CIRCULATORY

• Functions of the circulatory system

  • Regulates blood supply
  • Generates blood pressure
  • Routes blood
  • Ensures 1-way blood flow
• Heart


  • Location: between lungs in thoracic cavity
  • Orientation: apex (bottom) towards left side
  • Size: Approximately size of a man's fist
• Pericardium


  • Encloses and holds the heart in place
  • Confines the heart to its position in the mediastinum, and allow freedom of movement
  • Plastic-like cover
  • Thin sac that protects and lubricates the heart (pericardial fluid)

  
• Layers of pericardium

  • Fibrous - outer
  • Serous - inner
• Heart layers

  • Epicardium (Visceral Pericardium) - Surface of heart
  • Myocardium - Thick, middle layer composed of cardiac muscle
  • Endocardium - Smooth, Inner surface
• Cardiac muscle

  • Striated (actin and myosin)
  • Ca2+ and ATP used for contractions
  • Intercalated disks connect cells
• Heart chambers and blood vessels

  • Atria - Upper portion; Holding chambers
  • Ventricles - Lower portion; Pumping chambers
• Interatrial septum: separates right and left atria
• Interventricular septum: separates right and left ventricles
• Major veins

  • Superior vena cava
  • Pulmonary veins - blood transferred from the HTL (oxygenated), 4 main largest pulmonary veins
• Major arteries

  • Aorta - largest and main artery - Carries blood away from the HTB
  • Pulmonary trunk - transports deoxygenated blood from the HTL
• Heart valves

  TRICUSPID VALVE right valve

  BICUSPID VALVE left valve
• Right side of heart

  1. Right Atrium/Tricuspid Valve: receives blood from places: superior and inferior vena cava and coronary Sinus

  2. Right Ventricle/Pulmonary Valve: opens into pulmonary trunk

  3. Pulmonary trunk: splits into right and left pulmonary arteries

  4. Pulmonary arteries: carry blood away from heart to lungs
• Left side of heart


  1. Left Atrium/ Bicuspid Valve: 4 openings (pulmonary veins) that receive blood from lungs

  2. Left Ventricle/Aortic Valve opens into aorta

  3. Aorta: carries blood from Left Ventricle to body
• Atria


  Receiving chamber (THB)
• Ventricle


  Pumping chamber (FHB)
• Coronary arteries

  • Supply blood to heart wall
  • Originate from base of aorta (above aortic semilunar valve)
  • Left coronary artery: has 3 branches, supply blood to anterior heart wall and left ventricle
  • Right coronary artery: originates on right side of aorta, supply blood to right ventricle
• Action potential in cardiac muscle

  Changes in membrane channels' permeability are responsible for producing action potentials and is called pacemaker potential
• Cardiac cycle

  1. Heart is 2 side by side pumps: right and left

  2. Atria: primers for pumps

  3. Ventricles: power pumps

  4. Repetitive pumping action which includes contraction and relaxation

  5. Cardiac muscle contractions produce pressure changes within heart chambers

  6. Pressure changes are responsible for blood movement

  7. Blood moves from areas of high to low pressure
• Heart sounds

  • Stethoscope is used to hear lung and heart sounds
  • First sound is lubb, second is dupp
  • Sounds result from opening and closing valves
  • Murmurs are due to faulty valves
• Stroke volume

  • Volume of blood pumped per ventricle per contraction
  • 70 ml/beat
• Heart rate

  • Number of heart beats in 1 min.
  • 72 beats/min.
• Cardiac output

  • Volume of blood pumped by a ventricle in 1 min.
  • Cardiac output is the product of the heart rate (HR) and the stroke volume (SV)
  • CO = HR × SV
  • CO = HR (75 beats/min) × SV (70 ml/beat)
  • CO = 5250 ml/min = 5.25 L/min
• Factors modifying basic heart rate

  • Neural (ANS) controls
  • Sympathetic nervous system speeds heart rate
  • Parasympathetic nervous system, primarily vagus nerve fibers, slow and steady the heart rate
  • Hormones and ions
  • Epinephrine and thyroxine speed heart rate
  • Excess or lack of calcium, sodium, and potassium ions also modify heart activity
  • Physical factors
  • Age, gender, exercise, body temperature influence heart rate
• RIGHT SIDE OF HEART (Pulmonary circuit)

  From heart to lungs
• LEFT SIDE OF HEART (SYSTEMIC CIRCUIT)

  from heart to body
• NORMAL

  less than less than 120 and less than 80
• ELEVATED

  120 - 129 and less than 80
• HIGH BLOOD PRESSURE (hypertension) STAGE 1

  130 - 139 o 80 89
• HYPERTENSION STAGE 2

  140 higher or 90 higher
• HYPERTENSIVE CRISIS

  higher than 180 and/or higher than 120