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85 Cards in this Set

  • Front
  • Back

What causes cardiac valves to open or close?

Changes in pressure

If pressure in the atria is higher than that of the ventricles, which valves are open? (Names and corresponding sides)

Atrioventricular (AV) valves;

Tricuspid on the right side, Mitral(/bicuspid) on the left side.

In this moment in time, the semilunar valves are open. What does this tell you about pressure in the different parts of the heart?

Pressure is higher in the ventricles than in the aorta.

What are the names of the two semilunar valves? What do they lead to?

Pulmonary (R side); leads to pulmonary trunk.

Aortic (L side); leads to aorta.

Chordae tendinae are associated with these types of heart valves:

Atrioventricular (tricuspid, mitral) valves

The "first heart sound" is associated with this action:

Closing of the atrioventricular valves

"Insufficiency, prolapse, or regurgitation" in the heart can result in this condition and is associated with these valves:

Heart murmur; atrioventricular

What is stenosis in reference to heart valves?

Failure for valves to open completely

What are the two primarily contractile muscle types in the heart?

Atrial and ventricular myocytes

What feature connects cardiocytes?

Intercalated discs

What are the three components of intercalated discs?

Desmosomes, gap junctions, and interlocking plasma membrane.

What is responsible for allowing the atria and ventricles to operate as separate "synctiums"?

Thick fibrous tissue separation

What are the two reasons why it's important that the atria and ventricles are separate synctiums?

- Inappropriate communication via conductive cells is somewhat blocked

- Promotes a brief lapse in time for blood from atria to flow into ventricles before electrical signal for ventricular contraction is processed

In regards to length, how do action potentials in cardiac muscle cells compare to that of skeletal muscle cells?

Their action potentials last around 15x longer.

Describe the ion channel system responsible for the "plateau phase" of a cardiac muscle AP:

- Fast voltage-gated K channels (K out) close

- Slow voltage-gated K channels open

- Voltage gated "L-type" Ca channels open (slow Ca2+ in)

- Balance between slow K out and slow Ca in causes a membrane potential "plateau effect"

In cardiac muscle, what causes repolarization after the plateau effect? (2 actions)

- L-type Ca channels close,

- More slow-voltage K channels open

Where is the absolute refractory period occurring? What about the relative refractory period?

Where is the absolute refractory period occurring? What about the relative refractory period?

Why is the long absolute refractory period of cardiomyocytes essential?

Temporal summation of AP's is prevented, meaning that cardiomyocytes are not susceptible to tetany

What are T-tubules used for in myocytes? Where are they most common?

Excitation contraction coupling; ventricles

Where is extracellular calcium stored for use by cardiomyocytes?

On mucopolysaccharides bound to the T-tubules

How does Ca storage in cardiomyocyte SR's compare to that in skeletal muscle SR's?

(SR= sarcoplasmic reticulum)

Cardiomyocytes store much less Ca in their SR's.

To initiate contraction, what protein does Ca bind in the muscle? What is the effect of this binding?

Ca binds troponin, which causes movement of tropomyosin, which exposes the "active sites" for binding on actin fibers.

When is the Na/Ca exchanger in cardiomyocytes most active? What kind of transporter is this?

In cardiomyocyte relaxation; it's a secondary active antiporter.

In response to a single AP, how do cardiomyocytes differ from skeletal myocytes?

Cardiac response is graded; strength of contraction is dependent on amount of intracellular calcium. The amount of intracellular calcium is regulated in order to tightly control saturation of troponin with calcium.

Systole and diastole– which is contraction and which is relaxation?

Systole is contraction, diastole is relaxation.

When does isovolumetric contraction occur in the cardiac cycle?

Atrial diastole/ early ventricular systole

What is going on during the "ejection phase" of the cardiac cycle?

Late ventricular systole

What is happening with the atria/ventricles when "active filling" of the heart is occurring?

Atrial systole, ventricular diastole.

Isovolumetric relaxation is experienced during what phase of the cardiac cycle?

Early ventricular diastole

When does passive filling of the heart occur?

Between heartbeats.

What amount of blood for contraction is loaded into the heart during the "passive filling" phase between beats?


Between beats, the pressure of the atria compared to the pressure in the veins is described as what?

Pressure in atria is lower than the pressure in the veins.

There is only one phase where pressure in the atria is greater than the pressure in the veins. What is it?

Atrial systole.

How does the pressure in the ventricles compare to the pressure in the arteries during atrial systole?

Pressure in the ventricles is lower than the pressure in the arteries during atrial systole.

There is only one phase in which pressure in the ventricles is greater than pressure in the arteries. Which phase is this?

Late ventricular systole.

In atrial diastole and early ventricular systole, how does the pressure in the atria compare to that in the ventricles?

The atria are lower in pressure than the ventricles.

During late ventricular diastole, how does the pressure in the atria compare to the pressure in the ventricles?

The pressure in the atria is greater than that in the ventricles.

What is the stroke volume?

Volume of blood ejected per heartbeat

How do we find stroke volume?

End diastolic volume (EDV)- End systolic volume (ESV)

What part of the heart do we make volume pressure diagrams for?

The left ventricle

Describe what the "ejection fraction" refers to:

The amount of end diastolic volume ejected per beat

Is "end systolic volume" or "end diastolic volume" a higher value for the left ventricle?

End diastolic volume.

In this condition, a murmur is heard when heart valves are open.

In what condition is a murmur heard when heart valves are closed?

Open: stenosis (abnormally narrow opening).

Closed: Regurgitation/prolapse (incomplete closing)

What's the formula for cardiac output?

CO=HR (heart rate) x SV (stroke volume)

What's normal resting cardiac output?


What effects will blood loss and heart disease have on cardiac output?


What three factors change stroke volume?

- Change in preload (end diastolic volume)

-Change in afterload (end systolic volume)

-Change in contractility (this is force of contraction, would affect end systolic volume (ESV))

What does "VR" stand for?

Venous return; the rate at which blood is returned to the heart by veins

How much total blood volume can be held in veins?

Up to 60%

What three things can increase the venous return?

- Increasing the effect of the skeletal muscle pumps

- Increasing the effect of the thoracic pump

- Venoconstriction via sympathetic activation of alpha receptors

What has a greater effect on cardiac output– stroke volume or heart rate?

Heart rate

Greater maximal atrial pressure will result in a greater value for this measured volume of the left ventricle:

End diastolic volume (EDV)

What's the relationship between EDV and CO?

Greater EDV, greater CO

(EDV = end diastolic volume, CO = cardiac output)

Which ventricle requires a greater increase in atrial pressure to generate a greater output?

Left ventricle. The right ventricle is more sensitive to pressure increase in the right atrium, and will increase output more quickly.

Define "afterload"

The pressure that ventricles must overcome to force open aortic and pulmonary valves.

Hypertension would increase this element that affects stroke volume:


What is the effect of increased afterload on stroke volume?

Increased afterload (ESV) decreases stroke volume

Relationship between stroke volume, end diastolic and end systolic volumes?


What's the effect of hypertension on the equation SV = EDV-ESV?

Hypertension increases afterload; a factor affecting ESV. This increases ESV, thereby decreases SV.

Define "contractility"

Ability of the heart to contract at any given resting fiber length.

How is contractility changed by the heart?

Modifying the amount of Ca that enters contractile cells via manipulation of L-type voltage-gated Ca channels

What nervous system has no direct effects on contractility?


What's the primary molecular mechanism by which beta-1 receptors modify contractility?


What five molecules in the cardiomyocyte are phosphorylated in response to beta-1 receptor activation?

1) L-type Ca channels

2) Ryanodine receptors

3) Troponin

4) Myosin head ATPase

5) Ca ATPase in sarcoplasm

What's the difference between a positive and negative inotropic agent? Examples of each?

Positive: Increases heart contractility. Epi/Norepi are examples.

Negative: Decreases heart contractility. Beta-blockers, Ca channel blockers

What is digitalis?

A positive inotropic agent (increases contractility)

The dashed lines represent changes in stroke volume brought on by what effect?

The dashed lines represent changes in stroke volume brought on by what effect?

Increased preload

The dashed lines represent changes in stroke volume brought on by what effect? (Left vent. pressure on Y axis)

The dashed lines represent changes in stroke volume brought on by what effect? (Left vent. pressure on Y axis)

Increased afterload

The dashed lines represent changes in stroke volume brought on by what effect? (Left vent. pressure on Y axis)

The dashed lines represent changes in stroke volume brought on by what effect? (Left vent. pressure on Y axis)

Increased contractility

At what age does cardiac output peak (on average)

10 years

Effects of hyper- and hypo- calcemia on cardiac output?

Hyper- increases contractility, thus increases output

Hypo- opposite

What's the effect of hyperkalemia on conduction speed of AP's through cardiac tissue?

It decreases conduction speed.

What's the effect of hyperkalemia on rate of potassium movement through potassium channels (conductance)?

It increases this rate of movement

What's the overall effect of hyperkalemia on tissue excitability?


What's the effect of extreme tachycardia (HR) on cardia output?

Decrease in CO

Describe what causes cardiac tamponade and what its effect is on SV = EDV-ESV?

Card. tamponade occurs when blood or fluid accumulates in the pericardial sac; it increases interpericardial pressure, and decreases end diastolic volume because it decreases ventricular filling. Thus, SV (stroke volume) goes down.

What are the effects of high temperature or pregnancy on cardiac output?

They increase cardiac output

What's the effect of rapid arrythmias on cardiac output?

They decrease cardiac output

What element of stroke volume is affected by physiological cardiac remodeling?

Hypertrophy increases force of contraction which serves to decrease ESV, which in turn increases SV

What's the effect of physiological cardiac remodeling on heart rate?

Decrease (heart is more efficient, doesn't need to work as hard)

What are hallmarks of "pathological" cardiac remodeling?

Irreversible changes to heart proportions and function often brought on by pathology

Describe "concentric hypertrophy"

Increased wall thickness of the heart results in decreased compliance of ventricles and increased contractility. Overall effect is increased afterload (hypertension).

Describe "eccentric hypertrophy"

The lumen of ventricles increases. Also, speed of contraction increases. This decreases mechanical efficiency and also ejection fraction. Overall effect is increased preload.

Ventricular hypertrophy is often a side-effect of ____ and has this effect on cardiac output:

Exercise; increase

Concentric and eccentric hypertrophies often result in a heart described using this term: