BIOLOGY 12E CONNECT ACCESS CARD
12th Edition
ISBN: 9781264938513
Author: Raven
Publisher: MCG
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Textbook Question
Chapter 48, Problem 1A
In vertebrate hearts, atria contract from the top, and ventricles contract from the bottom. How is this accomplished?
a. Depolarization from the SA node proceeds across the atria from the top; depolarization from the AV node is carried to the bottom of the ventricles before it emanates over ventricular tissue.
b. The depolarization from the SA node is initiated from motor neurons coming down from our brain; depolarization from the AV node is initiated from motor neurons coming up from our spinal cord.
c. Gravity carries the depolarization from the SA node down from the top of the heart; contraction of the diaphragm forces depolarization from the AV node from the bottom up.
d. This statement is false; both contract from the bottom.
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Why is it necessary to stimulate papillary muscles in the ventricle slightly earlier than the rest of the ventricular wall myocardium?
a. to assure rapid conduction speed of the action potential
b. to pull on AV valve cusps to prevent backflow
c. to assure blood will surge toward the semilunar valves
d. to assure coordinated contraction of the ventricular myocardium
SA node is the main pacemaker of the heart. Why is the normal heart rate lower than the intrinsic firing rate of the SA node?
A. sympathetic inputs from the hypothalamus are slowing it down
B. parasympathetic inputs from medulla oblongata are slowing it down
C. there is inertia in heart muscle as it takes time for impulse to spread through all the cells
D. centrifugal inputs from the AV node are slowing it down
What is the consequence of the prolonged plateau of depolarization in ventricular myocytes?
a-it causes ventricular myocytes to contract for a longer time, allowing the ventricles time to empty
b-it gives additional time for the atria to contract, filling the ventricles more completely
c-it causes repolarization to be delayed which slows heart rate
d-it allows the ventricles a moment to rest before completing contraction
Chapter 48 Solutions
BIOLOGY 12E CONNECT ACCESS CARD
Ch. 48.1 - Prob. 1LOCh. 48.1 - Prob. 2LOCh. 48.2 - Prob. 1LOCh. 48.2 - Prob. 2LOCh. 48.2 - Prob. 3LOCh. 48.3 - Prob. 1LOCh. 48.3 - Prob. 2LOCh. 48.4 - Prob. 1LOCh. 48.4 - Prob. 2LOCh. 48.5 - Prob. 1LO
Ch. 48.5 - Prob. 2LOCh. 48.5 - Prob. 3LOCh. 48.5 - Prob. 4LOCh. 48 - Prob. 1DACh. 48 - Prob. 1IQCh. 48 - Prob. 2IQCh. 48 - An ECG measures a. changes in electrical potential...Ch. 48 - Systole is vitally important to heart function and...Ch. 48 - Which of the following is the correct sequence of...Ch. 48 - Which of the following statements is not true? a....Ch. 48 - Prob. 5UCh. 48 - Prob. 6UCh. 48 - When a sphygmomanometer is used, a. blood pulses...Ch. 48 - Prob. 8UCh. 48 - In vertebrate hearts, atria contract from the top,...Ch. 48 - Prob. 2ACh. 48 - The difference between the amphibian and mammal...Ch. 48 - Prob. 4ACh. 48 - Humans have a number of mechanisms that help to...Ch. 48 - Prob. 2SCh. 48 - Is the evolution of the four-chambered heart...Ch. 48 - Prob. 4S
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
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- The movement of which two ions is responsible for maintaining the plateau phase of the action potential of contractile cardiac muscle cells? Select one: a. Ca2+ and Na+ b. Ca2+ and K+ c. Na+ and Cl- d. Na+ and K+ e. K+ and Cl-arrow_forwardThe carotid artery of an animal is partially constricted proximal to the carotid sinus during a study. Which of the following cardiovascular changes most likely occurs in response to the constriction? (My opinion is the question is referring to carotid clamping not carotid massage ( carotid massage is usually done on carotid sinus to rapidly lower heart rate)) A. Decreased heart rateB. Decreased systemic arterial pressure C. Decreased venous return to the startD. Increased number of impulses from the carotid sinus E. Increased total peripheral resistance.arrow_forwardIn a healthy young adult, what happens to cardiacoutput when heart rate increases above 160 bpm?a. It increases.b. It decreases.c. It remains constant.d. There is no way to predictarrow_forward
- What two values are needed in order to calculate cardiac output (CO) for a ventricle? a. end-diastolic volume (EDV) and end-systolic volume (ESV) b. stroke volume (SV) and blood pressure (BP) c. stroke volume (SV) and heart rate (HR) d. heart rate (HR) and end-diastolic volume (EDarrow_forwardWhich of the following statement/s is/are not true about regulation of heart rate? A. The brainstem contains the cardiac centers which are the accelerator center and the inhibitory center. (medulla) B. Sympathetic impulses to the heart increase rate and force of contraction. C. Parasympathetic impulses from cranial nerve X to the heart causes reduction in the heart rate. D. The cranial nerve IX is motor for the carotid receptors. (sensory)arrow_forwardWhat will happen to the next level of exercise tolerance in a person whose heart is being paced by the AV node? A. Level of exercise tolerance will stay the same B. Level of exercise tolerance will decrease C. Level of exercise tolerance will increasearrow_forward
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