Which of the following drugs/substances causes a positive chronotropic effect on

Question

Which of the following drugs/substances causes a positive chronotropic effect on the heart?        (not C or B)

A atropine                          

B beta-blockers               

C acetylcholine                 

D ivabradine

Which sequence correctly represents the succession of action potentials in one heartbeat? (not c or d)

A -AV – SA – bundle branch                         

B - SA – bundle branch – AV                       

C - SA – Purkinje fibers – bundle branch

D - SA - AV - bundle branch

E - AV – Purkinje fibers – bundle branch

The effect of norepinephrine on SA nodal cells is to: (not e or a)

A move the threshold closer to -80 mV

B increase the rate of spontaneous depolarization

C decrease heart rate

D produce bradycardia

E hyperpolarize the pacemaker cells

Explanation / Answer

1) Atropine causes positive chronotropic effect on the heart, it increases heart rate by increasing the electrical conduction system of heart and increases the rhythm produced by sino atrial node.

2) Sequence of succession of action potentials in one heart beat is

Sa node- bundle branch- AV node

Bachmans bundle in left atrium.

3) Effect of norepinephrine on SA nod cells is to hyperpolarize the pacemaker cells ( SA node)

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.