Blood

BloodThe liquid form of

connective tissue in which cells are suspended in a circulating fluid, the plasma

About 5.5 L in humans

Composition of bloodLiquid Intercellular

substance (Plasma)50-60% of actual

blood volumeHomogenous,

slightly alkaline fluid which contains: Organic substances Inorganic substances Enzymes Hormones

Solid or formed elements40-50% of actual blood volumeCellular elements

RBC/erythrocytes WBC/leukocytes Platelets/

thrombocytesNon-cellular

elements Hemoconia – blood

dusts Chylomicrons or tiny

fat droplets

SerumClear yellow liquid of clotted bloodWhen circulation ceases, or when blood is

exposed to air, one of the globulins of plasma (fibrinogen) precipitates as a network of fine filaments, the fibrin. The contraction of clotted blood or plasma (syneresis) expresses a clear yellow fluid called SERUM

Composition of PlasmaPlasma is an aqueous solution containing

substances of low or high molecular weight that make up 10% of its volumePlasma proteins – 7%

Albumin – alpha and beta Gamma globulins Lipoproteins Proteins that precipitate in blood coagulation

(prothrombin and fibrinogen)Inorganic salts – 0.9%Organic compounds – amino acids, vitamins,

hormones, lipoproteins – of various origins

HematocritIs an estimate of the

volume of packed erythrocytes per unit volume of blood

Normal value:Adult male – 40-50%Adult female – 35-

45% and diminishes by physiologic hemodilution during pregnancy

Children up to 10 – 35%

Newborn – 45-60%

Cellular Elements of blood

RBC or ErythrocytesAnucleate (no nucleus)Packed with the oxygen-

carrying protein, HEMOGLOBIN (heme-iron portion;globin-protein portion)

Small 7.5 μm in diameter

Biconcave in profileNon-granularNon-motileAcidophilic staining

cells

RBC or Erythrocytes“dumbbell” in shape - in profile

osmotic pressure of vacuum of blood vessels sucks RBC membrane causing constriction at the middle

provides the erythrocytes a large surface-to-volume ratio, thus facilitating gas exchange

Elastic – suffers changes in shape when passing into environmental obstacles

Cytoplasm – homogenous and non-granularFresh cytoplasm – yellowish greenCytoplasm when stained – red, orange, pink

due to acid stain

RBC or ErythrocytesAcidophilic staining property is due to

hemoglobin (14-16 grams/100 cc of blood)Lifespan – 10 to 120 days (during its life =

700 miles of travel)Normal RBC count 4.5 M/cu mm of blood

Female – 3.9 to 5.5 M/cu mm of bloodMale – 4.1 to 6 M/cu mm of blood

Terminologies

AnemiaDecreased concentration of red blood cells in

the circulating bloodIt is also possible for the number of red blood

cells to be normal but for each cell to contain a reduced amount of hemoglobin

May be caused by:Loss of blood (hemorrhage)Insufficient production of red blood cells by the

bone marrowProduction of RBC with insufficient hemoglobin

– related to iron deficiency anemiaAccelerated blood cell destruction

Polycythemia or ErythrocytosisIncrease in RBC countPhysiologic adaptation – found in

people living in high altitudes where oxygen tension is low

Special Features/Behavior of Red Blood Cells

Rouleaux formationRBC adhere themselves to one another due to

surface tensionAppear as “columns” or “piles of coins”

CrenationRBC’s spiked shrunk appearanceInduced in vitro by: exposure to fatty

acids, lysolecithin, anionic compunds or elevated pH

Erythrocytes assume a spiny configuration with 10 – 30 spicules regularly distributed over their surface and are thus called echinocytes

Behavior of RBC when exposed to solutions of different concentrationsHypertonic solution Hypotonic solutionSolution of greater

concentration gradientFlow of water: from low

to highRBC shrinks

Isotonic solutionEqual concentration,

equal pressure (0.9% NaCl)

No change

Solution of lesser concentration and less osmotic pressure causing swelling of RBC

Water goes to cell causing the cell to swell and eventually burst and disintegrate

Anisocytosis – variation in RBC sizeMacrocyte – large RBC (9 μm)Normocyte – normal RBC (7 – 8 μm)Microcyte – small RBC (6 μm)

Poikilocytosis – variation in RBC shape

OvalocytesSpherocytes - inelasticSickle cells – “crescent-like”, sickling, inelastic, with

abnormal hemoglobin, hereditary factors (etiology)Target cells – abnormally shaped RBC in some cases

of anemia; do not undergo roleaux formation

Anisochromia – variation in RBC colorHyperchromic – more color, more hemoglobinNormochromic – normal color, normal

hemoglobinHypochromic – less color, less hemoglobin

Agglutination - sludging Clumping of RBC due to agglutinin (anti-

bodies)Happens in unmatched blood

RBC particlesHeinz bodies Granules found in normal RBCDue to congenital suseptibility to drugsHowell-Jolly bodiesRemnants of nuclear chromatin (inside RBC)Makes RBC with basophilic particles insideCabot’s ringRemnants of nuclear membrane (artifact)

WBC or Leukocytes

Leukocytes or WBCInvolved in the cellular

and humoral defense of the organism against foreign materials

Normal lifespan – a few days to a week

Normal count – 6,000 to 10,000 per microliter of blood

Divided into two groups:GranularNon-granular

TerminologiesDiapedesis – a process that accounts for

the unidirectional flow of granulocytes and monocytes thru intact walls of blood vessels

Chemotaxis – attraction of specific cells by chemical mediators; migration of blood cells to the site of infection

Granular WBC

Neutrophils/Heterophils60-70% 12-15 μm in diameter2-5 lobesIn females, the inactive

x-chromosome appears as a drumstick appendage on one of the lobes of the nucleus (Barr body)

First line of cellular defense (phagocytes)

Normal lifespan – 1-4 days (6-7 hours halflife)

Eosinophils or Acidophils2-4% Bilobed, with

numerous large acidophilic granules

Increase in number during parasitism and allergic reactions

BasophilsLess than 1%12-15 µm in

diameterS-shaped nucleus

obscured by large basophilic granules

May supplement the function of mast cells in immediate hypersensitivity reaction

Non-granular WBC

Lymphocytes6-8 µm (small),

medium-sized and large-sized (18 μm) are present in circulating blood

Diverse function, all related to immune reactions in defending against invading microorganism

Lifespan – a few daysThe only leukocyte

that return to the tissue after diapedesis

25 – 30%

Monocytes12-20 µm in

diameterU-shaped or kidney-

shaped nucleusPrecursor cells of

the mononuclear phagocyte system

4-8%

Platelets or Thrombocytes

ThrombocytesLightest formed elementsNonnucleated, disklike fragments 2-4 µmPromote blood clotting and help repair gaps

in the walls of blood vessels, preventing blood loss

Normal count – 200,000 to 400,000 per microliter of blood

Normal lifespan – about 10 days