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Cardio Vascular System
Audience: Health/Physical educators and health aspiring students
By Vince Colucci
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Size of Heart
Average Size of Heart
• 14 cm long
• 9 cm wide
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Location of Heart
• posterior to sternum
• medial to lungs
• base lies beneath 2nd rib
• lies upon diaphragm
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Coverings of Heart
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Wall of the Heart
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Heart Chambers
Right Atrium
• receives blood from
Right Ventricle
• receives blood from
right atrium
Left Atrium
• receives blood from
pulmonary veins
Left Ventricle
• receives blood from
left atrium
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Skeleton of Heart
• fibrous rings to which the heart valves are attached
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Path of Blood
Through the Heart
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Path of Blood
Through the Heart
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Electrocardiogram
• recording of electrical changes that occur in the myocardium
• used to assess heart’s ability to conduct impulses
P wave – atrial depolarization
QRS wave – ventricular depolarization
T wave – ventricular repolarization
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Electrocardiogram
A prolonged QRS complex may result from damage to the A-V
bundle fibers
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Regulation of Cardiac Cycle
Additional Factors that Influence HR
• physical exercise
• body temperature
• concentration of various ions
• potassium
• calcium
• parasympathetic impulses decrease heart action
• sympathetic impulses increase heart action
• cardiac center regulates autonomic impulses to the heart
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Blood Vessels
• arteries
• carry blood away from ventricles of heart
• arterioles
• receive blood from arteries
• carry blood to capillaries
• capillaries
• sites of exchange of substances between
blood and body cells
• venules
• receive blood from capillaries
• veins
• carry blood toward ventricle of heart
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Arteries and Arterioles
Artery
• thick strong wall
• endothelial lining
• middle layer of smooth
muscle and elastic tissue
• outer layer of
connective tissue
• carries blood under
relatively high pressure
Arterioles
• thinner wall than
artery
• endothelial lining
• some smooth muscle
tissue
• small amount of
connective tissue
• helps control blood
flow into a capillary
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Metarteriole
connects arteriole directly to venule
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Capillaries
• smallest diameter blood vessels
• extensions of inner lining of arterioles
• walls are endothelium only
• semipermeable
• sinusoids – leaky capillaries
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Capillary Network
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Venules and Veins
Venule
• thinner wall than arteriole
• less smooth muscle and elastic tissue than arteriole
Vein
• thinner wall than artery
• three layers to wall but middle layer is poorly developed
• some have flaplike valves
• carries blood under relatively low pressure
• serves as blood reservoir
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Arterial Blood Pressure
Blood Pressure – force the blood exerts against the
inner walls of the blood vessels
Arterial Blood Pressure
• rises when ventricles contract
• falls when ventricles relax
• systolic pressure – maximum pressure
• diastolic pressure – minimum pressure
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Pulse
• alternate expanding and recoiling of the arterial wall
that can be felt
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Informational Link
http://www.ambulancetechnician
study.co.uk/circsystem.html
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