HEART

• Cardiovascular System


  Aka as Circulatory System, an organ system that permits blood to circulate and transport nutrients, oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body
• Functions of the Cardiovascular System

  • Provide nourishment
  • Help in fighting diseases
  • Stabilize temperature and pH
  • Maintain homeostasis
• Cardiovascular System


  Consists of the heart, blood vessels, and blood that the vessels transport
• Heart


  A muscular pump that forces blood through a system of vessels made of arteries, veins and capillaries
• Location of the Heart

  • Its broad, flat base, or posterior surface, is about 9 cm wide and directed toward the right shoulder
  • The base extends vertically from the left second and fifth intercostal space and horizontally from the right edge of the sternum to the left midclavicular line
  • Its apex points inferiorly toward the left hip
• Position of the Heart in the Thorax

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

  
• Pericardium


  • Pericardial cavity is formed by the Pericardium
  • Pericardial sac surrounds the heart and anchors it within the mediastinum

  
• Fibrous Pericardium


  • Layer of connective tissue that provides support and protection for the heart
  • Attachments to the diaphragm, the sternum (via the sterno-pericardial ligaments), and the vertebral column
  • Holds the heart in place

  
• Serous Pericardium


  • Contains the pericardial fluid
  • Parietal pericardium lines the fibrous pericardium
  • Visceral pericardium (epicardium) lines the surface of the heart

  
• Layers of the Heart

  • Epicardium (visceral pericardium)
  • Myocardium
  • Endocardium

  
• Chambers and Internal Anatomy of the Heart

  • Humans have a 4 chambered heart
  • 2 atria and 2 ventricles
  • Left and right sides divided by the septum

  
• Valves of the Heart

  • Atrioventricular Valve - Tricuspid Valve, Bicuspid (Mitral valve)
  • Semilunar Valves - Pulmonic Semilunar Valves, Aortic Semilunar Valves
• Sequence of Systemic Blood Circulation

  Not provided
• Mechanism of a Heart Beat

  • The hearts conduction system consists of special electrical cells that generate and coordinate electrical impulses to the myocardial cells
  • Properties of the myocardial cells: Rhythmicity, Automaticity, Conductivity, Contractility, Excitability
• Components of Conduction System of the Heart

  • Sinoatrial Node (SA Node)
  • Atriventricular Node (AV Node)
  • Bundle of His / Atrioventricular Bundle
  • Left and Right Bundle Branches
  • Purkinjie Fibers

  
• Electrocardiogram (ECG / EKG)


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

  
• 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


  • Refers to the filling and emptying of heart chambers
  • Two phases: Diastole (Filling, Relaxation of Ventricles) and Systole (Emptying, Contraction of Ventricles)
• Phases of Cardiac Cycle

  • Atrial Systole
  • Ventricular Systole
  • Atrial Diastole
  • Ventricular Diastole
• 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
• How to Auscultate
• Heart Sounds


  • S1 (lubb) - Closure of AV valves
  • S2 (dubb) - Closure of semilunar valves
  • S3 (ventricular gallop) - Passive filling of left ventricle
  • S4 (atrial gallop) - Active LV filling when atrial contraction forces blood into a noncompliant LV
• Blood Vessels


  • Tubular structure carrying blood through the tissues and organs
  • Functions: Carries Blood, Exchange Nutrients/Waste/Gases, Transport Substances, Regulate Blood Pressure, Direct Blood Flow
• Layers of Blood Vessels

  Tunica Adventitia/Externa, Tunica Media, Tunica Intima
• Blood Vessels


  Capable of vasoconstriction and vasodilation
• Artery


  • Carries blood away from the heart, carries oxygenated blood
  • Classified as: Elastic Artery, Muscular Artery, Arterioles
• Capillary


  • Extremely small blood vessel located within the body tissues
  • Gasses, nutrients, and fluids are exchanged through capillaries
• Capillary Exchange


  • Most exchange across the capillary wall occur by diffusion
  • Blood pressure, capillary permeability and osmosis affect the movement of fluid form the blood to the tissues
  • The fluid gained by the tissues is removed by the lymphatic system
• Vein


  • Carries 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
• Types of Veins


  • Large Veins
  • Small Veins
  • Venules
• Varicose Veins


  • Swollen, twisted veins that can be seen just under the skin
  • Can be caused by weakened valves in the veins or weakened walls of the veins due to age, or by inflammation in the veins (phlebitis)
  • Treatment: Sclerotherapy
• Neck Vessels


  • Carotid arteries, Jugular Veins
  • Assessment of pulses of these vessels reflect the integrity of the heart muscle

  
• Edema


  • Occurs when too much fluid moves from the intravascular space to the interstitial space
  • Can be peripheral or generalized
• Pulse


  • The rhythmic dilation of an artery that results from beating of the heart
  • Pulse is often measured by feeling the arteries of the wrist or neck
• Peripheral Pulses


  • Temporal
  • Carotid
  • Brachial
  • Radial
  • Femoral
  • Popliteal
  • Dorsalis Pedis
  • Posterior Tibial
• Doppler Ultrasound


  • Transmits and receives ultrasound waves to evaluate blood flow
  • Works by transmitting ultra high-frequency sound waves that strike red blood cells (RBCs) in an artery or vein
  • Used to assess unpalpable pulses, determine patency of arterial bypass grafts, and assess tissue perfusion