Understanding the Circulatory System Anatomy

Nov 12, 2024

Lecture Notes: The Circulatory System

Overview

  • Lecture Topic: Structure of the Circulatory System
  • Two-part series; this part focuses on structure, the next on processes
  • Importance of understanding structure in relation to function in biology

Types of Circulatory Systems

  • Open Circulatory System

    • Blood vessels are open; blood leaks out into tissues
    • Found in insects (e.g., grasshoppers)
    • Not suitable for large animals
  • Closed Circulatory System

    • Blood remains inside blood vessels
    • Suitable for larger animals, e.g., humans, earthworms
    • Allows specialization of blood components
    • Blood only exits vessels in case of injury

Human Circulatory System

  • Double Circulatory System
    • Heart pumps blood twice around the body
    • Involves systemic and pulmonary circulation

Systemic Circulation

  • Blood circulation to the body
  • Oxygenated blood from lungs to heart to body
  • Blood collects CO2 as it moves through tissues

Pulmonary Circulation

  • Circulation to the lungs
  • Deoxygenated blood returns to heart, then to lungs to expel CO2

Heart Structure

  • External Structures

    • Superior Vena Cava: Largest vein, brings blood to heart
    • Right Atrium: Top chamber, receives blood
    • Coronary Arteries: Supply heart itself with blood
    • Right Ventricle: Muscular, pumps blood to lungs
    • Aorta: Largest artery, distributes oxygenated blood
    • Pulmonary Artery: Carries blood to lungs
    • Pericardium: Protective membranous layer
    • Left Atrium/Ventricle: Chambers for oxygenated blood
    • Apex: Pointy tip of heart
  • Internal Structures

    • Valves: Prevent backflow (Tricuspid, Mitral)
    • Papillary Muscles: Aid valve function
    • Septum: Divides heart into right (deoxygenated) and left (oxygenated)

Heart Layers

  • Pericardium: Outer protective layer
  • Epicardium: Inner layer beneath pericardium
  • Myocardium: Muscular middle layer
  • Endocardium: Innermost layer

Blood Vessels

  • Arteries

    • Thick, muscular walls
    • Carry oxygenated blood at high pressure
    • Narrow lumen for efficient blood flow
  • Veins

    • Thinner walls, larger lumen
    • Carry deoxygenated blood back to heart
    • Contain valves to prevent backflow
  • Capillaries

    • Microscopic, one cell thick
    • Connect arteries and veins
    • Facilitate nutrient and waste exchange

Summary

  • Closed and double circulatory systems in mammals
  • Systemic vs. pulmonary circulation
  • Heart's external and internal structures, including chambers and valves
  • Differences between arteries, veins, and capillaries

Key Terms

  • Closed System: Blood stays within vessels
  • Double Circulation: Blood returns to heart twice
  • Pulmonary/Systemic: Refers to lungs/body
  • Ventricles/Atria: Lower/upper heart chambers
  • Pericardium, Epicardium, Myocardium, Endocardium: Heart layers
  • Arteries/Veins/Capillaries: Types of blood vessels

  • Next focus: Processes in the circulatory system
  • Recommended to review diagrams and textbook for a better understanding of the heart's anatomy