HEART

• Cardiovascular system (circulatory system)


  Permits blood to circulate and transport nutrients, oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body
• Cardiovascular systemfunctions:


  • Nourishment
  • Fight diseases
  • Stabilizes temperature and pH
  • Maintain homeostasis
• Cardiovascular system


  Consists of heart, blood vessels and 5 liters of blood
• Heart


  Muscular pump that forces blood through a system of vessels made of arteries, veins and capillaries
• Mediastinum


  Central compartment of the thoracic cavity, loose connective tissue, as region that contains a group of structures within the thorax
• Precordium


  Part of the front of the chest wall that overlays the heart and the epigastrium
• Anatomy of the heart

  • Positioned obliquely between the lungs in the mediastinum
  • Lies in the pericardial cavity
• Pericardial cavity


  Formed by the Pericardium
• Covering of the heart

  • Fibrous pericardium
  • Serous pericardium
• Fibrous pericardium


  Layer of connective tissue that provides support and protection for the heart, attachments to the diaphragm, the sternum, and the vertebral column
• Serous pericardium


  Parietal pericardium - lines the fibrous pericardium, Visceral pericardium (epicardium) - lines the surface of the heart
• Heart


  • Generate blood pressure
  • Route blood
  • Ensure one-way blood flow
  • Regulation of blood supply
• Heart


  Hollow, cone-shaped, mass of 250 to 350 grams, broad, flat base about 9 cm wide, extends vertically from the left second and fifth intercostal space and horizontally from the right edge of the sternum to the left midclavicular line, apex points inferiorly toward the left hip
• Layers of the heart

  • Epicardium (visceral pericardium)
  • Myocardium
  • Endocardium
• Epicardium


  Outer layer, visceral pericardium, cardiac muscles responsible for the contractions of the chambers
• Myocardium


  Middle layer, makes up the majority of the heart's mass
• Endocardium


  Inner layer, lines the inner surface of the heart which allows blood to move easily through the heart
• Chordae tendinae


  Tendon-resembling fibrous cords of connective tissue that connect the papillary muscles to the tricuspid valve and the bicuspid valve in the heart
• Coronary system


  Circulation of blood that supply oxygen to the myocardium
• Chambers and internal anatomy of the heart

  • 2 atria and 2 ventricles
  • Left and right sides divided by the septum (Interatrial septum, Inter-ventricular septum)
• Valves of the heart


  • Atrioventricular Valve - Tricuspid Valve, Bicuspid (Mitral valve)
  • Semilunar Valves - Pulmonic Semilunar Valves, Aortic Semilunar Valves
• Sequence of the systemic blood circulation

  1. Systemic circulation

  2. Pulmonary circulation
• Mechanism of a heart beat

  • Rhythmicity - regularity of impulse transmission
  • Automaticity - ability to initiate electrical impulses
  • Conductivity - ability to transmit electrical impulses from one cell to another
  • Contractility - ability to contract in response to the flow of electrical impulse
  • Excitability - ability to respond to electrical stimuli
• Components of conduction system of the heart

  • Sinoatrial Node (SA Node)
  • Atrioventricular Node (AV Node)
  • Bundle of His /Atrioventricular Bundle
  • Left and Right Bundle Branches
  • Purkinje Fibers
• Examples of arrhythmia


  • Unifocal PVC's
• Electrocardiogram (ECG/EKG)


  Procedure that measures electrical signals in your heart, each time your heart beats, an electrical signal travels through the heart, can show if your heart is beating at a normal rate and strength, helps show the size and position of your heart's chambers
• Phases of the electrocardiogram

  • P wave
  • PR interval
  • QRS complex
  • ST segment
  • T wave
  • QT interval
  • U wave
• Normal heart beat


  60-100 beats per minute
• Normal heart sounds


  • Lubb (S1) - lower in pitch, occurs at the beginning of ventricular systole, results from closure of AV valves
  • Dubb (S2) - occurs at the beginning of ventricular diastole and results from closure of the semilunar valves
• Cardiac cycle


  1. Diastole - Filling, Relaxation of Ventricles

  2. Systole - Emptying, Contraction of Ventricles

  3. Atrial Systole - Contraction of two atria

  4. Ventricular Systole - Contraction of two ventricles

  5. Atrial Diastole - Relaxation of two atria

  6. Ventricular Diastole - Relaxation of two ventricles
• Cardiac output


  Volume of blood pumped by either ventricle per minute, CO (mL/min) = SV (mL/beat) x HR (beats/min)
• Stroke volume


  Volume of blood pumped per ventricle each time the heart contracts, approximately 70mL per beat
• Heart rate


  Number of times the heart contracts per minute, approximately 72 beats/min for normal adults
• Points of auscultation


  • Aortic Area
  • Pulmonic Area
  • Erb's Point
  • Mitral (Apical Area)
  • Tricuspid Area
• Blood vessels


  Tubular structure carrying blood through the tissues and organs, can be vein, artery, or capillary, carry blood, exchange nutrients, waste products and gases, transport substances, help regulate blood pressure, direct blood flow to the tissues
• Layers of blood vessels

  • Tunica Adventitia/Externa
  • Tunica Media
  • Tunica Intima
• Vasodilation


  Widening of blood vessels
• Vasoconstriction


  Narrowing of blood vessels
• Veins


  Carry deoxygenated blood back to the heart, veins with more than 2mm diameter contains valves which prevents blood from flowing toward the feet in response to the pull of gravity
• Arteries


  Carry blood away from the heart, carry oxygenated blood, can be elastic or muscular