Circulatory heart by lanyuehua

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									  Circulatory System: the Heart.


  The heart
Chapter 19 pgs
   715-743
                                                    -   I am right
       History                                          and a
                                                        genius.
                                                        Plato was
                                                        my teacher
• Aristotle thought the                                 and
                                                        Medieval
  heart was the seat of                                 Scholars
                                                        love me.
  emotion                                               Snap!
• Not until Vesalius’
                                                    -   No, you are
  dissections did                                       dead and
  Western science                                       wrong. I
                                                        am the
  correct its mistakes                                  dissection
                                                        King of the
• Eastern scientists had                                Sixteenth
  it right all along                                    Century.
                                                        Booyah!




    Confucius say western science needs some work
                 Overview
• Cardiovascular
  system = heart and
  vessels, not blood
• Arteries = away from
  heart
• Veins = toward heart
• Capillaries = small
  vessels that connect
  arteries and veins
        Two major divisions
• Pulmonary circuit
  takes blood to
  lungs for gas
  exchange
• Systemic circuit
  takes oxygen rich
  blood to the
  organs
• Right side of heart gets O2
  poor blood
  – Pulmonary artery takes it
    away from heart to lungs
  – Pulmonary veins bring it
    back O2 rich
• Left side of heart serves
  systemic system
  – Aorta takes O2 rich blood
    out to organs
  – Superior vena cava brings it
    back from head, neck,
    upper limbs
  – Inferior vena cava brings it
    back from organs below
    diaphragm.
        Where is your heart?
• 2/3s of it lies to the
  left of the median
  plane
• Adult heart 9 cm
  wide at base, 13
  cm long, 6 cm deep
• Weighs 300 g (10
  oz)
                 Pericardium
• Double walled sac
  enclosing heart
• In the pericardial
  cavity is pericardial
  fluid that allows the
  heart to beat without
  friction
• Pericarditis is the pain
  when the membranes
  are dry
                           Heart wall
3 layers
• Epicardium
     – outer layer
     – Fatty
• Myocardium
     – Thickest layer
     – Cardiac muscle
        that pulls
        against a
        fibrous skeleton
        of fibers
     – Focuses the
        movement of
        electricity
• Endocardium
     – Smooth inner
        lining
                Chambers
• Superiorly; Right and
  Left atria receive
  returning blood
  – Have an easier
    workload
• Inferiorly; Right and
  Left ventricles eject
  blood
                     Valves
• Ensure one way flow
• Made of flaps called
  cusps
• Open & Close as a
  result of pressure
  changes
• When ventricles relax
  valves are open
• Full ventricles contract
  pressure pushes
  valves shut
            Coronary Circulation
• Getting blood to your heart
• ~3 bil beats over an 80
  year life
• Needs 5% of bodies O2
   – Coronary artery delivers this
• Myocardial Infarction: fat
  deposits blocking arteries
  leading to necrosis of
  tissue
   – Anastomoses: our bodies
     defense
       • Two arteries covering the
         same area
  Cardiac Surgery Incision and Cannulation
                                      A Cannula is a flexible tube
The collar bones, angle and tip of the breast bone (sternum) guide the surgeon in making the incision
Cardiac Surgery Incision and Cannulation
          The sternum is opened with a saw (sternotomy)
  Cardiac Surgery Incision and Cannulation
During this operation, the tissues were covered with towels soaked in anti-septic solution. The breast
        bone is spread with a retractor. Plastic tubes are placed into the major artery (aorta)
Cardiac Surgery Incision and Cannulation
         and receiving chamber of the heart (right atrium)
  Cardiac Surgery Incision and Cannulation
These tubes are connected to the heart lung bypass machine (pump) which supports the patient's life
    while the heart is stopped during the surgery. The surgeon is assisted by a large team while
                                        performing the surgery
   Cardiac Surgery Incision and Cannulation
At the end of the surgery, the plastic tubes are removed after the heart lung bypass machine is turned
     off. The sternum is closed with heavy gauge wires and the chest is closed in layers of sutures
            Aerobic vs. Anaerobic
•   AAerobic activity = increases
    heartrate to at least 65% of it's
    maximum for an extended period
    of time.
     –   Best for cardiovascular strength,
         endurance and fat burning
•   Anaerobic activity = activity done
    in intense, short bursts (weight
    lifting, sprinting, calisthenics,
    etc.)
     – fuel used during anaerobic
       activity is glucose and glycogens
       (sugars that are stored in our
       bodies).
     – Best for strength training and
       body sculpting.
•   Aerobic activity should be the
    predominant exercise for good
    general health.
  Cardiac Muscle and The Cardiac
        Conduction System
• Cardiocytes: short,
  thick branched cells
   – Sarcoplasmic reticulum
     is less developed, but
     T-Tubules are more
     developed, lots of
     mitochondria
   – Do very little mitosis
• Intercalated discs join
  cells end to end
   – Gap junctions allow
     ions to flow between
     cells, keeping electrical
     current
        Cardiac conduction system
• We’re myogenic: the signal
  for the heart to beat comes
  from within the heart itself
• Our brain can modify the
  heartbeat, but not create it.
  Disembodied hearts can
  beat for hours.
• Sinoatrial (SA) node = the
  pacemaker
• Atrioventricular node =
  sends signals to the
  ventricles
  Electrical & Contractile activity
• Contraction = systole
• Relaxation = diastole
   – These can apply to parts, or just ventricles
• Sinus rhythm = normal beat
   – Can have ectopic focus (alternate source of beat, instead of SA
     node) called nodal rhythm
• Arrhythmia = abnormal rhythm
     Physiology of the SA node
• The nerves of the SA
  node are always slowly
  moving toward an action
  potential
• So as soon as the heart
  beats its already starting
  toward another beat
• ~75 beats per minute
• Cardiac muscle has a
  sustained contraction, and
  a longer refratcory period
   – This prevents tetanus:
     Continual contraction
 Electrocardiogram(ECG/EKG)
• Composite reading
  of many action
  potentials
• P wave: atria
  contract
• QRS complex: AV
  node fires, ventricles
  start to contract
• T wave: ventricles
  repolarizing
Cardiac cycle
             Now, can you…
• Describe the relationship of the heart to other
  thoracic structures?
• Identify the chambers and valves
• Trace the flow of blood through the heart
  chambers
• Contrast cardiac vs. skeletal muscle
• Describe the physiological properties of cardiac
  muscle
• Describe the heart’s electrical conduction
  system

								
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