BRS qs

Question 1

Dr. Jensen, a cardiovascular researcher, is examining the stages of the cardiac cycle using a state-of-the-art cardiac simulation model. The model is designed to accurately reflect changes in ventricular pressure, muscle fibre length, and blood volume within the ventricles. The researcher takes 5 measurements and each time records the ventricular pressure (mmHg), aortic pressure (mmHg), muscle fibre length (μm) and ventricular blood volume (mL) The ventricular pressure rises from measurement one up until measurement 3, after which there is a decline. The aortic pressure remains constant throughout all measurements. The ventricular blood volume decreases after measurement 3. What physiological process is being described in this experimental scenario and how would you expect muscle fibre length to change beyond measurement 3? VSAQ

Answer 1

Isotonic contraction, decrease

Question 2

How can the work done by heart to eject blood under pressure into aorta and pulmonary artery be calculated? VSAQ

Answer 2

Stroke volume x pressure

Question 3

What pattern of respiratory disease would be indicated via a blunted inspiratory and expiratory curve?

Answer 3

FIxed airway obstruction

Question 4

What happens to the force produced by cardiac muscle fibres as they are stretched to longer lengths?

Answer 4

The force initially increases due to passive force but eventually decreases past optimal length

Explanation: in the length-tension relationship, force increases due to the passive elastic properties of the muscle (passive force) as it is stretched, reaching a peak at the muscle’s optimal length, after which it declines if the muscle is overstretched.

Question 5

What is a key characteristic of restrictive lung disorders as it pertains to pulmonary function tests?

Answer 5

Decreased Forced Vital Capacity (FVC)

Explanation: Correct because in restrictive disorders, there is a limitation of chest expansion, leading to a reduced FVC.