Cardiovascular

Cardiovascular System Overview

Cardiovascular Function

  • Primary Functions:

    • Maintain homeostasis

    • Regulate blood flow

    • Act as a muscular pump

    • Remove waste and transport nutrients

  • Components:

    • Blood: Transports oxygen, nutrients, and wastes.

    • Heart: Muscular organ that pumps blood.

    • Vessels: Circulate blood throughout the body.

Key Functions of the Cardiovascular System

  • Fluid Balance: Maintained primarily through plasma.

  • Temperature Regulation:

    • Conducts heat to maintain body temperature.

  • pH Regulation: Normal range is 7.35 – 7.45.

  • Body Defenses: Plays a vital role in immunity.

  • Hemostasis: Process of stopping bleeding involving aggregates of cells and specialized proteins.

Blood Overview

  • Composition of Blood:

    • Mainly plasma (~90% water)

    • Dissolved gases (e.g., CO2, O2)

    • Electrolytes and proteins (albumin, immunoglobulins, clotting proteins)

    • Nutrients and wastes

Blood Cells

  • Erythrocytes (Red Blood Cells):

    • Responsible for oxygen transport.

    • Produced via erythropoiesis, stimulated by erythropoietin.

    • Life span: ~120 days.

  • Leukocytes (White Blood Cells):

    • Granulocytes: Neutrophils, Eosinophils, Basophils.

    • Agranulocytes: Lymphocytes, Monocytes.

  • Thrombocytes (Platelets):

    • Essential for blood clotting.

Hemostasis Process

  • Components:

    1. Formation of platelet plugs.

    2. Fibrin clot formation.

  • Clotting Factors:

    • 13 factors operate through a coagulation cascade.

  • Common Disorders in Hemostasis:

    • von Willebrand’s disease, Immune-mediated thrombocytopenia (IMTP), NSAID effects.

    • Hemophilia, Disseminated intravascular coagulation (DIC), Vitamin K deficiency.

Cardiovascular Anatomy

Heart Anatomy

  • Located in the thorax, within the mediastinum.

  • Divided into right and left hemithoraces, separated by the pleural cavity.

  • Pericardium: Encloses the heart, comprising:

    • Parietal layer and visceral layer (epicardium).

Cardiac Layers

  • Mural Composition:

    • Epicardium: Visceral pericardium.

    • Myocardium: Cardiac muscle tissue.

    • Endocardium: Epithelial tissue lining the chambers.

  • Chambers of the Heart:

    • Right Atrium, Right Ventricle, Left Atrium, Left Ventricle.

Heart Valves

  • Maintain one-way flow of blood:

    • Right Heart: Tricuspid (RAV) Valve, Pulmonic Valve.

    • Left Heart: Bicuspid (Mitral/LAV) Valve, Aortic Valve.

Heart Valve Auscultation Locations

  • Mitral Valve: Costochondral junction of the left 5th rib.

  • Tricuspid Valve: Low right 3rd-4th intercostal spaces.

  • Aortic Valve: High left 4th intercostal space.

  • Pulmonic Valve: High left 3rd intercostal space.

Vessels Overview

  • Arteries:

    • Carry blood away from the heart.

    • Thick walls; have three layers: intima, media (smooth muscle), and adventitia (fibrous).

  • Veins:

    • Carry blood toward the heart.

    • Thin walls; structures include +/- valves to promote one-way flow and prevent backflow.

  • Capillaries:

    • Single layer, highly permeable for nutrient and gas exchange.

Vascular Systems

  • Systemic Circulation: Blood flow throughout the body.

  • Pulmonary Circulation: Blood flow between heart and lungs.

  • Portal Circulation: Blood flow from the gastrointestinal system to the liver.

  • Coronary Circulation: Supplies blood to the heart muscle itself.

Cardiovascular Circulation

  • Blood Flow Pathway:

    • Vena cavae → Right atrium → Tricuspid valve → Right ventricle → Pulmonic valve → Pulmonary arteries → Lungs → Pulmonary veins → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins → Vena cavae.

Cardiac Cycle

  • Systole: Heart muscle contraction phase.

  • Diastole: Heart muscle relaxation phase.

  • Pressure Dynamics: Positive during systole, negative during diastole.

Fetal Circulation

  • Special Features:

    • Oxygenation occurs at the placenta.

    • Fetal shunts include:

      • Ductus venosus (liver bypass).

      • Foramen ovale (bypasses pulmonary circulation).

      • Ductus arteriosus (connects pulmonary artery to aorta).

Cardiac Auscultation

  • Heart Sounds:

    • S1: Closure of AV valves (Mitral, Tricuspid)

    • S2: Closure of Semilunar valves (Aortic, Pulmonic)

    • S3 and S4: Indicate abnormal conditions / rapid filling or atrial contraction.

Cardiac Physiology

  • Perfusion: Ensures adequate blood flow and pressure.

  • Cardiac Output (CO): CO = Stroke Volume (SV) x Heart Rate (HR).

  • Determinants of Stroke Volume:

    • Inotropy: Force of contraction.

    • Chronotropy: Heart rate.

    • Preload: Volume of blood in ventricles before contraction.

    • Afterload: Pressure to eject blood from the heart.

  • Blood Pressure Measurements:

    • Essential for perfusion assessment.

Cardiac Conduction Physiology

  • Functions:

    • Automaticity: Ability to initiate impulses independent of external stimuli.

    • Conductivity: Propagation of impulses throughout the heart muscle.

  • Conduction Pathway:

    • Sinoatrial Node (SA) → Atrioventricular Node (AV) → Bundle of His → Bundle branches → Purkinje fibers.

Electrocardiogram (ECG)

  • Displays electrical impulses generated by the heart.

  • Key features include:

    • P Wave: Atrial depolarization.

    • QRS Complex: Ventricular depolarization.

    • T Wave: Ventricular repolarization.

Interpretation of ECG:

  • Interval Measurements:

    • P-R Interval: Time for atrial depolarization and conduction through the AV node.

    • Q-T Interval: Time for ventricular contraction and repolarization.

Lymphatic System Overview

Functions

  • Fluid Return: Excess fluid and proteins returned to circulation.

  • Immune Response: Produces lymphocytes, filters out bacteria, foreign materials.

  • Fat Digestion: Transports dietary fats from the digestive system.

Components of the Lymphatic System

  • Structures: Lymphatic capillaries, vessels, ducts, lymph nodes, spleen, thymus, tonsils.

Lymph Nodes

  • Function: Mechanical filtering, immune processing, destruction of pathogens.

  • Commonly evaluated nodes include:

    • Submandibular, Prescapular, Inguinal, Popliteal.

Spleen Anatomy and Functions

  • Located adjacent to the stomach.

  • Functions:

    • Blood storage

    • Recycling of blood cells

    • Filtration and immune response (lymphocyte production).

Thymus

  • Location: Thoracic inlet, cranial to the heart.

  • Functions: Production of T-lymphocytes for cell-mediated immunity.

Tonsils

  • Location: Oral cavity and pharynx.

  • Functions: First line of defense in the immune system.