Pressure Contract

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					   Heart + Pressure = Circulation

 INTEGRATING HEART FUNCTION AS A
  PUMP WITH THE MOVEMENT OF
  FLUIDS THROUGHOUT A SYSTEM
 HEART GENERATES THE PRESSURE
  REQUIRED TO MOVE FLUID THROUGH
  A SYSTEM OF TUBES
Atria are filling with blood
From the veins; ventricles
Have just completed a
Contraction. As ventricles
Relax, the AV valves open,
And blood flows from the
Atria into the ventricles
Most blood enters the
Ventricles while the atria
Are relaxed; final 20% of
Filling occurs when
Atria contract. Atrial systole
Begins following depolarization
Of the autorhythmic cells in
The SA node. Wave of
Contraction signals the atria,
Pushing blood into the ventricles
Atria contract
Depolarization wave moves slowly
Through the conducting cells of the
AV node, then rapidly down the AV
Bundle to the apex of the heart
Ventricular systole begins at the apex
Blood is squeezed upward toward the
Base. Pushing upward on the underside
Of the AV valves force them closed –
Create the “lub”. Both sets of AV and
Semilunar valves are closed. High
pressureDevelops: Isovolumic ventricular
contraction
Atrial muscle fibers repolarize and relax
Pressure in atria falls below that in the veins
Blood flows into atria
Ventricles contract
Pressure opens the semilunar
Valves and blood is pushed out
Into the arteries;
Ventricles relax
Ventricular pressure decreases
Ventricular pressure < arterial
Pressure; blood flows backward
Into the heart, filling the
Semilunar valves, forcing them
Closed. “dub”
AV valves remain closed;
Ventricular pressure still
Higher than atrial pressure
When ventricular pressure
Falls to the point at which it
Is below atrial pressure,
AV valves open. Blood that
Accumulates in the atria during
Ventricular contraction rushes in
70 kg man
EDV = 135 mL
ESV = 65 mL    Fig 14-26
Chordae Tendinae
THE HEART
          Function of the Heart

 Every cell in your body
  needs oxygen in order to
  live and function.
 The role of the heart is
  to deliver the oxygen-
  rich blood to every cell
  in the body.
           Structure of the Heart

 Hollow, cone shaped pump
 Sizes vary in average:14cm long and 9 cm wide &
 weights about 7 to 15 ounces (about the size of
  your fist)
 **this amazing muscle
  pumps 4300 gallons
  of blood a day.
         “Location, location, location”…

 Base attached to several large
  blood vessels just behind the 2nd
  rib
 Apex is in the 5th intercostal space
      This allows for the apical heartbeat
       to be heard or felt between the 5th &
       6th rib
 Boarded by the lungs, the
  backbone and the sternum
                  Surrounding the Heart
 Pericardium- bi-layered sheet of
  connective tissue
 Outer layer is fibrous and
  connected to the diaphragm, the
  sternum and the thoracic
  vertebrae
 Inner layer is the surface of the
  heart
 Pericardial fluid reduces friction
  between the two layers
      *** Health note-Pericarditis
       Epicardium (visceral pericardium)

 –epithelial tissue that
  forms a protective outer
  covering and supports the
  blood capillaries, lymph
  capillaries, and nerve
  fibers.
                            Myocardium

 – cardiac muscle tissues
  separated by connective
  tissues and including blood
  capillaries and nerve fibers;
 produces muscular
  contractions that force blood
  from the heart chambers.
      *** Health note: Myocardial
       Infarction
                         Endocardium
 – membrane of
  epithelium and connective
  tissues, including blood
  vessels, and specialized
  muscle fibers
 forms a protective inner
  lining of the chambers and
  valves.
     *** Health note:
      Endocarditis
          Chambers of the Heart


The heart has four chambers;
  two left and two right.
Atria- The top two chambers
  that receive blood from the
  body or lungs.
Ventricles- The bottom two
  chambers. Pumps blood to
  the body or the lungs
                     Auricles

 The atrial walls have
  earlike projections
  extending out from the
  auricles
       Heart Valves
There are four valves in the
  heart that help to direct
  blood flow. As they open
  and close, the valves
  produce sounds that can be
  heard with a stethoscope.
The heart sounds can often
  tell your doctor about your
  hearts function.
              What are heart valves?

 The valves prevent the backward flow of
  blood.
 Each valve actually has three flaps, except the
  mitral valve, which has two flaps.
 tricuspid valve – one of the atrioventricular
  valves
 pulmonary valve - one of the semilunar
  valves
 mitral valve - one of the atrioventricular
  valves
 aortic valve - one of the semilunar valves
  How do the heart valves function?


 As the heart muscle
  contracts and relaxes,
  the valves open and
  shut, letting blood flow
  into the ventricles and
  atria at alternate times.
Semilunar valve


Semilunar valve
                   Cardiac Cycle

 Period of time from the beginning of one
  heartbeat to the beginning of the next
 2 phases:
     Diastole: the period of ventricular relaxation
     Systole: the period of ventricular contraction
Phase of the cardiac cycle when the ventricular heart chamber is
relaxed
Phase of the cardiac cycle
when the ventricualar heart
chamber is contracted
           “Lub”
The first heart sound “lub”
occurs during a ventricular
contraction when the A-V
       valves close
              “Dup”
The second sound “dup” occurs
 during ventricular relaxation
when the semi-lunar valves close
                 Coronary Arteries
 Your heart, just like all other muscles in the body,
  needs its own supply of oxygen in order to function
  properly.
 The heart gets its blood supply from the coronary
  arteries.
      The two major coronary arteries (the right coronary
       artery and the left main coronary artery) branch off the
       aorta, and then divide into many smaller arteries
       that lie in the heart muscle and feed the heart.
   Heart + Pressure = Circulation

 INTEGRATING HEART FUNCTION AS A
  PUMP WITH THE MOVEMENT OF
  FLUIDS THROUGHOUT A SYSTEM
 HEART GENERATES THE PRESSURE
  REQUIRED TO MOVE FLUID THROUGH
  A SYSTEM OF TUBES
                   Cardiac Cycle

 Period of time from the beginning of one
  heartbeat to the beginning of the next
 2 phases:
     Diastole: the period of ventricular relaxation
     Systole: the period of ventricular contraction
             Stroke Volume

 Amount of blood pumped by one ventricle
  during a contraction
 ml/beat
 Volume of blood in ventricles before
  contraction – volume of blood after
  contraction = stroke volume
 EDV-ESV = Stroke volume
 135 mL – 65 mL = 70 mL average
             Cardiac Output

 Effectiveness of Heart as a pump
 Cardiac Output: amount of blood pumped by
  the heart in a given period of time

 CO = amount of blood pumped per ventricle
  per unit time
 CO = heart rate x stroke volume
           Sinoatrial node (SA node)

• The natural pacemaker of
  the heart
• It is located in the Right
  Atrium
• The heart contains
  specialized fibers that
  conduct the electrical
  impulse from the
  pacemaker (SA node) to
  the rest of the heart
The electrical impulse has travels to the Atrioventricular Node (AV
node) (2), Then to the Bundle of His (3), then it divides into the
      The electrical impulse leaves the SA node (1) and
Right and Left Bundle Branches (4) where it rapidly spreads using
      travels to the right and left the Right and Left Ventricle,
Purkinje Fibers (5) to the muscles ofAtria, causing them to
causing them to together. This takes .04 seconds.
      contract contract at the same time.
              Functional Syncytium

 Mass of merging cells that act as a unit
     Two separate units in the heart

         Atrial Syncytium and the Ventricular Syncytium
Prolapsed Valve

				
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