MCAT - Organ Systems

A given arteriole has a resistance of 2. What would the new resistance of this vessel be it its radius were to double?

1/8

Which type of muscle is in the walls of the airways?

smooth muscle

What is the site of action of bronchodilators?

the smooth muscle in the walls of the airways

What is the path through the circulatory system that describes the passage of a blood clot originating in the left leg?

vena cava --> right atrium --> right ventricle --> lungs --> left atrium --> left ventricle --> aorta

What is the conducting zone?

A series of tubes through which gases travel

At the instant following the second heart sound, which heart valves are open?

All valves are closed

Which part of the respiratory system is only a single cell layer thick?

Alveoli

What makes up the respiratory zone?

Alveoli and the respiratory bronchioles / alveolar ducts

Which type of receptors do bronchodilators act on to induce smooth muscle relaxation?

Beta-adrenergic receptors

In terms of being open or closed, what is the state of the mitral and tricuspid valves (left and right atrioventricular valves, respectively) at the end of the first heart sound?

Both are closed

What produces the force which drives normal exhalation, and is the process active or passive?

Elastic force, passive

What layer of the heart would be most immediately susceptible to infections caused by bacteria circulating in the blood?

Endocardium

What lines the inside of the heart and is in direct contact with circulating blood?

Endocardium

What is the place where the pericardium comes in contact with the heart wall (at the myocardium) called?

Epicardium

In a situation where the respiratory bronchioles become inflamed and narrowed, such as seen in asthma, which aspect of respiration would be most mechanically impaired?

Forced expiration

Where are the lobar bronchi found in the respiratory system?

In the conducting zone

What is the muscular portion of the heart?

Myocardium

Do the walls of the alveoli contain smooth muscle?

No

What is the double walled sac that encloses the heart and provides structural support and lubrication?

Pericardium

Which zone of the lungs participates directly in gas exchange?

Respiratory zone

Which heart valves are NOT actively closed by the contraction of muscular structures?

Semilunar valves

What is the pressure of gas within the alveoli at the peak of inspiration, just before expiration, relative to that of atmospheric air?

The same as atmospheric air

What physical feature of large systemic arteries (resistance vessels) makes them relatively more responsive to changes in intracellular calcium concentrations?

Thick tunica media

How can the circulatory system promote heat retention/conservation, such as on a cold day?

Vasoconstriction