The positive inotropic effect of norepinephrine refers to: Increase in force of

Question

The positive inotropic effect of norepinephrine refers to: Increase in force of contraction of heart muscle caused by norepinephrine Increase in heart rate caused by norepinephrine Ability of norepinephrine to activate ion channels in smooth muscle Ability of norepinephrine to stimulate growth of muscle None of the above Which of the following is a determinant of the "preload" for cardiac contraction? Amount of blood that enters ventricle during diastole End-diastolic ventricular pressure End-diastolic ventricular volume Length of sarcomeres in ventricular muscle All of the above Frank-Starling law of the heart refers to: The staircase or "treppe" effect in which a slight increase in heart rate leads to a slightly increased force of contraction Increased force of contraction caused by increased end-diastolic volume, for example as a result of increased venous return The fact that cardiac output (CO) = heart rate (HR) times stroke volume (SV) The relationship between blood protein oncotic pressure and cardiovascular function None of the above Which of the following can cause "high output" cardiac failure? Valve damage Coronary artery disease Infectious diseases such as HIV Insufficient oxygen carrying capacity of blood (such as in sickle cell anemia) All of the above

Explanation / Answer

Answer 34 ----option A

Explain:-An inotrope agent alters the force or energy of muscular contractions. In case of positive  inotropic agents increase the strength of muscular contraction but in case of negative reverse will happen weaken the muscular contractionPositive inotropic increasing the concentration of intracellular calcium or increasing the sensitivity of receptor proteins to calcium can increase heart muscle contraction (myocardial contractility)

Answer 35:- D

Explain :- there are four cardiac function

Preload , afterload, intropic state , heart rate

Preload is stroke volume or passive wall stress (or tension) at the end of diastole, just before you start to contract.these factor can effect preload :-1Venous Return:-. If venous return is increased then a greater volume of blood will be in the ventricle at end diastole.This will increase the radius and the pressure resulting in an increase in preload.
2. Atrial Pressure :-dictates delta P during filling
3. End diastolic ventricular pressure and volume.

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