CARDIOVASCULAR SYSTEM

• Circulatory System

  Pumps and directs blood cells and substances carried in blood to all tissues of the body
• Functions of Circulatory System

  • Transport: For transport of nutrients, hormones, oxygen and other needed substances in the cell
  • Excretory: It also moves waste, carbon dioxide and secretory products to their disposal areas / organs
  • Protection: Aids in fighting off pathogenic microorganism by providing and/or transporting the cells and substances needed for this purpose
• Division of Circulatory System

  • Cardiovascular System (Blood Vascular System)
  • Lymph Vascular System
• Components of the Cardiovascular System

  • Heart
  • Blood Vessels
  • Blood

  
• Structure of the Circulatory System

  • An inner lining, the tunica intima [innermost layer], comprising a single layer of extremely flattened epithelial cells called endothelial cells supported by a basement membrane and delicate collagenous tissue
  • An intermediate predominantly muscular layer, the tunica media. contains alternating layers of smooth muscle and collagen or elastic lamellae
  • An outer supporting tissue layer called the tunica adventitia contains connective tissue, small vessels and nerves and vasa vasorum
• Endothelium


  Internal surface of all components of cardiovascular and lymphatic system, simple squamous epithelium, maintain a selectively permeable, antithrombogenic (inhibitory to clot formation) barrier, they also determine when and where white blood cells leave the circulation for the interstitial space of tissues, secrete a variety of paracrine factors - signals vessel dilation, constriction, and growth of adjacent cells

  
• Smooth Muscle


  Occur in the walls of all vessels larger than capillaries and are arranged helically in layers, permit regulated vasoconstriction and vasodilation
• Connective Tissue


  Collagen: found in subendothelial layer, Elastic Fibers: provide resiliency to blood vessel, Layer that is composed of Connective Tissue is the Tunica adventitia
• Heart


  Hollow muscular organ, about a size of a clenched fist, located in the central mediastinum of thoracic cavity, Modified artery that has a pumping capacity that propels blood to the arteries of both the systemic and pulmonary circulations
• Systemic Circulation

  1. Blood brings nutrients and removes wastes in tissue throughout the body

  2. Oxygenated blood will flow from the left atrium to the left ventricle and pump into aorta

  3. Passes from the aorta to the elastic arteries into the muscle arteries before entering the arterioles

  4. Blood from the arterioles enters the systemic capillaries of trunk and lower limbs and systemic capillaries of head, neck, and upper limbs

  5. Blood in arterioles enters capillaries for exchange of gases and nutrients

  6. Deoxygenated blood exits capillary beds into the venules and into the veins

  7. Deoxygenated blood conducted to either superior or inferior vena cava; enters right atrium of the heart
• Pulmonary Circulation


  1. Blood is oxygenated in both left and right lung

  2. Blood flows from the right atrium to the right ventricle and pumps into the pulmonary trunk and conducts deoxygenated blood into pulmonary arteries of both left and right lung

  3. Blood passes to the smaller arteries before entering the pulmonary capillary for gas exchange

  4. Oxygenated blood exits the lung via series of progressively larger veins that merge to form pulmonary veins

  5. Pulmonary veins drain into the left atrium

  6. The cycle repeats
• Layers of the Heart

  • Endocardium/Tunica Intima
  • Myocardium/Tunica Media
  • Epicardium/Tunica Serosa/Visceral Pericardium
• Cardiac Skeleton


  Forms base for all cardiac valves, Separates atria from ventricles & provides points of insertion for cardiac muscle in the atria and ventricles, Dense Irregular Connective Tissue in composition, Helps coordinate the heartbeat by acting as electrical insulation between atria and ventricles
• Cardiac Conducting System


  • Specialized to generate and conduct waves of depolarization which stimulates rhythmic contractions, Consists of modified cardiac muscle fibers, Composition: Sinoatrial Node (Pacemaker), Atrioventricular Node, Atrioventricular Bundle of His, Purkinje Fibers (Contractile Bundles, Abundant Glycogen, Sparse Bundles of Myofibrils)
• Blood Vessels


  Forms closed circuit to and from the heart, Walls of all blood vessels except capillaries contain smooth muscle and connective tissue in addition to the endothelial lining, Types: Capillaries, Arteries, Veins
• Capillaries


  Permit and regulate metabolic exchange between blood and surrounding tissues, Always function in networks called capillary beds
• Types of Capillaries


  • Continuous Capillaries
  • Fenestrated Capillaries
  • Discontinued Capillaries/Sinusoids
• Veins


  Carry blood back to the heart from microvasculature all over the body, Most veins are classified as small or medium veins that are usually located close and parallel to corresponding muscular arteries, Venules – numerous in the veins of our legs. These valves help keep the flow of our blood directed toward the heart
• Arteries


  Blood vessels that bring oxygen-rich blood from your heart to all of your body's cells
• Types of Arteries

  • Large Elastic Arteries (aka Conducting Arteries, with fenestrated elastic laminae in the thick tunica media, Contains Vasa Vasorum)
  • Muscular Arteries (Less elastic material than Elastic Artery, Distribute blood to all organs and maintain steady blood pressure and flow with vasodilation and constriction)
  • Small Arteries (no vasa vasourm, Distribute blood to arterioles, adjusting flow with vasodilation and constriction)
• Blood


  Specialized connective tissue consisting of cells and fluid extracellular material called plasma, 5L is unidirectionally moving within closed circulatory system, Liquid Portion of Blood is Plasma, When removed off clotting factors, the liquid portion is called Serum, Formed elements in the Blood: Leukocytes or WBC

  
• Large Elastic Arteries (Conducting Arteries)


  • With fenestrated elastic laminae in the thick tunica media
  • Contains Vasa Vasorum
• Muscular Arteries


  • Less elastic material than Elastic Artery
  • Distribute blood to all organs and maintain steady blood pressure and flow with vasodilation and constriction
• Small Arteries


  • No vasa vasourm
  • Distribute blood to arterioles, adjusting flow with vasodilation and constriction
• Blood


  Specialized connective tissue consisting of cells and fluid extracellular material called plasma
• 5L of blood is unidirectionally moving within closed circulatory system
• Plasma


  Liquid portion of blood
• Serum


  Liquid portion of blood when removed of clotting factors
• Formed elements in the Blood

  • Leukocytes or WBC
  • Erythrocytes or RBC
  • Thrombocytes or the Platelets

  
• Erythrocytes (Red Blood Cells)


  • Enucleated, biconcave discs
  • Completely filled with the O2-carrying protein hemoglobin
  • Only blood cells whose function does not require them to leave the vasculature
• Leukocytes (White Blood Cells)


  • Leave the blood and migrate to the tissues where they can be functional and perform various activities related to immunity
  • Grouped as either Granulocytes or Agranulocytes
• Granulocytes

  • Neutrophils
  • Eosinophils
  • Basophils
• Neutrophils


  • Most abundant type of leukocyte
  • Polymorphic, multilobed nuclei
  • Faint pink cytoplasmic granules
  • Phagolysosomal killing and removal of bacteria
• Eosinophils


  • Bilobed nuclei
  • Eosinophilic specific granules
  • Destruction of helminthic parasites and for modulating inflammation
• Basophils


  • Rarest type of circulating leukocyte
  • Irregular bilobed nuclei
  • Strongly basophilic specific granules
  • Important in allergies and chronic inflammatory conditions, including histamine, heparin and various hydrolases
• Agranulocytes


  • Lymphocytes
  • Monocytes
• Lymphocytes


  • Range widely in size
  • Have roughly spherical nuclei
  • T- and B-cell subtypes in the immune system
  • Little cytoplasm and few organelles
  • Effector and regulatory cells for adaptive immunity
• Monocytes


  • Distinctly indented or C-shaped nuclei
  • Precursors of macrophages and other cells of the mononuclear phagocyte system
• Platelets


  • Small cell fragments (2-4 μm) derived from megakaryocytes in bone marrow
  • - Open canalicular system

  
• Hematopoiesis/Hemopoiesis


  Production of mature blood cells from hematopoetic stem cells/progenitor cells