THE BLOODChapter 13

Introduction

• Specialized connective tissue– Plasma: fluid part (55%)– Formed blood cells (45%)

• Erythrocytes• Leukocytes• Thrombocytes

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FUNCTIONS OF THE BLOOD

Functions of the Blood (cont’d.)

• Transports: O2, CO2, nutrients, waste, hormones

• Regulates: body pH, body temperature• Clotting mechanism• Protection against foreign microbes and

toxins• Osmosis

THE CLASSIFICATION OF BLOOD CELLS AND THE COMPOSITION OF PLASMA

The Classification of Blood Cells

• Erythrocytes (RBCs)– 95% of the volume of blood cells

• Leukocytes (WBCs)– Granular: neutrophils, eosinophils, basophils– Agranular: monocytes, lymphocytes

• Thrombocytes: platelets

The Composition of Plasma

• Fluid portion of blood is 91% water• Plasma proteins: 7%

– Albumin, globulin, fibrinogen• Plasma solutes: 2%

– Ions, nutrients, waste products, gases, enzymes, hormones

FORMATION OF BLOOD CELLS: HEMATOPOIESIS

Formation of Blood Cells: Hematopoiesis (cont’d.)

• Produced in red bone marrow• Lymphocytes and monocytes produced by

– Lymph nodes, spleen, tonsils• Stem cells: undifferentiated mesenchymal

cells

BLOOD CELL ANATOMY AND FUNCTIONS

Blood Cell Anatomy and Functions (cont’d.)

• Erythrocytes– Biconcave disks– No nucleus– Contain hemoglobin

• Heme: binds O2

• Globin: binds CO2

Blood Cell Anatomy and Functions (cont’d.)

• Granular leukocytes– Neutrophils

• Phagocytize foreign substances– Eosinophils

• Produce antihistamines– Basophils

• Produce heparin, histamine, serotonin

Blood Cell Anatomy and Functions (cont’d.)

• Agranular leukocytes– Monocytes

• Phagocytize bacteria and cellular debris• Macrophages: in tissues

– Lymphocytes• T lymphocytes• B lymphocytes

Blood Cell Anatomy and Functions (cont’d.)

• Thrombocytes or platelets– Disk-shaped cellular fragments with a nucleus– Prevent fluid loss when blood vessels

damaged– Produced from large megakaryocytes

THE CLOTTING MECHANISM

The Clotting Mechanism (cont’d.)

Ruptured blood vessel attracts Thrombocytes

Damaged tissue releases Thromboplastin

Thromboplastin + Ca+, ions, and proteins

Prothrombin activator + Ca+ Prothrombin

Thrombin Fibrinogen Fibrin

The Clotting Mechanism (cont’d.)

• Clot– Fibrin forms long threads acting like a net– Platelets get enmeshed

• Syneresis: clot retraction• Fibrinolysis: dissolution of blood clot

The Clotting Mechanism (cont’d.)

• Thrombosis: unwanted clotting• Embolus: circulating blood clot• Infarction

– Tissues killed as a result of loss of blood supply

The Clotting Mechanism (cont’d.)

Animation – Blood

Click Here to Play Blood Animation

THE BLOOD GROUPS

Introduction

• Human blood is of different types– Only certain combinations are compatible

• Agglutination: clumping of RBCs– Occurs when blood groups mismatched– Transfusion reaction

The ABO Blood Group

• Type A– Anti-B antibodies

• Type B– Anti-A antibodies

• Type AB– No antibodies

The ABO Blood Group (cont’d.)

• Type O– Anti-A and anti-B antibodies

The Rh Blood Group

• Eight Rh antigens• Antigen D: most important• Anti-Rh antibodies develop after exposure

– Rh-negative mother carrying Rh-positive baby• Erythroblastosis fetalis• RhoGAM - protects Rh-positive fetus

Summary

• Described the functions of blood• Classified blood cells into different groups

based on anatomy and function• Discussed how and where blood cells are

formed• Explained the clotting mechanism• Named the different blood groups