES FOR BLOOD TYPING -To determine a persons blood group a suspension of his RBC is required along with testing anti-sera. suspension of RBC is prepared by mixing blood drops with isotonic Saline (0. 9% ). The test sera are:
- Antiserum A, containing anti A
- Antiserum B, containing anti B PROCEDURE
- A drop of antiserum A is placed on one end of glass slide and a drop of antiserum B on the other end.
- A drop of RBI suspension is mixed with both antiserums rocked for 2 mins.
- Presence of agglutination is marked by clumping of blood and Absence of agglutination is marked by no clumping of blood. RESULTS:
- If agglutination occurs with antiserum A: then blood contained antibody A, hence it is a blood group
- If agglutination occurs with B: blood group is B.
- If agglutination occurs with both AB: blood group is AB.
- If agglutination is absent: blood group is 0. importance of ABO BLOOD GROUPS IN BLOOD TRANSFUSION - → The person that gives blood is called the donor and the person receiving it is called the recipient.
- The antibody of donor antigen of recipient is generally ignored.
- universal donor: O group does not have A or B antigen, the RBC can be accepted by any blood group.
- Universal recipient. As AB group has both antigen AB, it does not have any antibody present in the blood hence can accept blood from all blood groups.
MATCHING and CROSSMATCHING → · Blood matching typing is done to determine a persons blood group. It is a laboratory test. · Blood crossmatching is done before blood transfusion, to find out if the donors RBC will be accepted by recipients body. BLOOD MATCHING = RBC suspension (blood + isotonic saline 0. 9% )+ test anti-sera BLOOD CROSSMATCHING = Recipients serum + Donors blood if clumping occurs then the recipients body is rejecting the blood, hence blood transfusion want occur. INHERITANCE → blood group depends on two genes. One from each parent. A B gene are both dominant 0 is recessive. H Antigen → H antigen is precursor for ABO group antigens. All individuals have I antigen present in their body. Antigen A and antigen B form from H antigen and at times it may not hence belong to O group Rarely, some people might not have a antigen, B antigen or H antigen hence called Bombay group as it was found in Bombay first. TRANSFUSION REACTIONS DUE TO ABO INCOMPATIBILITY → transfusion reactions occur due to transfusion of incompatible blood. This reactions occurs between donors RBCs and the recipients plasma. If donors plasma contains antibodies against the recipients RBC, agglutination will not occur as donors antibodies are diluted in recipients blood. If recipients blood contains antibodies against donors blood the immune system launches a reaction against new blood cells. The RBC is agglutinated and hemolyzed which can cause -
- Jaundice: Hemoglobin is released from fragmented RBC, this haemoglobin is degraded into bilirubin. when bilirubin serum level rises above 2mg/dL it causes jaundice.
- Cardiac failure: increased hemoglobin release causes viscosity of blood to increase which adds pressure to heart to pump blood and causes cardiac arrest.
HEMOLYTIC DISEASE OF FETUS AND NEW BORN-ERYTHROBLASTOSIS FETALIS →
it is a disease characterized by abnormal hemolysis of RBCs. Hemolytic disease leads to erythroblastosis fetalis which is characterized by presence of erythroblasts in blood. when a mother is Rh negative and baby is Rh positive, during gestation period there would be no issues as Rh antigen cannot cross placental barrier from baby to mother but during parturition a little blood can leak from baby to mother due to placental barrier breaking. This will cause production of Rh antibodies in mother as an initial reaction. If there is a second baby that is Rh positive then issues can arise because RH ANTIBODIES CAN CROSS PLACENTAL BARRIER BUT RH ANTIGEN CANNOT There will be severe hemolysis taking place in the fetus which can result in jaundice. RBC production also increases, not only from bone marrow but spleen a liver as well. severe hemolysis can lead to:
- Severe anemia: due to jaundice
- Hydrops Fetalis: characterized by edema, enlargement of liver, spleen and can cause cardiac failure which may lead to intrauterine death.
- Kernicterus: it is brain damage caused by high bilirubin content due to jaundice. PREVENTION →
- If a case like above appears, then the mother should be given anti D during 28th 34th week of gestation, as well as within 48 hours of delivery of baby in order to provide passive immunity and avoid formation of th antibodies in mothers blood.
- If a infant has erythroblastosis fetalis then we should transfuse Rh negative blood in order to replace infants own Rh positive blood. It will take about 6 months for infants blood to replace Rh negative blood, by this time all an antibody molecules will get destroyed. This is called EXCHANGE TRANSFUSION OTHER BLOOD GROUPS →
- I group
- P group
- Kell group
- Bombay group
- Ridd group
- sutter group
IMPORTANCE OF KNOWING BLOOD GROUP →
- medically, for blood transfusion tissue transplant
- Socially, so the individual can join Blood donors club and make them approachable during time of need.
- can help avoid erythroblastosis retalis.
- Judicially, helpful in mediocolegal cases to sort out parental disputes
