Transcript P Wave

HEART
PHYSIOLOGY
and
HEART DISORDERS
The Electrocardiogram
•
The conduction of APs through the heart
generates electrical currents that can be read
through the skin
•AP = Action Potential
•Currents picked up by electrodes
•The recording is called an
ELECTROCARDIOGRAM (ECG or EKG)
The Electrocardiogram, cont.
• Each heartbeat produces three
clearly recognizable waves.
•The P wave, the QRS Complex, and
the T wave
The Electrocardiogram, cont.
P Wave
•
•
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A small upward deflection
The P wave represents the AP as it
spreads throughout the Atria
A second after the P wave begins, the
atria contract
The Electrocardiogram, cont.
QRS Complex
• QRS complex occurs as the AP
spreads through the ventricles
• After the QRS complex begins,
the ventricles contract
The Electrocardiogram, cont.
T Wave
• Upward deflection that occurs just
before the ventricles relax
The Cardiac Cycle
A single Cardiac Cycle includes all
events associated with one heartbeat
The two atria contract while the two
ventricles relax; ventricles contract
while atria relax
The Cardiac Cycle, cont.
Systole
refers to the phase of contraction
Diastole
refers to the phase of relaxation
HEART
DISORDERS
1. Pericarditis
•
Inflammation of the pericardium (the membrane
that surrounds and protects the heart)
•
In one form of pericarditis, there is a build up of
pericardial fluid (fluid that prevents friction
between layers of the pericardium)
•
Too much fluid build-up in the pericardium will
compress the heart
•
Symptoms of pericarditis include low blood
pressure and difficulty breathing
1. Pericarditis
2. Heart Murmur
•
A heart murmur is an abnormal sound consisting
of a clicking, rushing, or gurgling noise that is
heart before, between, or after the normal heart
sounds
•
A heart murmur could mask the normal heart
sounds
•
Heart murmurs are very common in children and
are usually outgrown
•
In adults, the heart disorders could indicate a
valve disorder
Stenosis
•
Stenosis = Narrowing of a heart
valve opening that restricts
blood flow
•
The failure of a valve to close
completely is termed
insufficiency or incompetence
3. Mitral Stenosis
•
Scar formation from an infection
or a congenital defect causes
narrowing of the mitral valve
4. Mitral Valve Prolapse
•
In MVP, one or both cusps of the mitral
(bicuspid) valve protrude into the left
atrium during ventricular contraction
•
Backflow of flood from the left ventricle
into the left atrium
5. Aortic Stenosis
•
The aortic valve is narrowed
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A backflow of blood from the aorta into
the left ventricle
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Valves must be repaired or replaced by
human or pig donors or by artificial valves
6. Artificial Pacemaker
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•
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When the heart rate is too low, an artificial
pacemaker can restore normal heart rhythm
Sends out small electrical currents to stimulate
the heart to contract
Pacemaker wires are threaded through the
superior vena cava and placed on the right atrium
and right ventricle
Pace makers are implanted beneath the skin
inferior to the clavicle
7. Congestive Heart Failure
•
In congestive heart failure (CHF), the heart
begins to fail
•
Pumps less and less effectively, leaving blood in
the ventricles after every cycle
•
PULMONARY EDEMA - If the left ventricle fails
first, the heart cannot pump out all the blood it
receives and blood backs up in the lungs. Can
lead to suffocation.
•
PERIPHERAL EDEMA – The right ventricle fails
firsts, and blood backs up in systemic blood
vessels. First noticeable as swelling in the feet
and ankles.
8. Atherosclerosis
•
A progressive disease characterized by the
formation in the walls of large and medium of
lesions called atherosclerotic plaques
•
Two proteins are monitored in cholesterols for
this disease are LDL and HDL
•
LDL (low-density lipoprotein) and HDL (highdensity lipoprotein)
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HDL removes cholesterols – is known as “good
cholesterol”
•
The HDL should be high and the LDL should be
low
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9. Myocardial Infarction
A complete obstruction to blood flow in a
coronary artery
•
Myocardial Infarction (MI) = Heart Attack
10. Cardiac Arrest
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A clinical term meaning cessation of an effective
heartbeat
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The heart may be completely stopped or in
ventricular fibrillation (spontaneous contractions
of individual muscle fibers)
11. Cardiomegaly
An enlarged heart
12. Tachycardia
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Faster (than normal) heart rate at rest
13. Bradycardia
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Slower (than normal) resting heart rate
14. Rheumatic Fever
•
A streptococcal infection of the throat that
affects the bicuspid (mitral) and aortic
valves in the heart
•
Bacterial infection triggers immune response
that inflames damages the tissues – can
weaken entire heart