The great cardiac vein drains blood from the heart muscle to the
right atrium
The autonomic centers for cardiac function are located in
the cardiac centers of the medulla oblongata
the cardiac centers of the medulla oblongata
The serous membrane covering in the outer surface of the heart
visceral pericardium
The simple squamous epithelium covering the valves of the heart constitutes the
endocardium
The heart lies in the
mediastinum
The cardiac skeleton of the heart has which two of the following functions?
1)it physically isolates the muscle fibers of the atria from those of the ventricles
2)it maintains the normal shape of the heart
Cardiac output is equal to the
product of heart rate and stroke volume
During diastole, a chamber of the heart
relaxes and fills with blood
During the cardiac cycle, the amount of blood ejected from the left ventricle when the semilunar valve opens is the
stroke volume(SV)
What role do the chordae tendineae and papillary muscles play in the normal function of the AV valves?
during ventricular contraction, tension in the papillary muscles pulls against the chordae tendineae, which keep the cusps of the AV valve from swinging into the arium. this action prevents backflow, or regurgitation, of blood into the atrium as the ventr
Describe the three distinct layers that make up the heart wall.
1) the epicardium is the visceral pericardium, which covers the outer surface of the heart
2)the myocardium is the muscular wall of the heart, which forms both atria and ventricles. it contains cardiac muscle tissue and associate connective tissues, blood
What are the valves in the heart, and what is the function of each?
the right atrioventricular(AV) valve (tricuspid valve) and the left AV valve (( the tricuspid valve) prevent the backflow of blood from the ventricles into the aorta. the pulmonary and aortic semilunar valves prevent the backflow of blood from the pulmona
Trace the normal pathway of an electrical impulse through the conducting system of the heart.
SA node
AV node
AV bundle
right and left bundle branches
purkinje fibers(into the mass of ventricular muscle tissue)
What is the cardiac cycle? What phases and events are necessary to complete a cardiac cycle?
the cardiac cycle comprises the events in a complete heartbeat, including a contraction/relaxation period for both atria and ventricles. the cycle begins with atrial systole as the atria contract and push blood into the relaxed ventricles. as the atria re
What three factors regulate stroke volume to ensure that the left and right ventricles pump equal volumes of blood?
1) preload, the stretch on the heart before it contracts
2) contractility, the forcefulness of contraction of individual ventricular muscle fibers
3) after-load, the pressure that must be exceeded before blood can be ejected from the ventricles
The cells of the conducting system differ from the contractile cells of the heart in that
contractile cells do not normally exhibit automaticity
Which of the following is longer?
the refractory period of cardiac muscle
If the papillary muscles fail to contract
the AV valves will not close properly
Cardiac output cannot increase indefinitely because
the available filling time becomes shorter as the heart rate increases
Describe the function of the SA node in the cardiac cycle. How does this function differ from that of the AV node?
the SA node, which is composed of cells that exhibit rapid prepotential, is the pacemaker of the heart. the AV node slows the impulse that signals contraction, because its cells are smaller than those of the conduction pathway.
What are the sources and significance of the four heart sounds?
the first sound("lubb"), which marks the start of ventricular contraction, is produced as the AV valves close and the semilunar valves open. the second ("dubb" or "dupp") occurs when the semilunar valves close, marking the start of ventricular diastole. t
Differentiate between stroke volume and cardiac output. How is cardiac output calculated?
stroke volume(SV) is the volume of blood ejected by a ventricle in a single contraction. Cardiac output (CO) is the amount of blood pumped by the left ventricle in 1 minute: CO(in mL/min) = HR (in beats/mn) x SV ( in mL/ beat).
What factors influence cardiac output?
stroke volume and heart rate influence cardiac output.
What effect does sympathetic stimulation have on the heart? What effect does parasympathetic stimulation have on the heart?
sympathetic activation increase the heart rate increases the heart rate and the force of contractions; parasympathetic stimulation decrease the heart rate and the force of contractions.
Describe the effects of epinephrine, norepinephrine, glucagon, and thyroid hormones on the contractility of the heart.
all these hormones have positive inotropic effects, which means that they increased the strength of contraction of the heart.
Vern is suffering from cardiac arrhythmias and is brought into the emergency room of a hospital. In the emergency room he begins to exhibit tachycardia and as a result loses consciousness. Explain why Vern lost consciousness.
during tachycardia, there is less time between contractions for the heart to fill with blood again. thus, over time the heart fills with less and less blood, and pumps less blood out. as the stroke volume decreases, so does cardiac output. when cardiac ou
Harvey has a heart murmur in his left ventricle that produces a loud "gurgling" sound at the beginning of systole. Which valve is probably faulty?
Harvey probably has regurgitation mitral valve. when an AV valve fails to close properly, blood flowing back into the atrium produces a murmur. a murmur at the beginning of systole implicates the AV valve because this is the period when the valve has just
The following measurements were made on two individuals(the values recorded remained stable for one hour):
Person 1: heart rate, 75 bpm; stroke volume, 60 mL
Person 2: heart rate, 90 bpm; stroke volume, 95 mL
using CO= HR x SV, person 1 has a cardiac output of 4500 mL, and person 2 has a cardiac output of 8550 mL. According to Starling's law of the heart, in a normal heart the cardiac output is directly proportional to the venous return. This, person 2 has the
Karen is taking the medication verapamil, a drug that blocks the calcium channels in cardiac muscle cells. What effect should this medication have on Karen's stroke volume?
by blocking calcium channels, verapamil will decrease the force of cardiac contraction, which directly lowers Karen's stroke volume.