77. Atria contract before the ventricles and the ventricles contract from the base to the apex. a. true b. false 78. What structure prevents an excessive number of atrial impulses from entering the ventricle? a. AV node b. Bachmann's bundle c. internodal tracts d. SA node 79. At the ventricles, stimulation causes depolarization of the cells and then what is the sequence of contraction? a. basal to mid-ventricular to apex b. endocardium to epicardium & apex to base c. endocardium to epicardium & base to apex d. epicardium to endocardium & apex to base 80. What is the sequence of repolarization? a. endocardium to epicardium b. epicardium to endocardium c. opposite of myocardial relaxation d. same as depolarization
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- True Step 2: The structure that prevents an excessive number of atrial impulses from entering the ventricle is the AV node. Step 3: At the ventricles, stimulation causes depolarization of the cells and then the sequence of contraction is endocardium to Show more…
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Q1) The electrical events of the atria and ventricles are isolated from each other. a) So that the ventricles do not excite the atria. b) To prevent the backflow of blood between the chambers. c) So that the left and right sides of the heart have the same cardiac output. d) So that atrial contraction can finish before a ventricular contraction begins. e) So that the ventricular contraction terminates during the refractory period of the Na+ channel. Q2) What will happen if the parasympathetic nervous system secretes acetylcholine onto the sinoatrial node of the heart? a) The Na+ channels inactivate. b) There will be an increase in K+ permeability across the plasma membrane of the sinoatrial node. c) The action potential frequency will increase. d) Blood will stop flowing through the chambers of the heart. e) The funny current begins moving ions in the opposite direction. Q3) The transverse (t-) tubule system of skeletal muscle is an important structure that a) Allows a high frequency of action potentials to excite the muscle. b) Allows the fiber to be highly elongated. c) Allows action potentials to propagate rapidly into all areas of the fiber. d) Is an important source of Ca2+ ions. e) Allows action potentials to be brief in skeletal muscle. Q4) An important role of the Na+-Ca2+ exchanger in cardiomyocytes is to a) Allow influx of K+ ions during the diastolic phase. b) Directly move Ca2+ ions into the sarcoplasmic reticulum. c) Translocate Ca2+ ions from the cytoplasm to outside the cell in the diastolic phase. d) Repolarize the cell. e) Activate release of Ca2+ ions through the ryanodine receptor.
Caryl A.
22) Which of the following represents the accurate sequence of the spread of cardiac excitation? (2 pts) a) Right atrium – right ventricle – left atrium – left ventricle b) Right ventricle – left atrium – left ventricle – right atrium c) SA node – AV node – bundle of His – Purkinje fibers d) SA node – bundle of His – AV node – Purkinje fibers 23) During the P-Q interval, which of the following mechanical events is/are occurring? Choose ALL that apply. (2.5 points) a) Atria contract. b) AV valves close creating the S1 heart sound. c) Blood volume in the ventricles increases. d) Pressure in the atria increases. e) Ventricles depolarize. 24) Match the ECG components to the appropriate description. (4 points) Matching options: • P wave • PQ interval • QRS complex • ST segment • T wave • TP interval a) Which ECG component corresponds to atrial depolarization? b) Which ECG component corresponds to ventricular depolarization? c) Which ECG component represents the time from the beginning of atrial excitation to the beginning of ventricular excitation? d) Which ECG component represents the time when the contractile muscle fibers of the ventricles are completely depolarized? e) What ECG wave comes immediately before ventricular systole? f) If heart rate increased, which ECG component would change the most? g) Which ECG wave comes immediately before atrial contraction? h) Which ECG wave comes immediately before ventricular relaxation?
Madhur L.
Exterior: e. The boundary between atria and ventricles is called f. What marks the boundary between the ventricles on the anterior wall of the heart? g. What marks the boundary between the ventricles on the posterior wall of the heart? 9. Structure & Function of the Atria a. The right and left atria are the chambers of the heart. (discharging / receiving) b. Muscular pouches extending from the atria are called . Their function is to c. Atria are (thin- / thick-) walled chambers because d. The fossa ovalis is located in the right atrium. e. The foramen ovale is that existed in the f. How do the left and right atria differ in their function? 10. Structure & Function of the Ventricles a. The right and left ventricles are the (discharging / receiving) chambers of the heart. b. Ventricles are (thin- / thick-) walled chambers because c. are thin strands of collagen fibers that attach the atrioventricular valves to muscles in the wall of the ventricles. 11. Heart Valves a. Name the 2 major types of valves. i. ii. 12. Semilunar valves are found only in (arteries or veins). The tricuspid valve is found on the side of the heart; the bicuspid valve is found on the side of the heart. 13. AV valves prevent backflow into the , whereas the semilunar valves prevent backflow into the .
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