blood

Dr. Nithin Mathew – Gingiva

Contents• Introduction• Composition• Functions of Blood• Plasma Proteins

• Origin• Forms of plasma proteins• Variations in Plasma protein concentration• Functions of plasma proteins

• Haemoglobin• Structure• Normal Values• Functions

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• Synthesis of Haemoglobin• Catabolism of Haemoglobin• Varieties

• Erythrocytes / Red Blood Corpuscles (RBC)• General Characteristics• Variations in size, shape and structure of RBC• RBC indices• Erythropoiesis• Anaemias

• Pernicious Anaemia• Folic Acid Deficiency Anaemia• Iron Deficiency Anaemia• Sickle Cell Anaemia• Thalassaemia 4


• Leucocytes / White Blood Corpuscles (WBC)• General characteristics• Structure, Functions & Variations• Leucopoiesis

• Platelets / Thrombocytes• General Characteristics• Count & Variations• Thrombopoiesis/Megakaryocytosis• Functions

• Coagulation of Blood & Bleeding Disorders• Definition• Mechanism of Haemostasis• Clotting Mechanism

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• Anticoagulant Mechanism• Bleeding Disorders

• Blood Groups• Classical ‘ABO’ blood groups• Rhesus Blood Group• Uses of blood grouping tests• Significance of blood groups

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Composition

• The human vascular system consists of approximately70,000 miles of blood vessels.

• Blood vessels, along with the heart, are responsible forthe circulation of blood throughout the body.

• Maintains several functions in the body

• Total Blood Volume : 5 – 6 Litres (8% of total body weight/ 80ml/kg body weight)

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• Specific Gravity : 1050 – 1060

• Viscocity : 4 – 5 times that of water

• pH : 7.4 ± 0.05

• Blood, when allowed to stand, on settling, it will separate into two components• Liquid – Plasma (55%)• Solid – Formed Elements (45%) : RBC, WBC, Platelets

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CELLS

• Cellular elements of blood – 45%• Aka Packed Cell Volume (PCV) or Haematocrit

• Erythrocytes : 5 million/mL• Leucocytes : 4000 – 11000 cells/mL• Platelets : 1.5 – 4 lacs/mL

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PLASMA

• Clear, straw colored fluid

• 55% of total blood volume• 91% water• 9 % solids

• 1% inorganic molecules : Na+, Ca2+, Cl-, HCO3-, K+, Mg2+, Cu2+, PO4

3-

• 8% organic molecules : 7% plasma proteins, 1% Non-protein Nitrogenous(NPN) substances, sugars, fats, enzymes, hormones

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PLASMA

• Plasma proteins : 6.4 – 8.3 gm/dL• 55% Albumin : 3 – 5 gm/dL• 38% Globulin : 2 – 3 gm/dL• 7% Fibrinogen : 0.3 gm/dL• Prothrombin : 40 mg/dL

• Albumin : Globulin = 1.7 : 1

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Non-protein Nitrogenous (NPN) substances : 28-4-mg/dL• Derivatives of food and also waste products of tissue catabolism• Includes:

• Urea : 20 - 40 mg/dL• Uric Acid : 2 - 4 mg/dL• Creatinine : 1 - 2 mg/dL• Creatine : 0.6 - 1.2 mg/dL• Xanthine : Traces• Hypoxanthine : Traces

Other substances• Neutral fats : 30 - 150 mg/dL• Phospholipids : 150 - 300 mg/dL• Glucose : 70 - 90 mg/dL• Cholesterol : 120 - 200 mg/dL

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Functions of blood

• Respiratory• Transports oxygen from lungs to tissues and carbon dioxide from tissues to

lungs

• Nutritive• Transports absorbed food materials, amino acids, fatty acids, vitamins, etc from

alimentary canals to tissues

• Excretory• Transports metabolic wastes to kidney, skin and intestine for their removal

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• Regulation of body temperature• Blood preserves the very narrow range in body temperature with the help of

water since water hasi. High specific heat – buffers sudden change in body temperature.ii. High conductivity – helps to take out heat from an organ for uniform

distribution throughout the body.

• Chemical for communication and protection• Concentration of hormones and various substances in blood is regulated

through feedback mechanisms• Defensive action against infections, initiation of inflammation and regulation of

haemostasis

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• Plasma protein functions• Exerts the osmotic pressure which influences the exchange of fluid between

blood and tissues• Acts as reservoir of proteins• Combines with many substances such as iron, thyroxine, steroid hormones, to

form transportable complexes from which the active components are released

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Plasma Proteins• Clear, straw colored fluid• 55% of total blood volume

ORIGIN OF PLASMA PROTEINS

• Embryo: Mesenchymal cells through the process of secretion or dissolution oftheir substances, form plasma proteins

• Adults:i. Albumin from liver mainlyii. Fibrinogen from liveriii. Globulin from tissue macrophages, plasma cells and lymphocytes

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FORMS OF PLASMA PROTEINS

• Normal plasma protein conc.: 6.4 – 8.3 gm/dL

Type Normal plasma level55% 1. Pre-Albumin 0.03 gm/dL

2. Albumin 3 – 5 gm/dL

38% Globulin 2 – 3 gm/dL

7% Fibrinogen 200 – 450 gm/dL

Prothrombin 40mg/dL

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Types of Globulini. 13% α-globulin (α 1; α 2) : 0.78 – 0.81 gm/dLii. 14% β-globulin (β 1; β 2) : 0.79 – 0.84 gm/dLiii. 11% ϒ-globulin (ϒ 1; ϒ 2) : 0.66 – 0.70 gm/dL

Forms of Globulin

1. Glycoprotein: Carbohydrate + protein2. Lipoprotein: α 2 –globulin + lipid, water-soluble complex with following subtypes..

I. High Density Lipoprotein (HDL) – contains 50% protein with large amount ofcholesterol and phospholipids.

II. Low Density Lipoprotein (LDL) – contains large amount of glyceridesIII. Very Low Density Lipoprotein (VLDL) – they have higher proportion of fat in the

form of triglycerides or cholesterolIV. Chylomicrons – contains 2% protein and 98% triglycerides

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3. Transferin• Normal conc.: 3-6.5 mg/dL• Functions:

• Regulates and controls iron absorption• Protects against iron intoxication• Helps in iron transport

4. Haptoglobulins• Normal conc.: 40 – 180 mg/dL• Functions:

• Prevents loss of iron through urinary excretion• Protects the kidney from damage by haemoglobin• Regulates the renal threshold for haemoglobin

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5. Ceruloplasmin• Normal conc.: 15 – 60 mg/dL• Binds with copper and helps in its transport and storage

6. Fetuin• Present in foetus and new borns• It is a Growth promoting protein

7. Coagulation factors8. Angiotensinogen9. Haemagglutinins10. Immunoglobulin

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Variations in plasma protein concentration

• Decrease:- Haemorrhage results in loss of all forms of plasma proteins- After haemorrhage, fibrinogen, globulin and albumin are regenerated and

complete restoration in few days

• Increase:- Because of loss of more water from the plasma secondary to burns,

dehydration and diabetes insipidus

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Variations in plasma protein concentration

Decrease in Albumin

• Physiological Infancy and newborns Pregnancy (during first 6 months). Globulin also decreases

• Pathological Impaired protein synthesis due to

oHepatitis, cirrhosis of liver, chronic diseases, severe malnutrition

Excessive loss due tooBurns, Nephrosis

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Functions of Plasma Proteins1. Helps in coagulation

• Due to presence of fibrinogen, prothrombin and other clotting factors

2. Helps to maintain colloidal osmotic pressure (COP) across capillary wall• COP across capillary walls helps to maintain the exchange of fluid at tissue

level• The rate of fluid exchange( ie filtration-absorption) at anypoint along a capillary dependsupon a balance of forces calledStarling Forces.

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3. Helps in maintaining viscosity of blood• Since 80% of total plasma concentration is due to albumin, and fibrinogen

is present on traces, blood viscosity is maintained at low level.

4. Helps in maintaining systemic arterial blood pressure constant• Plasma proteins maintain the blood pressure constant by maintaining the

viscosity of blood.

5. Provides stability to blood• Due to presence of globulin and fibrinogen• If blood loses its stability, lead to Rouleaux formation

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6. Helps in maintaining acid-base balance in the body• Plasma proteins act as buffers• Buffering capacity is 1/6th of total buffering capacity of blood• Amphoteric in nature : behave as both acids and bases depending on

conditions

7. Transport and Reservoir function• Plasma proteins form loose bond with hormones, drugs and metals to serve as

reservoirs and from which they are released slowly at appropriate sites.

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Haemoglobin• Red, oxygen carrying pigment in the RBCs• Consists of protein Globin united with the pigment Haeme

STRUCTURE• Consists of:

• 4 globin molecules: consists of 2 α and 2 β chains• Each α chain contains 141 amino-acids• Each β chain contains 146 amino-acids

• 4 heme molecules: Transport oxygen• Iron is required for oxygen transport

• Each chain is associated with one haeme group• There are 4 haeme to 1 molecule of haemoglobin, so

it can carry 4 molecules of oxygen.27


NORMAL VALUES

• At birth: 23gm/dL (since RBC count is more)

• At the end of 3 months: 10.5gm/dL (since infant is milk fed which is devoid ofiron)

• After 3 months: haemoglobin increases gradually

• At the end of 1 year: 12.5gm/dL

• Adults:• Males: 14 – 18 gm/dL• Females: 12 – 15.5 gm/dL

• Clinically 14 – 18 gm/dL irrespective of sex is regarded as 100% haemoglobin29


Some Definitions of Haemoglobin

• OxyHaemoglobin• When Hb reacts with oxygen to form Oxyhaemoglobin• Affinity of Hb for oxygen is influenced by pH, temperature and concentration of

2,3 diphospho-glycerate (2,3 DPG) in the RBCs, a product metabolism ofglucose.

• CarbaminoHaemoglobin• Carbon dioxide reacts with haemoglobin to form carbaminohaemoglobin.

• Reduced (Deoxygenated) Haemoglobin• Haemoglobin from which oxygen has been removed.

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• CarboxyHaemoglobin• Carbon monoxide reacts with haemoglobin to form carboxyhaemoglobin• Affinity of Hb for Carbon monoxide is 210 times than its affinity for oxygen

which consequently displaces oxygen on haemoglobin, thus reducing theoxygen carrying capacity of blood.

• Methemoglobin• When reduced or oxygenated haemoglobin is exposed to various drugs or

oxidising agents, the compound is called methemoglobin.• Disadvantages:

• It cannot unite reversibly with gaseous oxygen• Dark colored and when present in large quantities in circulation, it mimics

cyanosis.

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Functions

• Facilitate transport of oxygen from the lungs to the tissues

• Facilitate transport of CO2 from the tissues to the lungs

• Acts as an excellent acid-base buffer, being a protein. It is responsible for 70% ofbuffering capacity of whole blood.

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Synthesis of Haemoglobin• Begins to be produced during the proerythroblast stage of the RBC cycle.

• The synthesis takes place in the mitochondria and ribosome by a series ofbiochemical reactions.

• In the mitochondria, the synthesis of the heme portion of hemoglobin takes place.Here, heme synthesis begins with the condensation of glycine & succinyl-CoA toform δ-aminolevulinic acid (ALA).

• ALA then leaves the mitochondria and form porphobilinogen through a series ofreaction forms coproporphyrinogen. This molecule then returns to themitochondria and produce protoporphyrin.

• Proto-porphyrin is then combined with iron to form heme. Heme then exits themitochondria and combines with the globin molecule which is synthesized in theribosome.

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Fate of Haemoglobin in the body

Haemoglobin

HAEMEGLOBIN

Remaining part Fe2+

BILIVERDIN

BILIRUBIN

FERRITIN

Tissue macrophage system

(Split off)

Oxidised by Haem Oxygenase

Reduced by Biliverdin Reductase(Stored in liver)

Combines with APOFERRITIN( tissue protein )

Reused for synthesis of Haemoglobin

(Enters aminoacid pool)

(Excreted in bile)

(Split off)

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Varieties of Haemoglobin

1. ADULT HAEMOGLOBIN (HbA)• 2 types:

i. Haemoglobin A (α2β2)ii. Haemoglobin A2 (α2δ2) :

• Here β chains are replaced by δ chains.• The δ chains also contain 146 amino acids but 10 individual amino

acids differ from those in the β chain.• It produces no abnormality and is regarded as normal haemoglobin

• HbA appears in foetus after 5 months of intrauterine life, when bone marrowbegins to function.

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2. FOETAL HAEMOGLOBIN (HbF – α2ϒ2)

• Structure is same as HbA except that β chains are replaced by ϒ chains.

• ϒ chains also contains 146 amino acids but have 37 amino acids that differ

from those in the β chains.

• It is much more resistant to the action of alkalies than HbA.

• HbF has greater affinity for oxygen because of poor binding of 2,3 DPG to the

ϒ-polypeptide chain, so it can take much larger volume of oxygen than HbA at

low oxygen pressure.

• Life span is less (about 80days) compared to that of HbA (120days)

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3. HAEMOGLOBIN-S (HbS)• When HbS is reduced, it becomes much less soluble than HbA.

• Haemoglobin precipitates into crystals within RBC’s causing the following:

• Damages cell membrane producing increased fragility of RBC’s

• Crystals elongate and RBC’s become sickle shaped which decreases theblood flow to the tissues due to sickling.

• This causes RBC’s to become more fragile producing severe anaemiacalled sickle cell anaemia.

• Finally patient dies within a few days due to severeanaemia and secondary infection

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Erythrocytes / Red Blood Corpurscles• RBC is a circular, biconcave, non-nucleated disc

• RBC cell membrane contains circular pores below which lies a contractile layer oflipoproteins – spectrin : which maintains the shape and flexibility of RBCmembrane.

• Spectrin also contains the specific blood group antigen.

• Composition:• 62.5% water• 35% haemoglobin• 2.5% sugar, lipids, protein, enzymes

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• Diameter: 6.5-8.8 µm• Thickness:

• Periphery: 2-2.4 µm• At the centre: 1.2-1.5 µm

• Surface area: 140 µm2

• Volume: 78-94 µm3

• Count:• At birth: 6-7 million cells/ mL• Adults: Male – 5-6 million cells/ mL

Female – 4.5 – 5.5 million cells/ mL

• Life span: 120 days40


Variation in Size, Shape & Structure

1. Anisocytosis: Variation in size of RBC2. Poikilocytosis: Variation in the shape of RBC3. Spherocytosis: Spherical RBCs; more fragile4. Anaemia: Reduction in the number of RBS less than 4 million cells/ mL or their

haemoglobin content less than 12gm/dL or both5. Polycythemia: RBC count increases more than 6 million cells/ mL

• Causes:• Physiological

• At birth• At high altitude due to chronic hypoxia

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• Pathological• Congenital heart diseases which produces hypoxia• Dehydration• Shock• Tumour of bone marrow (Polycythemia Vera) [ 7-8 million cells/ mL]

6. At birth• RBCs are larger in size and count is 6-7 million cells/ mL• PCV is 54% since count is more• Reticulocytes are 2-6% of RBC count. Decrease to less than 1% during first

week after birth after which they level and maintain throughout the life.

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RBC IndicesThey help in diagnosing the type of anemia.

MEAN CORPUSCULAR VOLUME (MCV)

• It is the volume of a single RBC in fL.

• MCV = PCV per 100ml blood × 10fLRBC count in million cells/ mL

• Normal range: 78-94fL• RBC with normal volume – Normocytes• RBC with less than normal volume – Microcytes• RBC with more than normal volume - Macrocytes

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MEAN CORPUSCULAR HAEMOGLOBIN (MCH)

• It is the average amount of haemoglobin in a single RBC in picogram or micro-microgram

• MCH = Haemoglobin in gm/dL × 10pgRBC count in million cells/ mL

• Normal range: 28 - 32pg• This index is not in use to find out the type of anaemia

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MEAN CORPUSCULAR HAEMOGLOBIN CONCENTRATION (MCHC)

• It is the amount of haemoglobin expressed as percentage of the volume of RBC or itis the haemoglobin concentration in a single RBC

• MCHC = Haemoglobin in gm/dL × 100PCV per 100ml of blood

• Normal : 33% (33gm/100ml of cells)• If MCHC is within normal range, then RBC is Normochromic• If MCHC is less than normal range, then RBC is Hypochromic

• MCHC is never more than 38%, since cells cannot hold Hb beyond its saturationpoint

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COLOR INDEX (CI)

• Ratio of haemoglobin to RBC

• CI = Hb % = 100 = 1 (Range: 0.85-1.15)RBC % 100

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Significance of Absolute Values

• In Iron Deficiency Anaemia and Thalassaemia, MCV, MCH and MCHC are reduced.

• In anaemias due to acute blood loss and haemolytic anaemia, MCV, MCH andMCHC are all within normal limits.

• In megaloblastic anaemia, MCV is raised above the normal level.

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ERYTHROPOEISIS

Development of RBC is termed erythropoiesis

In Intrauterine life – 3 stages

1. Mesoblastic stage• Early embryo upto 3 months of foetal life• RBCs are formed from the mesoderm of yolk sac or area vasculosa.• Since erythropoiesis occurs within the blood vessel, this stage is also called

intravascular erythropoiesis.2. Hepatic stage

• After 3 months of foetal life• Liver and spleen are the site of blood formation• Nucleated RBCs develop from mesenchyme between blood vessels and tissue

cells• This stage is also called extravascular erythropoiesis.

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3. Myeloid Stage• From middle of foetal life• Erythropoiesis occurs in the bone marrow• This stage is also called extravascular erythropoiesis.

In children• All bones with red marrow• Liver• Spleen

In Adults• After 18-20years, from red bone marrow• Ends of long bones like humerus and femur• Skull, vertebrae, ribs, sternum, pelvis• If marrow is destroyed then liver and spleen become important sites of

blood formation49

Terminology Cell Size Nucleus Cytoplasm Mitosis

Staining Haemoglobin

HAEMOCYTOBALST(STEM CELL)

19-23 µm Very big – occupies whole of the cell, 4-5 nucleoli

Rim all around the nucleus, deep basophilic

Absent Mitosis ++

PROERYTHROBLAST 15-20 µm Occupies 3/4th of cell volume, 2-3 nucleoli

Slightly more in amount, deep basophilic

Absent Mitosis ++

EARLY NORMOBLAST 14-16 µm Size decreases, no nucleoli Further increase in amount, less basophilic

Absent Mitosis ++

INTERMEDIATE NORMOBLAST

10-14 µm Nucleus size decreases Marked cytoplasm, polychromatophilic staining

Starts appearing Mitosis ++

LATE NORMOBLAST

i. EARLY 8-10 µm Nucleus very small with chromatin dot – Cartwheel Appearance

Increases markedly Increases in amount

Mitosis stops

II. LATE 7-8 µm Nucleus degenerates, becomes uniformly deeply stained

Futher increases, more acidic, less basophilic

Further Increases in amount

Absent

RETICULOCYTE 7-8 µm No nucleus, remants of RNA present

Acidophilic Further Increases in amount

Absent

ERYTHROCYTE 7.2–7.4 µm

Nil Acidophilic Increases in amount

Absent

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ERYTHROPOEISIS

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Regulation of Erythropeisis


ANAEMIA

Definition• Clinical condition characterised by reduction in the number of RBCs less than 4

million cells/mL or their content of haemoglobin less than 12 gm/dL or both

GRADING

• Mild Anaemia: Hb 8-12gm/dL• Moderate Anaemia: Hb 5-8gm/dL• Severe Anaemia: Hb less than 5gm/dL

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CLASSIFICATION

1. Etiological classification

• Haemorrhagic: anaemia due to blood loss• Dietary deficiency: due to iron, vitamins and proteins• Dyshaemopoiesis or abnormal haemopoeisis resulting in aplastic anemia

• X-ray irradiations• ϒ-ray irradiation• Hypersenstitivity of bone marrow to drugs

• Haemolytic anaemias: due to excessive destruction of RBCs

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2. Morphological or Wintrobe’s Classification

• Based on size of RBCs and its haemoglobin concentration

Normochromic Hypochromic

Normocytic i. After acute haemorrhageii. All haemolytic anemias except

Thalassaemiaiii. Aplastic anaemia

After chronic haemorrhage

Macrocytic All megaloblastic anaemias due to deficiency of Vit. B12, folic acid or intrinsic factor

Secondary to liver disease

Microcytic Chronic infections i. Iron def. anaemiaii. Thalassaemia

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PERNICIOUS ANAEMIA / ADDISONS ANAEMIA

Pernicious means destructive or injurious

• Cause:• Due to lack of intrinsic factor• Failure of absorption of Vit. B12

Characteristic features• Bone Marrow:

• Anaemia produces hypoxia which results in stimulation of erythropoiesis inbone marrow with maturation arrest, so bone marrow becomeshyperplastic

• This over activity of bone marrow is called Megaloblastic Anaemia

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• Blood changes:• RBC : Macrocytic Normochromic

• Count decreases markedly, less than 1 million cells/mL• Hb content: less than 12gm/dL• Diameter increases to 8.2 µm• MCHC is usually normal because both MCV and MCH increase• Peripheral smear shows nucleated RBC• Reticulocyte count is increases more than 5%

• WBC and platelets both increase

• Changes in GIT:• Deficiency of intrinsic factor• Atrophy and destruction of gastric mucosa causing marked or complete lack of gastric

juice production (Achlorhydria)• Soreness and inflammation of the tongue• Loss of appetite• Diarrhoea

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• Changes in nervous system:• Advanced cases, demyelination white fibres of spinal cord which affects the

dorsal column initially, later lateral columns – Subacute CombinedDegeneration of Spinal Cord

• This is associated with tingling and numbness in hands and feet, motor andpsychological disturbances.

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FOLIC ACID DEFICIENCY ANAEMIA

Folic acid deficiency also produces Megaloblastic Anaemia

• Cause:• Less dietary intake• Poor absorption from GIT• Increased demand (pregnancy)• Antifolate drugs (anti-cancer drugs)

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IRON DEFICIENCY ANAEMIA

Commonest anaemia in india

Definition:Any Anaemia which responds to adequate dosage of iron is called iron

deficiency anaemia.

• Causes:• Less dietary intake• Increased loss:

• Acute haemorrhage• Chronic hemorrhage

• Increased demand (infancy, childhood, pregnancy)• Defective utilisation due to decreased absorption in diseases of stomach and

duodenum60


• Characteristic Features:1. RBC – Microcytic hypochromic

i. Count decreases or remains normalii. MCV,MCH,MCHC, CI decreaseiii. Life span – normaliv. Peripheral smear shows anisocytosis and poikilocytosis

2. Bone marrow – Normoblastic hyperplasia3. WBC and Platlets – normal count4. Investigations

i. Serum bilirubin less than 0.4 mg/dLii. Serum iron decreases (normal: 60-160 µgm/dL)iii. Total iron binding capacity TIBC – increases (normal: 150-350 µgm/dL)

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5. Nails – dry, soft, spoon shaped6. Tongue – angry red7. CardioVascular/Respiratory system –

i. Early breathlessnessii. Palpitationsiii. Repeated chest infections

8. Nervous systemi. Irritabilityii. Loss of concentrationiii. Headacheiv. Generalized body achev. Impotence

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SICKLE CELL ANAEMIA

A serious condition in which red blood cells can become sickle-shaped

Normal red blood cells are smooth and round and so move easily through bloodvessels to carry oxygen to all parts of the body.

Sickle-shaped cells don’t move easily through blood. They’re stiff and sticky andtend to form clumps and get stuck in blood vessels.

The clumps of sickle cell block blood flow in the blood vessels that lead to the limbsand organs.

Blocked blood vessel can cause pain, serious infection, and organ damage.

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INHERITANCE of SICKLE CELL ANAEMIA

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• If one parent has sickle cell anaemia(HbSS) and the other is completelyunaffected (HbAA) then all the childrenwill have sickle cell trait.

• None will have sickle cell anemia.

• The parent whohas sickle cellanemia (HbSS) canonly pass the sicklehemoglobin geneto each of theirchildren.

• If both parents have sickle cell trait(HbAS) there is a one in four (25%)chance that any given child could beborn with sickle cell anemia.

• There is also a one in four chance thatany given child could be completely

unaffected.

• There is a one intwo (50%) chancethat any givenchild will get thesickle cell trait.


Clinical Features:

• Most common symptom of anemia is fatigue (tired & weak)• Shortness of breath• Dizziness• Headaches• Coldness in the hands and feet• Paler than normal skin or mucous membranes• Jaundice

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Complications:• Hand-Foot Syndrome• Splenic Crisis• Infections• Acute Chest Syndrome• Pulmonary Hypertension• Delayed Growth and Puberty in Children• Stroke• Eye Problems• Gallstones• Ulcers on the Legs• Multiple Organ Failure

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THALASSAEMIA

• Heritable, hypochromic anemias with varying degrees of severity

• Result of defective production of globin portion of hemoglobin molecule.

• May be either homozygous defect or heterozygous defect.

• Defect results from abnormal rate of synthesis in one of the globin chains.

• Globin chains are structurally normal, but have imbalance in production of twodifferent types of chains.

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• Results in overall decrease in amount of hemoglobin produced and may inducehemolysis.

• Two major types of thalassemia:• Alpha (α) - Caused by defect in rate of synthesis of alpha chains.• Beta (β) - Caused by defect in rate of synthesis in beta chains.

• Alpha thalassemia usually caused by gene deletion.• Beta thalassemia usually caused by mutation.

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Beta (β) Thalassemia

• Two types:• Beta thalassemia minor• Beta thalassemia major

BETA THALASSEMIA MINOR

• Caused by heterogenous mutations that affect beta globin synthesis.

• Usually presents as mild, asymptomatic hemolytic anemia unless patient in understress such as pregnancy, infection, or folic acid deficiency.

• Have one normal beta gene and one mutated beta gene.

• Hemoglobin level in 10-13 g/dL range with normal or slightly elevated RBC count.

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• Anemia usually hypochromic and microcytic including target cells andelliptocytes.

• Hepatomegaly or Splenomegaly are rarely seen.

• Have high Hb A2 levels (3.5-8.0%) and normal to slightly elevated Hb F levels.

• Normally require no treatment.

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BETA THALASSEMIA MAJOR

• Characterized by severe microcytic, hypochromic anemia.

• Detected early in childhood:• Infants fail to thrive.• Have pallor, variable degree of jaundice, abdominal enlargement, and

hepatosplenomegaly.

• Hemoglobin level between 4 and 8 gm/dL.

• Severe anemia causes marked bone changes due to expansion of marrow space forincreased erythropoiesis.

• Characteristic changes are seen in skull, long bones, and hand bones.

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• Physical growth and development delayed.

• Peripheral blood shows markedly hypochromic, microcytic erythrocytes withextreme poikilocytosis, such as target cells, teardrop cells and elliptocytes.

• Hemoglobin electrophoresis shows• Increased Hgb A2—delta globin production• Increased Hgb F—gamma globin production

• Hyperbilirubinemia

• MCV in range of 50 to 60 fL.

• Iron overload—increased absorption and transfusions• Endocrine disorders, Cardiomyopathy, Liver failure

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Leucocyte / White Blood Corpuscles

• White cells, or leukocytes , exist in variable numbers and types but make up avery small part of blood's volume--normally only about 1% in healthy people.

• Protect body against microorganisms and remove dead cells and debris

• Most are produced in the bone marrow from the same kind of stem cells thatproduce red blood cells and others are produced in the thymus gland, which is atthe base of the neck.

• Individual white cells usually only last 18-36 hours before they also are removed,though some types live as much as a year

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Different types of leucocytes present in the circulation are:

Granulocytes• WBC with granules in their cytoplasm

i. Neutrophils 50 - 70% 3000 - 6000 cells/mLii. Eosinophils 1 - 4% 150 - 300 cells/mLiii. Basophils <1% 10 - 100 cells/mL

Agranulocytesi. Lymphocytes 20 – 40% 1500 - 2700 cells/mLii. Monocytes 2 – 8% 300 - 600 cells/mL

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Total Leucocyte Count (TLC)

• At birth: 20,000 cells/mLcount decreases after 2nd week and reaches normal in 5-10yrs

• In adults: 4000 – 11000 cells/mL

Leucopenia: TLC decreases less than 4000 cells/mL• Causes:

• Starvation• Typhoid• Viral infection• Bone marrow depression

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Leucocytosis: TLC increases above 11000 cells/mL• Causes:

• New born• In the evening• Exercise• After injection of epinephrine or nor-epinephrine• Stress• Pregnancy• Steroid administration• Pyogenic or pyrogenic infections

Leukemia: cancerous condition of blood in which TLC is more than 50000 cells/mL

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Structure, Function & VariationsStructure is seen by Leishman’s staining – haematoxylin-eosin stain

NEUTROPHIL

• Size: 10-14 µm• Nucleus:

i. Purple in colorii. Multilobed (1-6 lobes) – polymorphonucleariii. Young cells have horse-shoe shaped nucleusiv. Older cells – multilobed, lobes are connected by chromatin threads

more the number of lobes, more mature is the neutrophil

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• Cytoplasm:i. Slightly bluish in colorii. Granules

a. Fine sand like particles called ‘pin-point’ granulesb. Neutrophilic in nature (take both acidic and basic stains)c. Contains variety of enzymes, so granules are regarded as lysosomesd. Granulocytes liberate histamine and peroxidase enzyme which aids in

killing ingested bacteria

• Functions:i. Phagocytosis : neutrophils are the first line of defence against bacterial

infectionsii. Contain fever producing substance – endogenous pyrogen

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• Neutrophilia:Causesi. Physiological

a. Exerciseb. After injection of epinephrinec. Pregnancy, menstruation, lactation

ii. Pathologicala. Acute pyogenic infectionsb. Following tissue destruction

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• Neutropenia:Causes

i. In childrenii. Typhoid, paratyphoid feveriii. Viral infectioniv. Bone marrow depression

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EOSINOPHIL


i. Purple in colorii. Bilobed – 2 lobes connected by chromatin thread

producing spectacle appearance

• Cytoplasm:i. Acidophilic, slight pink in colorii. Granulariii. Granules

a. Coarseb. Stain bright red with acidic dyec. Granules do not cover nucleusd. They contain peroxidase enzymes and lysozymes

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• Functions:i. Mild Phagocytosisii. They collect at sites of allergic reactions and limit their intensity by degrading

the effects of inflammatory mediators (histamine, bradykinin)iii. They attack parasites that are too large to be engulfed by phagocytosis

• Eosinophilia:Causes

i. Allergic conditionsii. Parasitic infectionsiii. Skin diseases

• Eosinopenia:Causes

i. Seen after injection of ACTH or corticosteroids

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BASOPHIL


i. Purple in colorii. As in eosinophil

• Cytoplasm:i. Slight basophilic, appears blue in colorii. Granulariii. Granules

a. Coarseb. Stains purple or blue with basic (methylene blue) dyec. Granules are plenty in number and overcrowd the nucleusd. They contain histamine and heparin

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• Functions:i. Mild Phagocytosisii. Liberates histamine which leads to allergic reactionsiii. Liberates heparin which act as anticoagulant and keeps blood in fluid state

• Basophilia:Causes

i. Chicken poxii. Small poxiii. Tuberculosisiv. influenza

• Basopenia:Causes

i. Seen after administration of glucocorticoids.ii. Drug induced reactions

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LYMPHOCYTES

• Two types:1. Large lymphocyte: 10-14 µm2. Small lymphocyte: 7-10 µm

• Nucleus:i. Single, very big, purple in colorii. Shape: round, oval or indentediii. Central position and occupies whole of the cell leaving marginal cytoplasmiv. Nuclear chromatin is coarse and shapeless

• Cytoplasm:i. Pale blue in colorii. Scanty cytoplasm

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• Functions:Produces antibodies, specialy in delayed hypersensitivity

• Lymphocytosis:Causes

i. In children – lymphocytes are more than neutrophils (RelativeLymphocytosis)

ii. Chronic infections (Tb)iii. Lymphatic leukemiaiv. Viral infections

• Lymphopenia:Causes

i. Hypoplastic bone marrowii. AIDS

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MONOCYTES

• Largest WBC

• Size: 10 – 18 µm with irregular outline

• Nucleus:i. Pale stainingii. Singleiii. Shape: round or indented (kidney shaped)iv. Eccentric position and present on one side of the cellv. Nuclear chromatin

• Cytoplasm:i. Pale blue in color, clear

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• Functions:i. Active phagocytosis : second line of defence against bacterial infectionsii. Life span: approx. 3 monthsiii. Monocytes also kill tumour cells after sensitization by lymphocytes

• Monocytosis:Causes

i. Tuberculosisii. Syphillisiii. Leukemias

• Monocytopenia:Causes

i. Hypoplastic bone marrow

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Leucopoiesis

90

Granulopoiesis:• Granulocytes develop mainly and exclusively in the red bone marrow• Wholly an extravascular process• Marrow – Reticulum cells (irregular in outline, free from granules or

mitochondria with faint basophilic cytoplasm)• Reticulum cells multiply by mitosis forming primitive WBCs (stem cells)

Agranulocytes:• They develop to a slight extend in the bone marrow• Main site or origin – lymphoid tissues (thymus, spleen, tonsils,etc.)

Terminology Cell Size Nucleus Cytoplasm Mitosis

PRIMITIVE WBC(Stem Cell)

18-23 µm Large, spherical, many nucleoli, open chromatin

Basophilic thin rim all around the nucleus

Mitosis +++

MYELOBLAST 16-20 µm Large, pale, purple blue, many nucleoli, fine stippled chromatin

Amount increases, narrow blue rim without nucleus

Mitosis +++

MYELOCYTE – A(Premyelocyte)

14-18 µm Size decreases, nucleoli disappears, chromatin condenses

Amount increases further Mitosis ++

MYELOCYTE – B(MyelocyteProper)

12-16 µm Round, Nucleus size furtherdecreases

Amount increases, less basophilic, granules appear with special staining reaction, maximum granules in neutrophils, scanty in eosinophils and basophils

Mulitplication is maximum

MYELOCYTE – C(Metamyelocyte)

10-14 µm Nucleus very small with chromatin dot – Cartwheel Appearance

Amount further increases and becomes more liquid, granules show amoeboid movements

Mitosis stops

MATURE WBC

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LEUCOPOEISIS


PLATLETS / THROMBOCYTES

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• Smallest blood cells, colorless, spherical, oval or rounded granulated bodies

• Size: 2-5µm in diameter

• Volume: 5.8 µm3

• Leishmans’ staining shows a faint blue cytoplasm with distinct reddish purplegranules

• Nucleus is absent

• It contains various receptors meant for combining with specific substances like

• Collagen

• Fibrinogen

• Von-willibrand’s factor


• Cytoplasm:i. Golgi apparatusii. Endoplasmic reticulumiii. Few mitochondriaiv. Contractile proteins like actin & myosin – helps in clot retractionv. Glycogenvi. Lyzosomesvii. Granules

• Dense granules: contain non-protein substances, ATP• α-granules: contain clotting factors, PDGF

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Count & Variations

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• Normal: 1.5 – 4 lac cells/mL• Circulating platelets: 60-75% of the platelet pool of the body• Remaining are mostly in spleen – reservoir of platelets

• Life span: 8-12 days• Destruction: mainly in spleen

• Thrombocytosis:Causes

i. After administration of epinephrine due to splenic contractionii. After traumaiii. Spleenectomy


• Thrombocytopenia:Causes

i. Bone marrow depressionii. Hypersplenismiii. Viral infectioniv. Drug hypersensitivity

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Thrombopoiesis / Megakaryocytopeiesis

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• Site of origin: Bone Marrow Pluripotent stem cell

Committed stem cell(polyploidy precursor cell)

Megakaryoblast (Stage 1)

Pro-megakaryocyte (Stage 2)

Granular megakaryocyte (Stage 3)

Platelets


Functions of platelets:

i. Haemostasis:Spontaneous arrest of bleeding by physiological processHaemostasis mechanism includes:

• Platelet Adhesion:

• When blood vessels are injured, platelets adhere to the exposed collagen present on the endothelial cells in the vessel wall

• Platelet Activation:

• Platelet binding to collagen initiate platelet activation

• Activated platelets: change shape, discharge granules and cause platelet aggregation

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• Platelet Aggregation:• Increased by platelet activating factor (PAF) secreted by

neutrophils, monocytes and platelet cell membrane

• Platelet aggregation activates Phospholipase ‘C’ which inturnactivates Phospholipase A2.

• This causes release of arachadonic acid from membrane phospholipids which inturn gets converted to Thromboxane A2 and prostacyclin.

• Thromboxane A2 : increase in platelet aggregation along with platelet adhesion and helps in the formation of temporary haemostatic plug, causes stoppage of bleeding

• Prostacyclin : inhibits Thromboxane A2 formation and thus prevents further platelet aggregation keeping platelet plug localised.

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ii. Blood Coagulation:• The loose aggregation of platelets in the temporary haemostatic plus is

bound together and converted into definitive haemostatic plug by fibrin

iii. Clot Retration:• Within 30mins of fibrin clot formation, clot retraction occurs• Ie it contracts down to 40% of its original volume.

iv. Phagocytic function:• Platelets help in phagocytosis of carbon particles and viruses.

v. Storage & Transport function:• Platelets store histamine, which are released when the platelets

disintegrate and act on the blood vessel

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COAGULATION OF BLOOD

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Haemostasis:• Spontaneous arrest or prevention of bleeding by physiological processes is

called haemostasis.

Major events that occurs in haemostasis are:

• Constriction of injured blood vessel• Formation of a temporary haemostatic plug of platelets• Conversion of temporary haemostatic plug into the definitive haemostatic clot

Dr. Nithin Mathew – Gingiva107

Clotting Factors

Factor I Fibrinogen

Factor II ProthrombinFactor III ThromboplastinFactor IV Ionic CalciumFactor V Labile FactorFactor VI -

Factor VII Proconvertin

Factor VIII Antihemophilic Factor

Factor IX Christmas Factor

Factor X Stuart prower Factor

Factor XI Plasma thromboplastin antecedent

Factor XII Hageman factor

Factor XIII Fibrin Stabilizing Factor

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CLOTTING MECHANISM


Anticoagulant Mechanism

109

• Factors that initiate the clotting mechanism also stimulate the dissolution of bloodclot, called Fibrinolysis.

• Fibrinolysis is due to the action of proteolytic enzymes ‘fibrinolysin’ or ‘plasmin’

• Present in circulation as inactive ‘plasminogen’ which gets converted to plasmin bythe action of thrombin and tissue plasminogen activator – TPA which is released bytissue damage.

• Plasmin lyses the fibrin and fibrinogen, with the production of fibrinogendegradation products

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FIBRINOLYTIC SYSTEM


BLEEDING DISORDERS

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Common causes of bleeding disorders can be classified as

1. Defective blood clotting due to:i. Deficiency of clotting factors (I,II,V,VIII,IX,X)ii. Deficiency of Vitamin Kiii. Anticoagulant overdose

2. Defective Capillary contractility – Purpura3. Combined Defects


DEFECTIVE BLOOD CLOT

In this disorder, a firm clot is not formed following an injury during the period ofcapillary contraction

Haemophilia

• Caused by an abnormality or deficiency of factor VIII.• Aka Hemophilia A or Classic Haemophilia• It is an inherited sex-linked anomaly due to an abnormal gene on X-chromosome• Transmitted by females to males who manifest signs of the disease• Gene responsible for Haemophilia is present in the X-chromosome


• In the presence of another normal X-chromosome, this gene acts as a recessive. i.e. the individual has no signs of the disease but can transmit the disease.

• Hemophilia A is classified as mild, moderate, or severe, depending on the amount of clotting factors in the blood.

Mild hemophilia 5–40 percent of normal clotting factor

Moderate hemophilia 1–5 percent of normal clotting factor

Severe hemophilia Less than 1 percent of normal clotting factor


Diagnosis

• Condition is characterised by a marked increase in clotting time (CT).• Bleeding time is normal (2-5mins)• Normal CT is about 3-8mins whereas Haemophilic blood takes 1-12 hours to clot

and may form only a soft clot.


Vitamin K Deficiency

• Vit K is required for the synthesis of prothrombin (factor II) and factors VII, IX and Xin the liver.

• Anticoagulants act by substrate competition by occupying vitamin K receptor sites.

• Vit K is absorbed from small intestine in the presence of adequate amounts of bilesalts.

• Gastrointestinal diseases, deficiency of Vit K occur as a result of poor absorption offats from the GI tract.


• Another reason is failure of the liver to secrete bile into the GI tract – Lack of bileprevents adequate fat digestion and absorption which depresses Vit. K absorptionas well.

• Deficiency is characterised by prolongation of clotting time and seroushaemorrhages may occur.


DEFECTIVE CAPILLARY CONTRACTILITY

Clinical condition in which the capillary abnormality results in bleeding is known asPurpura

Characterised by spontaneous haemorrhages beneath the skin, mucous membraneand in internal organs.

Severe purpura with haemorrhages in the skin and from mucous membrane is calledPurpura Haemorrhagica

PURPURA

Two types of Purpura:1. Primary (Idiopathic): congenital or hereditary and usually occurs in children2. Secondary (Symptomatic): due to allergies, infections, drugs, cancer


Diagnosis

• Clotting time: Normal (3-8mins)• Bleeding time: Increases• Capillary endothelium resistance: decreases, causing increased capillary fragility• Skin microscopy:

• In primary purpura: skin capillaries are very irregular and distorted in form.After puncture these vessels remain patent, therefore free bleeding proceedsfrom the needle track for several minutes

• In secondary purpura: capillaries are anatomically normal but because of thepresence of toxic agents or other causes, they do not contract effectively inresponse to injury.

• Platelet count: normal (1.5 – 4 lacs/mL)• In many cases, there was reported to be reduction in platelet count, called

Thrombocytopenic Purpura


Forms/Classification of Purpura

• Thrombocytopenic purpura:• Purpura with low platelet count• Results in poor clot retraction and poor constriction of injured blood vessel• Clinically seen as:

• Mild: platelet count less than 50,000 cells/mL• Moderate: platelet count less than 10,000 cells/mL• Fulminating: platelet count less than 1000 cells/mL

• Athrombocytopenic purpura: purpura with normal platelet count• Thromboasthenic purpura: due to abnormal circulating platelets but count is normal• Haemorrhagic Telengiectasis: entirely due to localized capillary abnormality, which do not

contract with stimuli. Profuse bleeding will occur following rupture of these vessels


BLOOD GROUPS

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• Experiments with blood transfusions, the transfer of blood or blood componentssince hundreds of years.

• Austrian Karl Landsteiner discovered human blood groups

• Blood transfusions became safer.

• The differences in human blood are due to the presence or absence of certainprotein molecules called antigens and antibodies.

• The antigens are located on the surface of the RBCs and the antibodies are in theblood plasma.


• Membrane of RBCs contains variety of blood group specific antigens calledagglutinogens.

• The antibody is present in the plasma called agglutinin.

• 30 commonly occurring antigens & hundreds of other rare antigens.

• Most of them are weak antigens.

• Each individual have different types and combinations of these molecules.

• Mixing incompatible blood groups leads to blood clumping or agglutination reaction,which is dangerous for individuals.

• Isoagglutinins: antibodies that agglutinate blood cells of some individuals of the samespecies.


• There are more than 20 genetically determined blood group systems known today

• Chief blood groups are

1. Classical ABO blood group2. Rhesus (Rh) blood group


CLASSICAL / ABO BLOOD GROUP

• Individuals are divided into 4 major blood groups depending on the presence orabsence of blood group specific substance called A, B and O.

• A and B are group specific substances, polysaccharide in nature. – Antigens(Agglutinogen)

• The antibody is present in each group – Agglutinin

• The agglutinin acting on agglutinogen A is called ‘α’ or Anti-A• The agglutinin acting on agglutinogen B is called ‘β’ or Anti-B• Group O doesn’t have agglutinogen as there is no corresponding agglutinin


• Agglutinins α & β are globulins of IgM type and hence cannot crossthe placenta

Based on these facts, Karl Landsteiner in 1901 framed the law calledLANDSTEINER’S LAW

1. If an agglutinogen is present in the RBC of an individual, thecorresponding agglutinin must be absent from the plasma.

2. If an agglutinogen is absent in the RBC of an individual, thecorresponding agglutinin must be present in the plasma.


INHERITANCE OF ‘ABO’ BLOOD GROUPS

• The Agglutinogen A and B are inherited as Mendelian dominant and first appear inthe sixth week of foetal life.

• Antigens A and B are not limited to the RBCs but are also found in any organs.

• The specific agglutinins are present in the plasma and appear at 10th day, rise topeak at 10 years and then decline.

• The specific agglutinins act best at low temperature (5°C - 20°C) – COLD ANTIBODIES

• The 4 classical ABO blood groups depend on 3 genes, named after thecorresponding factor A, B and O.


If a person receives a gene from each parent

His blood group or phenotype is

His Genotype is

A+A or A+O A AA• or AO*

B+B or B+O B BB• or BO*

A + B AB AB*

O + O O OO•

‘•’ – homozygous transmission‘*’ – heterozygous transmission

• Each person’s blood group is determined by the two genes which he receives from the parent.

• Six possible combinations of genes – AA, AO, BB, BO, AB and OO.• Each combination is known as the genotype.


DETERMINATION OF CLASSICAL BLOOD GROUPS

• Determined by mixing a drop of isotonic saline suspension of the subject RBCs witha drop of serum A and serum B separately on a glass side.

• Checked for agglutination reaction.


• If the blood agglutinates, it indicates that the blood have the antigens binding the special antibody in the reagent.

• The agglutination indicates that the blood has reacted with a certain antibody andtherefore is not compatible with blood containing that kind of antibody.

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BLOOD TYPE Anti – A Serum Anti – B Serum

AB + +

A + –

B – +

O – –


RHESUS (Rh) BLOOD GROUP

• Discovered by Landsteiner and Weine in 1940

• Many people also have a so called Rh factor on the red blood cell's surface.

• The Rh antigen is called ‘D’ and its antibody is called Anti-D.

• Rh antigen-antibody reaction occurs best at body temperature – WARMANTIBODIES

• Rh antibodies are of IgG type and hence they can cross the placenta.

• Unlike ABO system (spontaneous reactions), Rh system – No spontaneous reactions


• 6 common types of Rh antigens, each of which is called an Rh Factor.

• They are: C, D, E, c, d and e

• A person who has a ‘C’ antigen does not have the ‘c’ antigen.• A person missing the ‘C’ antigen always has the ‘c’ antigen.

• Same is the case with D-d and E-e antigens

• Type D antigen is the widely prevalent in population and is more antigenic than anyother Rh antigens.

• Anyone who has this antigen is said to be Rh positive, and who does not have aresaid to be Rh negative.


• Rh negative individuals, the Anti-D are not actually present in the plasma but itsproduction can be triggered by:

i. Transfusion of Rh positive bloodii. Entrance of Rh positive RBCs from the Rh positive foetus into the maternal

circulation of Rh negative mother – Haemolytic Disease of New Born /Erythroblastosis foetalis


Rh factor and Haemolytic Disease

• Mother: Rh Negative• Foetus: Rh Positive

• RBCs containing the antigen ‘D’ may cross the placenta from the foetus into themother either during pregnancy or during delivery.

• Mother responds: Anti-D which returns to the foetal circulation and begins todestroy foetal RBCs.

• Degree of damage depends on the magnitude of maternal Anti-D response and theability of maternal Rh antibodies to cross the placenta.


• Since sensitization of Rh negative mother occurs at birth, the first child is usuallynormal.

• But if the mother has been immunized previously by a Rh positive transfusion anytime even in childhood, a dangerously high response may occur during the firstpregnancy.

• This changes in the foetus is termed Hemolytic Disease of the New Born /Erythroblastosis Foetalis.

• ABO incompatibilities rarely produce haemolytic disease of new born, since α & βantibodies are IgM and cannot cross the placenta.


Clinical Picture of Erythroblastosis foetalis:

• New-born is jaundiced and usually anaemic at birth

• Anti-Rh antibodies from the mother circulate in theinfant’s blood for another 1-2 months after birth,destroying more RBCs.

• Hematopoietic tissues of the infant attempt to replace the haemolysed RBCs.

• Liver and spleen become greatly enlarged.

• Severe anaemia usually causes death of the infant.

• Infants who survive develop permanent mental impairment or damage to motorareas of brain – due to precipitation of bilirubin in neuronal cells causingdestruction.


Prevention of Rh Hemolytic Disease

1. Find out the Rh types of the expectant parents.• If mother is Rh-negative and father is Rh-positive, baby is at risk for developing

HDN.

2. Mother's serum is tested to make sure she doesn't already have Anti-D anitbodyfrom a previous pregnancy or transfusion.

3. Finally, the Rh-negative mother is given a dose of Rh Immunoglobulin (RhIg) at 28weeks of gestation and again after delivery, if the baby is Rh+.

The RhIg will attach to any Rh+ cells from the baby in the mother's bloodstream, thuspreventing them from triggering anti-D anitbody production in the mother.

The Rh- woman should also receive RhIg following a miscarriage, abortion, or ectopicpregnancy.


Agglutination Reaction

• When bloods are mismatched so that anti-A or anti-B plasma agglutinins are mixedwith red blood cells that contain A or B agglutinogens.

• The red cells agglutinate as a result of the agglutinins’ attaching themselves to thered blood cells.

• The agglutinins have two binding sites (IgG type) or 10 binding sites (IgM type).

• A single agglutinin can attach to two or more red blood cells at the same time,thereby causing the cells to be bound together by the agglutinin.


• This causes the cells to clump, which is the process of “agglutination.”

• Then these clumps plug small blood vessels throughout the circulatory system.

• These agglutinated clumps of cells are later destroyed by the phagocyticleucocytes, releasing haemoglobin into the plasma. – Hemolysis of RBCs.

• Released haemoglobin is converted by the phagocytes into bilirubin and laterexcreted in the bile by the liver.

• Bilirubin level in the body increases - Jaundice

141

Patient: Type A

Patient: Type B


BASIC RULES TO BE FOLLOWED DURING BLOOD TRANSFUSION

• The plasma of the donor which contains the agglutinins can usually be ignoredbecause the donor’s plasma in the transfusion is usually diluted so by the muchlarger volume of recipient’s plasma that it rarely cause agglutination.

• No Rh negative females at any age before menopause should ever be given a Rhpositive blood transfusion.

- This is because she may become sensitized by the injected Rh positive blood and forms Anti-D antibodies.

- Transfusion may make her permanently childless


• Group A and group B can only safely receive blood from their own group and groupO

• Persons with group AB have no circulating agglutinins and can therefore be givenblood of anyone without developing a transfusion reaction.

• AB group : UNIVERSAL RECEPIENTS

• Persons of group O contain no agglutinogen and their blood can be given toanyone, therefore its RBCs are not agglutinated by the members of the group.

• O group : UNIVERSAL DONORS

• The terms Universal donor and Universal recipient are no longer valid ascomplication can be produced by the existence of Rh and other factors.

• Therefore, the only safeguard against blood transfusion is Direct Cross Matching.


DIRECT CROSS MATCHING

Importance of Cross matching: It is a direct and final check to detect whether there isany mismatching between the bloods of potential donors and potential recipient.

• Major Cross Matching• Donor’s RBCs are mixed with recipient’s serum

• Minor Cross Matching• Recipient’s RBCs with donor’s serum

• Observed: if there is an agglutination or not.• NO AGGLUTINATION: in either case means that the two blood are perfectly

COMPATIBLE: Transfusion is allowed.

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DONOR’S BLOOD PATIENT’S BLOOD

MAJOR AND MINOR CROSS MATCHING OF BLOOD

Patient’s Plasma + Donor’s RBCs = Major Cross-Match

Donor’s Plasma + Patient’s RBCs = Minor Cross-Match

Plasma

RBCs


REFERENCES

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• Textbook of Medical Physiology : Guyton & Hall

• Textbook of Human Physiology : A.K Jain

blood

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