Transcript Cardiovascular System

Heart Sounds and EKG/ECG
Heart Actions and Vocab
• Contraction-systole
– Atria contract together and ventricles contract
together
• Relaxtion-diastole (heart relaxes and fills up with
blood)
• Heart sounds-caused by the open and close of valves
– Lubb-AV valves close/ventricles contract
– Dupp-pulmonary and aortic valves close/ventricles
relax
– How do valves close?
• Papillary muscles contract and pull on chordae
tendinae
• Relaxation-no muscle contraction and pulling
on valves
Cardiac Cycle Steps
High pressure in atria
High
pressure in
ventricles
Pressure
down in
ventricles;
build in atria
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Cardiac Conduction System
http://www.nhlbi.nih.gov/health/health-topics/topics/hhw/electrical.html
• Impulse travels through myocardium (middle
layer of heart)
• SA node-pacemaker (nerve tissue that sends
impulse)
– Posterior right atrium
– Creates impulse for heart beat
– Sends impulse 70-80 times per minute
• Impulse goes to atrial syncytium (mass
of merging cells)
– Left and right atria contract
• Impulse travels through junctional
fibers
– Slows signal down so atria can contract
completely and empty blood before the
impulse goes down to the ventricles
• Goes to AV (atrioventricular node)
– Located in septum
• Goes to AV bundle (bundle of His)
• Branch into purkinje fibers
– Make connection with papillary muscles
– Action squeezes blood out of ventricles
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Heart Sounds
• Open and close of valves
• Lubb-ventricular contraction, AV valves
closing
• Dupp-ventricles relax, pulmonary and aortic
valves close
• Heart murmur-cusps not close enough and
cause blood leak
Electrocardiogram
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• Record electrical changes that
occur during a cardiac cycle.
• P wave
– depolarization
(contraction) of the atria.
• QRS complex
– depolarization of ventricles
(contraction) and hides
the repolarization
(relaxation) of atria
– T wave-end the ECG
pattern
– ventricular repolarization
(relaxation)
1. Atria begin depolarize
2. Atria depolarize.
3. Ventricles depolarize at apex; atria repolarize
4. Ventricles depolarize
5. Ventricles begin repolarization at apex.
6. Ventricles repolarize.
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Diagnostic Value of ECG
•
•
•
•
•
Abnormalities in conduction pathway
Myocardial infarction (heart attack)
Heart enlargement
Electrolyte and hormone imbalance
Ischemia-blood supply restriction
Fast heart; chest pain,
Shortness of breath,
abnormal pacemaker
Heart rate is less
than 60 beats
ADD THIS INFO
• Regulation of Cardiac cycle-chamber
relaxation and contraction
– Exercise
– Temperature
– Ions (calcium-low levels make it slow; high
levels make it fast)
– Autonomic nervous system (sympathetic and
parasympathetic connected to SA node)
– Age and gender
Blood pressure
• Refers to pressure in arteries
• Systolic (pressure in arteries when
ventricles contract) over diastolic (pressure
in arteries when ventricles are filling up
with blood )pressure
• 120/80 is normal
• Pulse (normal is 60 to 100 beats)-expanding
and recoiling of arteries
• Many factors influence blood pressure
Heart Action
• This determines how much blood enters the
arterial system when the ventricles contract
• Stroke volume-volume of blood discharged
from LV
– About 70 ml in average male
• Cardiac output-- volume per minute
– Stroke volume x heart rate
• Cardiac output, blood pressure, and stroke
volume directly related
Blood volume-Factor that
influences this
• Sum of formed elements and plasma
volumes in the vascular system
• Blood pressure is directly proportional to
blood volume
• Can change due to loss of blood (bp drops),
blood transfusion, dehydration (bp drops)
Control of Blood Pressure
• Autonomic nervous system responses
• Peripheral resistance- Pressure between
blood and vessel walls
• Temperature change
– Higher temps, higher blood pressure
Baroreceptors
• Located in aortic arch
• Arterial blood increases, baroreceptors send
nerve impulse to medulla oblongata
• Sends impulse to SA node
– Cause heart rate to decrease
– Blood pressure return to normal
• Arterial blood decreases, sends signal to SA
node to increase heart work
– exercise, rise in temp, emotions
Hypertension
• Hypertension-high blood pressure in
arteries
– Caused by kidney disease, high sodium intake,
obesity, stress, arteriosclerosis
– Lead to enlarge heart due to increase pumping
action of LV
– Cause embolism, thrombosis, stroke
Vein Control
• Skeletal muscles - pushes blood to the heart
• Breathing movements
• Vasoconstriction-low pressure causes
muscles to contract
Sheep Heart Dissection
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23fdFVRvY