chapter 14
Put these phases of the cardiac cycle in the correct order. 1. opening of the 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
3, 5, 6, 4, 2, 1, 8, 7
put these autorhythmic cells into the correct order for conveying electrical signals through a normal heart. 1. bundle of His 2. internodal pathway 3. Purkinje fibers 4. atrioventricular node 5. sinoatrial nodes 6. left and right bundle branches
5, 2, 4, 1, 6, 3
If the membranes of the cardiac muscle cells in the SA node become more permeable to potassium ions, A) heart rate will decrease. B) intracellular concentration of calcium ion will increase. C) the membrane will depolarize. D) stroke volume will increase. E) heart rate will increase
A) heart rate will decrease.
the function of transverse tubules is to A) rapidly move action potentials to the interior of the muscle fiber. B) store Ca2+ ions inside the muscle fiber. C) ensure a supply of glycogen throughout the muscle sarcoplasm. D) conduct ATP molecules out of the mitochondria throughout the sarcoplasm. E) none of these answers
A) rapidly move action potentials to the interior of the muscle fiber.
As blood vessel length increases, A) resistance increases and flow decreases. B) resistance increases only. C) flow decreases only. D) friction decreases only. E) both resistance and flow increase.
A) resistance increases and flow decreases.
If the connection between the AV node and bundle of His becomes blocked, A) the ventricles will beat more slowly. B) tachycardia will occur. C) the stroke volume will increase. D) the ventricles will beat faster. E) the ventricular rate of contraction will not be affected.
A) the ventricles will beat more slowly.
When a quantity is expressed as ʺ4 cm/min,ʺ this is describing the A) velocity of flow. B) pressure. C) volume. D) pressure gradient. E) flow rate.
A) velocity of flow.
which of the following is not one of the assumptions for Poiseuille flow used in blood flow calculations? A. flow is turbulent B. the tube is rigid C. the tube is a right circular cylinder D. the fluid is Newtonian E. there is no "slippage" at the wall
A. flow is turbulent
The AV node is important because it A) serves as the pacemaker in a normal heart. B) slows the transmission of the electrical impulses to the ventricles in order for the atria to finish contracting. C) electrically opens the AV valves. D) directs electrical impulses from the ventricles to the atria. E) None of these answers are correct.
B) slows the transmission of the electrical impulses to the ventricles in order for the atria to finish contracting.
the rapid depolarization stage of the action potentials of myocardial contractile cells is due to which ion(s)? A. Ca2+ only B. Na+ only C. K+ only D. both Ca2+ and Na+ E. both Na+ and K+
B. Na+ only
Place these structures in the order that blood returning to the heart from the body would pass through them. 1. right ventricle 2. left atrium 3. right atrium 4. pulmonary trunk/pulmonary arteries 5. left ventricle 6. pulmonary veins A) 4, 2, 5, 6, 3, 1 B) 2, 5, 6, 4, 3, 1 C) 3, 1, 4, 6, 2, 5 D) 3, 2, 4, 6, 1, 5 E) 1, 3, 6, 4, 5, 2
C) 3, 1, 4, 6, 2, 5
Stretching a myocardial cell A) decreases the force of a contraction and allows more Ca2+ to enter. B) only allows more Ca2+ to enter. C) allows more Ca2+ to enter and increases the force of a contraction. D) only decreases the force of a contraction. E) only increases the force of contraction.
C) allows more Ca2+ to enter and increases the force of a contraction.
s a result of the long refractory period, cardiac muscle prevents A) recruitment. B) treppe. C) tetanus. D) fatigue. E) tonus.
C) tetanus.
Which statement about cardiac muscle is FALSE? A) Intercalated disks contain both desmosomes for firm attachment and gap junctions to allow communication. B) The energy demand of cardiac muscle cells is high because they have many mitochondria. C) Cardiac muscle cells use Ca2+ ions released from the sarcoplasmic reticulum. D) Cardiac muscle cells must obey the all-or-none law of contraction. E) Calcium-induced calcium release is when extracellular Ca2+ stimulates release ofCa2+ from the sarcoplasmic reticulum.
D) Cardiac muscle cells must obey the all-or-none law of contraction.
Ivabrandine selectively blocks If (funny current) channels in the heart. Which statement would be true in a patient who is taking this drug? A) This drug would increase the blood pressure of the patient. B) This drug would decrease contractility of the patientʹs heart. C) This patient is being treated for bradycardia. D) The amount of calcium entering the patientʹs heart cells would increase. E) The drug would slow down this individualʹs heart rate.
E) The drug would slow down this individualʹs heart rate.
Which change will NOT result in increased blood flow to a tissue?
decreased vessel diameter
The flattening of the action potentials of the myocardial contractile cells, called the plateau phase, is due to a combination of BLANK K+ permeability and BLANK Ca2+ permeability.
decreasing, increasing
in the condition known as complete heart block, what happens?
electrical signals from the SA node never reach the ventricles, so the contraction of the atria is not coordinated with the contraction of the ventricles.
blood in the left atria
enters the left ventricle through the mitral valve
Diastole is the
period of heart relaxation
the QRS complex of an ECG represents
the progressive wave of ventricular depolarization
If there is a blockage between the AV node and the AV bundle, how will this affect the appearance of the electrocardiogram?
there will be more P waves than QRS complexes
left ventricular pressure is higher than pressure in the aorta during
ventricular systole only
in which situation would end-systolic volume be the greatest
when heart rate decreases because the nervous system decreases SA node discharge rate AND when the heart rate is increased
