Author Question: The anatomy and physiology instructor is discussing reflex systems with the prenursing class. What ... (Read 43 times)

Diane · **on:** Jul 23, 2018

The anatomy and physiology instructor is discussing reflex systems with the prenursing class. What system would the instructor say causes a muscle fiber contraction that relieves the stretch?

A) Arch reflex system
B) Spinal reflex system
C) Spindle gamma loop system
D) Stretch receptor system

Question 2

A patient with a history of atrial fibrillation has had a worsening of his or her condition. The nurse knows that the drug of choice for long-term stabilization of atrial fibrillation following electrocardioversio n is what?

A) Disopyramide (Norpace)
B) Moricizine (Ethmozine)
C) Procainamide (Pronestyl)
D) Quinidine (generic)

mfedorka · **Reply #1 on:** Jul 23, 2018

Answer to Question 1

C
Feedback:
A spindle gamma loop system responds to stretch receptors or spindles on muscle fibers to cause a muscle fiber contraction that relieves the stretch. In this system, nerves from stretch receptors form a synapse with gamma nerves in the spinal cord, which send an impulse to the stretched muscle fibers to stimulate their contraction. These reflexes are responsible for maintaining muscle tone and keeping an upright position against the pull of gravity and are important in helping venous return when the contracting muscle fibers massage veins to help move the blood toward the heart. The arch reflex system and the stretch receptor system are distracters for this question. The spinal reflex system is not the reflex systems that respond to stretch receptors in the body.

Answer to Question 2

D
Feedback:
Quinidine is often the drug of choice for long-term stabilization of atrial fibrillation after the rhythm is converted by electrocardioversio n. Quinidine is a class I antiarrhythmic and stabilizes the cell membrane by binding to sodium channels, depressing phase 0 of the action potential, and changing the duration of the action potential. Disopyramide, moricizine, and procainamide are all used in the treatment of life-threatening ventricular arrhythmias.