The Cardiovascular System

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The Cardiovascular System
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The Cardiovascular System

• The functions of the cardiovascular system are
• Supply oxygen to tissues from the lungs
• Supply nutrients to tissues from the digestive
  tract
• Remove wastes from tissues and take them to the
  lungs or kidneys or liver.
• The study of the heart and diseases associated
  with it is termed cardiology.
• The heart lies in the mediastinum between the
  lungs with about 2/3 of it on the left of the
  bodys midline.
• The heart is the size of a closed fist.

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Coverings of the Heart

• The pericardium surrounds and protects the
  external heart and holds it in place.
• 3 parts to the pericardium from the outside to
  the inside
• Fibrous pericardium- Tough, inelastic connective
  tissue that prevents overstretching.
• Parietal pericardium- Fused to the fibrous
  pericardium.
• Visceral pericardium- Also called the epicardium
  and adheres tightly to the heart.
• Between the parietal and visceral layers is the
  pericardial space containing pericardial fluid
  which reduces friction as the heart moves.
• Inflammation of the pericardium is called
  pericarditis.

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• The inside of the hollow heart (where the blood
  flows) is a smooth covering called the
  endocardium.
• The majority of the heart is the myocardium which
  is the cardiac muscle that pumps the blood
  throughout the body.

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Heart Chambers

• The heart has four internal chambers two atria
  (right/left) on top and two ventricles
  (right/left) on bottom.
• Atria receive blood returning to the heart and
  have thin walls. On the exterior surface of each
  is a wrinkled pouch-like structure called an
  auricle.
• The thick-muscled ventricles pump blood to out of
  the heart. The left ventricle is considerably
  larger.
• The right and left atria are divided by an
  interatrial septum.
• The right and left ventricles are separated by an
  interventricular septum.

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Heart Valves

• Valves are one-way doors that open and close in
  response to pressure changes. They allow blood
  to flow in one direction in the heart.
• Atrioventricular valves (AV) are between the
  atria and ventricles. The right AV valve is the
  tricuspid and the left AV valve is the bicuspid
  or mitral.
• Both of these valves have tendonlike cords called
  chordae tendineae. Chordae tendineae are
  attached to papillary muscles in the inner heart
  wall that contract when ventricles contract to
  prevent the backflow of blood through the AV
  valves.

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Heart Valves continued.

• In between the ventricles and the major arteries
  taking blood away from the heart are 2 semilunar
  valves (SL).
• The right SL valve is the pulmonary valve and the
  left SL valve is the aortic valve.

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Major Heart Blood Vessels

• Superior Vena Cava- Returns blood to the right
  atrium from above the heart.
• Inferior Vena Cava- Returns blood to the right
  atrium from below the heart.
• Pulmonary Trunk- Carries blood from the right
  ventricle and branches into the right and left
  pulmonary arteries leading to the lungs.
• Pulmonary Veins- Return oxygenated blood to the
  left atrium.
• Aorta- Carries oxygenated blood away from the
  left ventricle and directs it to the body.

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Label the Heart
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How the Chordae Tendineae Work
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Blood Vessel Types

• There are 5 types of blood vessels in the
  cardiovascular system
• Arteries- Carry blood away from the heart
• Arterioles- Smaller arteries
• Capillaries- Smaller arterioles that are 1 cell
  thick
• Venules- Groups of capillaries
• Veins- Return blood to the heart

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Blood Vessels
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Flow of blood through heart and body

• There are 2 branches of the cardiovascular
  system pulmonary and systemic circulation.
• Pulmonary circulation- The right side of the
  heart pumps blood to the lungs to pick up oxygen
  and drop off carbon dioxide.
• Systemic circulation- The left side of the heart
  pumps blood to the body to drop off the oxygen
  and pick up carbon dioxide waste.
• Pulmonary and Systemic circulation happen
  simultaneously

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Pulmonary Circulation Blood Flow
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Systemic Circulation Blood Flow
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Differences in Right and Left Ventricles- Now
that you know the blood flow, why is the left
ventricle so large?
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Blood Supply to the Heart

• The first branches off of the aorta, which carry
  freshly oxygenated blood, are the right and left
  coronary arteries that feed the heart muscle
  itself.
• Branches of the coronary arteries feed many
  capillaries of the myocardium.
• When these arteries become clogged due to the
  build up of fats and cholesterol, various
  techniques can be used including angioplasty and
  stents. If they are unsuccessful, new arteries
  must be attached to by pass these clogged
  arteries.
• Cardiac veins drain blood from the heart muscle
  and carry it to the coronary sinus (large vein on
  posterior side of heart), which empties into the
  right atrium.

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Coronary Sinus
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Coronary ArteriesBypass Graft Animation
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SHEEP HEART DISSECTION
External AortaSuperior Vena CavaR/L
AuricleR/L AtriumR/L VentriclePericardiumMyoca
rdiumPulmonary Artery Pulmonary Vein
Internal Tricuspid Valve Mitral/Bicuspid
Valve Pulmonary Valve Aortic Valve Chordae
Tendineae Papillary Muscle Endocardium Interventri
cular Septum R/L Atrium R/L Ventricle Pulmonary
Artery Pulmonary Veins Aorta

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The Heart Beat

• The heart beat is due to electrical impulses
  flowing throughout the heart.
• A node is a group of muscles. The heart has 2
  nodes that control the heart beat.
• The Sinoatrial (SA) node is in the right atrium
  just below the opening of the Superior Vena Cava.
• The SA node receives the electrical message from
  the brain and signals for the muscle tissue in
  the right and left atria to simultaneously
  contract- forcing blood into the ventricles.
• The SA node is called the pacemaker because it
  regulates the heart rate.

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• The second node in the heart is the
  Atrioventricular (AV) node.
• The AV node is also located in the right atrium
  and receives the message from the SA node.
• The AV node forwards the message onto the
  atrioventricular bundle, then onto the right and
  left bundle branches and finally the Purkinje
  fibers.
• When the message is received by the Purkinje
  fibers, the ventricles contract.

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Animation and Practice Quiz
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Heart Sounds

• Heart sounds can be described as a "lubb-dupp"
  sound.
• The first sound (lubb) occurs as the ventricles
  contract and the AV valves close.
• The second sound (dupp) occurs as the ventricles
  relax and the SL valves close.
• A heart murmur is an abnormal sound consisting of
  a rushing or gurgling noise. Most often this is
  due to a valve disorder.

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What causes the valves to close?

• When the atria fill, the blood pressure
  eventually forces the AV valves open. This
  causes approximately 75 of the atrial blood into
  the ventricles.
• As the atria contract (due to the signal from the
  SA node), the remaining blood into the
  ventricles.
• When the ventricles contract (due to the Purkinje
  fibers), the blood is forced against the SL
  valves. They are pushed open and blood enters
  the aorta and pulmonary trunk.
• As the ventricles contract, the blood is also
  forced against the open AV valves, causing them
  to close (lubb). The chordae tendineae prevent
  them from opening into the atria.

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• As the ventricles relax, the blood in the aorta
  and pulmonary trunk fall back due to gravity.
• This puts pressure on the SL valves, causing them
  to close (dupp).

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Operation of the AV valves
When the atria fill with blood, the AV valves
open and 75 of the blood in the atria passes
down into the ventricles
When the atria get the message to contract, the
remaining 25 of the blood is forced into the
ventricles.
AV valves open
Ventricles
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When the ventricles contract,blood is
forcedagainst the AV valves, forcing them to
close.
Chordae tendineaetighten, preventingvalve flaps
fromeverting into the atria
AV valves closed
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As ventriclesrelax,blood flowsback from
thearteries, putting pressure on the
semilunarvalves andforcing themto close
As ventriclescontract,blood is pushedup
againstsemilunarvalves, forcingthem open
Aorta
Pulmonarytrunk
Semilunar valveopen
Semilunar valveclosed
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The Heart Cardiac Cycle

• The term systole means contraction and diastole
  means relaxation.
• The cardiac cycle consists of 3 phases
• 1. Relaxation period- Brief period of time when
  all 4 chambers are relaxed (AV valves open-SL
  valves closed).
• 2. Atrial systole (ventricular diastole)- This
  is when the atria contract (AV valves open-SL
  valves closed).
• 3. Ventricular systole (atrial diastole)- This
  is when the ventricles contract (SL valves
  open-AV valves closed).

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Animation and Practice Quiz
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Electrocardiogram

• Electric currents that run through the heart can
  be picked up by electrodes that are placed on a
  persons skin. A recording of the electrical
  changes during a persons heart beat is called an
  electrocardiogram or ECG or EKG.
• There are 3 waves viewed during an EKG
• 1. P wave- when the current passes from the SA
  node throughout the atria- which causes them to
  contract (atrial depolarization).
• 2. QRS complex- When the current spreads
  throughout the ventricles- which causes them to
  contract (ventricle depolarization and atrial
  repolarization).

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EKG continued

• 3. T wave- Current change of the ventricles as
  they start to relax (ventricle repolarization).

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A
B
C
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Valves open Valves closed Active node and/or nerves Sound made EKG wave
Ventricular Systole
Atrial Systole
Relaxation Period
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Common Heart Disorders

• Heart block- Disorder when the electrical system
  of the heart is damaged.
• Angina pectoris- Chest pain due to reduced blood
  flow to the myocardium.
• Arrhythmia- Irregular heart rhythm
• Tachycardia- Heart beat that is too rapid.
• Bradycardia- Heart beat that is too slow.
• Fibrillation- Rapid, irregular, and
  unsynchronized contraction of muscle fibers.
• Cardiac arrest- Cessation of a regular heart
  beat.

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For the following, write the word that comes next
in the blood flow

1. Mitral valve 9. Tricuspid valve
2. Pulmonary venules 10. Left atrium
3. Pulmonary trunk
4. Right atrium
5. Left ventricle
6. Arteries
7. Pulmonary veins
8. Veins

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