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, 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
rdiumApexBase Pulmonary Artery Pulmonary
Vein R/L Coronary Artery Coronary Sinus
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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Stress and Heart Disease

• Prolonged stress can wreak havoc on your
  cardiovascular system.
• Stress means that we are operating in a fight or
  flight manner- Preparing the body to meet a
  challenge
• This reaction is caused by the release of
  adrenaline
• Adrenaline causes the heart beat to increase,
  blood pressure to increase, blood sugar levels to
  increase, and the digestion and immune systems to
  become suppressed.
• The body frequently experiencing this can be
  damaging.

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The Heart Beat

• The heart beat is due to electrical impulses
  flowing throughout the heart.
• This begins in the Sinoatrial (SA) node
  (nodegroup of muscles) in the right atrium just
  below the opening of the Superior Vena Cava.
• The SA node is called the pacemaker because it
  regulates the heart rate.
• This signals the muscle tissue in the right and
  left atria to simultaneously contract- forcing
  blood into the ventricles.
• The Atrioventricular (AV) node located in the
  interatrial septum also receives the message from
  the SA node and forwards it onto the
  atrioventricular bundle, then onto the right and
  left bundle branches and finally the Purkinje
  fibers.

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Heart Beat continued

• When the message is received by the Purkinje
  fibers, the ventricles contract (including the
  papillary muscles inside of them).

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Putting it all together

• The atria contract at the same time, followed by
  the ventricles contracting at the same time.
• When the atria fill, pressure in the atria is
  greater than that of the ventricles, which forces
  the AV valves open.
• Pressure inside atria rises further as they
  contract (due to the SA node), forcing the
  remaining blood into the ventricles.
• When ventricles contract (due to the Purkinje
  fibers), pressure inside them increases sharply,
  causing the aortic and pulmonary valves to open.
• - As the ventricles contract, papillary muscles
  contract, pulling on chordae tendineae and
  preventing the backflow of blood through the AV
  valves.

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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, fillingthe leaflets of the
semilunarvalves andforces themto close
As ventriclescontract,blood is pushedup
againstsemilunarvalves, forcingthem open
Aorta
Pulmonarytrunk
Semilunar valveopen
Semilunar valveclosed
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Heart Sounds

• Heart sounds can be described as a "lubb-dupp"
  sound.
• The first sound (lubb) occurs as ventricles
  contract and AV valves are closing.
• The second sound (dupp) occurs as atria contract
  and SL valves are closing.
• 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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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.
• 2. Atrial systole (ventricular diastole)- This
  is when the atria contract and the AV valves are
  open (SL closed).
• 3. Ventricular systole (atrial diastole)- This
  is when the ventricles contract and the SL valves
  are open (AV closed).

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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.
• 2. QRS complex- When the current spreads
  throughout the ventricles- which causes them to
  contract.
• 3. T wave- Current change of the ventricles as
  they start to relax.

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Normal ECG
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Valves open Valves closed Active node and/or nerves Sound made EKG wave
Ventricular Systole
Atrial Systole
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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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• A pacemaker is an electronic device placed most
  often below your collarbone on the left or right
  side of your chest. A pacemaker contains a
  battery and computer circuitry in a metal case to
  correct slow heart rhythms. The pacemaker
  monitors your heart all the time, and if it
  detects a slow rhythm issue, it sends out small
  undetectable electrical signals to correct it.