Human Physiology: An Integrated Approach (8th Edition)
8th Edition
ISBN: 9780134605197
Author: Dee Unglaub Silverthorn
Publisher: PEARSON
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Textbook Question
Chapter 14.3, Problem 11CC
If a myocardial contractile cell is placed in interstitial fluid and depolarized, the cell contracts. If Ca2+ is removed from the fluid surrounding the myocardial cell and the cell is depolarized, it does not contract. If the experiment is repeated with a skeletal muscle fiber, the skeletal muscle contracts when depolarized, whether or not Ca2+ is present in the surrounding fluid. What conclusion can you draw from the results of this experiment?
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Chapter 14 Solutions
Human Physiology: An Integrated Approach (8th Edition)
Ch. 14.1 - A cardiovascular system has what three major...Ch. 14.1 - What is the difference between (a) the pulmonary...Ch. 14.2 - Which is more important for determining flow...Ch. 14.2 - The two identical tubes below have the pressures...Ch. 14.2 - All four tubes below have the same driving...Ch. 14.2 - Two canals in Amsterdam are identical in size, but...Ch. 14.3 - What prevents electrical signals from passing...Ch. 14.3 - Prob. 8CCCh. 14.3 - Prob. 9CCCh. 14.3 - Compare the receptors and channels involved in...
Ch. 14.3 - If a myocardial contractile cell is placed in...Ch. 14.3 - A drug that blocks all Ca2+ channels in the...Ch. 14.3 - Which ions moving in what directions cause the...Ch. 14.3 - At the molecular level, what is happening during...Ch. 14.3 - Lidocaine is a molecule that blocks the action of...Ch. 14.3 - What does increasing K+ permeability do to the...Ch. 14.3 - A new cardiac drug called ivabradine selectively...Ch. 14.3 - Do you think that the Ca2+ channels in...Ch. 14.3 - What happens to the action potential of a...Ch. 14.3 - In an experiment, the vagus nerve, which carries...Ch. 14.4 - Name two functions of the AV node. What is the...Ch. 14.4 - Prob. 22CCCh. 14.4 - Occasionally an ectopic pacemaker {ktopos, out of...Ch. 14.4 - Prob. 24CCCh. 14.4 - Which chamberatrium or ventriclehas higher...Ch. 14.4 - Prob. 26CCCh. 14.4 - Prob. 27CCCh. 14.4 - Prob. 28CCCh. 14.4 - Prob. 29CCCh. 14.4 - Why does ventricular pressure shoot up suddenly at...Ch. 14.4 - Prob. 31CCCh. 14.4 - Prob. 32CCCh. 14.4 - A persons aortic valve opening has become...Ch. 14 - What contributions to understanding the...Ch. 14 - List three functions of the cardiovascular system.Ch. 14 - Prob. 3RQCh. 14 - Prob. 4RQCh. 14 - Prob. 5RQCh. 14 - Prob. 6RQCh. 14 - Prob. 7RQCh. 14 - Distinguish between the two members of each of the...Ch. 14 - Prob. 9RQCh. 14 - Prob. 10RQCh. 14 - What is the proper term for each of the following?...Ch. 14 - List the events of the cardiac cycle in sequence,...Ch. 14 - Prob. 13RQCh. 14 - Compare and contrast the structure of a cardiac...Ch. 14 - Prob. 15RQCh. 14 - Correlate the waves of an ECG with mechanical...Ch. 14 - Prob. 17RQCh. 14 - List and briefly explain four types of information...Ch. 14 - Define inotropic effect. Name two drugs that have...Ch. 14 - Prob. 20RQCh. 14 - Police Captain Jeffers has suffered a myocardial...Ch. 14 - Prob. 22RQCh. 14 - Prob. 23RQCh. 14 - Police Captain Jeffers in question 21 has an...Ch. 14 - Prob. 25RQCh. 14 - Prob. 26RQCh. 14 - Prob. 27RQCh. 14 - A person has a total blood volume of 5 L. Of this...
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- Which of the following statements best describes the differences in the regulation of cardiac and skeletal muscle contraction? The amount of contractile force actively generated by muscle cells is increased by stretch in skeletal muscle and decreased by stretch in cardiac muscle. Cardiac muscle is stimulated by motor neurons and skeletal muscle by neurones from the autonomic nervous system. Skeletal muscle contractile force is augmented by increasing the firing frequency of action potentials whereas cardiac muscle contractile force is enhanced by noradrenaline increasing calcium influx through ion channels. Ryanodine receptors in skeletal muscle are opened by a mechanism that requires calcium influx whereas in cardiac muscle membrane depolarisation alone without calcium influx is sufficient to open ryanodine receptors.arrow_forwardBelow are drawings of three different action potentials. Two of these occur in the heart, and one occurs in skeletal muscle. Which one comes from a contractile cardiac muscle cell? A skeletal muscle cell? A cardiac pacemaker cell? For each one, state which ion is responsible for the depolarization phase and which ion is responsible for the repolarization phase.arrow_forwardConsider the ventricular cardiomyocyte action potential shown below: a) Which phase of the cardiac myocyte action potential would be most significantly affected by the L-type calcium channel blocker nifedipine? b) Draw the predicted effects of nifedipine on the cardiac myocyte action potential.arrow_forward
- Describe why a doctor would give a patient that is diagnosed with acute myocardial infarction the treatment of tissue plasminogen activator(tPA)? What will it do?arrow_forwardWhat can you say about the amplitude of the various waves in different cardiac cycles? The P wave and the QRS complex represent depolarization of the atrial and ventricular muscle respectively. Why does the QRS complex have the largest amplitude? In Steps 7 and 8, heart rate was calculated based upon the peak-to-peak interval of the R waves. Was there variability between the beats? Would you expect the interval between beats to be identical? Why or why not? The range for a normal resting heart rate is 60 to 90 bpm. A trained athlete could have a resting heart rate of 45 to 60 bpm. Why might a very fit person have a slower heart rate than someone of average fitness? Are the amplitudes and durations of the various waves in different individuals similar or very different? What variations in heart rate did you observe between individuals? Explain why ventricular contraction (systole) and the ‘lub’ sound occur immediately after the QRS complex. Explain why ventricular relaxation…arrow_forwardCan cardiac muscle exhibit (normally or under experimental conditions) summation or complete tetanus as does skeletal muscle? Why not? (highlight the main answer)arrow_forward
- Unlike skeletal muscle, cardiac muscle doesn’t undergo tetany. Explain how this is achieved and why is this necessary?arrow_forwardThe entry of calcium into a ventricular muscle cell helps to maintain depolarization of the membrane during the plateau phase of the action potential, but this calcium also performs what other function?arrow_forwardThe muscle cells of a heart chamber work as a functional syncytium. In terms of heart function this means... A) All the cardiac muscle cells are controlled by one motor neuron, resulting in coordinated contraction. B) All the cardiac muscle cells are electrically connected by gap junctions, resulting in coordinated contraction. C) All the cardiac muscle cells are stimulated to contract by hormone release, resulting in near-coordinated contraction. D) All the cardiac muscle cells contract independently of each other (fibrillation).arrow_forward
- The contracting cells of the heart are a type of striated muscle that is said to work as a functional syncytium. Provide a definition for “functional syncytium” and describe important functional characteristics and cellular specializationsarrow_forwardAn elephant has an aorta that is approximately 8 cm in diameter and a restingheart beat of 35 beats/min. Over the cardiac cycle, do you think that velocityprofiles in the aorta will be: fairly flat, oscillating back and forth, or more parabolic, oscillating back and forth?Make and state necessary assumptions.arrow_forwardWhat is the role of Ca2+ in the shape and duration of an action potential. (Cardiac muscle cell)arrow_forward
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