Question

the frank-starling law states that:
○ cardiac muscle cannot develop tetanus.
○ as more blood enters the heart, contractility decreases and stroke volume
decrease.
○ as more blood enters the heart, more cardiac muscle fibers are recruited to
develop summation.
○ as more blood enters the heart, contractility and stroke volume will increase.
○ none of the above.

Explanation:

The Frank - Starling Law of the heart states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end - diastolic volume). This increased filling leads to increased contractility and stroke volume.

• The first option is about cardiac muscle not developing tetanus, which is not related to the Frank - Starling Law.
• The second option says contractility and stroke volume decrease with more blood entering the heart, which is the opposite of the law.
• The third option mentions recruitment for summation, which is not part of the Frank - Starling Law.
• The fourth option correctly states that as more blood enters the heart, contractility and stroke volume will increase, which matches the Frank - Starling Law.
• The fifth option is incorrect as the fourth option is correct.

Answer:

D. as more blood enters the heart, contractility and stroke volume will increase.