Loose-leaf Version for What Is Life? A Guide to Biology 4E & LaunchPad for What is Life? A Guide to Biology 4E (Twelve Month Access)
4th Edition
ISBN: 9781319154639
Author: Jay Phelan
Publisher: W.H. Freeman & Co
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Chapter 22, Problem 3MC
Summary Introduction
Introduction:
The heartbeat is controlled by the SA node, which fires spontaneously.
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Which 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)
The heart’s internal pacemaker beats by: a. an internal implant that sends an electrical impulse through the heart b. the excitation of cardiac muscle cells at the sinoatrial node followed by the atrioventricular node c. the excitation of cardiac muscle cells at the atrioventricular node followed by the sinoatrial node d. the action of the sinus
A heartbeat starts when autorhythmic cells in the 1
[ Select ]
(located in the right
atrium) create an action potential (electric signal).
From there, the signal passes along the internodal
pathway to the 2 [ Select]
causing the atria to contract.
After a slight pause, the signal travels to the 3
[ Select ]
, which divides into
left and right bundle branches and carries the signal
down through the 4 [ Select ]
to the apex of the heart. At that point, specialized 5
[ Select ]
carry the signal to
individual cardiac muscle cells and the 6
[ Select ]
contract.
Chapter 22 Solutions
Loose-leaf Version for What Is Life? A Guide to Biology 4E & LaunchPad for What is Life? A Guide to Biology 4E (Twelve Month Access)
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- During the ventricular ejection phase of the normal human cardiac cycle, one option is correct: a. ejection takes less time than filling, in a resting human. b. the left ventricle diameter increases and the ventricle elongates from base to apex. c. papillary muscles close the atrioventricular valves. d. the chordae tendineae are relaxed. e. the apex beat is best felt in the anterior axillary line, fifth intercostal space.arrow_forwardSA 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 downarrow_forwardAll of the following mechanisms assist in returning venous blood to the heart except: a. an increase in heart rate b. pressure changes in the abdominal and thoracic cavities due to breathing c. contraction of skeletal muscles in the legs d. one-way valves located inside veinsarrow_forward
- The function of structure X is to Select one: a. act as the pacemaker of the heart. b. initiate the atrial contraction. c. open the atrioventricular (AV) valve when stimulated by an electrical impulse. d. prevent the atrioventricular (AV) valve from inverting.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_forwardA pithed frog in which the brain and spinal cord are severed is technically dead but some of its organs such as heart, continue to function for some time. An experiment was performed on a pithed frog. After recording the normal heartbeats (normal cardiogram or sinus rhythm), a ligature (ie. tying) is applied between the sinus venosus and right auricle. (Sinus venosus is the pacemaker in amphibian heart). It is the first ligature (I ligature). After a while, a second ligature is applied between auricles and ventricle (II ligature). The heart rates record is shown below. What can we learn from this experiment about the rhythmicity of our cardiac muscle? List THREE points. A в 5 sec 5 sec 5 sec I ligature Il ligaturearrow_forward
- Which of the following is the correct circulatory sequence forblood to pass through part of the heart?a. R. atrium → right AV valve → R. ventricle → pulmonarysemilunar valveb. R. atrium → left AV valve → R. ventricle → pulmonarysemilunar valvec. L. atrium → right AV valve → L. ventricle → aorticsemilunar valved. L. atrium → left AV valve → L. ventricle → pulmonarysemilunar valvearrow_forwardWhich of the following is true of propagation of longitudinal electrical flow in cardiac muscle. A. Current flows longitudinally from a region of depolarization through ryanodine receptors. B. Longitudinal current flows through inward rectifier potassium channels. C. This current can be detected at the body surface, if the source is large enough. D. A and B. E. All are true.arrow_forwardThe delivery of blood by the left ventricle into the sorta is intermittent, whereas blood flow in the peripheral circulation is usually continuous. Which of the following best explains this difference? A. Arteries contain more elastic tissue than veins . B Capillary walls contain little elastic or muscular tissue . C. Continuous flow is needed to meet metabolic requirements. D. Passive recoil of the arteries delivers blood to the periphery during diastole E . Rhythmic contractions of arterial smooth muscie increase the diastolic pressure to above zeroarrow_forward
- The AV node delay: a. allows the atria and ventricles to depolarize and contract as a unit. b. allows the two ventricles to depolarize and contract separately. c. allows the atria and ventricles to depolarize and contract separately. d. speeds up the impulse transmission from the atria to the ventriclesarrow_forwardWhich of the following is not true about Ventricular cardiac action potentials? O A. Action potentials arise from current flow across membranes. B. Current is carried by neutral ions. O C. Action potentials fire in an all-or-none fashion. OD. A stimulus usually initiates the action potential in healthy cells. O E. Potassium is the dominant current during the diastolic interval. HELENTarrow_forwardConduction of a neural signal through the walls of the ventricles of the heart is accomplished along: A. Interatrial Fibers B. The sinoatrial node C. The AV bundle D. The purkinje fibersarrow_forward
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