The BloodThe Blood“Transport System”

Composition of the BloodComposition of the Blood

• Blood makes up ~8% of total body weight• ~55% plasma• ~45% formed elements

• 4 to 5 liters for average females• 5 to 6 liters for average male

*the higher percent body fat the less blood you have per kilogram of weight

PlasmaPlasma

• 90% water• 10% solutes (salts and minerals)

Formed ElementsFormed Elements

• Red Blood Cells (RBCs) (erythrocytes)• White Blood cells (WBCs) (leukocytes)• Platelets (thrombocytes)

RBCs make up about 45% of blood volumeWBCs and platelets make up about 1%

Blood CompositionBlood Composition

Red Blood Cells(erythrocytes)Red Blood Cells(erythrocytes)

• Mature cells lack a nucleus and most organelles

• Hemoglobin, red pigment, makes up 1/3 of cell volume

• RBCs are highly flexible because of spectrin protein

• Flexibility can determine the speed of blood flow

• Men have more RBCs because of the influence of testosterone

Hematocrit tubesHematocrit tubes

Hematocrit tubes show normal, anemic and polycythemia

Function of RBCsFunction of RBCs

• Hemoglobin and carbonic anhydrase both work to transport O2 and CO2

• Total surface area of all of an adult’s RBCs is about as big as a football field

HemoglobinHemoglobin

• Made up of 4 protein chains called globins

• Each chain is bound to a heme group which contains one Fe

• The iron can bind to one O2

• Each globin can bind to one CO2

Formation of RBCsFormation of RBCs

• Erythropoiesis begins with hematopoietic stem cells in red bone marrow

• New red blood cells take 4 days to mature

• Sickle cell anemia- inherited defect, causes a defective hemaglobin. Cells become sickle shaped and can clog blood vessels.

Formation of RBCsFormation of RBCs

• Decreased levels of oxygen stimulate the production of RBCs by secreting erythropoietin (EPO) from the kidneys

Destruction of RBCsDestruction of RBCs• ~200 million RBCs are formed each

day to replace the equal amount destroyed

• Lifespan of RBCs is 105-120 days

• Lining of blood vessels in liver and spleen destroy damaged or fragmented RBCs

• Components of the cells are broken and reused to make more RBCs

• Bone marrow must have a constant supply of iron, B12, and amino acids to make new RBCs

• B12 is called the antianemic principle

White Blood Cells(leukocytes)White Blood Cells(leukocytes)

Granulocytes – Neutrophils – multi-lobed

• make up about 65% of WBC count

• Move from blood vessels into tissues through diapedesis

– Eosinophils – orange-ish• Fight infection caused by

parasitic worms and allergic reactions

– Basophils – dark purple• Granules contain

histamine and heparin (anticoagulant)

neutrophils

basophils

eosinophils

Who has pimples?Who has pimples?

BEN does. Basophils, eosinophils, neutrophils

White Blood Cells(leukocytes)White Blood Cells(leukocytes)

Agranulocytes– Lymphocytes – “eyes”

• Ingest infected or cancerous cells

• Create antibodies

– Monocytes – “Mongo” kidney-shaped lobe

• Largest of the leukocytes

• Ingest infected cells

lymphocytes

monocytes

White blood cells numbersWhite blood cells numbers

Differential white blood cell count can indicate different types of infections.

Certain drugs can cause leukopenia (low WBC count)

PlateletsPlatelets

• Are small cells with special characterisitcs: agglutination, adhesiveness, and aggregration.

• Once they leave the blood vessels they become misshapen and clump together

Platelet ActionPlatelet Action

Platelets have two roles, hemostasis (blood flow stoppage) and coagulation (blood clotting).

Hemostatic action will occur when a platelet encounters a tear in a capillary. It will form a platelet plug to stop blood from flowing into the tissue.

Coagulation occurs when sticky platelets release chemicals to cause the blood to clot.

Platelets have a life span of ~7 days

resting platelets

activated platelets

Blood ClottingBlood Clotting

• Clotting Factors in the blood, in blood cells, and in tissues combine in a metabolic cascade when damage to cells or tissues occurs.

• Factors in the blood are called intrinsic• Factors in tissues are called extrinsic• Prothrombin→Thrombin→Fibrinogen→Fibrin→Clot

Blood ClottingBlood ClottingAs platelets bind to injury site they

release chemicals that trigger the clotting process.

Fibrin forms at site of injury and entangle RBCs.

Calcium in the blood and vitamin K are an important cofactors in coagulation.

Arteriosclerosis can increase clotting because platelets stick to rough patches.

Applying a rough surface such as gauze, heat or pressure as well as direct application of clotting agents can speed up clotting.

Clot DissolvingClot Dissolving

• After a while, the clot must dissolve.• Fibrinolysis • Heparin is major anticoagulant

produced in by the liver

Blood DisordersBlood Disorders

Anemia-inability of blood to transport O2

– Aplastic anemia-caused by destruction of bone marrow, drugs, radiation or idiopathic.

– Pernicious anemia- results from lack of vitamin B12

– Folate-deficiency anemia- results from lack of folic acid, common in alcoholics

– Acute blood loss anemia- occurs after serious injury.

Blood DisordersBlood DisordersClotting disorders

– Thrombus- is a localized blood clot, thrombosis.

– Embolus- when a clot circulates in blood stream, embolism.

• Hemophilia is an inherited (sex linked) disorder where the blood has difficulty clotting. No Factor VIII

• Thrombocytopenia- bleeding occurs throughout the body because of low platelets usually caused by destruction of bone marrow.

Blood TypesBlood Types

• Blood type is determined by the type of antigens found on the outside of RBC’s.

• Blood plasma will then contain antigens only for the type not found on the person’s RBC’s.

AgglutinationAgglutination

Agglutination will only occur when antibodies encounter foreign antigens.

Blood DonationsBlood DonationsHomologous transfusion- when a persons receives a matching blood type from

another person

Autologous transfusion- when a person donates blood to themselves.

Rh factorRh factor

• Rh+ positive persons carry the Rh antigen

• Rh- negative person has no antibodies against the antigen until they are exposed to it through either blood transfusions or pregnancy.