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Author Question: Which of the following medications increases heart rate by accelerating the SA node discharge rate ... (Read 62 times)

dakota nelson

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on: Jun 25, 2018
Which of the following medications increases heart rate by accelerating the SA node discharge rate and blocking the vagus nerve?
 
  a. Digitalis
  b. Atropine
  c. Amiodarone
  d. Beta-blocker

Question 2

Indicate the heart surface viewed by each of the following:
 
  Leads II, III, aVF ___________________ _
  Leads V1, V2 ___________________ _
  Leads V3, V4 ___________________ _
  Leads I, aVL, V5, V6 ___________________ _
 
  Fill in the blanks with correct word


yeungji

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Reply #1 on: Jun 25, 2018
Answer to Question 1

B
Atropine is a vagolytic drug that is used to increase the heart rate. Vago refers to the vagus nerves (right and left), which are the main nerves of the parasympathetic division of the autonomic nervous system. Lytic refers to lyse, which means to interfere with. Atropine works by blocking acetylcholine at the endings of the vagus nerves. The vagus nerves innervate the heart at the SA and AV nodes. Thus, atropine is most effective for narrow-QRS bradycardia. By blocking the effects of acetylcholine, atropine allows more activity from the sympathetic division of the autonomic nervous system. As a result, the rate at which the SA node can fire is increased. Areas of the heart that are not innervated or that are minimally innervated by the vagus nerves (e.g., the ventricles) will not respond to atropine. Thus, atropine is usually ineffective for the treatment of wide-QRS bradycardia. Atropine also increases the rate at which an impulse is conducted through the AV node. It has little or no effect on the force of contraction.

Answer to Question 2

Leads Heart Surface Viewed
II, III, aVF Inferior
V1, V2 Septal
V3, V4 Anterior
I, aVL, V5, V6 Lateral


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