Blood

S Naghma RizviMarch, 2015.

Acknowledgement :Muhammad Nisar

Objectives Define blood, its general properties and function. Explain the composition. Describe the formation of Blood cells Discuss the structure and functions of blood cells

RBC (Erythrocytes) WBC (Leukocytes) Platelets (thrombocytes

Discuss the composition of plasma Describe the three mechanism that contribute towards

hemostasis Briefly discuss the ABO blood groups and Rh factor.

BloodIt is a connective tissue which consists of plasma and formed elements (blood cells) flowing inside the closed vessels.

Physical characteristics of bloodColor Red (varies with O2 content)

Volume 5-6 (males) & 4-5 (Females)pH 7.35 - 7.45Viscosity (relative to water) 4.5 – 5.5% of total body mass 8%Temperature 380CSalinity 0.9% Nacl

Functions of Blood1.Transportation

oxygen and carbon dioxide food molecules (glucose, lipids, amino acids) Na+, Ca+2, HCO−3) ions (e.g., wastes (e.g., urea) hormones

2.Regulation Body temperature pH

3.Protection Clotting Defense

Un-clotted/

un- centrifu

ged blood

CentrifugedbloodRBCs & WBCs are whole cells platelets are

cell fragments

Composition of blood

PlasmaYellowish clear liquid, composed of:Water = 91%Proteins = 7% (all synthesized by the liver)• Albumin = 54%, regulates osmotic pressure of blood• Globulins = 38%, alpha and beta globulins in transport,• gamma globulins in defense (antibodies)• Fibrinogen = 7%, coagulationOther solutes =2%• Electrolytes - Na+, K+, Ca++, Mg++

• Nutrients - glucose, amino acids, fatty acids, monoglycerides

• Gases - O2, N2, CO2• Regulatory substance - hormones, enzymes• Vitamins and wastes

HemopoiesesThe process of development

of blood cells

Erythrocytes (RBC)

contains 280 millions Hb molecules, that can carry

Physical characteristics of Erythrocyte

Size 7 µm in diameter & 2.2 µm thick

Shape Flattened and biconcave disc

Mean count 4.5-5.5 per mm3 of blood

Morphology Red color, (variable) non-nucleated, each RBC

over a billion O2 molecule

Site for production Bone marrow

Life span 120 days

Function Carries O2 and nutrients, removes CO2 & wastes

Structure of Erythrocyte(Hemoglobin molecule)

•

oxygen in the tissue.Globin Molecule

Hemoglobin molecule contain 4 protein chains called globins, each of which is bound to 1 heme (iron). Iron is able to combine with oxygen in the lungs and deliver it to body tissues.is able to combine withoxygen in the lung and release

HEME molecule

Life Cycle of RBC

Life Cycle of RBCMacrophage in spleen & liver, phagocytize RBC &split heme & globinGlobin broken into amino acids to be reusedFe removed from heme & attaches to transferrin Fe-transferrin → red marrow → Hb synthesis Erythropoiesis in red marrowFe removed from heme → non-Fe portion →biliverdin →bilirubin →bile → GI tractBilirubin →urobilinogen in large intestine →some urobilinogen →blood → urobilin → yellow pigment in urineMost urobilinogen → feces → as brown pigmentstercobilin

•

•••••

•

•

Leukocytes (WBC)They are largest of all blood cells, have nuclei anddo not contain Hb.Forms 1% of blood volumeOn the basis of presence of absence of chemicalfilled cytoplasmic granulesinto two types:Granular leukocyte

WBCs are classified

Agranular leukocyte

Granules

Granulocyte or PMNLSAgranulcytes

GranulocytesMulti-lobed nucleiNamed according to dyes they take up

lBasophilEosinophiNeutrophil

Neutrophils (PMNLs)Life span 6-9 hours%of WBCs 60%-70%Nucleus lobularGranules Reddish-violetFunctions Phagocytosis, diapedesis, chemotaxis,

extravasation, release antimicrobial subs

Basophil (PMNLs)

leukotrien & heparin

Life span%ofWBCs:

0.5%-1%

Nucleus large and U to S shapedGranules BlueFunctions Secretes histamine ,serotonin, prostaglandin,

Eosinophil (PMNLs)

parasites

complex, and allergens

Life span

%of WBCs: 2-4%

Nucleus 2 large lobes

Granules Stain red

Functions Release enzyme that destroy

Phagocytosis of antigen antibody

AgranulocytesTheir nucleus are round orstains darkLymphocyte

T- lymphocyte(T cells) B- lymphocyte(B cells)

slightly indented and

Natural killer cells (NK cells)

Monocyte

Lymphocyte

cells.

infected cells, Natural killer cell tumor

T lymphocyteB lymphocyte Natural Killercells

%of WBCs: 20-25 %

Nucleus Nucleus round or slightly indented

Types B-lymphocytes, T-lymphocytes & Natural killer

Functions B-cells bacteria, T-cells attack microorg and

Monocyte

pathogens, dead neutrophil and debris of dead

%of WBCs: 3-8Nucleus Kidney or horse shoe shape nucleus

Functions Differentiate into macrophages. Phagocytize

cells

Platelets orThrombocyt

esSize 4 µm in diameter

Shape Disc shape

Mean count 130000-400000 per mm3 of blood

Morphology Non-nucleated fragments of cells

Site for production Bone marrow

Life span 5-9 days

Function Blood clotting

Hemostasis/Haemostasis

Heamostasis orplace through ainclude.• Vasospasm

cessation of bleeding takesseries of responses, these

• Platelet plug formation:• CoagulationFollow the sequence to events initiatedwhen platelets come into contact with aninjured surface

Vasospasm• Vessel wall constricts for a short period• Platelets (sticky) adhere to the injured wall• Platelets change their shape• Platelets (activated) release serotonin that

constrict the vessel

Platelet Plug formation• Passing platelets stick to the site and release

chemicals that attract more platelets.• More platelets move leading to platelets

aggregation (positive feedback.• Platelets form a plug or a temporary sealwithin six minutes.

Coagulation• Thromboplastin (TP) or tissue factor released

by damaged tissue cells.• TP activates (through series of chemical

reactions) the inactive clotting factors already present in the blood.

• Prothrombin activato, first step in finalcommon pathway.This final common pathway can be initiated bytwo processes usually occurring together…

The insoluble fibrin threads increase in number and forms a meshwork that trap blood cells and is much stronger than platelet plug

Vasospasm

Platelet Plug Formation

Plasma clotting FactorsFactor Name FunctionI Fibrinogen Converted to

fibrinII Prothrombin EnzymeIII Tissue

ThromboplastinCo factor

IV Ca++ Co factorV proaccelerin,

Labile factorCo factor

VII proconvertin EnzymeVIII AHF A Co factor

IX AHF B Enzyme

X Trombokinase Enzyme

XI AHF C Enzyme

XII HagemanFactor

Enzyme

XIII Fibrin stabilizing factor

Enzyme

ABO Blood SystemThis

Two

system consists of threeAntigen A Antigen B Antigen Rh

types of antibodies Anti-A antibody Anti-B antibody

types of antigens

ABO system forms four major types of blood groups.The table below shows the possible combinations of antigens and antibodies with the corresponding ABO type ("yes" indicates the presence of a component and "no"indicates its absence in the blood of an individual).

ABOblood type

Antigen

AAntigen

BAntibody

AAntibody

B

A Yes No No Yes

B No Yes Yes No

AB Yes Yes No No

O No No Yes Yes

Anti-B antibody Ant-Rh antyibody

Anti-A antibody

Blood Transfusion

Hemolytic disease in Newborn