When the doctor listened to Janet's heart, he heard 'lub-hiss, lub-hiss' instead of the normal 'lub-dup' sounds. The hiss is most likely due to _________ . (Explain your answer.)
a. A defective atrioventricular (AV) valve
b. A damaged pacemaker (SA node)
c. A defective semilunar valve
d. High blood pressure

Verified step by step guidance

Step 1: Understand the normal heart sounds 'lub-dup'. The 'lub' sound is caused by the closing of the atrioventricular (AV) valves (tricuspid and mitral valves) during ventricular contraction (systole). The 'dup' sound is caused by the closing of the semilunar valves (aortic and pulmonary valves) during ventricular relaxation (diastole).

Step 2: Analyze the abnormal sound 'lub-hiss'. The 'hiss' indicates a potential issue with valve closure, as it suggests turbulent blood flow or leakage (regurgitation) through a valve that is not closing properly.

Step 3: Evaluate the options provided. A defective atrioventricular (AV) valve would cause abnormal sounds during the 'lub' phase, but the hiss is heard after the 'lub' sound. A damaged pacemaker (SA node) would affect the rhythm of the heartbeat, not the valve sounds. High blood pressure could strain the heart but does not directly cause a 'hiss' sound.

Step 4: Focus on the semilunar valves. A defective semilunar valve could fail to close properly during diastole, leading to regurgitation of blood and producing the 'hiss' sound after the 'lub' phase.

Step 5: Conclude that the abnormal 'lub-hiss' sound is most likely due to a defective semilunar valve, as this aligns with the timing and nature of the sound described in the problem.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Heart Sounds

The heart produces sounds during its cycle, primarily 'lub' and 'dup.' The 'lub' sound is caused by the closure of the atrioventricular (AV) valves, while the 'dup' sound results from the closure of the semilunar valves. Abnormal sounds, such as a 'hiss,' can indicate issues with these valves or other cardiac functions.

Atrioventricular (AV) Valve Function

The AV valves, which include the tricuspid and mitral valves, separate the atria from the ventricles. They ensure unidirectional blood flow from the atria to the ventricles. A defect in these valves can lead to regurgitation, causing abnormal heart sounds like a 'hiss' due to turbulent blood flow.

Semilunar Valve Function

The semilunar valves, comprising the aortic and pulmonary valves, control blood flow from the ventricles into the aorta and pulmonary artery, respectively. If these valves are defective, they may not close properly, leading to backflow or turbulence, which can also produce abnormal heart sounds, such as a 'hiss.'

Recommended video:

Guided course

06:04

Functional Groups

Related Practice

Textbook Question

Use the following diagram to review the flow of blood through a human cardiovascular system. Label the indicated parts, highlight the vessels that carry oxygen-rich blood, and then trace the flow of blood by numbering the circles from 1 to 10, starting with 1 in the right ventricle. (When two locations are equivalent in the pathway, such as right and left lung capillaries or capillaries of top and lower portion of the body, assign them the same number.)

3453

views

comments