1. What brings a cardiac muscle cell to threshold in a pacemaker cell? Group of

1. What brings a cardiac muscle cell to threshold in a pacemaker cell? Group of answer choices K+ rushing in Na+ slowly entering the cell Ca++ rushing in K+ rushing out 2. Once threshold is reached in a cardiac muscle cell, what happens? Group of answer choices Voltage gated Ca++ channels open and Ca++ rushes out Chemically gated Ca++ channels open and Ca++ rushes in Voltage gated Na+ channels open and Na+ rushes in Voltage gated Ca++ channels open and Ca++ rushes in 3. What causes repolarization in a cardiac muscle cell? Group of answer choices K+ leaving the cell Ca++ rushing into the cell K+ entering the cell Na+ slowly entering the cell 4. After repolarization in a pacemaker cell, what occurs? Group of answer choices K+ open, Ca++ channels close Fast Na+ channels open Slow Na+ channels open, K+ channels close. Ca++ channels open, slow Na+ channels close 5. Why don’t cardiac muscle cells need innervation from the nervous system? Group of answer choices Because slow Na+ channels spontaneously open after repolarization. Cardiac muscle cells do need innervation from the nervous system. Two of these are correct Because pacemaker cells automatically depolarize. 6. What cells set the pace or rythmn of the heart? Group of answer choices Cells interspersed around the heart tissue. Cells that cluster together in the S/A node. Cells that cluster together in the A/V node. Cells housed in the brain. 7. The cells that take the depolarization from the atria into the ventricles are known as the: Group of answer choices S/A node A/V node Atrioventricular bundle Purkinje fibers 8. In the average person, the heart depolarizes __________ times per minute while at rest. Group of answer choices 100 140 75 60 9. Systole is a term that describes: Group of answer choices Contraction of chambers of the heart. High blood pressure. Relaxation of chambers of the heart. Depolarization of pacemaker cells 10. Blood moves down what kind of gradient? Group of answer choices It moves until ratios of solutes are equal. Concentration It moves to where concentration of salt is highest. Pressure 11. The term ‘end diastole volume’ is: Group of answer choices At the end of ventricular systole, the ventricles are as empty as they will be. At the end of atrial diastole, the volume of blood in the ventricles. At this time, it is as high as it will be. At the end of atrial systole, the volume of blood in the ventricles. At this time, it is as high as it will be. At the end of atrial systole, the volume of blood in the ventricles. At this time, it is as low as it will be. 12. During isovolumetric contraction: Group of answer choices All 4 heart valves are open and the ventricles are contracting. All 4 heart valves are closed and the ventricles are contracting. The A/V valves are closed and the semi-lunar valves are open. The ventricles are contracting. All 4 heart valves are closed and the ventricles are relaxing. 13. The ‘lub-dub’ sound of heart contraction is: Group of answer choices The first sound (the ‘lub’) is back-flow against closed A/V valves. The backflow of blood against the closed valves All of these are correct. The second sound (the ‘dub’) is the backflow of blood against the semi-lunar valves. 14. How can we figure out how much blood is pumped out of the heart per minute? Group of answer choices Take the total amount of blood in the body and divide by heart rate. Multiply the number of times the heart beats (heart rate) by the amount of blood that leaves the heart with each beat. Multiple the number of times the heart beats (heart rate) by the amount of blood in the body. Divide the number of times the heart beats (heart rate) by the amount of blood that leaves the heart with each beat. 15. If the heart beats 70 times per minute and cardiac output is 5 liters of blood, then the stroke volume is: Group of answer choices 71 mls 1000 mls, 1 liter 25 mls 50 mls 16. If the heart muscle weakens over time then stroke volume decreases. In this case, what would happen to heart rate to ensure that body tissues still have access to the same amount of blood over time? Group of answer choices Heart rate decreases Innervation from the sympathetic nervous system decreases Cardiac output decreases Heart rate increases

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