CARDIO

• Circulatory System


  Delivers blood and substances to all tissues of the body
• Cardiovascular System

  • Heart
  • Arteries
  • Capillaries
  • Veins
• Lymphatic System

  • Lymphatic Capillaries
  • Lymphatic Vessels

  
• Heart

  • Cardiac muscles
  • Three layers: Endocardium, Myocardium, Epicardium

  
• Pericardium


  Thin fluid filled sac that surrounds the heart and large blood vessels that protects and lubricates the heart

  
• Heart Chambers

  • Right Atrium
  • Left Atrium
  • Right Ventricle
  • Left Ventricle
• Cardiac Skeleton


  • Dense irregular connective tissue
  • Separates the musculature of the atria from that of the ventricles
  • Forms part of the interventricular and interatrial septa
  • Extends into the valve cusps and chordae tendinae
  • Surround, anchor, and support all heart valves
  • Provide firm points of insertion for cardiac muscle
  • Coordinate the heart beat by acting as electrical insulation between atria and ventricles

  
• Conducting System of the Heart

  • Sinoatrial Node (Pacemaker)
  • Atrioventricular Node
  • AV bundle (Bundle of His)
  • Purkinje Fibers

  
• Sinoatrial Node


  Located at the right atrial wall, stimulates contractions of both right and left atria
• Atrioventricular Node


  Located at the floor of the right atrium, stimulate depolarization of the ventricles
• AV bundle (Bundle of His)


  Passes through an opening in the cardiac skeleton, enters interventricular septum and bifurcates into left and right bundles
• Purkinje Fibers


  Subendocardial network of muscle fibers, trigger waves of contraction through both ventricles simultaneously
• Cells of the Vascular Wall

  • Endothelium
  • Smooth Muscle fibers
  • Connective Tissue
• Endothelium


  Specialized epithelium that acts as a semipermeable barrier between blood and interstitial tissue fluid, squamous, polygonal and elongated

  
• Endothelium


  • Provide non-thrombogenic surface on which blood will not clot and actively secretes anticoagulants
  • Regulate local vascular tone and blood flow
  • Plays a role in inflammation and local immune response
  • Secrete growth factors promoting proliferation of wbc lineages and cells

  
• Smooth Muscle fibers

  • Present in the wall of all blood vessels that are larger than capillaries
  • Arterioles: connected by gap junctions
  • Permit vasoconstriction and vasodilation
• Connective Tissue


  • Variable amounts, depend on the size of vessel
  • Collagen Fibers: found in subendothelial layer, between smooth muscle layers and in the outer covering
  • Elastic Fibers: provide resiliency required for the vascular wall to expand under pressure
• Layers of Vascular Wall

  • Tunica Intima
  • Tunica media
  • Tunica adventitia/ Tunica externa
• Tunica Intima


  Innermost layer, consist of endothelium and a thin subendothelial layer of loose connective tissue, Arteries: Internal Elastic Lamina
• Tunica media


  Middle layer, consist chiefly of concentric layers of helically arranged smooth muscles, variable amounts of elastic fibers reticular fibers, and proteoglycans, Arteries: External Elastic Lamina
• Tunica adventitia/ Tunica externa


  Connective tissue consisting primarily of Type I collagen and elastic fibers
• Vasa vasorum


  Blood vessels within large blood vessels, supplies nutrients to tunica media
• Vasomotor Nerves


  Unmyelinated nerve fibers at the tunica adventitia of large vessels, release norepinephrine for vasoconstriction
• Vasculatures

  • Arteries
  • Capillaries
  • Veins
• Arteries


  Carry oxygenated blood and nutrients from the heart to different tissues
• Capillaries


  Site of exchange of oxygen and nutrients
• Veins


  Carry unoxygenated blood and toxins from different tissues to the heart

  
• Elastic Arteries


  • Aorta, pulmonary artery and their largest branches, "Conducting arteries" – role to carry blood to smaller arteries
• Layers of Elastic Arteries

  • Tunica intima
  • Tunica media
  • Tunica adventitia
• Arterial Sensory Structures


  • Baroreceptors: Monitor blood arterial pressure
  • Chemoreceptors: Monitor blood pH, O2 and CO2 concentration

  
• Muscular Arteries


  • "Distributing arteries": distribute blood to organs, Regulate BP by contracting or relaxing its smooth muscles

  
• Layers of Muscular Arteries

  • Tunica intima
  • Tunica media
  • Tunica adventitia
• Arterioles


  Branches of muscular arteries, Smallest arteries: microvasculature of the organs where exchanges between blood and tissue fluid occurs
• Layers of Arterioles

  • Tunica intima
  • Tunica media
  • Tunica adventitia
• Arterioles


  • Branch to form anastomosing networks of capillaries
  • Muscle fibers act as sphincters and produce periodic blood flow in the capillaries
  • Arteriovenous shunts/ arteriovenous anastomoses
  • Venous portal system

  
• Capillaries


  Allow and regulate metabolic exchange between blood and surrounding tissues, Simple layer of endothelial surrounded by basement membrane, Size allows transit of blood cells one at a time
• Capillary Subtypes

  • Continuous Capillaries
  • Fenestrated Capillaries
  • Discontinuous Capillaries "Sinusoids"
• Pericytes

  • Mesenchymal cells that surround the capillaries, Dilate and constrict the capillaries, Regulate blood flow in some organs, Proliferate and differentiate after an injury

  
• Venules


  Connected to capillaries, and with larger pericytes, Primary site where WBCs adhere to endothelium and leave the circulation at site of infection
• Layers of Venules

  • Tunica intima
  • Tunica media
  • Tunica adventitia