Transcript Heart Anatomy

Exercise 27
Gross Anatomy of the Heart
BI 232
Mediastinum
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The heart and pericardial
cavity are located within
the mediastinum, a
centrally located area
within the thoracic cavity.
The Pericardium
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Membranous sac
2 parts: outer fibrous
pericardium that is
fused to adjacent
structures and an inner
serous pericardium
which is a delicate serous
membrane that forms a
double-layered sac around
the heart.
The serous pericardium
consists of parietal and
visceral layers.
The heart
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Two-sided, doublepumping organ.
The left side controls the
flow of blood to all tissues
and cells in the body,
where oxygen and
nutrients are delivered
and wastes are taken away.
The right side sends blood
to the lungs, where
oxygen stored in RBCs is
replenished and CO2 is
released
External Anatomy of the Heart
External Anatomy of the Heart
Internal Anatomy of the Heart
Coronary Circulation
Coronary Circulation
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On the posterior surface
of the heart, the coronary
artery branches to
become the posterior
interventricular artery
Near the apex of the
heart the anterior and
posterior interventricular
arteries form an
anastomosis
(connection)
Coronary Circulation
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On the posterior surface
of the heart, the
coronary sinus runs
along the coronary sulcus
and empties into the right
atrium.
Great cardiac vein
found in the anterior
interventricular sulcus
Middle cardiac vein
ascends along the
posterior interventricular
groove
Blood flow Through the Heart
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Pulmonary
Circulation- Blood from
the right side of the heart
flows to and from the
lungs
Systemic CirculationBlood from the left side of
the heart flows from and
to all body tissues.
Position of Heart
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Base of the heart
extends from the inferior
border of the second
costal cartilage on the left
side to the superior
border of the third costal
cartilage on the right.
Apex of the heart is
located in the left fifth
intercostal space, left of
the median plane
Heart: muscular pump
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Actually 2 pumps acting in
unison
Systole is contraction of
heart muscle
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Atrial systole
Ventricular systole
Diastole is relaxation of
heart muscle
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Atrial diastole
Ventricular diastole
Conduction system of the Heart
(Exercise 32)
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Electrical activity of the heart
stimulates the heart muscle to
contract.
Sinoatrial (SA) node =
pacemaker of the heart
Atrioventricular (AV) node:
there is a slight delay (0.10
second)
Atrioventricular bundle
(bundle of His)
Right and left bundle
branches
Purkinje fibers: stimulate cardiac
muscle of the ventricles to
contract
http://youtu.be/te_SY3MeWys
Electrical activity of the Heart
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Heart produces low-voltage
electrochemical impulses
The average potential difference is
-90 millivolts
These impulses can travel through
the saline medium of the body and
be picked up by sensors attached
to the skin
The collective action potentials
generated by the atria and
ventricles depolarizing and
repolarizing can be recorded using
an electrocardiograph machine
EKG Waveform
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P wave
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The P wave indicates the depolarization of the atria just
prior to the beginning of atrial contraction or systole
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QRS complex (QRS interval)
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Represents the depolarization of the ventricles which
precedes ventricular systole.
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T wave
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Results from ventricular repolarization, which occurs
before ventricular relaxation or diastole.
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Analysis of the ECG
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Irregularities in Heart rate:
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Tachycardia: Above 100
in adults (in small children
this may be normal)
Bradycardia: in young
adults below 60 beats per
minute (unless person is
highly trained aerobic
athlete)
Heart Blocks
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PR intervals are normally about
0.16 second.
Time between the beginning of
atrial depolarization and the
beginning of ventricular
depolarization.
Long PR might indicate a
heart block (reduced conduction
between atria and ventricles)
Longer than 0.2 second
Complete heart block the atria
do not stimulate ventricular
depolarization at all, so atria fire
independently of ventricles
Heart Blocks
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Normal QRS is 0.08 to
0.10 second on average.
Longer than 0.12 may
indicate a right or left
bundle branch block
QT interval is normally
about 0.3 second
This is shorter as the
heart rate increases and
longer as heart rate slows.
Cardiac Arrhythmias
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A major diagnostic use is to detect
arrhythmias, abnormal rhythms of
the heart
Atrial fibrillation: electrical
activity of the heart is
uncoordinated causing the upper
chambers to quiver.
Ventricular fibrillation: where
electrical signals in the ventricles
fire in a very fast uncontrolled
manner.
Premature ventricular
contraction (PVC): electrical
signal causes an early heartbeat
that usually goes unnoticed
Today’s lab
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Dissect sheep heart
ID structures on the heart models
We will also be doing EKGs (We will be using the Vernier
EKGs rather than the BIOPAC machines mentioned in
the lab manual)
After performing your EKG follow the instructions in
your lab manual and calculate the mean electrical axis
of your heart
The End
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