The Cardiovascular System

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The Cardiovascular System

• Part II
• The Heart

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Heart

• A hollow muscular organ
• Located in thorax between 2 lungs
• 4 chambers
• 4 valves
• 2 atria (atrium) 2 ventricles
• 2 separate pumps (R L sides)
• Right side receives blood from the body and sends
  it to the lungs (pulmonary)
• Left side receives blood from lungs and sends it
  to the body (systemic)

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2 Pumps
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Position of Heart
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(No Transcript)
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Pericardium

• A sac that covers and surrounds the heart

Pericardial cavity
Cardiac Tamponade
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Structure of the Heart
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Structure of the Heart
LA
RA
RV
LV
apex
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Apex of Heart

• Part of left ventricle
• Left intercostal space (ICS) 5
• Space between left ribs 5 6
• App. 1 inch inferior to male nipple
• Location where heart is most superficial and most
  easily heard

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Apex of Heart
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Structure of the Heart
Note the thickness of the LR ventricles. Why?
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Ventricle Wall Thickness
Left ventricular wall is much thicker.
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Structure of the Heart
RA LA
RV LV
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Structure of the Heart
RA LA
RV LV
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Valves of the Heart

• 4 valves
• One way flow
• Leaky valve heart murmur
• 2 atrioventricular valves
• 2 semilunar valves

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Valves of the Heart
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Atrioventricular Valves

• Right AV valve
• Between right atrium and right ventricle
• Also called the tricuspid valve because it has
  three cusps.
• Cusps close when right ventricle
  contracts.preventing blood from going back up
  into the right atrium

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Atrioventricular Valves
Cusps attached to chordae tendineae Chordae
tendineae attached to papillary
muscles Papillary muscles part of
ventricular wall
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Atrioventricular Valves

• Left AV valve
• Between the left atrium and the left ventricle
• Also called the bicuspid valve because it only
  has two cusps
• Also called the mitral valve
• Cusps close when left ventricle
  contracts.preventing blood from back up into the
  left atrium

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Atrioventricular Valves
Sowhere does blood go when it leaves the
ventrilces?
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Semilunar Valves
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Semilunar Valves

• Pulmonary semilunar valve
• When right ventricle contracts, blood is forced
  through this valve to enter pulmonary trunk
• Aortic semilunar valve
• When left ventricle contracts, blood is forced
  through this valve to enter the aorta

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Semilunar Valves
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Structure of the Heart
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The Cardiac Cycle

• Heart beats 1/sec. In that second, all 4
  chambers must contract (systole) and relax
  (diastole)
• 4 chambers.in which sequence do they contract?
• 2 atria contract first (superior half of heart)
  and simultaneously
• While the atria are contracting, the ventricles
  are relaxing (in order to receive the blood from
  the atria)
• Ventricles fill and then they contract while the
  atria are relaxing and filling with blood.
• How does the heart know how to do this?

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Conduction System of the Heart
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Conduction System of the Heart

• Sino-atrial node (SA nodeaka pacemaker) is
  located in superior wall of right atrium
• It consists of nerve cells that generate and fire
  off an electrical impulse 1/sec

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SA node
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Conduction System of the Heart

• Electrical impulses from SA node then follow
  preferential pathways through the heart
• Electrical activity first goes to both atria

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Conduction System of the Heart
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Atrioventricular Node

• After causing contraction of atrial muscles,
  electrical current goes to the atrioventricular
  node (AV node)
• AV node is located on the inferior wall of the
  right atrium.

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AV node
From AV node, electrical activity enters AV bundle
AV bundle the splits into RL bundle branches
which then cause ventricles to
contract
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Oxygen to the heart muscles

• The heart requires a significant amount of O2
• Where does the oxygen come from?
• Coronary arteries..2 of them RL
• But each artery immediately branches into 2 other
  arteries.
• Cardiologists will tell you that you have 4
  coronary arteries.

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Coronary Arteries
Atherosclerosis is an accumulation of fat on the
inner walls of arteries. When coronary arteries
become partially blocked.angina When coronary
arteries become significantly blocked.myocardial
infarction
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Myocardial Infarction

• Without oxygen, heart cells die (MI) or heart
  attack.
• Read p. 562 and look and the figures to observe
  normal and obstructive blood flow through the
  coronary arteries.