Cardiovascular System: Human Anatomy and Physiology 1 Module 5

BMSC11010: Human Anatomy and Physiology 1 Module 5: Cardiovascular System

Acknowledgements

  • Acknowledgement to Australia’s First Nations Peoples.

    • CQUniversity recognises and acknowledges the important role of First Nations peoples in our communities and values Australian Indigenous knowledge systems as part of our teachings.

Topic 1: Introduction to Blood, Heart, and Blood Vessels

Learning Objectives

  • LO1: Identify the components of the cardiovascular system.

  • LO2: Describe the functions of the heart, blood, and blood vessels.

  • LO3: Explain the importance of cardiovascular health.

Cardiovascular System Highlights

  • Cardiovascular Disease (CVD) Statistics (2018):

    • 1 in 4 deaths had CVD as the underlying cause.

    • An estimated 1.2 million Australian adults had 1 or more heart or vascular conditions (self-reported data for 2017-18).

    • CVD accounted for almost 14% of Australia's total burden of disease (2015).

    • More than 1.2 million hospitalizations associated with CVD in 2017-18 — 11% of all hospitalizations in Australia.

    • Indigenous Australians had CVD hospitalization and death rates over 60% higher than non-Indigenous Australians.

    • The CVD death rate was 50% higher among those in the lowest socioeconomic area compared to the highest.

    • Those in remote areas had CVD hospitalization and death rates over 30% higher than those in major cities.

Topic 2: Composition of Blood

Learning Objectives

  • LO1: Identify the primary functions of blood and its components.

  • LO2: Describe the proteins and solutes present in blood plasma.

Blood Functions and Composition

  • Blood is a specialized connective tissue composed of:

    • Cellular elements (formed elements):

    • Red blood cells (erythrocytes)

    • White blood cells (leukocytes)

    • Platelets

    • Extracellular matrix (plasma)

Major Functions of Blood

  1. Transportation

    • Transports:

      • Oxygen and carbon dioxide

      • Nutrients (e.g., glucose)

      • Hormones

      • Metabolic waste products (e.g., urea)

  2. Defence

    • White blood cells defend against pathogens, destroy infected/abnormal cells, and support blood clots to prevent excessive blood loss.

  3. Regulation and Homeostasis

    • Regulates body temperature, pH of body fluids, ion composition of interstitial fluid, and water balance in cells.

Composition of Blood

  • Blood consists of:

    • Plasma: ~55%

    • Formed elements: ~45%

  • Blood volume is about 8% of body weight:

    • Males: ~5-6 L

    • Females: ~4-5 L

Centrifugation of Blood

  • Separation of blood into:

    • Erythrocytes (bottom layer)

    • Buffy coat (WBCs + platelets)

    • Plasma (top layer)

  • Hematocrit: percentage of red blood cells in blood.

Composition of Whole Blood

  • Whole Blood Composition by Volume:

    • Plasma: 55%

    • Water: 91%

    • Proteins: 7%

      • Albumins: 57%

      • Globulins: 38%

      • Fibrinogen: 4%

      • Prothrombin: 1%

    • Other solutes: 2%

    • Formed elements: <1%

    • Erythrocytes: >99%

    • Leukocytes: <1%

      • Neutrophils: 65%-75%

      • Lymphocytes: 20%-25%

      • Monocytes: 3%-8%

      • Eosinophils: 2%-5%

      • Basophils: 0.5%-1%

Major Plasma Proteins

  • Albumin: Maintains osmotic pressure; transport various substances.

  • Globulins: Immune function; transport proteins.

  • Fibrinogen: Critical for blood clotting.

  • Prothrombin: A precursor to thrombin for clotting.

Other Solutes in Plasma

  • Ions (Na⁺, K⁺, Ca²⁺)

  • Nutrients (e.g., glucose, amino acids)

  • Waste products (urea)

  • Dissolved gases (O₂, CO₂)

  • Hormones

Plasma Versus Serum

  • Plasma: liquid part minus blood cells (55%).

  • Serum: liquid part minus blood cells and clotting elements.

Characteristics of Blood

  • Temperature: ≈38°C

  • Viscosity: greater than water.

  • pH: 7.35-7.45 (slightly alkaline).

Summary

  • Blood is a specialized connective tissue composed of plasma and formed elements.

  • Performs critical functions; transportation, immune defense, and regulation of homeostasis.

Topic 3: RBC, WBC, and Platelets

Learning Objectives

  • LO1: Describe the structure and function of red blood cells (RBCs).

  • LO2: Explain the process of erythropoiesis.

  • LO3: Identify five major types of white blood cells (WBCs).

  • LO4: Describe the structure and role of platelets.

Overview of Formed Elements of Blood

  • Formed elements include:

    • Erythrocytes (RBCs)

    • Leukocytes (WBCs)

    • Thrombocytes (platelets)

  • Each type plays a vital role in transport, immunity, or homeostasis.

Structure and Function of Formed Elements

  • Erythrocytes:

    • Structure: Flattened biconcave disk, no nucleus, pale red color.

    • Function: Transport oxygen and carbon dioxide.

    • Lifespan: Approximately 120 days.

    • Production: In red bone marrow; recycled by macrophages in the liver/spleen.

  • Leukocytes:

    • Structure: Cells with obvious dark-staining nucleus and abundant granules (for granulocytes).

    • Function: All types assist in immune defense.

    • Classification: Depending on the presence of granules, leukocytes are classified as granulocytes and agranulocytes.

    • Granulocytes:

      • Neutrophils: First responders to infection, phagocytic.

      • Eosinophils: Combat parasites, involved in allergic reactions.

      • Basophils: Release histamine and heparin during inflammation.

    • Agranulocytes:

      • Lymphocytes: B cells, T cells (adaptive immunity);

      • Monocytes: Become macrophages in tissues; phagocytic.

  • Platelets:

    • Structure: Cell fragments derived from megakaryocytes.

    • Function: Essential for hemostasis; form platelet plugs and initiate the clotting cascade.

Topic 4: Coagulation and Blood Types

Learning Objectives

  • LO1: Describe the function of platelets in hemostasis.

  • LO2: Describe the significance of the AB and Rh blood groups in blood transfusions.

Hemostasis

  • Processes involved include:

    • Activation pathways: Intrinsic and extrinsic.

    • Thrombin formation.

    • Fibrin clot formation.

Stages of Hemostasis

  1. Activation—Activation of the intrinsic or extrinsic pathway.

  2. Thrombin formation—Conversion of prothrombin to thrombin.

  3. Fibrin clot formation—Thrombin converts fibrinogen to fibrin, completing the clot.

Blood Types and Transfusions

  • ABO Blood System:

    • Types depending on present antigens:

    • Type A: Antigen A present, antibody B present.

    • Type B: Antigen B present, antibody A present.

    • Type AB: Both antigens present, neither antibody present.

    • Type O: Neither antigen present, both antibodies present.

  • Rh System:

    • Rh-positive: Rh antigen present; Rh-negative: Rh antigen absent.

    • Importance: For blood transfusions, matching blood type vital to avoid agglutination.

Topic 5: Structure and Function of Blood Vessels

Learning Objectives

  • LO1: Identify the three layers of the blood vessel wall.

  • LO2: Compare the structure and function of different blood vessels.

Types of Blood Vessels

  • Arteries: Carry blood away from the heart.

  • Arterioles: Smallest branches of arteries.

  • Capillaries: Microscopic vessels where exchange occurs.

  • Venules: Small veins collecting blood from capillary beds.

  • Veins: Return blood to the heart.

Structure of Blood Vessels

  1. Tunica Externa: Connective tissue anchoring the vessel.

  2. Tunica Media: Smooth muscle, thicker in arteries.

  3. Tunica Intima: Endothelial layer; only layer in capillaries.

Arteries

  • Elastic Arteries: Major, largest; withstand high pressure.

  • Muscular Arteries: Deliver blood to organs; thick tunica media.

Veins

  • Structure: Thinner walls than arteries, containing valves to prevent backflow.

  • Function: Act as collectors and reservoir vessels (hold ~64% of blood volume).

Capillaries

  • Microscopic; not evenly distributed, abundant in metabolically active tissues.

  • Types include: continuous, fenestrated, and sinusoid capillaries.

    • Continuous: Most tissues, straight endothelial lining.

    • Fenestrated: Allow rapid exchange, found in kidneys and intestines.

    • Sinusoid: Large lumen and very porous, found in liver and spleen.

Topic 6: Pulmonary, Systematic, and Coronary Circulations

Learning Objectives

  • LO1: Identify major blood vessels in the pulmonary, systemic, and coronary circulations.

Pulmonary Circulation

  • Function: Carries deoxygenated blood from the right ventricle to the lungs for gas exchange, returning oxygenated blood to the left atrium.

Systemic Circulation

  • Function: Carries oxygenated blood from the left ventricle to the body and returns deoxygenated blood to the right atrium.

Coronary Circulation

  • Function: Supplies blood to the heart muscle (myocardium).

  • Coronary arteries: Right and left coronary arteries originate from the aorta to supply myocardial cells.

Topic 7: Blood Pressure

Learning Objectives

  • LO1: Describe the theory of blood pressure.

  • LO2: Describe the physiology of blood pressure.

  • LO3: Describe how blood pressure is measured.

Blood Pressure Categories

  • Hypertension: >140/90 mmHg.

  • Hypotension: Lower than normal; can be acute or chronic.

Factors Affecting Blood Flow and Pressure

  • Cardiac output, compliance, blood volume, blood viscosity, vessel length and diameter.

Topic 8: Heart Structures and Function

Learning Objectives

  • LO1: Identify interior/exterior structures of the heart.

  • LO2: Describe blood flow through the heart.

  • LO3: Describe the heart valves and heart sounds.

Heart Structure

  • Four chambers:

    • Two upper atria (receiving chambers).

    • Two lower ventricles (ejecting chambers).

Blood Flow Through the Heart

  • Pathway of blood flow, through various structures and valves, ensuring one-way movement.

Heart Valves

  1. Tricuspid Valve: Between the right atrium and ventricle.

  2. Pulmonary Valve: Between the right ventricle and pulmonary artery.

  3. Bicuspid (Mitral) Valve: Between the left atrium and ventricle.

  4. Aortic Valve: Between the left ventricle and aorta.

Heart Sounds

  • Systolic sound: caused by ventricular contraction and AV valve closure.

  • Diastolic sound: short, sharp sound caused by semilunar valve closure.

Topic 9: Cardiac Conduction System

Learning Objectives

  • LO1: Describe the pathway of the cardiac conduction system.

  • LO2: Identify characteristics of an electrocardiogram.

Cardiac Conduction Pathway

  1. SA Node - Initiates the heartbeat (pacemaker).

  2. Internodal Tracts - Transmits signal through the right atrium.

  3. AV Node - Slows impulses to allow atrial contraction before ventricular contraction.

  4. Bundle of His - Carries impulses from the AV node.

  5. Purkinje Fibers - Spread impulses throughout the ventricles.

Electrocardiogram (ECG)

  • Graphic record of the heart's electrical activity, demonstrating atrial and ventricular depolarization and repolarization through distinct waves and complexes.

  • P Wave: Atrial depolarization.

  • QRS Complex: Ventricular depolarization.

  • T Wave: Ventricular repolarization.