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Interesting Facts At rest, the heart pumps 30xs its own weight each minute. There are 60,000 miles of blood vessels. In one day, the heart can pump 7000 L. In one ... – PowerPoint PPT presentation

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Title: The%20Heart

The Heart
Chapter 20
Interesting Facts
  • At rest, the heart pumps 30xs its own weight each
  • There are 60,000 miles of blood vessels.
  • In one day, the heart can pump 7000 L.
  • In one year, the heart pumps about 5 million L.
  • The average body contains about 5 L of blood

Functions of the Heart
  • Generating blood pressure
  • Routing blood
  • Heart separates pulmonary (lungs to left side)
    and systemic (O2 nutrients) circulations
  • Ensuring one-way blood flow
  • Heart valves ensure one-way flow
  • Regulating blood supply
  • Changes in contraction rate and force match blood
    delivery to changing metabolic needs

Size, Shape, Location of the Heart
  • Size of a closed fist
  • Shape
  • Apex Blunt rounded point of cone (pointed
  • Base Flat part at opposite of end of cone
    (rounded top)
  • Located in thoracic cavity in mediastinum (b/w
    the lungs 2/3 to left of center)

  • Encloses the heart and holds it in place
  • Two layers
  • Outer, fibrous pericardium prevents the heart
    from overstretching
  • The inner, serous pericardium contains
    pericardial fluid to prevent friction

Heart Wall
  • Three layers
  • Epicardiumthin, transparent outer layer
  • Myocardiumcardiac muscle tissue bulk of the
  • Endocardiumlines the inside of the myocardium
    and covers the valves

Heart Chambers
  • Two upper chambers Atria
  • Receiving chambers
  • Separated by interatrial septum
  • Two lower chambers Ventricles
  • Pumping chambers
  • Separated by interventricular septum

Thickness of Heart Chambers
  • Vary according to each chambers functions.
  • Atriathin walls because they only pump blood to
  • Right ventriclepumps blood to lungs slightly
    bigger than atria
  • Left ventriclepump blood to entire body and keep
    up with the other chambers thickest of the four

Concept Check
  • What are the functions of the heart?
  • Blood pressure, routing blood, one-way blood
    flow, regulating blood supply
  • Name and describe the 3 layers of the heart.
  • Epicardium (thin/transparent outer layer),
    myocardium (cardiac muscle tisssue bulk),
    endocardium (lines inside of myocardium covers
  • What is the difference between atria and
  • Atria receives blood ventricles pumps blood

Blood Vessel Structure
  • Arteries
  • Elastic, muscular, arterioles
  • Capillaries
  • Blood flows from arterioles to capillaries
  • Most of exchange between blood and interstitial
    spaces occurs across the walls
  • Blood flows from capillaries to venous system
  • Veins
  • Venules, small veins, medium or
  • large veins

Valves of the Heart
  • Four valves one for each chamber
  • They keep blood from flowing back to where it
    came from
  • They open and close in response to the pressure
    of blood against them

Valves of the Heart
  • Atrioventricular (cuspid) valves
  • Tricuspid valve between right atrium and right
    ventricle 3 flaps or cusps
  • Chordae tendinae tendon-like cords that prevent
    the cusps from being pushed back
  • Bicuspid valve between left atrium and left
    ventricle two cusps

Path of Blood
  • Right atrium receives deoxygenated blood from 3
  • Superior Vena Cavablood from above the heart
  • Inferior Vena Cavablood from below the heart
  • Coronary Sinusblood from the heart wall

Vessels of the Heart
Right Ventricle
  • Blood goes from to the pulmonary trunk
  • Pulmonary trunk divides into left and right
    pulmonary arteries
  • Pulmonary arteries lead to the lungs

From the Lungs
  • Oxygenated blood enters the left atrium via four
    pulmonary veins

From the Left Ventricle
  • Blood enters the ascending aorta
  • To the coronary arteries
  • To the arch of the aorta
  • To the thoracic aorta
  • To the abdominal aorta

Valves of the Heart
  • Semilunar Valves
  • Pulmonary semilunar valve between right
    ventricle and pulmonary artery
  • Aortic semilunar valve between left ventricle
    and the aorta

Blood Supply of the Heart
  • Coronary Circulationblood flow through the
  • Left and right coronary arteries bring blood to
    the tissue
  • Coronary sinus take deoxygenated blood from the

Blood Flow Through Heart
Concept Check
  • What are the 3 types of blood vessels?
  • Arteries, veins, capillaries
  • Describe the flow of blood through the heart
    starting w/ the body.
  • Body, (SVC, IVC, CS), R Atrium, Tricuspid Valve,
    Chordae Tendinae, R Ventricle, Pulmonary SLV,
    Pulmonary Trunck, Pulmonary Arteries, Lungs,
    Pulmonary Veins, L Atrium, Bicuspid Valve,
    Chordae Tendinae, L Ventricle, Aortic SLV, Aorta,

Disorders ?
  • Ischemia faulty circulation weakens cells due to
    lack of oxygen, but the cells dont die
  • Angina Pectoris chest pain resulting from
    ischemia also from stress, over exertion, high
    blood pressure, or narrow arteries

Disorders ?
  • Myocardial Infarction (MI) heart attack
  • Infarction is the death of an area due to
    interrupted blood supply usually from a clot
  • Tissue beyond the clot will die and become scar
  • Location of the infarction area is key to how
    serious it is

Conduction System of the Heart
  • This is an intrinsic regulating system
  • It does not need a stimulus from the nervous
  • All cardiac muscle is capable of self-excitation
  • Cardiac muscle generates its own action potential

Sinoatrial (SA) Node
  • Located in the right atrial wall just below the
    superior vena cava
  • Known as the pacemaker of the heart
  • Rate of self-excitation is faster than all other
    heart fibers
  • Its impulses are spread to all the other areas
    thus setting the rhythm of the heart
  • Both atria will contract at the same time
  • This will then depolarize the AV node (ventricles

Atrioventricular (AV) Node
  • Located in the interatrial septum
  • Last part of atria to depolarize
  • This impulse will depolarize fibers in the
    interventricular septum bundle of His
  • This is the only electrical connection between
    the atria and ventricles

Atrioventricular (AV) Node
  • The impulse passes toward the apex through left
    and right bundle branches to the ventricles
  • The actual contraction of the ventricles is done
    by the Purkinje fibers

Conducting System of Heart
Electrocardiogram (ECG)
  • A record of the electrical changes that accompany
    the heartbeat.

  • Action potentials through myocardium during
    cardiac cycle produces electric currents than can
    be measured
  • Pattern
  • P wave
  • Atria depolarization
  • QRS complex
  • Ventricle depolarization
  • Atria repolarization
  • T wave
  • Ventricle repolarization

Cardiac Arrhythmias
  • Tachycardia Heart rate in excess of 100bpm
  • Bradycardia Heart rate less than 60 bpm
  • Sinus arrhythmia Heart rate varies 5 during
    respiratory cycle and up to 30 during deep
  • Premature atrial contractions Occasional
    shortened intervals between one contraction and
    succeeding, frequently occurs in healthy people

Alterations in Electrocardiogram
Cardiac Cycle
Cardiac Cycle
  • Heart is two pumps that work together, right and
    left half
  • Repetitive contraction (systole) and relaxation
    (diastole) of heart chambers
  • Blood moves through circulatory system from areas
    of higher to lower pressure.
  • Contraction of heart produces the pressure

Concept Check
  • Why does the SA node act as the pacemaker?
  • Impulses are spread to other areas setting the
    rhythm of the heart
  • How does the heart contract without an impulse
    from the brain?
  • Intrinsic regulation / Self-excitation / Cardiac
    muscle generates own action potentials
  • What actually contracts the myocardium of the
  • Purkinje fibers
  • What is an infarct?
  • Death of an area due to interrupted blood supply
    usually a clot

Concept Check
  • What does an EKG measure?
  • Electrical changes in the heart that accompany
    heart beat
  • Why is QRS bigger than P?
  • QRS contraction of ventricles
  • P contraction of atria
  • What is a fibrillation or arrhythmia?
  • Fibrillation hearts electrical activity has
    become disordered contraction rapid,
    unsynchronized flutter rather than beat heart
    pumps little or no blood

Heart Rate
  • Cardiac Output amount of blood ejected from the
    left ventricle into the aorta per minute
  • Stroke volume amount of blood ejected from the
    left ventricle per contraction

Factors Affecting Heart Rate
  • Autonomic control baroreceptorsneurons
    sensitive to blood pressure changes
  • Chemicals too much or too little K, Na, or Ca
    either increases or decreases heart rate oxygen
  • Temperature increase temperature, increase heart
    rate lower temperature, decrease heart rate
  • Emotions fear, anxiety, anger all increase heart
    rate while depression and grief lower heart rate
  • Sex and age faster in females fastest at birth
    but slows as one gets older

More Disorders ?
  • Arteriosclerosis - thickening of the walls of the
    arteries and loss of elasticity
  • Atherosclerosis - Deposition of plaque on walls
  • Congenital defectsa defect that exists at birth
  • Interventricular septal defecthole in septum
  • Valvular stenosisnarrowing of a valve
  • Arrthymiaany irregularity in heart rhythm

Effects of Aging on the Heart
  • Gradual changes in heart function, minor under
    resting condition, more significant during
  • Hypertrophy of left ventricle
  • Maximum heart rate decreases
  • Increased tendency for valves to function
    abnormally and arrhythmias to occur
  • Increased oxygen consumption required to pump
    same amount of blood

Heart Sounds
  • First heart sound or lubb
  • Atrioventricular valves and surrounding fluid
    vibrations as valves close at beginning of
    ventricular systole
  • Second heart sound or dupp
  • Results from closure of aortic and pulmonary
    semilunar valves at beginning of ventricular
    diastole, lasts longer
  • Third heart sound (occasional)
  • Caused by turbulent blood flow into ventricles
    and detected near end of first one-third of

Blood Pressure
  • Measure of force exerted by blood against the
  • Blood moves through vessels because of blood
  • Measured by listening for Korotkoff sounds
    produced by turbulent flow in arteries as
    pressure released from blood pressure cuff

Pulse Pressure
  • Difference between systolic (contraction of
    ventricles) and diastolic (relaxation of
    ventricles) pressures
  • Increases when stroke volume increases or
    vascular compliance decreases
  • Pulse pressure can be used to take a pulse to
    determine heart rate and rhythmicity

Concept Check
  • What types of things would increase your heart
    rate? Decrease?
  • What is a congenital disorder? Describe the
    problems with interventricular septal defect.
  • What is the difference between systole and
    diastole if they both measure on the arteries?
  • What causes the heart sounds?