CV

Lecture Presentation by Raymond J. Clark

Cardiovascular System - The Heart

© 2018 Pearson Education, Inc.

Overview of the Cardiovascular System

  • Function: The cardiovascular system moves blood through body systems to supply cells with oxygen (O2) and nutrients, while also facilitating the removal of carbon dioxide and other wastes.

  • Key Components:
      - Heart
      - Blood vessels
        - Arteries
        - Veins
        - Capillaries

  • Muscle Type: The heart is composed of cardiac muscle and is responsible for pumping blood throughout the body.

Circulatory Pathways

Pulmonary Circuit

  • Function: Carries deoxygenated blood to the lungs for gas exchange.

  • Major Structures:
      - Pulmonary Arteries: Carry blood from the right ventricle to the lungs.
      - Pulmonary Veins: Return oxygenated blood from the lungs to the left atrium.
      - Capillaries in the Lungs: Site of gas exchange between blood and air in the alveoli.

Systemic Circuit

  • Function: Delivers oxygenated blood to body tissues and returns deoxygenated blood to the heart.

  • Major Structures:
      - Systemic Arteries: Carry oxygen-rich blood from the left ventricle to body tissues.
      - Systemic Veins: Return deoxygenated blood to the right atrium.
        - Key capillary networks in various locations such as:
          - Head and neck
          - Abdominal organs
          - Upper limbs
          - Trunk and lower limbs

Location of the Heart in the Thoracic Cavity

  • Anatomical Position: The heart is located in the thoracic cavity, slightly left of the midline, between the lungs, and above the diaphragm.

  • Key Landmarks:
      - Base of the Heart: Top part of the heart where great vessels emerge.
      - Apex of the Heart: Lower tip of the heart that points toward the left.

  • Notable Surroundings:
      - Trachea
      - Lungs (Left and Right)
      - Major Blood Vessels

Heart Anatomy

Chambers of the Heart

  • Right Atrium (RA): Receives deoxygenated blood from the body.

  • Right Ventricle (RV): Pumps deoxygenated blood to the lungs.

  • Left Atrium (LA): Receives oxygenated blood from the lungs.

  • Left Ventricle (LV): Pumps oxygenated blood to the body.

Valves of the Heart

  • Tricuspid Valve: Separates the right atrium and right ventricle; prevents backflow during ventricular contraction.

  • Bicuspid (Mitral) Valve: Separates the left atrium and left ventricle; similar function to tricuspid.

  • Aortic Valve: Controls blood flow from the left ventricle to the aorta; prevents backflow.

  • Pulmonary Valve: Controls blood flow from the right ventricle to the pulmonary arteries; prevents backflow.

Functioning of Heart Valves

  • During Diastole (Relaxation):
      - AV valves (tricuspid and mitral) are open, allowing blood to fill the ventricles.

  • During Systole (Contraction):
      - AV valves close, preventing backflow into the atria; semilunar valves (aortic and pulmonary) open to allow blood ejection into the aorta and pulmonary arteries.

Coronary Circulation

  • Definition: The supply of blood to the heart muscle itself via coronary arteries.

  • Major Arteries:
      - Right Coronary Artery (RCA)
        - Supplies blood to the right atrium, ventricle, and parts of the conducting system.
      - Left Coronary Artery (LCA)
        - Branches into:
          - Circumflex Branch: Supplies the left atrium and parts of the left ventricle.
          - Anterior Interventricular Branch: Supplies the anterior part of the right and left ventricles.

Anatomy of Major Blood Vessels

  • Aorta: The largest artery in the body that carries oxygen-rich blood from the left ventricle to the systemic circulation.

  • Pulmonary Trunk: Extends from the right ventricle and bifurcates into the right and left pulmonary arteries to carry blood to the lungs.

  • Brachiocephalic Trunk: Branches into the right common carotid and right subclavian arteries on the right side.

  • Subclavian Arteries: Supply blood to the arms and thoracic structures.

  • Common Carotid Arteries: Supply blood to the head and neck.

Structural and Funtional Overview of the Venous System

Major Venous Return Pathways

  • Superior Vena Cava (SVC): Drains blood from the upper body (head, neck, upper limbs) into the right atrium.

  • Inferior Vena Cava (IVC): Drains blood from the lower body into the right atrium.

  • Coronary Sinus: Drains blood from the heart muscle itself into the right atrium.

Key Superficial Veins

  • Great Saphenous Vein: The longest vein in the body, running along the length of the leg, draining into the femoral vein.

  • Small Saphenous Vein: Drains blood from the lateral side of the leg into the popliteal vein.

Summary Points to Remember

  • Heart Function: Acts as a pump to circulate blood throughout the body and to the lungs for oxygenation.

  • Circulation Types: Recognize the distinct pathways of pulmonary and systemic circuits.

  • Anatomy of Blood Vessels and Veins: Pay attention to the layout of arteries and veins as per their respective regions in the body.

  • Valves' Role: Understanding the mechanics of valves is crucial for comprehending heart function and blood flow regulation.