Cardiovascular System Lab

• Cardiovascular system

  Functions of the Heart

  
• Functions of the Heart

  • Managing blood supply
  • Producing blood pressure
  • Securing one-way blood flow
  • Transmitting blood

  
• Heart


  • Approximately the size of a person's fist, the hollow, cone-shaped heart weighs less than a pound
  • Snugly enclosed within the inferior mediastinum, the medial cavity of the thorax, the heart is flanked on each side by the lungs
  • Its more pointed apex is directed toward the left hip and rests on the diaphragm, approximately at the level of the fifth intercostal space
  • Its broad posterosuperior aspect, or base, from which the great vessels of the body emerge, points toward the right shoulder and lies beneath the second rib

  
• Pericardium


  • The heart is enclosed in a double-walled sac called the pericardium and is the outermost layer of the heart
  • The loosely fitting superficial part of this sac is referred to as the fibrous pericardium, which helps protect the heart and anchors it to surrounding structures such as the diaphragm and sternum
  • Deep to the fibrous pericardium is the slippery, two-layer serous pericardium, where its parietal layer lines the interior of the fibrous pericardium

  
• Layers of the Heart

  • Epicardium
  • Myocardium
  • Endocardium

  
• Epicardium


  The epicardium or the visceral and outermost layer is actually a part of the heart wall

  
• Myocardium


  The myocardium consists of thick bundles of cardiac muscle twisted and whirled into ringlike arrangements and it is the layer that actually contracts
• Endocardium


  The endocardium is the innermost layer of the heart and is a thin, glistening sheet of endothelium hat lines the heart chambers

  
• Chambers of the Heart

  • Receiving chambers (atria)
  • Discharging chambers (ventricles)
• Receiving chambers


  The two superior atria are primarily the receiving chambers, they play a lighter role in the pumping activity of the heart
• Discharging chambers


  The two inferior, thick-walled ventricles are the discharging chambers, or actual pumps of the heart wherein when they contract, blood is propelled out of the heart and into the circulation
• Septum


  The septum that divides the heart longitudinally is referred to as either the interventricular septum or the interatrial septum, depending on which chamber it separates
• Associated Great Vessels


  • Superior and inferior vena cava
  • Pulmonary arteries
  • Pulmonary veins
  • Aorta

  
• Superior and inferior vena cava

  The heart receives relatively oxygen-poor blood from the veins of the body through the large superior and inferior vena cava and pumps it through the pulmonary trunk

  
• Pulmonary arteries

  The pulmonary trunk splits into the right and left pulmonary arteries, which carry blood to the lungs, where oxygen is picked up and carbon dioxide is unloaded
• Pulmonary veins

  Oxygen-rich blood drains from the lungs and is returned to the left side of the heart through the four pulmonary veins
• Aorta

  Blood returned to the left side of the heart is pumped out of the heart into the aorta from which the systemic arteries branch to supply essentially all body tissues

  
• Heart Valves

  • Atrioventricular valves
  • Semilunar valves

  
• Atrioventricular valves


  Atrioventricular or AV valves are located between the atrial and ventricular chambers on each side, and they prevent backflow into the atria when the ventricles contract
• Bicuspid valve


  The left AV valve- the bicuspid or mitral valve, consists of two flaps, or cusps, of endocardium
• Tricuspid valve


  The right AV valve, the tricuspid valve, has three flaps
• Semilunar valves


  The second set of valves, the semilunar valves, guard the bases of the two large arteries leaving the ventricular chambers, thus they are known as the pulmonary and aortic semilunar valves
• Pulmonary semilunar valve


  Lies between the right ventricle and the pulmonary artery and has three cusps

  
• Aortic semilunar valve


  Lies between the left ventricle and the aorta and has three cusps

  
• Blood Vessels


  • Arteries
  • Arterioles
  • Veins

  
• Arteries


  As the heart beats, blood is propelled into large arteries leaving the heart

  
• Arterioles


  It then moves into successively smaller and smaller arteries and then into arterioles, which feed the capillary beds in the tissues
• Veins


  Capillary beds are drained by venules, which in turn empty into veins that finally empty into the great veins entering the heart
• Tunics


  • Tunica intima
  • Tunica media
  • Tunica externa
• Tunica intima

  The tunica intima, which lines the lumen, or interior, of the vessels, is a thin layer of endothelium resting on a basement membrane and decreases friction as blood flows through the vessel lumen
• Tunica media

  The tunica media is the bulky middle coat which mostly consists of smooth muscle and elastic fibers that constrict or dilate, making the blood pressure increase or decrease
• Tunica externa

  The tunica externa is the outermost tunic composed largely of fibrous connective tissue, and its function is basically to support and protect the vessels
• Major Arteries of SYSTEMIC CIRCULATION

  • Ascending Aorta
  • Aortic Arch
  • Thoracic Aorta
  • Abdominal Aorta

  
• Coronary arteries

  The only branches of the ascending aorta are the right and left coronary arteries, which serve the heart

  
• Brachiocephalic trunk

  The brachiocephalic trunk, the first branch off the aortic arch, splits into the right common carotid artery and right subclavian artery

  
• Left common carotid artery

  The left common carotid artery is the second branch off the aortic arch and it divides, forming the left internal carotid, which serves the brain, and the left external carotid, which serves the skin and muscles of the head and neck

  
• Left subclavian artery

  The third branch of the aortic arch, the left subclavian artery, gives off an important branch- the vertebral artery, which serves part of the brain
• Axillary artery


  In the axilla, the subclavian artery becomes the axillary artery
• Brachial artery


  The subclavian artery continues into the arm as the brachial artery, which supplies the arm
• Radial and ulnar arteries


  At the elbow, the brachial artery splits to form the radial and ulnar arteries, which serve the forearm