The Cardiovascular System

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The Cardiovascular System

• The Heart and Related Blood Vessels

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Introduction

• The major function of the cardiovascular system
  is to transport substances throughout the body.
• The heart and blood vessels are the major
  components of the cardiovascular system.

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Introduction

• The nutrients and waste products of the body are
  transported through the blood vessels with a push
  from the heart.
• The blood is connective tissue transported
  through the blood vessels which act as highways
  for the blood (vehicles).

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Introduction

• Cardiology is the study of the heart and diseases
  associated with it.

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The Heart

• The heart is located in the thoracic cavity
  behind the sternum.
• The size of a persons heart is approximately the
  same size as their closed fist.
• On average it weighs about 300g.

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The Heart

• The base of the heart is the wide superior
  portion.
• The apex is the inferior point.

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The Heart

• The heart is covered by a sac made up of two
  layers.
• 1.) Serous Pericardium
• 2.) Fibrous Pericardium

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The Heart

• The serous pericardium is made up of the visceral
  and parietal pericardium which are delicate
  layers of epithelial and connective tissue which
  aid in lubrication of the heart.

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The Heart

• The fibrous pericardium is an outer tough layer
  of connective tissue that prevents the heart from
  over stretching.

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The Heart

• The wall of the heart is composed of three
  layers
• 1.) epicardium, outer most layer
• 2.) myocardium, middle layer made up of cardiac
  muscle(bulk of heart)
• 3.) endocardium, inner layer and smooth inner
  wall of heart

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The Heart

• The heart is made up of four chambers.
• The top chambers are atria.
• The bottom chambers are ventricles.

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The Heart

• The atria are broken up into the right and left
  atria which are separated by the interatrial
  septum.
• The atria receive blood from veins.
• They are very thin walled.

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The Heart

• The ventricles are divided into the right and
  left ventricle which are separated by the
  interventricular septum.
• Ventricles are responsible for pumping blood from
  the heart into arteries.
• They have much thicker walls because of their
  active role in pumping blood.

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The Heart

• The major blood vessels associated with the heart
  are veins and arteries.
• Arteries carry blood away from the heart.
• Veins carry blood to the heart.

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Blood Vessels

• Arteries carry blood that is high in oxygen and
  low in carbon dioxide away from the heart.
• - The aorta carries blood from the left
  ventricle to the body.
• The pulmonary arteries carry blood from the right
  ventricle to the lungs.
• The coronary arteries carry blood to the
  myocardium.

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Blood Vessels

• Veins carry blood that is high in carbon dioxide
  and low in oxygen into the heart.
• - The superior vena cava brings blood from the
  head and upper limbs and the inferior vena cava
  brings blood from the trunk and lower limbs.
• - The coronary sinus brings blood back from the
  myocardium.
• - The pulmonary veins bring blood from the lungs
  into the left atrium.

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Valves of the Heart

• The general function of heart valves is to
  prevent the back flow of blood.

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Valves of the Heart

• Atrioventricular valves are valves within the
  heart that separate the atria and the ventricles.
• The tricuspid valve lies between the right atrium
  and ventricle.
• The bicuspid valve lies between the left atrium
  and ventricle.

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Valves of the Heart

• These valves are opened and closed with the help
  of muscles called papillary muscles.
• The valves are held in place by tendon like cords
  called chordae tendineae.

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Valves of the Heart

• The semilunar valves are valves located near the
  end of the major blood vessels into and out of
  the heart.
• The pulmonary semilunar valve is found in the
  pulmonary trunk.
• The aortic semilunar valve is found in the aorta.

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Valves of the Heart

• These valves can become damaged or diseased
  requiring them to be changed.
• Heart Valves
• Heart Valve Surgery

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Pathway of Blood

• The general path taken by all blood is the same
• 1.) The heart pumps oxygenated blood out of the
  left ventricle to aorta which branches out into
  arteries.
• 2.) The arteries are then branched and funneled
  into arterioles.

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Pathway of Blood

• 3.) The arterioles are then in turn branched out
  and funneled into capillaries which are located
  in the tissues of your body.
• This is where gas exchange occurs, which is
  the swapping of oxygen and carbon dioxide by
  the blood.
• 4.) The capillaries then begin to get larger and
  branch together into venules.

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Pathway of Blood

• 5.) The venules branch together into veins and
  the veins then come together to form the vena
  cava.
• 6.) The vena cava then enter the heart in the
  right atrium.

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Pathway of Blood

• The pathway of blood through the heart and lungs
  is known as the pulmonary circuit.
• 1.) It begins in the right atrium with
  deoxygenated blood entering the heart.
• 2.) The tricuspid valve then opens and the blood
  rushes into the right ventricle

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Pathway of Blood

• 3.) The pulmonary semi-lunar valve opens the
  pulmonary trunk and the deoxygenated blood
  travels into the pulmonary arteries.
• 4.) The blood then gets funneled into the
  capillaries in the lungs, which run along side
  alveoli.
• 5.) The blood in the alveoli picks up oxygen from
  the walls of the lungs and the blood is
  transferred to the pulmonary veins.

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Pathway of Blood

• 6.) The pulmonary veins then take the oxygenated
  blood into the left atrium
• 7.) The tricuspid valve of the left atrium then
  opens and the blood is forced into the left
  ventricle.
• 8.) The aortic semi-lunar valve then opens and
  the left ventricle pumps the blood into the aorta
  which transports blood throughout the body.

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Pathway of Blood

• The supply of blood for the heart is carried to
  the myocardium by the coronary artery and sinus.
• 1.) Coronary circulation begins in the ascending
  aorta with oxygenated blood.
• 2.) The blood travels down one of two paths the
  right or left coronary artery.

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Pathway of Blood

• The presence of multiple pathways for blood is
  common throughout the body, they are known as
  anastosomes.
• 3.) The capillaries within the myocardium then
  undergo gas exchange.
• 4.) The cardiac veins then transport blood to
  the coronary sinus which takes the blood back to
  the right atrium.

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Heart Disorders and Diseases

• Blood clots, fatty atherosclerotic plaques, and
  smooth muscle spasms within the coronary vessels
  lead to most heart problems.

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Heart Diseases and Disorders

• Go to the following link
• http//www.wisc-online.com/objects/OTA1604/OTA160
  4.swf
• Make a list outlining the basic causes and
  severity of the four disorders found there.
• Make predictions based on your knowledge of the
  heart on how easily these disorders can be
  treated.

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Heart Disorders and Diseases

• Common heart disorders include
• 1.)An ischemia is a reduction of blood
  flow.
• 2.) Hypoxia is a reduced oxygen supply due to
  an ischemia.
• 3.) An angina pectoris is severe pain that
  accompanies an ischemia.
• -A crushing pain radiating down the left
  arm.

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Heart Disorders and Diseases

• 4.) A myocardial infarction is a heart attack.
• - A heart attack is the death of a portion
  of myocardium due to a thrombus (blood clot).
• 5.) Reperfusion damage occurs when oxygen
  deprived tissue has its blood supply
  regenerated, the formation of oxygen free
  radicals in the blood damages cardiac tissue.

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Cardiac Conduction System (CSC)

• There are specialized portions of cardiac muscle
  tissue that are autorhythmic or self exciting.
• This autorhythmic property of portions of cardiac
  tissue is what generates the electrical signal
  causing the heart to beat.

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Cardiac Conduction System (CSC)

• The sinoatrial node is located in the right
  uppermost atrial wall.
• This node generates an electrical signal that is
  passed throughout atrial muscle fibers causing
  them to contract.
• This pacemaker generates an electrical signal 60
  to 100 times per minute in a resting state.

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Cardiac Conduction Systems (CSC)

• The atrioventricular node (A-V Node) is located
  in the interatrial septum.
• - It acts as a delay mechanism which
  allows for the ventricles to fill by holding up
  the electrical signal.

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Cardiac Conduction System (CSC)

• The atrioventricular bundle acts as the only
  electrical transfer station between the atria
  and ventricles.
• The right and left bundle branches lead downward
  toward the apex of the heart allowing the
  electrical signal to propagate.

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Cardiac Conduction System (CSC)

• Throughout the heart the electrical signal makes
  contact with the muscle fibers due to the
  purkinje fibers, which are primarily responsible
  for the large scale contraction of the
  ventricles.
• Electrical Signals of Beating Heart

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Physiology of a Cardiac Muscle Contraction

• The contractile fibers of the heart have a
  resting potential of -90mV and the opening of Na
  channels depolarizes them and drops the potential
  to -70mV.
• This rapid depolarization causes the release of
  Ca2 ions which are a part of the muscle
  contraction.

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Physiology of a Cardiac Muscle Contraction

• The K channels are then opened triggering a
  repolarization of the muscle fibers.
• After the contraction is complete there is a
  refractory period in which no contraction can
  occur.
• - This is the time that calcium, sodium and
  potassium levels are resupplied.

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Electrocardiogram (ECG or EKG)

• An ECG is a recording of the electrical changes
  that occur in the myocardium during the cardiac
  cycle.
• There are three waves per heart beat.
• ECG Tutorial

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Electrocardiogram(ECG or EKG)

• The first small upward wave is called the p wave.
• This wave represents atrial depolarization.

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Electrocardiogram(ECG or EKG)

• The QRS Complex is a grouping of waves consisting
  of a downward deflection followed by a large up
  sweep and ending as a small downward wave.
• - This wave is the start of the ventricular
  contraction.

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Electrocardiogram(ECG or EKG)

• The t wave is the dome shaped upward deflection.
• - This wave represents the repolarization of
  the ventricles.

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Cardiac Cycle

• The cardiac cycle is made up of alternating
  contractions and relaxations.
• The contractions are known as systole.
• The relaxations are known as diastole.
• There is a systole and diastole for both atria
  and ventricles.

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Cardiac Cycle

• When taking a blood pressure there are two
  numbers measured.
• The first number is systole and the second is
  diastole.
• The perfect healthy blood pressure is 120/80,
  these numbers are pressures calculated based on
  readings done with a blood pressure cuff.

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Cardiac Output

• A persons cardiac output is the volume of blood
  pumped by each ventricle in one minute.
• CO heart rate ? stroke volume
• Stroke volume is the amount of blood pumped out
  by a ventricle with each beat.
• The normal CO is 5 liters.

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Blood Vessels

• Blood vessels are made up of three layers.
• 1.) tunica interna, is the inside layer of the
  vessel
• 2.) tunica media, is the middle layer
• 3.) tunica externa, is the outer layer

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Blood Vessels

• The tunica media is much thinner in the walls of
  veins than it is in arteries.
• Artery walls are thicker so it is easier for
  oxygen and nutrients to diffuse out where they
  are supposed to.

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Blood

• Blood is a liquid tissue that flows through the
  blood vessel.
• Blood consists of plasma, blood cells and
  platelets

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Blood

• In the average human man there are over 5,000,000
  red blood cells (rbc) per cubic millimeter of
  blood.
• In the average human woman there are over
  4,500,000 rbc per cubic millimeter of blood.

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Blood

• The primary function of rbcs is to carry oxygen
  which is picked up by and attached to the bloods
  hemoglobin.
• Hemoglobin is a protein containing iron which is
  bright red in the presence of oxygen and burgundy
  without oxygen.

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Blood

• The white blood cells of the body act as a line
  of defense in the blood.
• They are macrophages which are responsible for
  attacking and destroying foreign bodies in the
  blood.

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Blood

• There are far less wbcs in the blood,
  approximately 5000-9000 per mm3.
• There are two types of wbcs
• 1.) granular, grainy exterior texture
• 2.) agranular, smooth exterior texture
• The major difference between the two is the type
  of foreign bodies they are responsible for
  destroying.

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Blood

• When a vessel opens to the outside the
  coagulation of the blood by the formation of a
  platelet plug occurs.
• Platelets are small pieces of cellular material
  which originate by breaking off pieces of bone
  marrow.

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Blood

• Plasma is the liquid in which all blood particles
  are suspended.
• Plasma is where nutrients, salts and hormones are
  transported throughout the body.