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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

Left Atrium• receives blood from pulmonary veins

Right Ventricle• receives blood from right atrium

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 BloodThrough 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 depolarizationQRS wave – ventricular depolarizationT 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

• 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

Additional Factors that Influence HR

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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

Informational Link

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http://www.ambulancetechnicianstudy.co.uk/circsystem.html