Download The Heart

The Heart
And how it works…
Heart Beats
Heat Beats
Step 1: Enter Atrium
Right Side
- Deoxygenated blood
enters the right atrium
through 2 large veins
- Superior vena cava:
upper half of the body
- Inferior vena cava:
below the diaphragm
Left Side
- Oxygenated blood
(from the lungs) enters
the left atrium through
the pulmonary vein
- Comes from the lungs
Heart Beats
Step 2: Contract Atrium
• Blood flows from the
atrium into the
ventricle
• The atrioventricular
(AV) valve allows for
a one-directional flow
• The AV valve closes
once the ventricle is
full - LUB
Heart Beats
Step 3: Contract Ventricle
• Right ventricle
contracts
• Blood flows through
the semilunar valve
into the left pulmonary
artery – DUB
• Blood flows towards
the lungs
• Left ventricle
contracts
• Blood flows through
the semilunar valve
into the right
pulmonary artery
• Blood flows out
towards the body
Path of Blood through the Heart
Heart Sounds
• Two normal heart sounds
– Lub: closure of the AV valves (beginning of
ventricular contraction - systole)
– Dub: closure of the semilunar valves (end of
ventricular systole – diastole)
• Other sounds
– Heart murmur: turbulent blood flow
Heart Murmur: back flow
Overview: Blood Flow
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Blood in body
Into heart via vena cava (vein)
Right atrium
Right Ventricle
Left pulmonary artery (deoxygenated)
Lungs (becomes oxygenated)
Pulmonary vein
Left atrium
Left ventricle
Arteries (oxygenated towards body tissue)
Connecting the Heart
to the Lungs & the Body
Setting the Heart’s Tempo
• Heart muscles contract without being stimulated
by external nerves (myogenic muscles)
• Heart muscle does not all contract at the same
rhythm when separated
• Heart rhythm is set by the sinoatrial (SA) node –
specialized nerve cells
• Nerve impulses travel to a second node AV node
which sends the message toward the ventricles
Normal Sinus Rhythm
• P wave followed by a ventricular response
Atrial Fibrilation
• Most common arrhythmia
• Result of hypertension
AV Block
• Delay in the AV node
• Caused by many things but could be
decreased levels of Oxygen in the blood
Ventricular Fibrilation
• The ventricles are not contracting as a unit
• There is no clear cardiac output
• Commonly known as a Heart Attack
Flatline:
• Asystole: no cardiac electrical activity (no
contractions or blood flow) – cannot be
treated with defibrillation