The Blood

The BloodThe Blood

The BloodThe Blood

DefinitionDefinitionBlood is a connective tissue, made of fluid (plasma) and Blood is a connective tissue, made of fluid (plasma) and

cellular elements (RBC, WBC, and platelets)cellular elements (RBC, WBC, and platelets) Its volume is 5-6 L in males and 4-5 L in femalesIts volume is 5-6 L in males and 4-5 L in females It is slightly alkaline, with a pH of ~ 7.4It is slightly alkaline, with a pH of ~ 7.4 Its color varies from bright to dark redIts color varies from bright to dark red It has a salty metallic tasteIt has a salty metallic taste

The BloodThe Blood

FunctionsFunctions

The bloodThe blood is an organ that reaches all the other tissuesis an organ that reaches all the other tissues Transports oxygen and nutrientsTransports oxygen and nutrients Removes CORemoves CO22 and other by-products of cell activity and other by-products of cell activity Participates in the defense against infectionParticipates in the defense against infection Participates in hemostasisParticipates in hemostasis Participates in body heat distribution and regulationParticipates in body heat distribution and regulation

Marieb and Hoehn Human Anatomy & Physiology seventh edition Pearson Benjamin Cummings

The BloodThe Blood

PlasmaPlasma

Straw colored fluid made of water (~90%), other contents include: Straw colored fluid made of water (~90%), other contents include: Proteins make the bulk of the solutes: Proteins make the bulk of the solutes: Albumens (60%), manufactured in the liver are the most abundantAlbumens (60%), manufactured in the liver are the most abundant Globulins (36%) are immune bodiesGlobulins (36%) are immune bodies Fibrinogen (4%) for blood clottingFibrinogen (4%) for blood clottingNutrients: glucose, amino acids, lipids, cholesterolNutrients: glucose, amino acids, lipids, cholesterolElectrolytes: NaElectrolytes: Na++, K, K++, Ca, Ca++++, Mg, Mg++++, H, H++, Cl, Cl--, HCO, HCO33

--, PO, PO44----, SO, SO44

---- Waste: urea, creatinine, uric acid, bilirubinWaste: urea, creatinine, uric acid, bilirubinGases: OGases: O22 , CO , CO2 2 , N, N22

ProteinProteinPlasma without clotting factors is called “serum”Plasma without clotting factors is called “serum”

Peripheral blood smear

Marieb and Hoehn Human Anatomy & Physiology seventh edition Pearson Benjamin Cummings

Pathophysiology McCance & Huether fifth edition Elsevier Mosby

Electron micrograph of blood smear

The BloodThe Blood RBCRBCAn RBC is a 7.5 micron disc shaped body with a central An RBC is a 7.5 micron disc shaped body with a central

depressiondepressionNO nucleus NO mitochondriaNO nucleus NO mitochondria AN RBC contains hemoglobin AN RBC contains hemoglobin Antigens on RBC cell membrane determine blood typeAntigens on RBC cell membrane determine blood typeRBCs function is gas exchange: ORBCs function is gas exchange: O22 to the tissues and CO to the tissues and CO22 to the to the

lungslungs

The BloodThe Blood

RBCRBCDevelopment of RBCsDevelopment of RBCs Hypoxia Hypoxia → erythropoietin (kidney)→→ erythropoietin (kidney)→ red marrow of long bones red marrow of long bones→→The normal number of RBCs is 4.3-5 million/mmThe normal number of RBCs is 4.3-5 million/mm3 3 in the female and 5.1-5.8 million/mm3 in the male The normal values for Hgb are 13-15 gm/dl for females and 14-16 gm/dl in malesAmino acids, lipids, carbohdrates, iron, vitamin B12 and folic acid are essntial for

hemoglobin synthesis

The BloodThe Blood RBCRBC

Hemoglobin has a remarkable ability to bind with oxygen Hemoglobin has a remarkable ability to bind with oxygen forming oxyhemoglobinforming oxyhemoglobinIt can also release the oxygen to the tissues becoming It can also release the oxygen to the tissues becoming

deoxyhemoglobindeoxyhemoglobin

The BloodThe Blood

RBCRBCDestructionDestruction Life span ~ 120 daysLife span ~ 120 days RBCs are phagocytosed by the reticulo-endothlial cells of the spleenRBCs are phagocytosed by the reticulo-endothlial cells of the spleen

The BloodThe Blood

RBCRBCDisorders of RBCsDisorders of RBCs Anemia is reduced RBC countAnemia is reduced RBC count Anemias can be caused byAnemias can be caused by RBC loss or reduced production RBC loss or reduced production Hemorrhage, hemolysis, depressed bone marrowHemorrhage, hemolysis, depressed bone marrow Reduced hemoglobin content of RBCsReduced hemoglobin content of RBCs Iron, intrinsic factor, folic acid, or BIron, intrinsic factor, folic acid, or B12 12 deficiencydeficiency Congenital hemoglobin defectsCongenital hemoglobin defects Thalassemia, sickle cell anemia, spherocytosisThalassemia, sickle cell anemia, spherocytosis

Normal and sickle cell RBCIn sickle cell disease hemoglobin S replaces the β chainIn thalassemias, the α or β chains can be absent or defective

Marieb and Hoehn Human Anatomy & Physiology seventh edition Pearson Benjamin Cummings

The BloodThe Blood

White Blood Cells (WBC)White Blood Cells (WBC)FunctionFunction Lymphocytes are the effectors of the immune functionLymphocytes are the effectors of the immune function WBCs main function is to fight bacterial infectionsWBCs main function is to fight bacterial infections WBCs are the only nucleated blood formed elementsWBCs are the only nucleated blood formed elements They exercise their functions in the tissues not the blood streamThey exercise their functions in the tissues not the blood stream WBC migrate to the tissue spaces WBC migrate to the tissue spaces WBC destroy the bacterial cell wall WBC destroy the bacterial cell wall Life span 1 – 9 daysLife span 1 – 9 days

The BloodThe Blood White Blood Cells (WBC)White Blood Cells (WBC)

Lymphocytes, the smallest and second most abundantLymphocytes, the smallest and second most abundant T cells (80%) mediate cellular immunityT cells (80%) mediate cellular immunity B cells mediate humoral immunityB cells mediate humoral immunity Monocytes, the largest, migrate to the tissues and become Monocytes, the largest, migrate to the tissues and become macrophages involved in cellular immunitymacrophages involved in cellular immunity

Davidson’s The Priciples and Practice of Medicine, eigthteenth edition Churchill Livingstone

White blood cells, the granulcytes

Monocytes and lymphocytes

Davidson’s The Priciples and Practice of Medicine, eighteenth edition Churchill Livingstone

The BloodThe Blood

Blood CoagulationBlood Coagulation

Coagulation is a natural mechanism that acts to diminish Coagulation is a natural mechanism that acts to diminish blood loss from hemorrhageblood loss from hemorrhage

Coagulation occurs in three StagesCoagulation occurs in three Stages Platelet plugPlatelet plug The cascade leading to fibrin (clot) formationThe cascade leading to fibrin (clot) formation Clot retraction and repair (PDGF)Clot retraction and repair (PDGF)

The BloodThe Blood

Blood CoagulationBlood Coagulation The Platelets The Platelets

Platelets are cell fragments Platelets are cell fragments Their life span is 8-14 daysTheir life span is 8-14 days

The structure of a platelet

Davidson’s The Priciples and Practice of Medicine, eighteenth edition Churchill Livingstone

Initial vasoconstriction and platelet plug

vVander’s Physiology eighth edition Mc Graw Hill

Intrinsic and extrinsic coagulation pathways

Vander’s Physiology eighth edition Mc Graw Hill

Calcium ions are essential for the coagulation cascade

The role of the liver in blood coagulation

Vander’s Physiology eighth edition Mc graw Hill

EM of a blood clot: RBC’s and fibrin

NIBSC?Science Photo Libraray – Taken from Vander Physiology eighth edition Mc Graw Hill

The BloodThe Blood

Blood TypesBlood Types

RBC’s have surface antigensRBC’s have surface antigensRBC’s can be grouped according to the presence or absence RBC’s can be grouped according to the presence or absence

of certain antigensof certain antigensThere are many RBC antigens but only a A, B, AB and the Rh There are many RBC antigens but only a A, B, AB and the Rh

are of are of clinical significanceclinical significanceEach one of the four types can be Rh positive or negativeEach one of the four types can be Rh positive or negativeDonor blood is mixed with recipient serum to decide Donor blood is mixed with recipient serum to decide

compatibility, donor cell clumping indicate incompatibilitycompatibility, donor cell clumping indicate incompatibility

Major blood groups

Marieb and Hoehn Human Anatomy & Physiology seventh edition Pearson Benjamin Cummings

A certain group posseses its antigen on the RBC surface and antibodies against the others

The BloodThe Blood

Rh FactorRh FactorThere are no preformed Rh antibodies in RhThere are no preformed Rh antibodies in Rh -- individuals individuals They develop after exposure to RhThey develop after exposure to Rh++ factors (antigens) factors (antigens)This explains the fact that an RhThis explains the fact that an Rh++ fetus of an Rh fetus of an Rh-- mother mother does not usually sufferdoes not usually sufferBut the RhBut the Rh-- mother can be sensitized to the Rh mother can be sensitized to the Rh++ antigens during antigens during

the first pregnancy, especially during deliverythe first pregnancy, especially during deliverySubsequent fetuses can suffer from the mother’s Rh antibodies Subsequent fetuses can suffer from the mother’s Rh antibodies

passedpassed to it and its blood hemolyzesto it and its blood hemolyzesThis can be prevented by giving the mother serum that blocks This can be prevented by giving the mother serum that blocks

the Rhthe Rh++

factors antigenicityfactors antigenicity

The BloodThe Blood

Rh FactorRh Factor

Eighty five percent of the population have Rh antigens (RhEighty five percent of the population have Rh antigens (Rh++))There are several Rh groups (factors, antigens)There are several Rh groups (factors, antigens)Three groups: Rh, C, D, and E, are of clinical importanceThree groups: Rh, C, D, and E, are of clinical importanceAn RhAn Rh-- mother may develop antibodies against her Rh mother may develop antibodies against her Rh++ fetus fetusThe RhThe Rh-- mother antibodies can pass to the Rh mother antibodies can pass to the Rh++ fetus resulting fetus resulting

in hemolysis of its RBCs, a condition know as in hemolysis of its RBCs, a condition know as erythroblastosis fetaliserythroblastosis fetalis

This sequence usually occurs after the first pregnancyThis sequence usually occurs after the first pregnancy