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Chapter 18 & 19 – Cardiovascular System

Blood Classification

  • Blood is classified as a connective tissue because:

    • It consists of cells suspended in a liquid matrix called plasma.

Components of Blood

  • Two components of blood:

    • Plasma- Lots of plasma proteins, 92% water, 7% plasma protein, 1% other solutes

    • Formed elements

Formed Elements of Blood

  • Three formed elements of blood:

    • Erythrocytes (red blood cells)

    • Leukocytes (white blood cells)

    • Thrombocytes (platelets)

Functions of Blood

  • Three main functions of blood:

    • Transport:

    • Transports gases (O2 and CO2), nutrients, hormones, and wastes.

    • Regulation:

    • Regulates pH, temperature, and fluid balance in the body.

    • Protection:

    • Provides protection through clotting mechanisms and immune defense functions, WBCs and platelets.

  • Blood accounts for 8% of body weight

  • Blood ph is regulated to be slightly alkaline

  • Blood is 5x more viscous than water, the more hydrated you are the less viscous your blood is.

Hematocrit

  • Definition:

    • Hematocrit is the percentage of red blood cells in whole blood.

  • Conditions that may increase hematocrit:

    • Dehydration

    • High altitude

    • Polycythemia

Relationship Between Formed Elements and Viscosity

  • As the number of formed elements increases:

    • Blood viscosity increases, making blood thicker and harder to pump.

Plasma vs. Interstitial Fluid

  • Differences:

    • Plasma contains plasma proteins, while interstitial fluid does not.

    • These plasma proteins are produces in the liver: Albumin (58%) Alpha-1 and beta-globulins (37%), Fibrinogen (4%) and other clotting proteins

  • Colloid Nature of Blood:

    • Blood is a colloid, which means it contains large suspended molecules that do not easily cross capillary walls.

Colloid Osmotic Pressure (COP)

  • Definition:

    • COP helps maintain blood volume and pressure by drawing water into the bloodstream.

  • Plasma Proteins and COP:

    • Plasma proteins create COP; a reduction in COP can lead to edema (swelling due to fluid accumulation)

Hematopoiesis

  • Definition:

    • Hematopoiesis is the formation of blood cells.

  • Location of Hematopoiesis:

    • It occurs in red bone marrow.

  • Stem Cells of Formed Elements:

    • The stem cells of all formed elements are called hemocytoblasts or hematopoietic stem cells.

Formed Elements Derived from Myeloid and Lymphoid Lines

  • Formed elements derived from the myeloid line:

    • Erythrocytes, Platelets, Neutrophils, Eosinophils, Basophils, Monocytes

  • Formed elements derived from the lymphoid line:

    • Lymphocytes

Structure of Erythrocytes (RBCs)

  • Description:

    • Erythrocytes are biconcave, anucleate, flexible discs with a high surface area for gas exchange.

Hemoglobin Characteristics

  • Two characteristics of hemoglobin:

    • Contains iron.

    • Binds oxygen reversibly.

  • Oxygen Binding Details:

    • O2 binds to the iron ion within the heme group.

  • Carbon Dioxide Binding Details:

    • CO2 binds to the globin chains.

Oxygen Capacity of RBCs

  • How much oxygen can 1 RBC carry:

    • 1 Oxygen per iron ion

    • 4 Iron ions per hemoglobin

    • Approximately 270,000,000 hemoglobin molecules per RBC.

Erythropoietin (EPO)

  • Primary Organ for EPO Production:

    • The kidneys are primarily responsible for the production of EPO.

  • High Altitude Influence:

    • Low oxygen levels at high altitudes increase EPO production, leading to increased RBC production.

  • Effect of Testosterone on EPO:

    • Testosterone increases EPO production, resulting in higher RBC counts.

Antigens and Antibodies in Blood

  • Location of Antigens:

    • Antigens are found on the surface of red blood cell membranes.

  • Location of Antibodies:

    • Antibodies are found in the plasma.

Agglutination

  • Definition:

    • Agglutination is the clumping of red blood cells due to antigen-antibody reactions.

  • Blood Type Determination:

    • When blood clumps in the presence of specific antibodies, the corresponding antigen is present.

Leukocytes

  • General Function:

    • Leukocytes are responsible for defense against pathogens and foreign substances.

Diapedesis

  • Definition:

    • Diapedesis is the movement of leukocytes out of capillaries into tissues.

Chemotaxis

  • Definition:

    • Chemotaxis is the movement of leukocytes toward chemical signals released by damaged tissues.

Platelets

  • Description:

    • A platelet is a cell fragment derived from megakaryocytes that functions in clotting.

  • Circulation Duration:

    • Platelets circulate for approximately 10 days before being broken down.

Hemostasis

  • Definition:

    • Hemostasis is the process that stops bleeding.

  • Three Phases of Hemostasis:

    • Vascular spasm

    • Platelet plug formation

    • Coagulation

Cardiovascular System Structure and Function

  • Structures Included:

    • The heart, blood, and blood vessels.

  • Primary Function:

    • The primary function of the cardiovascular system is to transport substances and maintain adequate tissue perfusion.

Heart Chambers

  • Function of Heart Chambers:

    • Atria receive blood

    • Ventricles pump blood.

Heart Valves

  • Function of Heart Valves:

    • AV valves prevent backflow into the atria.

    • Semilunar valves prevent backflow into the ventricles.