Human Anatomy & Physiology (2nd Edition)
2nd Edition
ISBN: 9780134553511
Author: Erin C. Amerman
Publisher: PEARSON
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Chapter 17, Problem 3CYU
When the SA node doesn’t function properly, the AV node takes over pacing the heart and produces what is known as a junctional rhythm. Explain why we don’t see P waves on the ECG of an individual with such a rhythm.
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When the SA node doesn’t function properly, the AV node takes over pacing the heart and produces what is known as a junctional rhythm. Explain why we don’t see P waves on the ECG of an individual with such a rhythm?
Although not considered the primary pacemaker of the heart, the atrioventricular node can indeed be considered as playing SOME role in setting the rhythm of the heart (kind of a secondary pacemaker). Explain how/why.
While the SA node is considered the pacemaker of the heart, the AV node is also capable of generating spontaneous action potentials, allowing it to serve as a “backup system” in case of SA node failure. If the SA node fails, how would you anticipate the baseline heart rate to change, and why is this the case?
Chapter 17 Solutions
Human Anatomy & Physiology (2nd Edition)
Ch. 17.1 - Where is the heart located, and how large is it?Ch. 17.1 - What are the hearts upper and lower chambers...Ch. 17.1 - What are the sources from which blood flows into...Ch. 17.1 - 4. Which side of the heart is considered the...Ch. 17.1 - Which side of the heart is considered the systemic...Ch. 17.2 - Prob. 1QCCh. 17.2 - Prob. 2QCCh. 17.2 - 3. What are the three layers of the heart wall,...Ch. 17.2 - 4. What are the four main great vessels? From...Ch. 17.2 - How do the right and left ventricles differ in...
Ch. 17.2 - 6. Why do you think it is important to ensure via...Ch. 17.2 - 7. What is the overall pathway of blood flow...Ch. 17.2 - Prob. 8QCCh. 17.2 - Prob. 9QCCh. 17.2 - Prob. 10QCCh. 17.3 - How do pacemaker and contractile cells differ?...Ch. 17.3 - 2. What are intercalated discs? What is their...Ch. 17.3 - Prob. 3QCCh. 17.3 - Prob. 4QCCh. 17.3 - What is the sequence of events of a contractile...Ch. 17.3 - How does the refractory period of cardiac muscle...Ch. 17.3 - 7. What does an ECG record?
Ch. 17.3 - What are the five waves in an ECG, and what do...Ch. 17.4 - What causes the heart sounds S1 and S2?Ch. 17.4 - Prob. 2QCCh. 17.4 - Prob. 3QCCh. 17.4 - Is the end-diastolic or the end-systolic volume of...Ch. 17.4 - 5. Walk through the mechanical events of the...Ch. 17.4 - 6. Relate the ECG waves to the cardiac cycle...Ch. 17.4 - 7. How does the left ventricular pressure...Ch. 17.5 - Prob. 1QCCh. 17.5 - What is cardiac output? How does it relate to...Ch. 17.5 - Prob. 3QCCh. 17.5 - What is the Frank-Starling law, and how does it...Ch. 17.5 - What is a chronotropic agent?Ch. 17.5 - Prob. 6QCCh. 17.5 - 7. What effects does the parasympathetic nervous...Ch. 17.5 - How would a hormone that decreases the amount of...Ch. 17.5 - How is heart failure defined?Ch. 17 - 1. Mark the following statements as true or false....Ch. 17 - 2. The pericardial cavity is located between:
a....Ch. 17 - 3. Which of the following statements is true?
a....Ch. 17 - Match the following terms with the correct...Ch. 17 - Fill in the blanks: The coronary arteries are the...Ch. 17 - 6. How do pacemaker cardiac muscle cells differ...Ch. 17 - 7. Cardiac muscle cells are joined by structures...Ch. 17 - Prob. 8CYRCh. 17 - Prob. 9CYRCh. 17 - 10. The _________is the primary pacemaker of the...Ch. 17 - The AV node delay: a. allows the atria and...Ch. 17 - Explain what each of the following terms...Ch. 17 - 13. Mark the following statements as true or...Ch. 17 - Prob. 14CYRCh. 17 - 15. Fill in the blanks: The first heart sound is...Ch. 17 - Cardiac output is equal to: a. end-diastolic...Ch. 17 - Prob. 17CYRCh. 17 - 18. Which of the following statements is false?
a....Ch. 17 - 1. A birth defect called transposition of great...Ch. 17 - 2. Predict which would be more damaging to...Ch. 17 - 3. When the SA node doesn’t function properly, the...Ch. 17 - Prob. 4CYUCh. 17 - Prob. 1AYKACh. 17 - Prob. 2AYKACh. 17 - Prob. 3AYKACh. 17 - Prob. 4AYKB
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- Clusters of neurons in the medulla oblongata that regulate blood pressure are known collectively as ________. baroreceptors angioreceptors the cardiomotor mechanism the cardiovascular centerarrow_forwardIn an EKG reading: | the P wave corresponds to the AV node firing. the QRS complex corresponds to a time when ventricular pressure is greater than atrial pressure. When in sympathetic mode, the AV Bundle will be receiving impulses at a faster rate then when in parasympathetic mode. | The T wave represents the time when the SA node first fires. The P-R interval represents the delay that occurs when the AV Bundle transmits signals to the Purkinje fibers.arrow_forwardThe standard EKG consists of 10 sensors that record 12 leads of the heart’s electrical activity from different angles, allowing for a thorough three-dimensional interpretation of its activity. This is transmitted by the electrodes to the equipment to be interpreted and is used to diagnose cardiac medical conditions. In case of an abnormal EKG, the second step would be to use a Holter monitor. How would you explain to your classmates how to perform an EKG (steps)? Where will you place the electrodes when performing and EKG? Why? What are the different lead types, connections, and placements? When you conclude an EKG, what are the different components that you need to observe and confirm before you disconnect the patient? Can you explain the difference between normal, abnormal, and artifacts? What is a Holter monitor? Under what circumstances would one be ordered for a patient? How do you use a Holter monitor? Educate a patient: What you will do before, during, and after an…arrow_forward
- A class of drugs called beta-blockers are commonly prescribed to cardiac patients in order to reduce their heart rate. Beta-blockers slow heart rate by reducing the conduction of action potentials through the A-V (atrioventricular) node. The most likely effect on an ECG shorter R-R interval shorter Q-T interval longer P-R interval longer T wavearrow_forwardIn the figure below on the left, label the P, QRS and T waves. Describe what is happening in the heart in the P wave: Relate the P wave to the cardiac cycle:o Is the heart in systole or diastole?o Is the pressure high or low?o Where is blood flowing? Which valves are open? closed? o Which muscle fibers are contracting, if any?arrow_forwardThe right and left atria of the heart look alike and perform similar functional demands. The right and left ventricle are very different, structurally and functionally. Why are the atria similarities and the difference in the ventricles significant in the role they play in the functional activity of the heart? How would these differences be manifested on an EKG, with details given to the P wave and QRS complex?arrow_forward
- A variety of ways to calculate heart rate from an ECG may be used. The quickest way to calculate heart rate on a rhythm strip is: Count the number of large squares between one R-R interval, and divide this number into 1500. Calculate the number of QRS complexes in 1 minute Count the number of R-R intervals in 6 seconds, and multiply by 10 Count the number of small squares between one R-R interval, and multiply this number by 300.arrow_forwardConsider a hypothetical disorder where a patient did not have an arterioventricular-bundle. As a result, the action potential radiated from the AV node down to the apex of the heart. Sketch/describe how the resultant EKG would differ from a healthy patient’s EKG.arrow_forwardYou are presented with a stack of ECGs on your fist day of your cardiology rotation and are given a single instruction: “read them”. As you progress through the pile, you note the following abnormalities. Explain form where in the heart of the cardiac conduction system each abnormality might have come: Absent P waves Abnormally long QRS complex Abnormally long P-R interval Extra QRS complexarrow_forward
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