Chapter 18: The Cardiovascular System: The Heart

The pacemaker of the heart is the - Purkinje fibers. - the bundle branches. - Bundle of His. - AV node. - SA node.

- SA node.

The second heart sound (the 'dup' of 'lub-dup') is caused by: - opening of the atrioventricular valves. - closure of the atrioventricular valves. - opening of the semilunar valves. - closure of the semilunar valves.

- closure of the semilunar valves.

Which of the following ions has the greatest affect on the autorhythmic capabilities of the myocardium? - Ca2+ - K+ - Na+ - Cl-

- Ca2+

Which of the following is the cause of the "plateau" in cardiac muscle action potentials? - Sodium ion influx - Calcium ion influx - Calcium ion outflux - Chloride ion outflux - Potassium ion influx

- Calcium ion influx

Which is correctly paired? - Arrhythmia: AV node failure - Fibrillation: premature contraction - Heart block: uncoordinated atrial and ventricular contraction - Ectopic focus: an abnormal pacemaker

- Ectopic focus: an abnormal pacemaker

Which is the correct sequence of layers in the heart wall, starting with the outer layer? - Parietal pericardium, myocardium, endocardium - Endocardium, epicardium, myocardium - Myocardium, pericardium, endocardium - Endocardium, smooth muscle, epicardium - Epicardium, myocardium, endocardium

- Epicardium, myocardium, endocardium

Which of the following is an age-related change of the heart that affects function? - Stretching of myocardium due to overuse - Thinning of the valve flaps - Loss of elasticity of cardiac muscle - Increase in cardiac reserve - Fibrosis of cardiac muscle

- Fibrosis of cardiac muscle

Which of the following is not a role of the pericardium? - It facilitates heart contraction. - It prevents overfilling of the heart with blood. - It anchors the heart to surrounding structures. - It protects the heart.

- It facilitates heart contraction.

Which of the following vessels is most likely to supply the anterior left ventricular myocardium? - Marginal artery - Posterior interventricular artery - Circumflex artery - Left anterior descending artery - Right coronary artery

- Left anterior descending artery

Into which chamber of the heart do the pulmonary veins deliver blood? - Left ventricle - Left atrium - Right atrium - Right ventricle

- Left atrium

Which of the following drains blood DIRECTLY from the myocardium? - Right coronary artery - Middle cardiac vein - SVC - IVC - Coronary sinus

- Middle cardiac vein

Which of the following would lead to a decrease in heart rate? - Exercise - Norepinephrine - Sharply decreased blood volume - Parasympathetic stimulation

- Parasympathetic stimulation

Identify the correct sequence of blood flow through the chambers of the heart. - Lungs, right ventricle, left ventricle, right atrium, left atrium - Right ventricle, left ventricle, left atrium, lungs, right atrium - Left atrium, left ventricle, right ventricle, right atrium, and lungs - Right atrium, right ventricle, lungs, left atrium, left ventricle - Left ventricle, left atrium, lungs, right ventricle, right atrium

- Right atrium, right ventricle, lungs, left atrium, left ventricle

Choose the correct sequence of current flow through the heart wall. - AV node, SA node, Purkinje fibers, AV bundle of His, right and left bundle branches - SA node, AV node, AV bundle of His, right and left bundle branches, Purkinje fibers - SA node, Purkinje fibers, AV node, AV bundle of His, right and left bundle branches - AV node, Purkinje fibers, AV node, AV bundle of His, right and left bundle branches - Purkinje fibers, AV node, AV bundle of His, right and left bundle branches, SA node

- SA node, AV node, AV bundle of His, right and left bundle branches, Purkinje fibers

Which statement about the extrinsic innervation of the heart is NOT true? - Sympathetic nerve stimulation of the heart increases the rate and force of the heart. - The cardiac centers are located in the medulla oblongata of the brain stem. - Parasympathetic nerve stimulation reduces the heartbeat. - Sympathetic impulses travel through the vagus nerve. - The vagus nerve is the tenth cranial nerve.

- Sympathetic impulses travel through the vagus nerve.

Which of the following statements is NOT true about the shape, position and location of the heart? - The heart is located between the two lungs within the mediastinum. - Approximately two-thirds of the heart is found to the left of the midline. - The heart is enclosed in a double-layered sac called the pleural membrane. - The heart is shaped like a cone with the base facing the right shoulder.

- The heart is enclosed in a double-layered sac called the pleural membrane.

All but which of the following statements about autorhythmic myocardial cells are correct? - They do not maintain a stable resting membrane potential. - They have special ion channels in their sarcolemma. - They are the first myocardial cells to contract. - They make up the intrinsic cardiac conduction system.

- They are the first myocardial cells to contract.

Which of the following is a difference between cardiac muscle and skeletal muscle? - Unlike skeletal muscle cells, cardiac muscle cells do not rely on an influx of calcium ions for depolarization. - Unlike skeletal muscle, cardiac muscle does not use a sliding filament mechanism for contraction. - Unlike skeletal muscle, cardiac muscle is not striated. - Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic.

- Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic.

The pacemaker potential produced in autorhythmic cells is due to the presence of - a continuously depolarizing membrane that slowly reaches threshold. - intercalated discs at cell junctions. - desmosomes. - many large mitochondria in the cytoplasm.

- a continuously depolarizing membrane that slowly reaches threshold.

Which of the following factors gives the myocardium its high resistance to fatigue? - the presence of intercalated discs - a very large number of mitochondrion in the cytoplasm - gap junctions - the coronary circulation

- a very large number of mitochondrion in the cytoplasm

An enlarged R wave on an ECG would indicate - a myocardial infarction. - an enlarged ventricle. - cardiac ischemia. - repolarization abnormalities.

- an enlarged ventricle.

The coronary arteries arise from the - aorta. - inferior vena cava. - superior vena cava. - right atrium. - pulmonary trunk.

- aorta.

The dicrotic notch observed on tracing of blood pressure recording is due to - mitral valve closure. - aortic semilunar valve closure. - pulmonary semilunar valve closure. - tricuspid valve closure.

- aortic semilunar valve closure.

The superior chambers of the heart are called the: - ventricles. - superior sulci. - atria. - coronary chambers.

- atria.

The P wave of an electrocardiogram represents: - ventricular depolarization. - atrial depolarization. - atrial repolarization. - ventricular repolarization.

- atrial depolarization.

The P-wave is a measure of - ventricular depolarization. - ventricular hyperpolarization. - atrial repolarization. - ventricular contraction. - atrial depolarization.

- atrial depolarization.

The ability of some cardiac muscle cells to initiate their own depolarization and cause depolarization of the rest of the heart is called - absolute refractory period. - fibrillation. - a functional syncytium. - an action potential. - automaticity.

- automaticity.

Attached to the AV valve flaps are the - trabeculae carneae. - papillary muscles. - chordae tendineae. - pectinate muscles.

- chordae tendineae.

The vessels that carry oxygen to the myocardial cells are called - aortic arteries. - pulmonary arteries. - pulmonary veins. - coronary veins. - coronary arteries.

- coronary arteries.

The lining of the heart chambers is called the: - myocardium. - epicardium. - pericardium. - endocardium.

- endocardium.

Which of the following is clinically significant as an ectopic pacemaker of the heart? - drinking several cups of caffeinated coffee - extrasystole contractions associated with angina pectoris - excessive smoking - anxiety

- extrasystole contractions associated with angina pectoris

The cells of the myocardium behave as a single coordinated unit called a - pacemaker. - functional syncytium. - contractile unit. - sarcomere. - cardiac cycle.

- functional syncytium.

A doctor puts his stethoscope on a patient's chest over the location of the heart and hears a swishing sound. Which of the following conditions is the best diagnosis for the patient's condition? - angina pectoris - myocardial infarction - incompetent cardiac valve - cardiac tamponade

- incompetent cardiac valve

Positive inotropic agents - decrease the contractility of the heart. - cause hemolysis of blood clots. - prevent blood clotting. - increase the contractility of the heart.

- increase the contractility of the heart.

Autorhythmic cardiac cells are found in all the following location except the - SA node. - interatrial septum. - Purkinje cells. - AV node.

- interatrial septum.

The fossa ovalis is located in the - interventricular septum. - atrium. - ventricle. - interatrial septum.

- interatrial septum.

Which of the following events would cause the gap junctions between cardiac cells to close? - ischemia - atrial fibrillation - premature ventricular contractions (PVCs) - arrhythmia

- ischemia

The phase in the cardiac cycle in which the ventricles are completely closed and the volume of blood in them is constant is referred to as the - quiescent period. - isovolumetric relaxation phase. - ventricular ejection phase. - isovolumetric contraction phase.

- isovolumetric contraction phase.

The interventricular septum forms a dividing wall between the - left atrium and left ventricle. - left atrium and right atrium. - right ventricle and left atrium. - right atrium and right ventricle. - left and right ventricles.

- left and right ventricles.

Freshly oxygenated blood is delivered to the _____ and then it passes into the _______, to be pumped to the entire body. - left ventricle; left atrium - right ventricle; right atrium - left atrium; left ventricle - right atrium; right ventricle

- left atrium; left ventricle

The most muscular chamber of the heart is the ________. - right atrium - left atrium - right ventricle - left ventricle

- left ventricle

During systemic circulation, blood leaves the - left ventricle and goes directly to the aorta. - right ventricle and goes directly to the aorta. - right ventricle and moves to the lungs. - lungs and moves to the left atrium. - right atrium and goes directly to the lungs.

- left ventricle and goes directly to the aorta.

When the mitral valve closes, it prevents the backflow of blood from the - left atrium into the left ventricle. - left ventricle into the left atrium. - right atrium into the right ventricle. - left ventricle into the aorta. - right ventricle into the pulmonary trunk.

- left ventricle into the left atrium.

Guided by powerful signaling molecules, the human heart develops from - ectoderm and endoderm. - ectoderm. - blood cells. - mesoderm. - endoderm.

- mesoderm.

The inner lining of the fibrous pericardium is formed by the - pericardial cavity. - myocardium. - diaphragm. - endocardium. - parietal layer of serous pericardium. - epicardium.

- parietal layer of serous pericardium.

The tricuspid valve is located between the - right and left atria. - right and left ventricles. - right atrium and right ventricle. - left atrium and left ventricle. - right ventricle and the aorta.

- right atrium and right ventricle.

The inferior vena cava brings blood from the lower regions of the body and empties into the - left atrium. - right atrium. - Aorta. - left ventricle. - right ventricle.

- right atrium.

During pulmonary circulation blood leaves the - right ventricle and goes directly to the aorta. - right ventricle and moves to the lungs. - right atrium and goes directly to the left ventricle. - right atrium and goes directly to the lungs. - left ventricle and moves to the lungs.

- right ventricle and moves to the lungs.

The endocardium is composed of - simple cuboidal epithelium. - simple squamous epithelium. - cardiac muscle cells. - simple columnar epithelium. - stratified squamous epithelium.

- simple squamous epithelium.

The role of the atrioventricular node (AV node) is to: - initiate a sinus rhythm. - initiate ventricular depolarization. - slow down impulses so that the atria can contract to fill the adjacent ventricles with blood. - conduct impulses to the sinoatrial node (SA node).

- slow down impulses so that the atria can contract to fill the adjacent ventricles with blood.

The cardioacceleratory center fibers are part of the - cranial peripheral nervous system. - somatic peripheral nervous system. - sympathetic nervous system. - parasympathetic nervous system.

- sympathetic nervous system.

Cardiac Output is - the amount of blood pumped out of each ventricle in one minute. - the number of impulses fired by the SA node in one minute. - the amount of blood pumped out of the heart during every ventricular contraction. - the number of times the heart beats in one minute. - the amount of blood filling each ventricle at the end of diastole.

- the amount of blood pumped out of each ventricle in one minute.

Which of the following structures is continuous with the inner lining of blood vessels? - the pectinate muscles - the pericardial sac - the epicardium - the endocardium

- the endocardium

Which of the following structures lies on the outside surface of the heart and is an integral part of the cardiac wall? - the epicardium - The parietal layer of serous pericardium - the fibrous pericardium - the pericardial sac

- the epicardium

If the circumflex artery of the heart was blocked, the myocardium in the _________________ would be ischemic. - the left atrium and the posterior wall of the left ventricle - the apex - the lateral aspects of the heart - interventricular septum and the anterior wall of the ventricles

- the left atrium and the posterior wall of the left ventricle

What part of the heart is considered the systemic circuit pump? - the right atrium - the right ventricle - the left atrium - the left ventricle

- the left ventricle

Which of the following valves is most often faulty in the heart? - the aortic semilunar valve - the tricuspid valve - the pulmonary semilunar valve - the mitral or bicuspid valve

- the mitral or bicuspid valve

The absolute refractory period refers to the time during which - the muscle cell is ready to respond to a threshold stimulus. - a skeletal muscle cannot respond to any stimulus and lasts about 250 ms. - a cardiac muscle cannot respond to any stimulus and lasts only 1 to 2 milliseconds. - the muscle cell is ready to respond to any stimulus. - the muscle cell is NOT in a position to respond to a stimulus of any strength.

- the muscle cell is NOT in a position to respond to a stimulus of any strength.

The cardiac cycle includes all of the following events EXCEPT - the movement of impulse from the SA node to all regions of the heart wall. - the closing and opening of the heart valves during each heart beat. - the number of times the heart beats in one minute. - the changes in pressure gradients in all chambers of the heart. - the changes in blood volume in all chambers of the heart.

- the number of times the heart beats in one minute.

The myocardium functions as a functional syncytium due to - the presence of striations in the myocardium. - branching of myocardial cells. - the presence of gap junctions. - the presence of desmosomes.

- the presence of gap junctions.

During the spike of an action potential in a cardiac muscle cell - there is a rapid influx of Na+ into the cell. - Ca2+ moves out of the cell into the extracellular fluid. - K+ channels open to let K+ move into the cell. - both Na+ and Ca2+ move into the cell at the same time. - Na+ moves out of the cell into the extracellular fluid.

- there is a rapid influx of Na+ into the cell.

The _________ nerve carries parasympathetic fibers to the SA node. - hypoglossal - facial - accessory - vagus

- vagus

Blood spurts back into the _____________ when the right atrium contracts. - aorta - pulmonary trunk - venae cavae - pulmonary veins

- venae cavae

The trabeculae carneae are located in the - endocardium. - atrium. - epicardium. - ventricles.

- ventricles.

The end diastolic volume is the - volume of blood in the atria at the end of atrial relaxation. - volume of blood in the ventricle at the end of ventricular relaxation. - volume of blood in the ventricle at the end of ventricular contraction. - volume of blood in the atria at the end of atrial contraction.

- volume of blood in the ventricle at the end of ventricular relaxation.