PHYS 261 MIDTERM QUESTIONS WITH DETAILED VERIFIED ANSWERS BRAND NEW EXAM 2025

Abnormally slow conduction through the ventricles would change the _______ in an ECG tracing. - T wave - PR interval - RT interval - P wave - QRS complex - Correct Answer-QRS complex Which is the correct relationship among pressure, flow, and resistance? - flow is inversely proportional to change in pressure and directly proportional to resistance - flow is directly proportional to change in pressure and inversely proportional to resistance - flow is inversely proportional to change in both pressure and resistance - flow is directly proportional to change in both pressure and resistance - Correct Answer-Flow is directly proportional to change in pressure and inversely proportional to resistance The function of transverse tubules is to - ensure a supple of glycogen throughout the muscle sarcoplasm - rapidly move action potentials to the interior of the muscle fiber - conduct ATP molecules out of the mitochondria throughout the sarcoplasm - store Ca2+ ions inside the muscle fiber - Correct Answer-rapidly move action potentials to the interior of the muscle fiber The molecular event that occurs immediately after the power stroke is the - release of actin from the myosin head - release of ADP from the myosin - hydrolysis of ATP by the myosin head - binding of actin to the myosin - binding of tropomyosin to the myosin - Correct Answer-release of ADP from the myosin During ventricular systole - the pressure in the ventricular declines - blood is entering the ventricles - the AV valves are closed - the ventricles are relaxed - the atria are contracting - Correct Answer-the AV valves are closed Most if the time, the parallel thick and thin filaments of the myofibrils are connected by _____ that span the space between myosin and actin molecules. - tropomyosin molecules - sarcomeres - nebulin molecules - calcium ions - crossbridges - Correct Answer-crossbridges How does the process of smooth muscle contraction differ from contraction in skeletal muscle? - there is no active myosin ATPase producing energy for the myosin heads - Ca2+ comes home from extracellular fluid and the SR - myosin pulls on troponin instead of actin - relaxation occurs when calmodulin is released from its receptors - Correct Answer-Ca2+ comes from the extracellular fluid and the SR Increased blood volume _______ blood pressure. - increases - decreases - has no effect on - Correct Answer-increases Your instructor announces a pop quiz. Which would you expect? - increased parasympathetic signaling and decreased cardiac output - increased sympathetic signaling and increased cardiac output - increased sympathetic signaling and decreased cardiac output - increased parasympathetic signaling and increased cardiac output - Correct Answer-increased sympathetic signaling and increased cardiac output If the membranes of the cardiac muscle cells in the SA node become more permeable to potassium ions, - heart rate will increase - the membrane will depolarize - heart rate will decrease - intracellular concentration of calcium ion will increase - stroke volume will increase - Correct Answer-heart rate will decrease In which situation would the stroke volume be the greatest? - when the difference between the end-diastolic volume and the end-systolic volume is small - when venous return is increased - when calcium channel blockers are present - when venous return is decreased - when the force of contraction is decreased - Correct Answer-when venous return is increased Cardiac Cycle 1. opening of semilunar valves 2. isovolumic contraction 3. beginning of atrial systole 4. closure of the AV valves 5. completion of ventricular filling 6. beginning of ventricular systole 7. ventricular relaxation 8. ventricular ejection - Correct Answer-3,5,6,4,2,1,8,7 Which event results in the first heart sound? - the atria contract - the semilunar valves open - the semilunar valves close - the AV valves open - the AV valves close - Correct Answer-the AV valves close For what are |f channels responsible in cardiac autorhythmic cells? - the pacemaker potential - action potential - membrane repolarization - cardiac diastole - Correct Answer-the pacemaker potential Compensation for decreased blood volume includes increases in - sympathetic stimulation to blood vessels, sympathetic stimulation of the heart, and water conservation by the kidneys - water conservation by the kidneys - sympathetic stimulation of the heart sympathetic stimulation to blood vessels and water conservation by the kidneys - sympathetic stimulation to blood vessels - Correct Answer-sympathetic stimulation to blood vessels, sympathetic stimulation of the heart, and water conservation by the kidneys Which will increase the heart rate? - only sympathetic stimulation of the SA node - only the application of acetylcholine to stimulation of the SA node - both sympathetic stimulation and acetylcholine stimulation of the SA node - only epinephrine stimulation of the SA node - both sympathetic stimulation and epinephrine stimulation of the SA node - Correct Answer-both sympathetic stimulation and epinephrine stimulation of the SA node As ATP binds to the myosin head at the beginning of the muscle contraction cycle, the myosin head immediately - tightens its bond to actin - initiates binding with actin - releases actin - swivels - Correct Answer-releases actin Ventricular contraction begins - during the first part of the P wave - just after the Q wave - just after the T wave - during the latter part of the P wave - none of the answers are correct - Correct Answer-just after the Q wave The volume of blood ejected from each ventricle during a contraction is called the - end-systolic volume - end-diastolic volume - cardiac output - cardiac reserve - stroke volume - Correct Answer-stroke volume The action potential traveling along the t-tubule changes the conformation of the - ryanodine receptor - dihydropydrine (DHP) receptor (L-type calcium channel) - acetylcholine receptor - Ca2+ ATPase - Correct Answer-dihydropydrine (DHP) receptor (L-type calcium channel) According to the Frank-Starling law of heart, the cardiac output is directly related to the - thickness of the myocardium - size of the ventricle - venous return - heart rate - end-systolic volume - Correct Answer-venous return The binding of acetylcholine to its receptor at the neuromuscular junction causes the opening of a - channel for both Na+ and K+ - Ca2+ channel - Na+ channel - ryanodine receptor - Correct Answer-channel for both Na+ and K+ The end of the plateau phase of cardiac contractile cell action potentials is due to the ______ of Ca2+ channels and _______ of K+ channels. - closing, opening - closing, closing - opening, closing - opening, opening - Correct Answer-closing, opening Which change will NOT result in increased blood flow to a tissue? - decreased peripheral resistance - increased blood volume - increased blood pressure - decreased vessel diameter - relaxation of precapillary sphincters - Correct Answer-decreased vessel diameter The values obtained when measuring blood pressure, such as 120/80, - exactly match the pressures inside the ventricle during systole and diastole - estimates the pressure in the major arteries during ventricular systole and diastole - are the same on both the pulmonary and systemic circuits - exactly match the pressures inside the ventricle during systole and diastole and reflect the pressure in the major arteries during ventricular systole and diastole - all of the answers are correct - Correct Answer-estimates the pressure in the major arteries during ventricular systole and diastole Bile is - secreted by hepatocytes and made by the gallbladder - released into the stomach only - made by the gallbladder only - secreted by hepatocytes only - secreted by hepatocytes,