The Cardiac Cycle Refers to the events of 1 complete heart beat – Both atria & ventricles...

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