Cardiovascular & Hematological Systems

Chapter 6Pathology

Circulatory Systemcirculatory system - the heart, blood vessels and

bloodcardiovascular system - the heart and blood vesselshematology – the study of blood functions of circulatory system

◦ transport O2, CO2, nutrients, wastes, hormones

◦ protection limit spread of infection, destroy microorganisms

and cancer cells, and initiates clotting◦ regulation

fluid balance, stabilizes pH of ECF, and temperature control

TransportationBloodCarries oxygen to tissuesCarries carbon dioxide from

tissuesTransports nutrients and other

substances to cellsTransports waste products from

cellsCarries hormones to organs

RegulationBloodBuffers keep pH of body fluids

between 7.35 and 7.45Substances maintain osmotic

pressure to regulate fluid in tissues (fluid balance)

Transports heat generated in muscles to aid in regulation of body temperature

ProtectionBloodCarries cells and antibodies of

immune systemCarries factors to protect against

blood loss

Components and General Properties of Bloodadults have 4-6 L of blooda liquid connective tissue consisting

of cells and extracellular matrix◦plasma – matrix of blood a clear, light yellow fluid

◦formed elements - blood cells and cell fragments red blood cells, white blood cells, and

platelets

Components and General Properties of Bloodseven kinds of formed elements

◦erythrocytes - red blood cells (RBCs)◦Platelets - thrombocytes

cell fragments from special cell in bone marrow

◦leukocytes - white blood cells (WBCs) five leukocyte types divided into two

categories: granulocytes (with granules)

neutrophils eosinophils basophils

agranulocytes (without granules) lymphocytes monocytes

Formed Elements of Blood

Neutrophil

Erythrocyte

Eosinophil

Monocyte

NeutrophilBasophil

Neutrophil

Platelets

MonocyteSmalllymphocyte

Young (band)neutrophil

Smalllymphocyte

Largelymphocyte

Separating Plasma From Formed Elements of Blood

hematocrit (packed cell vol.)- centrifuge blood to separate components◦erythrocytes are

heaviest and settle first 37% to 52% total volume

(hematocrit)◦leukocytes and platelets

1% total volume; buffy coat◦plasma

the remainder of volume 47% - 63%

Centrifuge

Withdrawblood

Plasma(55% of whole blood)

Buffy coat: leukocytesand platelets(<1% of whole blood)

Erythrocytes(45% of whole blood)

Formedelements

Plasma and Plasma Proteins

plasma – liquid portion of blood3 major categories of plasma

proteins◦albumins – smallest and most

abundant◦globulins (antibodies)

provide immune system functions alpha, beta and gamma globulins

◦fibrinogen precursor of fibrin threads that help form

blood clots

Percentages show the relative proportions of the different components of plasma and formed elements.

Composition of Whole BloodComposition of Whole Blood

Blood Plasma

Plasma is 55% of blood91% water8% protein

◦ Albumin◦ Clotting factors◦ Antibodies◦ Complement

•1% other materials–Glucose–Amino acids–Lipids–Electrolytes–Vitamins–Hormones–Wastes–Drugs–Dissolved gases

Hemopoiesisadult production of 400 billion platelets, 200

billion RBCs and 10 billion WBCs every dayhemopoiesis – the production of blood,

especially its formed elementshemopoietic tissues produce blood cells

◦yolk sac produces stem cells for first blood cells colonize fetal bone marrow, liver, spleen and

thymus◦liver stops producing blood cells at birth◦spleen remains involved with lymphocyte

production◦red bone marrow produces all seven formed

elements

The Formed ElementsThe Formed ElementsProduced in red bone marrowHematopoietic (blood-forming)

stem cells can develop into any blood cell

Short-lived tissue cells

ErythrocytesRed blood cells (RBCs) most

numerousMature cells anuclearContain hemoglobin

◦Binds to oxygen for transport◦Carries hydrogen ions for buffering◦Carries carbon dioxide for

elimination

Erythrocytes (RBCs)

Erythrocytes (RBCs)Erythrocytes are an example of the

complementarity of structure and function

Structural characteristics contribute to its gas transport function◦Biconcave shape has a huge surface area

relative to volume◦Erythrocytes are more than 97% hemoglobin◦ATP is generated anaerobically, so the

erythrocytes do not consume the oxygen they transport

Erythrocyte FunctionRBCs are dedicated to respiratory gas

transportHb reversibly binds with oxygen and most

oxygen in the blood is bound to HbHb is composed of the protein globin,

made up of two alpha and two beta chains, each bound to a heme group

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

Each Hb molecule can transport four molecules of oxygen

Erythrocytes and Erythrocytes and HemoglobinHemoglobin RBC count and hemoglobin concentration indicate amount of O2 blood can carry◦ hematocrit (packed cell volume) – percentage of

whole blood volume composed of red blood cells men 42- 52% cells; women 37- 48% cells

◦ hemoglobin concentration of whole blood higher in men

◦ RBC count higher in men Why values are lower in women

◦ androgens stimulate RBC production ◦ women have periodic menstrual losses◦ hematocrit is inversely proportional to percentage of

body fat

Hemoglobin (Hb)Oxyhemoglobin – Hb bound to

oxygen◦Oxygen loading takes place in the lungs

Deoxyhemoglobin – Hb after oxygen diffuses into tissues (reduced Hb)

Carbaminohemoglobin – Hb bound to carbon dioxide ◦Carbon dioxide loading takes place in

the tissues

Production of ErythrocytesHematopoiesis – blood cell

formationHematopoiesis occurs in the red

bone marrow of the:◦Axial skeleton and girdles◦Epiphyses of the humerus and femur

Hemocytoblasts give rise to all formed elements

Hormonal Control of ErythropoiesisErythropoietin (EPO) release by the

kidneys is triggered by:◦Hypoxia due to decreased RBCs◦Decreased oxygen availability◦Increased tissue demand for oxygen

Enhanced erythropoiesis increases the: ◦RBC count in circulating blood◦Oxygen carrying ability of the blood

Homeostasis: Normal blood oxygen levels

IncreasesO2-carryingability of blood

Erythropoietinstimulates redbone marrow

Reduces O2 levelsin blood

Kidney (and liver to a smallerextent) releases erythropoietin

Enhancederythropoiesisincreases RBC count

Stimulus: Hypoxia due todecreased RBC count,decreased amount of hemoglobin, or decreased availability of O2

Start

Imbalance

Imbalance

Erythropoietin Mechanism

Erythrocyte HomeostasisErythrocyte Homeostasis negative feedback control

◦ drop in RBC count causes kidney hypoxia

◦ kidney production of EPO stimulates bone marrow

◦ RBC count increases in 3 - 4 days

stimuli for increasing erythropoiesis◦ low levels O2 (hypoxemia)◦ high altitude◦ increase in exercise◦ loss of lung tissue in emphysema

leaves

Hypoxemia(inadequate O2 transport)

Sensed by liver and kidneys

Secretion oferythropoietin

Acceleratederythropoiesis

IncreasedRBC count

IncreasedO2 transport

Stimulation ofred bone marrow

ErythrocyteErythrocyte Disorders Disorders polycythemia - an excess of RBCs

◦ primary polycythemia (polycythemia vera) cancer of erythropoietic cell line in red bone marrow

RBC count as high as 11 million/L; hematocrit 80%

◦ secondary polycythemia from dehydration, emphysema, high altitude, or

physical conditioning RBC count up to 8 million/L

dangers of polycythemia◦ increased blood volume, pressure, viscosity

can lead to embolism, stroke or heart failure

AnemiaAnemiacauses of anemia fall into three categories:

◦ inadequate erythropoiesis or hemoglobin synthesis kidney failure and insufficient erythropoietin iron-deficiency anemia inadequate vitamin B12 from poor nutrition or

lack of intrinsic factor (pernicious anemia) hypoplastic anemia – slowing of

erythropoiesis aplastic anemia - complete cessation of

erythropoiesis◦ hemorrhagic anemias from bleeding◦ hemolytic anemias from RBC destruction

AnemiaAnemiaanemia has three potential

consequences:◦tissue hypoxia and necrosis

patient is lethargic shortness of breath upon exertion life threatening necrosis of brain, heart, or

kidney◦blood osmolarity is reduced producing

tissue edema◦blood viscosity is low

heart races and pressure drops cardiac failure may ensue

Blood TypesBlood Typesblood types and transfusion

compatibility are a matter of interactions between plasma proteins and erythrocytes

blood types are based on interactions between antigens and antibodies

Blood Antigens and Blood Antigens and AntibodiesAntibodies

antigens◦complex molecules on surface of cell

membrane that are unique to the individual used to distinguish self from foreign foreign antigens generate an immune

response agglutinogens – antigens on the

surface of the RBC that is the basis for blood typing

Blood Antigens and Blood Antigens and AntibodiesAntibodies

antibodies◦proteins (gamma globulins) secreted by

plasma cells part of immune response to foreign

matter bind to antigens and mark them for

destruction forms antigen-antibody complexes agglutinins – antibodies in the plasma

that bring about transfusion mismatch

ABO GroupABO Groupyour ABO blood type is determined

by presence or absence of antigens (agglutinogens) on RBCs◦blood type A person has A antigens◦blood type B person has B antigens◦blood type AB has both A and B antigens◦blood type O person has neither antigen

most common - type O rarest - type AB

Universal Donors and Universal Donors and RecipientsRecipientsSafest transfusion is same blood typeuniversal donor

◦Type O – most common blood type◦lacks RBC antigens◦donor’s plasma may have both antibodies

against recipient’s RBCs (anti-A and anti-B) may give packed cells (minimal plasma)

universal recipient ◦Type AB – rarest blood type◦lacks plasma antibodies; no anti- A or B

Labels on the bottles denote the kind of antiserum (antibodies) added to the blood samples.

Anti-A serum agglutinates (causes to clump) red cells in type A blood, but anti-B serum does not.

Anti-B serum agglutinates red cells in type B blood, but anti-A serum does not. Both sera agglutinate type AB blood cells, and neither serum agglutinates type O blood

Blood TypingBlood Typing

Type A

Type B

Type AB

Type O

LeukocytesLeukocytesWhite blood cells (WBCs) colorless, round

◦Granulocytes Neutrophils (polymorphs) Eosinophils Basophils

◦Agranulocytes Lymphocytes Monocytes

Prominent nuclei Clear body of foreign material, cellular

debris, pathogens

HemostasisHemostasisPrevents blood loss when blood

vessel rupturesContraction of smooth muscles in

blood vessel wall (vasoconstriction)

Formation of platelet plugFormation of blood clot

Uses of Blood and Blood Uses of Blood and Blood ComponentsComponentsBlood stored in blood banks up to

35 days◦Anti-clotting solution added◦Expiration date added

Blood donated before elective surgery (autologous blood)

Whole Blood TransfusionsUsed for loss of large volume of

bloodMassive hemorrhage from serious

injuriesDuring internal bleedingDuring or after an operationBlood replacement in treatment of

HDN

Use of PlasmaReplace blood volumeTreat circulatory failure (shock)Treat plasma protein deficiencyReplace clotting factorsProvide needed antibodies

Blood DisordersBlood DisordersBlood abnormalitiesAnemia (low level of hemoglobin

or red cells)Leukemia (increase in white cells)Clotting disorders (abnormal

tendency to bleed)

AnemiaAnemia causesExcessive loss or destruction of red cells

◦Hemorrhagic anemia◦Hemolytic anemia◦Sickle cell anemia

Impaired production of red cells or hemoglobin◦Deficiency anemia◦Thalassemia◦Bone marrow suppression

LeukemiaLeukemia is characterized by

enormous increase in white cellsMyelogenous leukemia from bone

marrowLymphocytic leukemia from

lymphoid tissueBone marrow transplants sometimes

successful in restoring blood-producing stem cells lost after leukemia treatment

Clotting DisordersAbnormal bleeding through

disruption of coagulation processHemophiliaVon Willebrand diseaseThrombocytopeniaDisseminated intravascular

coagulation (DIC)

The Blood Slide (Smear)Complete blood count (CBC)

performed on drop stained blood slide

Red cells examinedPlatelets examinedParasites may be foundDifferential white count performed