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.