blood formation& rbc 17th aug

8/14/2019 Blood Formation& RBC 17TH AUG

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Blood and Formation of

RBCs

Dr. Trisha Majumdar


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DEFINITIONBlood is a liquid connective tissuepresent in the circulatory system.

It is red in color due to the presenceof hemoglobin.

Blood id made up of fluid componentplasma 55% and formed elementsRBC, WBC and platelets(thrombocytes) 45%

The total volume of blood is around5L .


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FUNCTION OF BLOOD

Transport of oxygen and carbon dioxide.

Supply of nutrition to various tissues.

Transport of waste materials for excretion.

Transport of hormones, vitamins , drugs 7chemicals.

Maintenance of acid base balance

Regulation of body temperature.

Protection against infection

Helps in blood clotting.


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PLASMA

It is the fluid portion of the blood.

Its normal volume is 3500ml.

Mainly composed of water.

Inorganic substances are Na, K, Ca,Fe,& Cu.

Organic substances are proteins,

lipids, glucose, urea, & creatinine.Serum is plasma without clotting

factors.


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PLASMA PROTEINS

Most of them are synthesized in the liver.

The important plasma proteins arealbumin, globulin, fibrinogen &

prothrombin.

Main functions aremaintains colloidalosmotic pressure, acts as buffer to regulate

Ph, acts as protein reserve, provides

immunity, responsible for blood clotting and

helps in transport of drugs, hormones andmetabolites.


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ERYTHROCYTES (RBC)

They are the most abundant cells presentin our body.

They contain a red pigment hemoglobin injelly form.

They are biconcave in shape and flexibleand can pass through capillaries.

Normal count is

Males- 5-5.5 million cells/cu.mm

Females4.5-5 million cells /cu.mmInfants -6-7 million cells/cu.mm

Normal life span of RBCs is 120 days.


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Function of RBCTransport of oxygen.

Transport of carbon dioxide

Regulation of acid base balance.


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Formation of erythrocytes

The process of formation of RBC is

called erythropoises.

Red Bone marrow is the site of RBC

production.

In adults it is present in flat bones like

cranial bones, vertebrae, pelvic

bones, ribs, sternum, upper ends of

long bones like femur and humerus.


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Stages of erythropoiesis

All the cells are produced from the

stem cells.

They have the capacity to form

different types of blood cells and are

termed as pluripotent haemopoieticstem cell.

These cells differentiate to form the

committed stem cellsThe myeloid series gives rise to both

RBC and few WBCs


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The myeloid committed stem cells give rise toprogenitor cells called CFU-E called colonyforming units.

Pro Erythrocytes- 15-20miu. Develop from CFU-E. They have scanty cytoplasm . They do not havecytoplasm. Contain a large basophilic nucleoli.

Early NormoblastThese cells are 10-16 miu in

diameter. Hemoglobin begins to appear. Theyshow active mitosis. Nucleus is large , cytoplasmis basophilic.

Intermediate Normoblast - these cells are 10- 14miu in diameter. Mitosis stops at this stage .

Hemoglobin concentration begins to increase andcells become acidophilic also called aspolychromatophilic erythrocyte.


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Late Normoblast- these cells are 8- 10 miu

in diameter . Nucleus is lost.

Reticulocytethis is flat disc shaped non-nucleated cells slightly bigger than mature

RBC. Hb concentration increase to reach

the level of mature cell. The red cell attains

maturity in 1-2 days after loss of the

basophilic material.

Erythrocytesthis is a mature cell 7-2 miu

in diameter eosinophilic (dyes with eosinred), non nucleated and biconcave disc.


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Factors influencing

ERYTHROPOIESIS

Erythropoietin- a hormone that stimulateserythropoisis.

They stimulate erythropoises, so men havehigh RBC count compared to women.

They have a inhibitory effect onErythropoises.

Thyroxin, cortisol, and growth hormone arenecessary for RBC production.

Dietary factors- iron, VitB 12 and folic acidare necessary for HB synthesis andmaturation of RBC.


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Applied Physiology

Anaemia.- it is a clinical conditionwherein RBC count or HB% or both

decreased.

Classification- 1. anemia due to

decreased RBC formation.

2. Anemia due to increased RBC

destruction.

3. Anemia due to blood loss.


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Anaemia due to decreased RBC

formation

Iron deficiency anaemia.

Vit B12 and Folic acid deficiency

anaemia.

Aplastic anaemic - due to bone

marrow suppression by drugs, toxins,

&exposure to X-rays.


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Anemia due to increased RBC

destruction

Thalassemia - premature destruction

of RBC.

Sickle cell anemia- contains abnormal

HB.

Hereditary Spherocytosis - bioconvex

and prone to autolysis.

Glucose 6 dehydrogenase deficiency.


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Anemia due to blood loss.

Acute blood loss- hemorrhage due to

accidents or surgery.

Chronic blood loss- seen in peptic

ulcers etc.


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POLYCYTHEMIA

This is a condition where RBC count

is increased above 8 million cells/ cu.

mm


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THANK YOU

blood formation& rbc 17th aug

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