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
