(5 points). Place a number (1-5, first to last) in the space before each structu
ID: 3521586 • Letter: #
Question
(5 points). Place a number (1-5, first to last) in the space before each structure to indicate
its order in the spread of the contraction impulse through the heart.
_____ AV bundle
_____ Purkinje fibers
_____ AV node
_____ SA node
_____ Right & Left bundle branches
2. What is the effect of vagal stimulation on the heart?
3. Which portion of the conduction system is the only electrical connection between the atria
and ventricles?
4. At which structure in the sequence is the impulse temporarily delayed? Why?
5. How does the long absolute refractory period of cardiac muscle affect wave summation and tetanus in the heart?
Explanation / Answer
Answer-
2 AV bundle
4 Purkinje fibers
3 AV node
1 SA node
5 Right & Left bundle branches
2. What is the effect of vagal stimulation on the heart?
Answer- Vagal Stimulation is the response caused by stimulation of the vagus nerve. After transmission excitation through parasympathetic ganglia, ACh is released in the SA node of the heart. Slowing or stoppage of the heart ensues.
3. Which portion of the conduction system is the only electrical connection between the atria and ventricles?
Answer- This impulse spreads throughout the atria like ripples in a pond, and then travels down to what we call the atrioventricular (AV) node. The AV node is similar to a wire or cable connecting the atria and the ventricles and is responsible for sending electrical impulses from the atria to the ventricles.
4. At which structure in the sequence is the impulse temporarily delayed? Why?
Answer- atrioventricular (av) node; this delay is important because it ensures that the atria have ejected their blood into the ventricles first before the ventricles contract.
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