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The Heart
•
Define the function of the heart
•
Identify the different layers of the heart and their function
•
Identify the chambers of the heart
•
Understand the function of the valves of the heart
•
Understand blood flow and the cardiac cycle
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Understand the conducting system of the heart
Location
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The heart is located in the
thoracic cavity
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Posterior to the sternum
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Superior to the diaphragm
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Between the lungs
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The tip of the heart is called
the ‘apex’
Image source – See slide 28
Anatomy
Image source – See slide 28
The heart has:
3 layers
• pericardium
• endocardium
• myocardium
4 chambers
• 2 atrium
• 2 ventricles
4 valves
• Mitral
• Aortic
• Tricuspid
• Pulmonary
Function
•
The heart pumps oxygen and nutrient
rich blood to the organs, tissues and
cells of the body, and eliminates
waste products
Image source – See slide 28
Function
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Blood is carried from the heart
to the organs through arteries,
arterioles and capillaries
•
Blood returns to the heart
through venules and veins
Image source – See slide 28
Layers of the Heart
Pericardium:
The heart is surrounded by a fibro serous
sac called the pericardium
The function of the pericardium is:
• To limit cardiac distension and restrict
excessive movement
• To protect and lubricate
The pericardium is composed of:
• Visceral pericardium
• Parietal pericardium
• Pericardial cavity
Image source – See slide 28
Layers of the Heart
Endocardium:
•
Innermost/deepest layer of the heart
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Lines the heart chambers and the valves
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Smooth thin lining to reduce friction of
blood flow through the chambers
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Cardiac conduction system located in this
layer
Image source – See slide 28
Layers of the Heart
Myocardium:
•
Middle, thickest layer
of the heart
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Contains the muscle fibres
which are responsible for
pumping
•
Contraction of this layer
allows blood to be pumped
through to the blood vessels
Image source – See slide 28
Chambers of the Heart
The heart is divided into four
chambers:
RA: Right Atrium
RV: Right Ventricle
LA: Left Atrium
LV: Left Ventricle
Image source – See slide 28
Upper Chambers
The upper chambers are:
•
The atria
- Right
- Left
Image source – See slide 28
Upper Chambers
The right atrium:
Receives deoxygenated blood from
the body through the:
•
superior vena cava (head and
upper body)
•
inferior vena cava (legs and lower
torso)
The left atrium:
Receives oxygenated blood from the
lungs through the:
•
pulmonary vein
Image source – See slide 28
Lower Chambers
The lower chambers are:
•
Image source – See slide 28
The ventricles
– Right
– Left
Lower Chambers
The right ventricle:
Receives de-oxygenated blood
as the right atrium contracts
The left ventricle:
LV
RV
Receives oxygenated blood
as the left atrium contracts
Valves of the heart
The valves are located within
the chambers of the heart.
The function of the valves:
• Controls the direction of
blood flow
• Allows one way flow of blood
- through chambers
- from the heart to the body
Image source – See slide 28
Valves of the heart
The four valves are known as:
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the tricuspid valve
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the pulmonic or pulmonary valve
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the mitral valve
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the aortic valve
Image source – See slide 28
Valves of the heart
The tricuspid valve:
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Is an atrioventricular valve,
situated between the atria and the
ventricle
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Controls the opening between the
right atrium and the right ventricle
The mitral valve:
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Is an atrioventricular valve,
situated between the atria and the
ventricle
•
Controls the blood between the
left atrium and the left ventricle
Image source – See slide 28
Valves of the heart
The pulmonic or pulmonary valve:
Image source – See slide 28
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Is a semi lunar valve which controls
the blood leaving the heart
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Situated between the right ventricle
and the pulmonary valve
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Controls the flow of blood from the
right ventricle
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Prevents blood flow back to the
right ventricle, as it relaxes
Valves of the heart
The aortic valve:
Image source – See slide 28
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Is a semi lunar valve which
controls the blood leaving the
heart
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Controls blood flow between
the left atrium and the aorta
The Cardiovascular system
The Cardiovascular System consists of the:
•
•
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Heart
Lungs
Blood vessels
It includes:
• Pulmonary circulation
• Systemic circulation
• Coronary circulation
Image source – See slide 28
Pulmonary circulation
Pulmonary circulation is:
•
The carriage of oxygen-depleted blood
away from the heart to the lungs via the
pulmonary artery
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The return of oxygen-rich blood to the
heart via the pulmonary vein
Image source – See slide 28
Pulmonary circulation
Pulmonary circulation and the heart
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The inferior and superior vena cava carry oxygen depleted blood to the relaxed right
atrium of the heart
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The right atrium contracts and blood travels through the tricuspid valve into the relaxed
right ventricle
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The right ventricle contracts, the blood is pumped through the pulmonary valve into the
pulmonary artery to the lungs
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Gas exchange occurs in the lungs
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Co2 is released and oxygen is absorbed
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The oxygen rich blood then travels via the pulmonary veins to the left atrium
Systemic circulation
Systemic circulation is:
•
The carriage of oxygen-rich blood
away from the heart to the body
•
The return of oxygen-depleted blood
back to the heart
Image source – See slide 28
Systemic circulation
Systemic circulation and the heart
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Oxygen rich blood travels from the lungs via the pulmonary veins to the left
atrium
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The left atrium contracts, and blood flows through the mitral valve into the
relaxed left ventricle
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The strong left ventricle contracts and pumps oxygen rich blood through the
aortic valve into the aorta
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The aorta carries blood to the organs of the body
The Conducting system
Cardiac conduction is:
•
the rate the heart conducts
electrical impulses
The electrical pulses determine the
order in which the chambers contract:
the heart rate
The path the impulses travel:
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Sinoatrial node (SA node)
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Atrioventricular node (AV node)
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Bundle branches
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Purkinge fibres
Image source – See slide 28
The Conducting system
The Sinoatrial node (SA) :
Is also known as the pace maker of the
heart
The Sinoatrial node is:
• Located in the upper wall of the
right atrium
• Made up of nodal tissue - both
muscle and nervous tissue
• Where the electrical impulse begins
When the SA node contracts:
• Nerve impulses travel through the
heart wall
• Both atria contract
Image source – See slide 28
The Conducting system
The Atrioventricular (AV) node:
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Is located between the atria and
ventricles of the heart
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Made up of nodal tissue
The electrical impulse is carried from
the SA node, and the AV node is
stimulated.
The AV node delays the path of the
impulse, long enough for the atria to
contract and empty
Image source – See slide 28
The Conducting system
Atrioventricular bundle branches:
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are located between the atria and
the ventricles.
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Fibres branch into two bundles -left
and right side of the heart
The electrical impulse travels from the
AV node to the bundle branches after
the atria have contracted and emptied.
The AV bundle branches then carry the
impulses down the centre of the heart
to the left and right ventricles
Image source – See slide 28
The Conducting system
The AV bundles start to divide
further into:
•
Purkinje fibres
Purkinje fibres:
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Located at the end of the AV bundle
branches, at the base of the heart
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The Purkinje fibres are responsible
for the contraction of the ventricles
Image source – See slide 28
Anatomy - Overview
1.
Arch of aorta
2.
Superior vena cava
3.
Pulmonary artery
4.
Pulmonary veins
5.
Right atrium
6.
Tricuspid valve
7.
Right ventricle
8.
Inferior vena cava
9.
Pulmonary artery
10. Pulmonary veins
11. Left atrium
12. Mitral valve
13. Aortic valve
14. Left ventricle
15. Descending aorta
Image source – See slide 28
A summary
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The heart is located in the thoracic cavity
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The heart has: 3 layers, 4 chambers, 4 valves
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The heart pumps oxygen and nutrient rich blood to the organs, tissues and cells of the
body, and eliminates waste products
•
The Cardiovascular System: Pulmonary circulation, Systemic circulation, Coronary
circulation
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Cardiac conduction is: the rate the heart conducts electrical impulses
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The path the impulses travel: Sinoatrial node (SA node), Atrioventricular node (AV node),
Bundle branches, Purkinge fibres: the heart rate
Image sources
Slide 3
http://www.bem.fi/book/06/06.htm
Slide 4
top:
http://www.nuclearcardiologyseminars.net/structure.htm
bottom:
http://www.texasheartinstitute.org/hic/anatomy/anatomy2.cfm
Slide 5
http://www.thewellingtoncardiacservices.com/the-heartcardiovascular-system
Slide 6, 12
http://www.texasheartinstitute.org/hic/anatomy/anatomy2.cfm
Slide 7
http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiol
ogy/2020/2020%20Exam%20Reviews/Exam%201/CH18%20Per
icardial%20Cavity%20and%20Pathology.htm
Slide 8
http://www.courseweb.uottawa.ca/medicinehistology/english/cardiovascular/Fig08_Cardiovascular.htm
Slide 9
http://webhome.broward.edu/~jlarson/WebCT_6/Instructional_D
esign/12Leads/05.htm
Slide 10
http://www.skillstat.com/heartscape/chambers.htm
Slide 11, 13
http://www.starsandseas.com/SAS%20Physiology/Cardiovascul
ar/Cardiovascular.htm
Slide 15,16
http://nyp.org/health/cardiac-valves.html
Slide 17
http://www.texasheartinstitute.org/hic/topics/cond/valvedis.cfm
Slide 18 - As per copyrighted
Slide 19
http://www.tutorvista.com/content/biology/biology-iv/circulationanimals/components-circulatory-system.php
Slide 20
http://revisionworld.co.uk/a2-level-level-revision/biology/physiologytransport/human-circulatory-system
Slide 21
http://en.wikipedia.org/wiki/Pulmonary_artery
Slide 23
http://www.prevent-stroke-and-heart-attack.com/pulmonary-andsystemic-circulation.html
Slide 25
http://biology.about.com/library/organs/heart/blcardiacconduction.htm
Slide 26
http://hyperphysics.phy-astr.gsu.edu/hbase/biology/sanode.html
Slide 27, 28, 29
http://www.tutorvista.com/content/biology/biology-iv/circulationanimals/blood-circulation-mammalian-heart.php
Slide 30
http://sjesci.wikispaces.com/Heart+and+Lungs
References:
Drake, Richard L., Vogl, Wayne. A, Mitchell, Adam W.M., Grays
Anatomy for Students, Second Edition, Churchill Livingstone