Blood

Learning objectives:

Composition of blood. Functions of blood. How plasma is separated from the blood cells. Hematocrit /PCV and its clinical significance ESR and its clinical significance Plasma proteins – types , functions Functions of lymph

Study of components and functions of blood is known as HEMATOLOGY. Blood is a homogenous fluid connective tissue which is in constant circulation throughout the body. In a normal adult, the volume of blood is about 70 ml/kg body weight and in an infant it is about 90 ml/kg body weight. On an average in a normal adult weighing about70 kg, the volume of blood present is about 5 liters.

The functions of blood :

Respiratory Excretory Nutritive Protective Regulation of body temperature pH regulation.

Packed Cell Volume(PCV)/ hematocrit: Definition Principle Normal value Significance Erythrocyte Sedimentation Rate(ESR): Definition Principle Normal values Significance

tube Westergren’s

Rouleaux formation

Plasma Is the fluid part of blood in which formed elements (cellular components) are suspended. The normal proportion of plasma in blood is about 55%. About 91 – 93% of plasma is made up of water. The remaining 7 – 9% is contributed by organic and inorganic constituents.

Inorganic constituents of plasma –

positively charged ions

Sodium normal sodium level of plasma is about 150 mEq/L of water Potassium normal potassium level of plasma is about 5 mEq/L of water. Calcium its concentration is about 9 to 11 mg%.

Negatively charged ions in plasma: Chloride Normal level is about 110 mEq/L of water.

Bicarbonate normal level is about 24 mEq/L of water . Plasma reflects the overall inorganic composition of extra cellular fluid (ECF) in the body.

The organic constituents are Plasma proteins- 6 – 8 g% Glucose- 60 – 90 mg% (fasting) Urea- 15 – 40 mg% Cholesterol - about 150 to 250 mg% Creatinine- about 0.3 -1.3 mg%

Non nucleated Central pallor Biconcave disc Elastic - can squeeze through narrow capillaries Normal count

Diameter – 6.8 – 8.8 µm Surface area - 140µm2

ANISOCYTOSIS

Variations in size

Microcytes:

Decrease in the red cell size. Red cells are smaller than ± 7µm in diameter. Found in: Iron deficiency anemia. Thalassaemia N

Lead poisoning. Anemia of chronic disease Macrocytes: Morphology: Increase in the size of a red cell. Red cells are larger than 9µm in diameter. May be round or oval in shape.

Found in: N Folate and B12 deficiencies (oval) Liver disease (round) Reticulocytosis (round) POIKILOCYTOSIS

Variations in shape

Spherocytes

Normochromic Hypochromic

Erythropoiesis

Definition: A process of formation of a mature RBC from its precursor stem cells. Duration: 6-7 days Sites of erythropoiesis:

Mesoblastic stage (first 3 months of intrauterine life )- mesoderm of yolk sac(area vasculosa) Hepatic stage: third month to fifth month of fetal life- Liver and spleen form blood cells Myeloid stage : 5th month of IUL onwards - bone marrow form blood forming organ In adults- Bone marrow is the sole source for erythropoiesis

Bone marrow: Types – red and yellow At birth all bone marrows are red in nature- source for erythropoiesis As age advances, red bone marrow replaced by yellow bone marrow At the age of 20, Red bone marrow persist in vertebrae, sternum, ribs, bones of skull and pelvis.

Functions of red bone marrow Production of RBCs, WBCs and Platelets. Destruction of senile RBCs (by the reticuloendothelial cells). For any laboratory investigation a sample of the red bone marrow can be obtained from one of the following regions: In males ----Sternal puncture. In female----Iliac crest. In child ------Tibial tuberosity

Erythropoiesis (Basophilic erythroblast) (Orthochromatic erythroblast) The differentiation and proliferation of RBC. Common features during erythropoiesis Cell size change Staining property Accumulation of Hb Disappearance of nucleoli and nucleus Mitotic cell division

Reticulocyte: Is an immature erythrocyte.

Size is about 8 – 9. (1.12 to 1.16 times bigger than RBC) Is also non-nucleated like red blood cell. Has reticulum, which is remnant of RNA. Normal % in adult will be around 0.5 – 1.0. In newborn infant it is more (2 –6). Reticulum gets stained when the cells are treated with brilliant cresyl blue - supra vital stain (stains the cells in living condition outside the body) Reticulocytosis occurs in conditions like Hemolytic anemia. Anemias after treatment with vitamin B12, folic acid and iron. After hemorrhage. Erythroblastosis foetalis Regulation of Erythropoiesis: Importance Must Not fall

To supply oxygen from lungs to tissues Must Not rise Blood viscosity may increase May impede blood flow

Factors affecting Erythropoiesis Tissue Oxygenation Vitamins Metals Proteins Hormones Tissue Oxygenation –Crucial Regulator of Erythropoiesis

High altitudes Cardiac Failure Lung diseases

All conditions have one common problem Erythropoietin Glycoprotein Mol weight 34000

Sites of production – KIDNEYS, liver and spleen Stimulants of Erythropoietin production Hypoxia – decreased oxygen to kidney Vitamins

Vit B12 & Folic acid (maturation factors) Essential for formation of thymidine triphosphate Essential building block of DNA Vit.C, pyridoxine. Iron Hormones- Testosterone , Growth hormone, Thyroid hormone, Cortisol, Adrenocorticotrophic hormone (ACTH) Learning objectives: Iron in erythropoiesis Iron deficiency anemia Maturation factors in erythropoiesis Megaloblastic anemia : cause clinical features Treatment

The lifespan of RBCs Site of destruction Process of destruction. Applied aspect- jaundice. Iron : Daily requirement Adult man – 10mg/day Menstruating women – 20mg/day Pregnant and lactating woman- 40 mg/day Children - >10mg/day Iron is required for Hemoglobin, myoglobin, cytochromes, peroxidase, catalase …etc Total body iron – 4-5 gms About 65% - Hb

4%- Myoglobin 1%- heme compounds (promote oxidation) 15-30% in stores Dietary sources of iron : Leafy vegetables, fish , pulses, dried fruits , cereals, meat.

There are 2 types of iron in the diet; haem iron and non-haem iron

Haem iron is present in Hb containing animal food like meat, liver & spleen

Non-haem iron is obtained from cereals, vegetables & beans Site of absorption: duodenum (small intestine) Gastric HCl release Fe+++ from food. Ascorbic acid, cysteine favor conversion of ferric(Fe+++ )to ferrous(Fe++) form

The dietary phenols & phytic acids compounds bind with iron decreasing free iron in the gut & forming complexes that are not absorbed. Apotransferrin + iron (diet) transferrin Transferrin bind to epithelial receptor absorption by pinocytosis released as plasma transferrin. Iron deficiency anemia: Causes(etiology): CHRONIC BLEEDING : menorrhagia peptic ulcer stomach cancer ulcerative colitis intestinal cancer Haemorrhoids

DECREASED IRON INTAKE INCREASED IRON REQUIRMENT ( PREGNANCY, LACTATION) Features: Fatigue, dizziness, palpitation, dry, pale skin, spoon shaped nails (koilonychia), hair loss pica (apetite for non food substances such as an ice, clay) Peripheral blood : Decreased number of erythrocytes Erythrocytes are smaller and paler Decreased amount of Hb MCV,MCH,MCHC are decreased.

Pale RBC with more central pallor

KOILONYCHIA

Erosion of lower lip

Depigmentation of upper lip

Depapillated tongue

Treatment: Administration of ferrous(Fe++) - oral /intramuscular route

Maturation factors: vitamin B12 and folic acid : Vitamin B12: Daily requirement is about 1 g. Is stored in the liver to the extent of 1000 g. Is absorbed at the ileum part of small intestine. Absorption in the intestine requires Intrinsic factor secreted by the parietal cells of stomach.

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Folic acid sources Folic acid daily requirement is about 75 – 100 g. Both vit.B12 and folic acid required for the formation of thymidine triphosphate, the essential building blocks of DNA. lack of vitamin B12 or folic acid - abnormal and diminished DNA- failure of nuclear maturation and cell division. The erythroblastic cells of the bone marrow -fail to proliferate rapidly, produce larger than normal red cells called macrocytes.

•Macrocyte has a fragile membrane and is often irregular, large, and oval instead of the usual biconcave disc. Normal oxygen carrying capacity but short life span Deficiency may be due to deficiency of intrinsic factor (pernicious anemia) vitamin B12in the diet. delayed maturation of RBC, • decreased cell division This type of anemia is called as megaloblastic anemia. Pernicious anemia: vitamin B12 deficiency due to lack of intrinsic factor Changes seen in Blood – peripheral blood smear Bone marrow Central nervous system (CNS) Peripheral nervous system (PNS)

•Gastro intestinal tract (GIT) a. Peripheral blood smear changes are: Size of red blood cells will be more than normal (macrocytes). More hemoglobin will be present per cell – mean corpuscular hemoglobin (MCH) increases. (Normal is 28-32 pg.) Mean corpuscular volume (MCV) is more than normal. (Normal is 78-94 3)

The average volume of RBC occupied by hemoglobin alone is known as mean corpuscular hemoglobin (MCHC) and normally this will not get affected. (Normal range is 32 – 38 g %) Red blood cell count will be markedly decreased. decreased red blood cell count, along with decrease in leucocytes and platelet count pancytopenia.

• b. Bone marrow changes are: Instead normal normoblastic type, it will be megaloblastic type. There will be hyperplasia(abnormal increase in number of cells ) of bone marrow. Red bone marrow can be observed in the shafts of long bones even in the adult Gastro intestinal tract changes are: No hydrochloric acid secretion in the stomach Atrophy of gastric mucosa. Tongue becomes more smooth and glistening. Central nervous system changes are: Tracts in the spinal cord are affected especially in the lateral white matter area of spinal cord and lead to sub

•acute combined degeneration of the cord (both ascending and descending tracts are affected). Peripheral nervous system changes are: Degeneration of myelin sheath in the nerves leads to numbness and tingling sensation.

Treatment: Injection of cobalmin- Megaloblastic bone marrow to normal Reticulocytosis in a week after treatment Folic acid administration – corrects the anemia due to folic acid deficiency

Life span of RBCs – 120days Site of destruction of RBCs: Reticuloendothelial cells (macrophages) of

Bone marrow(littoral cells) Spleen and Liver (kupffer cells)

Excreted in to the bile in to the intestine as bilinogens Most of the colorless bilinogens formed in the colon by the fecal flora are oxidized there to stercobilinogen (colored compounds) and are excreted in the feces Normal excretion of stercobilinogens in feces-80240mg/day the rest enters the portal blood, to be excreted in the bile or in the urine.-as urobilinogens. Amount excreted per day – 0.5-2mg

Jaundice is yellow discoloration of skin, mucus membrane and sclera of eyes. Normal serum bilirubin level- 0.2-0.8 mg% >0.8mg%- hyperbilirubinemia When it exceeds 2mg% - clinical jaundice

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RBC Indices • RBC indices include: Mean Corpuscular Volume (MCV) Mean Corpuscular Hemoglobin (MCH) Mean Corpuscular Hemoglobin Concentration (MCHC) RBC Distribution Width (RDW)

MCV Mean corpuscular volume MCV is the volume of single RBC MCV = PCV in liter RBC (millions/cubic mm) Expressed in femtoliter (fL) or cubic microns(µm3) If 80-94 fL, normal range, RBCs considered normocytic If < 80 fL are microcytic If > 94 fL are macrocytic MCH MCH is average amount of hemoglobin in a single RBC. MCH = Hb x 10 RBC (millions) Expressed in picograms(pg) Normal value- 28-32 pg MCHC

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MCHC is average hemoglobin concentration in a single RBC MCHC = Hb in gm% x 100 PCV (%) Normal range – 35-38% If MCHC is normal, cell described as normochromic If MCHC is less than normal, cell described as hypochromic There are no hyperchromic RBCs RDW Most automated instruments now provide an RBC Distribution Width (RDW) An index of RBC size variation Normal range is 11.5% to 14.5% for both men and women

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Anemia Learning objectives: Definition Features of anemia Classification : based on Etiology morphology Based on etiology: Hemorrhagic anemia- loss of blood Dietary deficiency anemia- iron, vitamin B12 deficiency Dyshemopoietic anemia- aplastic anemia

Hemolytic anemia – malaria, erythroblastosis fetalis Based on morphology : Normocytic normochromic anemia Microcytic hypochromic anemia Macrocytic normochromic anemia.