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The Cardiac Cycle• Refers to the events of 1 complete heart
beat –Both atria & ventricles contract then relax
(0.8 sec if beating 75x/min)• Key terms to know–Diastole- relaxation–Systole- contraction–Lub-dub- the sound created by the closing of
the heart valves (AV and semilunar)
Filling Heart Chambers: Cardiac Cycle
Figure 11.7, step 1a
Mid-to-late diastole(ventricular filling)
Ventricularfilling
Left atrium
Right atrium
Left ventricle
Right ventricle
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Mid-to-late diastole— blood flows from the atria into the ventricles (both chambers are relaxed, AV valves open) then the atria contract to squeeze remaining blood into the ventricles
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricular systole(atria in diastole)
Isovolumetriccontraction phase
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricular systole(atria in diastole)
Isovolumetriccontraction phase
Ventricularejection phase
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Ventricular systole— blood pressure builds before ventricles contract, when ventricles begin to contract pressure gets high enough opening the semilunar valves allowing blood to be pushed out to the lungs and body
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricular systole(atria in diastole)
Early diastole
Isovolumetriccontraction phase
Ventricularejection phase
Isovolumetricrelaxation
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Early diastole— atria finish refilling, when the pressure in the atria exceeds the pressure in the ventricles the AV valves will open allowing blood to fill the ventricles the cycle begins again
Murmur- condition in which one of the valves is not functioning properly (could be an AV or semilunar valves) and blood can flow backwards/inefficiently through the heart.
Which phase of the cardiac cycle does this picture show? How can you be sure?
Factors that Affect CO1. Venous return (amount of blood that
enters the heart)– Inc. venous return inc. stretching
2. How much the ventricle is stretched prior to contraction– Inc. stretching inc. force of contraction
3. High blood pressure
Factors that Change Heart Rate• Crisis stressors– Electrical system of the heart is more strongly
stimulated to beat inc heart rate• Congestive heart failure – Heart “worn out” – digitalis (drug) prescribed, strengthens
contractions to inc. cardiac output• Epinephrine & thyroxine increase heart rate• Electrolyte levels (ions)– Low calcium depresses heart; high calcium causes
sustained contraction can cause cardiac arrest– Low potassium irregular heartbeat
Physical Factors that Affect Heart Rate
• Age – HR decreases with age (healthy) • Gender – Females > males• Exercise – increases HR• Body temp – higher temp
increases HR
The Cardiac Cycle• Refers to the events of 1 complete heart
beat –Both atria & ventricles contract then relax
(0.8 sec if beating 75x/min)• Key terms to know–Diastole- relaxation–Systole- contraction –Lub-dub- the sound created by the closing of
the heart valves (AV and semilunar)
Filling Heart Chambers: Cardiac Cycle
Figure 11.7, step 1a
Mid-to-late diastole(ventricular filling)
Ventricularfilling
Left atrium
Right atrium
Left ventricle
Right ventricle
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Mid-to-late diastole— blood flows from the atria into the ventricles (both chambers are relaxed, AV valves open) then the atria contract to squeeze remaining blood into the ventricles
Why?
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricular systole(atria in diastole)
Isovolumetriccontraction phase
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricular systole(atria in diastole)
Isovolumetriccontraction phase
Ventricularejection phase
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Ventricular systole— blood pressure builds before ventricles contract, when ventricles begin to contract pressure gets high enough opening the semilunar valves allowing blood to be pushed out to the lungs and body
Filling Heart Chambers: Cardiac Cycle
Atrialcontraction
Mid-to-late diastole(ventricular filling)
Ventricular systole(atria in diastole)
Early diastole
Isovolumetriccontraction phase
Ventricularejection phase
Isovolumetricrelaxation
Ventricularfilling
Left atriumRight atrium
Left ventricleRight ventricle
Early diastole— atria finish refilling, when the pressure in the atria exceeds the pressure in the ventricles the AV valves will open allowing blood to fill the ventricles the cycle begins again
https://www.youtube.com/watch?v=rguztY8aqpk
Think about it…
• What do you suspect happens to the coronary blood vessels as the heart goes through the cardiac cycle?–What would happen to them during
systole?–What would happen to them during
diastole?
Coronary Blood Vessels• Feed the cardiac muscle
with oxygen rich blood• The coronary vessels
branch off of the base of the aorta
• Only fill with blood when the pressure inside of the aorta is low and the blood flows back towards the heart
https://www.youtube.com/watch?v=tBQa8IBzP6I&feature=related
What happens to a heart if it can’t get enough oxygen?
HEART ATTACK
Why?
https://www.youtube.com/watch?v=eTKICIpShaA&feature=related
http://www.youtube.com/watch?v=DGxS44-rcps
Factors that Affect CO1. Venous return (amount of blood that
enters the heart)– Inc. venous return inc. stretching
2. How much the ventricle is stretched prior to contraction– Inc. stretching inc. force of contraction
3. High blood pressure
Factors that Change Heart Rate• Crisis stressors– Electrical system of the heart is more strongly
stimulated to beat inc heart rate• Congestive heart failure – Heart “worn out” – digitalis (drug) prescribed, strengthens
contractions to inc. cardiac output• Epinephrine increase heart rate• Electrolyte levels (ions)– Low calcium depresses heart, high calcium can cause
sustained contraction leading to cardiac arrest– Low potassium causes irregular heartbeat
Physical Factors that Affect Heart Rate
• Age – HR decreases with age (healthy) • Gender – Females > males• Exercise – increases HR• Body temp – higher temp
increases HR
