THE BLOOD

Chapter 13

Introduction

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

• Erythrocytes• Leukocytes• Thrombocytes

2

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