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BC 2086
Exam 1
| Question | Answer |
|---|---|
| All of the following statements are true regarding the heart except? | * Impulses are conducted from one muscle cell to the next , A # of heart cells have unstable membrane potentials, A # of heart cells have stable membrane potentials & Conduction is NOT initiated by nerve impulse (SA Node or pressure gradient) |
| The sinoatrial node is the pacemaker for the heart because the SA node | Highest rate of automatic discharge |
| An independence of the P waves and the QRS complexes of the ECG indicates | No AV node conduct |
| One of the factors that controls the force of heart contraction is the | The Initial length (preload) of cardiac fiber muscles |
| Positive inotropism refers to | increase contractility |
| The effect of parasympathetic nervous stimulation on the heart is | slow down the hear |
| The P wave of a normal EKG is associated with | Atrial contraction |
| Which of the following mechanisms is most important for maintaining an increased blood flow to skeletal muscle during exercise? | Muscle vessel vasodilation |
| Which of the following events is represented on the EKG? | atrial muscular depolarization |
| An EKG is recorded and it displays no P waves, but a normal appearing QRS and T wave. The pacemaker most likely is located in the | AV node |
| Which of the following best describes conditions consistent with increased contractility? | Increased cardiac output for given end-diastolic volume |
| The tendency to form edema will be increased by | Increased venous pressure |
| Myocardial contractility is best correlated with the intracellular concentration of | Ca 2+ |
| Cardiac output of the right heart is what percentage of the left heart? | 100 % |
| The greatest pressure drop in the circulation occurs across the arterioles because | greatest resistance |
| During rapid acceleration, as a fighter pilot might experience, the pooling of blood in the extremities will | decrease arterial blood pressure |
| The reflex organization of the cardiovascular system is designed to principally maintain | constant pressure |
| The physiological function of the relatively slow conduction through the AV node is to allow sufficient time for | filling of ventricles |
| The foramen ovale in the fetal heart is located in the: | interarterial septum |
| If communication between the SA node and the AV node becomes blocked which is most certainly affected: | Just ventricles will contract at a slower rate |
| A valve damaged by rheumatic fever is stiffened and fails to open completely. This is called: | Stenosis |
| Blood returning from the lungs enters the heart through the: | left atrium |
| According to Starling's Law of the heart, cardiac output is directly related to: | Amount of blood returning to the heart |
| The T wave on an ECG represents: | Ventricular Repolarization |
| Cardiac output is equal to: | HR X SV |
| During ventricular systole: | Av valves closed, mitral closed |
| In general, veins exhibit this characteristic when compared to arteries: | thinner walls |
| The blood vessels that play the most important role in the regulation of blood flow to a tissue and blood pressure are the: | Arterioles |
| As blood travels from the aorta to the capillaries: | Resistance increases |
| A patient with a hypothalamic tumor causes excessive ADH secretion. When her blood pressure is taken which of the following readings would you expect: | 165/100 |
| The difference between the systolic and diastolic pressures is called the: | pulse pressure |
| Caffeine causes the SR to release Ca and also has effects on cAMP metabolism. What might caffeine do to the heart's contraction? | Increase contractility |
| Offer explanations for why epinephrine increases: contraction strength and rate of relaxation. | ^ contractile strength by ^ intracellular calcium levels. |
| Why can't the heart contract tetanically? | Because cells have long refractory periods |
| What provides nutrition to the heart muscle cells? | Coronary blood vessels |
| T or F? Cardiac action potentials proceed in the sequence: atria, SA node, bundle of His, AV node, ventricles | False |
| T or F? Cutting the vagus nerve causes the heart to speed up. Explain your answer. | True Vafal stimulation causes the resting heart rate to be lower tan the intrinsic rate of the SA node. If the vagus is secered, this influence is lost and heart rate will rise to this intrinsic rate which is about 100bpm |
| If the end diastolic volume is 200 mls, and the end systolic volume is 130 mls, What is the stroke volume? | 70 mls |
| T or F? Stroke volume of the left ventricle is larger than that of the right ventricle. | False |
| If the end diastolic volume is 100 mls and the ejection fraction is 70% , what is the stroke volume? | 70 |
| In cardiac muscle, the depolarization phase of the action potential is the result of | Increased membrane permeability to sodium ions |
| ) In cardiac muscle | At least half of the calcium ion required for contraction comes from outside the cell. |
| components of the conducting system of the heart in sequence AP move thru system | SA NOde, AV NOde, AV bundle, bundle branches, purkinje fibers |
| Depolarization of the ventricles is represented on an electrocardiogram by the | QRS complex |
| The first heart sound is heard when the | AV valves close |
| During the isovolumetric phase of ventricular systole, the | AV valves & semilunar valves are close |
| During the cardiac cycle, the | QRS Complex of ecg precedes the increase in ventricular pressur |
| Each of the following factors will increase cardiac output, except | Venous return, sympathetic stimulation, ^ heart rate not increased parasympathethic stimulation. |
| According to Starling's "law of the heart," the cardiac output is directly related to the | Venous return |
| Each of the following conditions would increase heart rate, except | increased parasympathetic stimulation of nodal fibers |
| ) The pericardial fluid is important because it | lubricates reduce friction acts as cushion |
| If an action potential is initiated in the AV node, you would expect the heartbeat to be ________ beats per minute. | 40 - 60 |
| Tetanic muscle contractions cannot occur in a normal cardiac muscle cell because | refractory period lasts until the muscle cell relaxes |
| The amount of blood that is forced out of the heart depends on | degree of stretching at the end of ventricular diastole, the amount of pressure required to eject blood, the contractility of the ventricle |
| During ventricular systole, the | AV valves are closed |
| Which of the following is greater regarding [] of calcium ion in the sarcoplasmic reticulum | [] of calcium ion in the sarcoplasmic reticulum of skeletal muscle |
| ) Cardiac output would be greatest when | sympathetic stimulation of the heart increases |
| Which of the following would be greater? regarding stroke volume when extracellular calium ion [] high or low? | high |
| Abnormally slow conduction through the ventricles would change the shape of the ________ in an ECG tracing. | QRS complex |
| In which of the following situations would the end-systolic volume (ESV) be the greatest? | when parasympathetic stimulation of the heart is increased |
| In which situation would the stroke volume be the greatest? | Venous return ^ |
| Manganese ion blocks the calcium channels in the cardiac muscle membrane. How would the presence of manganese in the extracellular fluid affect the contraction of the heart muscle? | heart would beat less forcefully |
| The end diastolic ventriculate volumes are increased ( within physiologic limits) | Increase in stroke volume |
| What would happen to cardiac muscle contractility and excitability in the presence of drugs specifically Ca channels blocks in the plasma membrane | They would both decrease |
| drugs known as calcium channel blockers can be used to | decrease the force of cardiac contraction |
Created by:
yrosero