BLOODBY

Dr shamshad Begum .A.Loni

Lecture notes

Composition of Blood

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Plasma 55%Formed elements 45%

Constituents of blood

91.5% water

7% gm% proteins3.8gm % albumin (54%)2.7gm% globulin (38%)0.5gm % fibrinogen (7%)

1.5% ElectrolytesNutrientsGasesRegulatory substancesWaste products

RBCs 5 million/cumm (µl)

WBCs 10,000/cumm (µl) neutrophils 60-70% Eosinophils 2-4% monocytes 3-8% lymphocytes 25-30% basophils 1%

Platelets 140-400000/µl

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Constituents of blood

Thicker than water with a Specific gravity around 1.58

pH 7.35-7.45 Colour: bright red when oxygenated dark red when de-oxygenated 8% body weight 20% of ECF Volume about 5 liters(70 ml/Kg body wt.) Sampling by venipuncture; finger pick/heel

prick arterial puncture

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Physical characteristics of blood

Functions of blood

1. Transportation of respiratory gases (O2 & CO2); nutrients ; hormones; waste products

2. Regulatory: body temperature; pH

3. Protection against disease (immune functions); against blood loss (coagulation)

Erythrocytes are dedicated to respiratory gas transport

Hemoglobin reversibly binds with oxygen and most oxygen in the blood is bound to hemoglobin

Composition of hemoglobin◦ A protein called globin

made up of two alpha and two beta chains◦ A heme molecule

Each heme group bears an atom of iron, which can bind to one oxygen molecule

Each hemoglobin molecule thus can transport four molecules of oxygen

Erythrocyte Function

Neutrophils are our body’s bacteria slayers◦ Protect the body from infectious microorganisms◦ Can leave capillaries via diapedesis◦ Move through tissue spaces (amoeboid motion)◦ Many are phagocytic (possess numerous

lysosomes)

Leukocytosis – WBC count over 11,000/mm3

◦ Normal response to bacterial or viral invasion Leucopenia - a decrease in WBC count below

4,800/mm3 Leukemia - a cancer of WBC

Leukocytes (WBCs) Neutrophils

Eosinophils account for 1–4% of WBCs ◦ Have red-staining, bilobed nuclei◦ Have red to crimson granules◦ Function:

Lead the body’s counterattack against parasitic infections

Lessen the severity of allergies by phagocytosing immune complexes (ending allergic reactions)

Eosinophils

Account for 0.5-1% of all WBCs◦ Have U- or S-shaped nuclei with two or three

conspicuous constrictions◦ Are functionally similar to mast cells◦ Have large, purplish-black (basophilic) granules

that contain histamine Histamine – inflammatory chemical that acts as a

vasodilator and attracts other WBCs (antihistamines counter this effect)

Granulocytes: Basophils

Account for 20-25% or more of WBCs and:◦ Have large, dark-purple, circular nuclei with a

thin rim of blue cytoplasm◦ Are found mostly enmeshed in lymphoid tissue

(some circulate in the blood) Most important cells of the immune

system There are two types of lymphocytes: T

cells and B cells◦ T cells - attack foreign cells directly◦ B cells give rise to plasma cells, which produce

antibodies

Agranulocytes: Lymphocytes

Monocytes account for 3–7% of leukocytes ◦ They are the largest leukocytes◦ They have purple-staining, U- or kidney-shaped

nuclei◦ They leave the circulation, enter tissue, and

differentiate into macrophages

Monocytes

Platelets are fragments of megakaryocytes

Their granules contain serotonin, Ca2+, enzymes, ADP, and platelet-derived growth factor (PDGF)

Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels

Platelets not involved in clotting are kept inactive by Nitric Oxide (NO) and prostaglandins

Platelets

Red Blood Cells (erythrocytes)

No. 4-5 million/cumm (μL)

Size 7μ, bi-concave discs

No nucleus: can not reproduce = More surface area & center becomes thinner (biconcave):- More O2 can be carried- Squeeze into narrow capillaries- Allow O2 & CO2 Diffusion

NO mitochondria: ATP by anaerobic means (advantage: do not use up O2 they carry)

RBCs carry blood group antigens (A,B, O) on their cell membranes

Life span 120 days

Destroyed in the body by RE cells: by products are recycled (mostly at Spleen)

Coagulation of blood

It is Actions of the protein coagulation factors to form fibrin in response to injury to the blood vessels

Liquid Blood changes into a solid

Hemostasis: Consists of three stages

◦ Primary Hemostasis Process of blood clotting in response to injury blood vessels (vasculature) and platelets play important role Primary Hemostatic plug temporarily arrests bleeding. Insoluble fibrin strands deposit on the initial plug to reinforce

and stabilize. The fibrin originates from soluble plasma proteins.

◦ Secondary Hemostasis Actions of the protein coagulation factors form fibrin in

response to injury At this time, blood has changed into a solid state

◦ Fibrynolysis Clot is removed following healing of wound

Secondary Hemostasis

Primary Hemostasis

Categories of Hemostasis Primary

◦ Vascular System Endothelia Sub endothelia/collagen

◦ Platelets Secondary

◦ Coagulation System Plasma Proteins Cells: Platelets

◦ Fibrinolytic System Plasma proteins Cells: Platelets,

Endothelia

Coagulation Cascade Pathways Pathways to achieving a stable blood clot

◦ Extrinsic◦ Intrinsic◦ Common

The ABO blood groups consists of:◦ Two antigens (A and B) on the surface of the

RBCs ◦ Two antibodies in the plasma (anti-A and anti-B)

Agglutinogens and their corresponding antibodies cannot be mixed without serious hemolytic reactions

ABO Blood Groups

ABO Blood GroupsABO

GroupAntigen Present

Antigen Missing

Antibody Present

A A B anti-B

B B A anti-A

O None A and B anti-A, anti-B, anti-A,B

AB A and B None None

Presence of the Rh agglutinogens on RBCs is indicated as Rh+ve 85% of population is +

Lack of antigen indicated as Rh –ve in 15% of popn.

Anti-Rh antibodies are not spontaneously formed only in Rh– individuals

However, if an Rh– individual receives Rh+ blood, anti-Rh antibodies form

A second exposure to Rh+ blood will result in a typical transfusion reaction

Rh Blood Groups

Blood Typing

Blood typing involves determination of the antigens present on an individual’s RBCs

The two most common blood typing systems used are the A-B-O method and the Rh method

type A blood – contain “A” antigen on RBCs type B blood – contain “B” antigen on RBCs type AB blood – contains both A and B antigens type O blood – contain no A or B antigens Rh+ blood – contain Rh antigen Rh- blood – no Rh antigen

Blood Typing

When serum containing anti-A or anti-B agglutinins is added to blood, agglutination will occur between the agglutinin and the corresponding Agglutinogens

Positive reactions indicate agglutination

PLATELET COUNT (CBC) NORMAL 100,000 - 400,000 CELLS/MM3

< 100,000 Thrombocytopenia

50,000 - 100,000 Mild Thrombocytopenia

< 50,000 Sever Thrombocytopenia

Clotting time Clotting time was used as a screening test to measure

all stages in the intrinsic coagulation system and to monitor heparin therapy

. Severe hemophilia, a fibrinogenemia, and sever

fibrinolytic states cause a prolonged clotting time, as do circulating anticoagulants ( inhibitors), and heparin

Clotting Time - Slide Method(Intrinsic)

The surface of the glass tube initiates the clotting process. This test is sensitive to the factors involved in the intrinsic pathway

The expected range for clotting time is 4-10 min.

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Normal HB levelMale: about 13-15 gm%Female about 12-14 gm%

Clinical implications

Anemia means a deficiency of Hb which can be caused by either too few RBCs or too little Hb in the cells. For diagnosis of anemia:Hemoglobin<13.0 g/dl for males< 12.0 g/dl. for females

Rh typing

Another group of antigens found on the RBC of the most of the people is the Rh factor (named for the rhesus monkey )

There are number of different antigens in this group,

This Rh antigen is termed as D and is often indicated as RH D + or _ve