Question

Which of the following statements is true regarding the given cystometrogram?

• A. Segment la is due to residual urine
• B. Segment lb is due to Laplace law
• C. Micturition fails to happen in segment ll
• D. The dotted line represents that micturition has occurred

Answer 1

The Correct Option is B

The cystometrogram is a graphical representation of the relationship between the volume of fluid within the bladder and the intravesical pressure. Understanding each segment of the cystometrogram is crucial for analyzing bladder function.
The options regarding the cystometrogram are:

• Segment la is due to residual urine
• Segment lb is due to Laplace law
• Micturition fails to happen in segment ll
• The dotted line represents that micturition has occurred

Looking closely at the provided cystometrogram:
Explanation:

• Residual Urine: Segment la cannot represent residual urine as this part of the graph typically shows the initial filling phase of the bladder, where the pressure slightly rises as the bladder starts to fill. Residual urine usually pertains to urine left in the bladder post-voiding, not depicted in segment la.
• Laplace Law: Segment lb demonstrates a constant pressure during filling, which aligns with Laplace's law: \(P = \frac{2T}{r}\), where P is the pressure, T is the wall tension, and r is the radius of the curvature of the bladder. The bladder can accommodate increased volumes without pressure change due to wall tension adjustment, hence matching the characteristics of segment lb.
• Micturition in Segment ll: This segment does not reflect the failure of micturition, rather it may depict the threshold where micturition reflex could initiate under normal conditions, not applicable in this statement.
• Dotted Line: A dotted line might typically represent either a conceptual threshold or change in the state but is not necessarily indicative of micturition.

Thus, the correct interpretation of the cystometrogram is:
Correct Statement: Segment lb is due to Laplace law.