Chapter 5 L2 Circulatory System Flashcards

Why is the tricuspid valve called tricuspid?

It has three leaflets.

What is the primary function of the tricuspid valve?

Prevent backflow of blood from the right ventricle into the right atrium.

Through which valve does blood pass from the right atrium to the right ventricle?

The tricuspid valve.

What causes the pulmonic valve to open?

Right ventricular pressure exceeding pulmonary artery pressure.

What causes the pulmonic valve to close?

Pulmonary artery pressure becoming greater than right ventricular pressure.

Where does blood travel after leaving the pulmonary artery?

The lungs.

How many pulmonary arteries are there?

Two.

Are pulmonary arteries oxygenated or deoxygenated?

Deoxygenated.

What occurs to blood in the lungs?

It becomes oxygenated.

How many pulmonary veins return blood to the heart?

Four.

Into which chamber do pulmonary veins empty?

The left atrium.

Are pulmonary veins oxygenated or deoxygenated?

Oxygenated.

What is unusual about pulmonary arteries?

They carry deoxygenated blood.

What is unusual about pulmonary veins?

They carry oxygenated blood.

Through which valve does blood pass from the left atrium to the left ventricle?

The mitral (bicuspid) valve.

What are the two names for the left AV valve?

Mitral valve and bicuspid valve.

Through which valve does blood leave the left ventricle?

The aortic valve.

Into which vessel does blood enter after passing through the aortic valve?

The aorta.

What is the function of the systemic circulation?

Deliver oxygenated blood to tissues and return deoxygenated blood to the heart.

Which vessels return blood from the body to the right atrium?

The superior and inferior vena cava.

How does most ventricular filling occur?

Passively.

What is the atrial kick?

The final atrial contraction that pushes additional blood into the ventricles.

Approximately what percentage of ventricular filling is provided by the atrial kick?

About 20%.

What is regurgitation?

Backward flow of blood through a valve.

Why is regurgitation harmful?

It increases the workload of the heart.

During ventricular diastole, which valves are open?

The tricuspid and mitral valves.

During ventricular diastole, which valves are closed?

The pulmonic and aortic valves.

During ventricular systole, which valves are open?

The pulmonic and aortic valves.

During ventricular systole, which valves are closed?

The tricuspid and mitral valves.

What is systole?

Ventricular contraction.

What is diastole?

Ventricular relaxation.

What is isovolumetric relaxation?

The brief period after ventricular contraction when all four valves are closed.

When does isovolumetric relaxation occur?

Immediately after the semilunar valves close.

Why are all four valves closed during isovolumetric relaxation?

Ventricular and atrial pressures are equalizing.

What causes the AV valves to open after isovolumetric relaxation?

Ventricular pressure falls below atrial pressure.

During isovolumetric relaxation, how many valves are open?

None.

What does systolic blood pressure represent?

Pressure generated during ventricular contraction.

What does diastolic blood pressure represent?

Pressure during ventricular relaxation.

What is a normal blood pressure?

120/80 mmHg.

Which number in a blood pressure reading is the systolic pressure?

The top number.

Which number in a blood pressure reading is the diastolic pressure?

The bottom number.

What is cardiac output?

The amount of blood pumped by a ventricle each minute.

What is the normal cardiac output of an adult?

Approximately 5 L/min.

What is stroke volume?

The amount of blood ejected from a ventricle during one contraction.

What three factors determine stroke volume?

Preload, afterload, and contractility.

What is venous return?

Blood returning to the heart through the veins.

What is end-diastolic volume (EDV)?

The amount of blood in a ventricle at the end of diastole.

What is end-systolic volume (ESV)?

The amount of blood remaining in a ventricle after contraction.

Why is end-systolic volume clinically important?

Excessive ESV indicates poor ventricular pumping function.

What is ejection fraction (EF)?

The percentage of blood ejected from the left ventricle during each contraction.

What is a normal ejection fraction?

Approximately 55–70%.

How is ejection fraction commonly measured?

By echocardiogram.

What does an ejection fraction below 50% indicate?

Heart failure.

What does an ejection fraction below 30% generally indicate?

Severe heart failure.

Why is left ventricular ejection fraction closely monitored?

The left ventricle supplies the entire body.

What is the formula for cardiac output?

CO = SV × HR.

What abbreviation is used for cardiac output?

Q.

What abbreviation is used for stroke volume?

SV.

What units are used for stroke volume?

Milliliters (mL).

What units are used for heart rate?

Beats per minute (bpm).

What units are used for cardiac output?

Liters per minute (L/min).

What is the PMI?

The Point of Maximal Impulse.

Where is the PMI located?

Left 5th intercostal space at the midclavicular line.

Why is the PMI clinically important?

It is where the heartbeat is heard loudest.

What happens to cardiac output when stroke volume increases?

Cardiac output increases.

What happens to cardiac output when heart rate increases?

Cardiac output increases.

What happens to cardiac output when stroke volume decreases?

Cardiac output decreases.

What happens to cardiac output when heart rate decreases?

Cardiac output decreases.

What is preload?

The amount of blood returning to and filling the ventricles before contraction.

Which system primarily determines preload?

The venous system.

What happens to preload when venous return decreases?

Preload decreases.

What is another definition of preload?

Stretching of cardiac muscle fibers before contraction.

What are cardiac myocytes?

Heart muscle cells.

What mechanism explains increased contraction with increased preload?

The Frank-Starling mechanism.

What does the Frank-Starling mechanism state?

Increased preload increases force of contraction.

What happens if ventricular fibers become excessively stretched?

Contraction becomes weaker.

What can excessive ventricular stretching lead to?

Reduced ejection fraction.

What commonly causes excessive ventricular stretching?

Fluid overload.

What condition commonly causes excessive preload?

Heart failure.

What is pulmonary capillary wedge pressure (PCWP)?

An indirect measurement of preload.

What is the best clinical estimate of preload?

Pulmonary capillary wedge pressure.

What catheter is used to measure PCWP?

A Swan-Ganz catheter.

What is another name for a Swan-Ganz catheter?

A pulmonary artery catheter.

Where does a Swan-Ganz catheter ultimately sit?

In a branch of the pulmonary artery.

Why is Swan-Ganz called a wedge pressure?

The balloon wedges into a pulmonary artery branch.

What happens when preload is low?

Force of contraction is low.

What is hypovolemia?

Decreased blood volume.

What can cause hypovolemia?

Vomiting, diarrhea, or blood loss.

How does hypovolemia affect preload?

It decreases preload.

What preload state is considered ideal?

Adequate preload with matching contractility.

What is hypervolemia?

Excessive blood volume.

What happens when the heart becomes overdistended?

It cannot contract effectively.

What is afterload?

The resistance the ventricle must overcome to eject blood.

What factors contribute to afterload?

Blood volume, blood viscosity, and vascular resistance.

What is polycythemia?

An abnormally increased number of red blood cells.

How does polycythemia affect afterload?

It increases afterload.

What is anemia?

A condition with reduced red blood cells and thinner blood.

How does anemia affect afterload?

It decreases afterload.

How does increased blood volume affect afterload?

It increases afterload.

What does PVR stand for?

Pulmonary Vascular Resistance.