The Circulatory System

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The Circulatory System A Transport Service
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Circulatory System Consists of

• Heart
• Blood Vessels
• Blood

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• HEART The Vital Pump

On average, the heart contracts 72 times a
minute, pumping about 5 quarts of blood.
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Structure

• FXN Keeps blood moving
• Large organ composed of
• cardiac muscle,
• rich in mitochondria
• Enclosed by a PERICARDIUM sac

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Structure of Heart (cont)

• Four chambers
• Two upper (Atria)
• Two lower (Ventricles)

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Structures of the Heart
Left Atrium
Right Atrium
Left Ventricle
Septum
Right Ventricle
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Heart - as two separate pumps

• Circulation of blood between the heart and the
  lungs- PULMONARY circulation
• Circulation of blood between the heart and the
  rest of the body- SYSTEMIC circulation

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Circulatory System/Blood Vessels Pathway of
Circulation

• 3 types of vessels
• Arteries
• Capillaries
• Veins

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Arteriescarry blood Away from heart

• Large
• Thick-walled, Muscular
• Elastic
• Oxygenated blood
• Exception -Pulmonary Artery
• Carried under great pressure
• Steady pulsating

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Capillaries

• - Smallest vessels
• Microscopic
• Walls one cell thick
• Nutrients and gases diffuse here

Capillary
Artery
Vein
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VeinsCarry blood to heart

• Carry blood that contains waste and CO2
• Exception -pulmonary vein
• Blood not under much pressure
• Valves to prevent much gravity pull

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The Blood

• Body contains 4-6 L
• Consists of
• Water
• Red Blood Cells
• Plasma
• White blood cells and platelets

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Carbon Dioxide in the Blood

• CO2 is a waste product of cellular work
• 70 of CO2 combines with water
• The rest travels to the lungs

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RBC

• Transporters of
• Oxygen
• Carbon Dioxide
• RBC
• Lack a nucleus
• Contain hemoglobin
• Disk-shaped
• RBC are produced in red bone marrow of
• ribs,
• humerus,
• femur,
• sternum, and other long bones
• Lives for 120 days
• Old RBC are destroyed in liver and spleen

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WBC

• WBC fight infection
• Attack foreign substances
• Less abundant
• Large cells
• Some live for months
• Most just a few days
• Several types
• ALL contain nuclei

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Platelets

• PLATELETS are for CLOTTING blood
• Cell fragments
• Produced in bone marrow
• Short life span (1 week)
• Fibrin (sticky network of protein fibers)
• Form a web trapping blood cells