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The Heart
Overview
• 4 chambered pump
– separated by a muscular wall called the
septum
• Two upper atria
• Two lower ventricles
• Major portion is the myocardiumcardiac muscle
– Inner surfaces lined with endocardium
– Outer surfaces lined with pericardium
•
Overview cont’d
• Controlled by our autonomic
nervous system
– We don’t have control over this…
even if we think we do!
– Breathing, blinking, etc…
Structure
• Atria
– Singular: atrium
– Thin walled
– Top portion of heart
• left and right atria
• Ventricles
– Thick muscular walls
– Bottom portion of heart
Structure cont’d
• Atrioventricular valves
– Lie between the atrium and ventricle
on each side
– Mitral valve-between the left atrium
and left ventricle
– Tricuspid valve- between the right
atrium and right ventricle
Structure cont’d
• Semilunar valves
• Between the ventricle and great
vessel on each side
• Aortic valve-between the left
ventricle and aorta
• Pulmonary valve-between the
right ventricle and the pulmonary
artery
– Valves control the flow of blood
through the heart
Two Systems
• Pulmonary Circulatory System
– Carries deoxygenated blood to the lungs
– Brings oxygenated blood back to the heart
• Systemic Circulatory System
– Carries oxygenated blood to the body
– Brings deoxygenated blood back to the
heart.
Two System
cont’d
• The heart is effectively 2 pumps
• Right side  pulmonary pump
• Left side  systemic pump
– deoxygenated and oxygenated
blood never mix
– Left ventricle pumps blood under
higher pressure
• Left ventricular wall is more
muscular
External heart anatomy
• Fig 12.3
Internal view of the heart
• Fig 12.4
12-10
Path of Bloodflow
• Deoxygenated blood from the body
enters the right atrium via the vena
cava.
– Superior Vena Cava
• blood from the head and neck
– Inferior Vena Cava
• blood from the lower body
• When full, the tricuspid valve opens for
a short time and then shuts.
– Blood flows to the right ventricle
Path of Bloodflow cont’d
• Right Ventricle fills with blood
– When filled, it contracts.
• The pulmonary valve opens and
closes quickly.
• Blood travels through the
pulmonary arteries to your lungs
to pick up oxygen.
Path of Bloodflow cont’d
• Oxygen-rich blood returns from
the lungs to your left atrium
through the pulmonary veins.
• As your heart's left atrium fills
with blood, it contracts.
• The mitral valve opens and closes
quickly.
Path of Bloodflow cont’d
• As the left ventricle fills with
blood, it contracts.
• The aortic valve opens and closes
quickly allowing blood to flow into
the aorta.
– carries blood from your heart to the
rest of your body.