Chapter 9.1

Introduction

• Chapter 9 focuses on medical terms related to blood and the immune system.

• Chapter 10 will cover the cardiovascular and lymphatic systems, including the heart, blood vessels, and lymph vessels.

Basic Functions of Blood and the Immune System

Transport

• The primary function of blood is to transport substances throughout the body.

• Gases: Oxygen (O2) and carbon dioxide (CO2).

• Nutrients: Glucose, amino acids.

• Electrolytes: Sodium, potassium.

• Vitamins, hormones, and waste products.

Protection

• Blood protects against foreign invaders via immune system components.

• Clears bacteria, viruses, and fungi.

• Immune system components include cells and molecules like antibodies (Y-shaped proteins produced by white blood cells).

• Clotting: Platelets help patch broken blood vessels to prevent hemorrhage.

Blood as a Connective Tissue

• Blood is a fluid connective tissue found in the circulatory system.

• Located in the heart chambers, arteries, capillaries, and veins.

• Transports oxygen and materials to body tissues.

Formed Elements

• Blood cells are referred to as "formed elements."

• Formed in the bone marrow.

• Most are incomplete cells or cell fragments.

• White blood cells are the only true whole cells.

Plasma

• Plasma is the liquid portion of blood.

• Composed mostly of water.

• Carries formed elements, clotting factors, minerals, and proteins.

Serum

• Serum is the liquid portion of blood (plasma) after removing clotting factors, proteins, and formed elements.

Connective Tissue Clarification

• Blood is classified as a connective tissue, similar to tendons, ligaments, fat, bone, and cartilage.

Composition of Blood

Centrifugation

• Whole blood centrifuged separates into components based on size and weight.

  • 45% formed elements (cells).

  • 55% plasma (liquid portion).

Plasma Composition

• Plasma is mostly water with proteins and other solutes.

Formed Elements Composition

• Erythrocytes (red blood cells) make up 99% of formed elements.

• Leukocytes (white blood cells) and platelets make up the remaining 1%.

Buffy Coat

• Leukocytes and platelets form a buffy coat on top of the red blood cells after centrifugation.

Medical Terms for Blood Cells

• Red blood cells: Erythrocytes (erythro- means red).

• White blood cells: Leukocytes (leuko- means white or clear).

• Platelets: Thrombocytes (thrombo- means clot, -cyte means cell).

• Erythrocytes carry oxygen; leukocytes provide immune protection; thrombocytes aid in clotting.

Visual Representation of Blood Cells

Microscopic Images

• Scanning electron micrograph showing erythrocytes, leukocytes, and platelets at 3,500x magnification.

Blood Smear

• Blood smear shows erythrocytes, neutrophils, lymphocytes, and eosinophils.

• Dyes are added to blood smears to visualize cells.

Leukocyte Types

• Neutrophils, lymphocytes, and eosinophils are shown.

• Leukocytes have different nuclear morphologies.

Platelets

• Platelets are small cell fragments important in clotting.

Erythrocyte Appearance

• Erythrocytes appear to have a hole in the center due to their biconcave shape, which allows light to pass through.

Blood Organs: Bone Marrow

Location and Types

• Bone marrow is a soft connective tissue inside bones.

• Found in spongy bone and hollow cavities of long bones.

• Red bone marrow produces blood cells.

Hematopoiesis

• Hematopoiesis (or hemopoiesis) is the formation of blood cells.

Erythropoietin (EPO)

• Erythropoietin is a hormone produced by the kidneys that stimulates red blood cell production.

Blood Organs: Spleen

Location and Function

• The spleen is a highly vascularized lymphatic organ located on the left side of the body, behind the stomach.

• Filters blood and destroys old red blood cells (red blood cell graveyard).

• Acts as a blood reservoir.

Red Blood Cell Lifespan

• Red blood cells live for about 120 days.

Erythrocytes

Function

• Carry oxygen (O2) and carbon dioxide (CO2).

Hemoglobin (Hb)

• Hemoglobin is a red pigmented protein that binds to oxygen.

• Contains four iron atoms (Fe) per molecule, which bind to oxygen.

• Red blood cells are essentially sacks of hemoglobin.

Blood Types (ABO and Rh Factor)

• ABO blood types are determined by protein receptors on the surface of red blood cells (A, B, AB, O).

• Rh factor: Individuals either have it (Rh positive) or do not (Rh negative).

• Blood type compatibility is crucial for transfusions.

Erythrocyte Abnormalities

• Macrosites are abnormally large erythrocytes, which may indicate a blood disorder.

Leukocytes (White Blood Cells)

Function

• Protect against foreign pathogens and remove cell debris.

• True whole cells.

Types

• Granulocytes: Neutrophils, eosinophils, and basophils.

• Agranulocytes: Lymphocytes and monocytes.

Granulocytes

• Contain visible granules when stained.

Neutrophils

• Granules absorb both acidic and basic dyes (neutral).

• Also known as polymorphonuclear leukocytes (PMNs) due to multi-segmented nuclei.

Eosinophils

• Attracted to acidic dyes (eosin).

Basophils

• Attracted to basic dyes.

Agranulocytes

• Lack clearly visible granules.

Lymphocytes

• Smallest leukocytes with a large nucleus.

• Types: T cells and B cells.

• B cells produce antibodies.

• T cells can mature into cytotoxic killer cells.

• Provide sophisticated immune responses and can last for years.

Monocytes

• Largest leukocytes with a horseshoe-shaped nucleus.

• Can move into body tissues and become macrophages.

Functions of Leukocytes

• Neutrophils: Most abundant, first responders to infection, bacterial slayers.

• Eosinophils: Fight parasitic worm infections, markers of inflammation, counter basophil action.

• Basophils: Induce allergic responses by releasing histamine.

• Lymphocytes: B cells make antibodies, T cells kill infected cells.

• Monocytes: Differentiate into macrophages in tissues, involved in phagocytosis.

Platelets (Thrombocytes)

Function

• Cell fragments that help form blood clots.

• Prevent blood loss when there is trauma to blood vessels.

Clotting Factors

• Molecules involved in the clotting process, such as calcium (clotting factor IV), enzymes, and proteins.

Coagulation

• The process of changing blood from a liquid to a solid state.

• Involves the formation of fibrin, a protein fiber that creates a solid seal over damaged vessels.

Fibrin Formation

• Fibrin normally exists in an inactive state called fibrinogen in the blood plasma.

• Fibrinogen is soluble in water until chemical reactions convert it into insoluble fibrin threads.

Conclusion

• Review of basics of blood cells and formed elements.

• The next video will cover the immune system in more detail.