ch 19 practice exam pt 1 Flashcards
choose correct statement(s) associated with the metabolism of cardiac muscle
cardiac muscle depends almost exclusively on anaerobic respiration
choose correct statement(s) that accurately explains impulse conduction to the myocardium
- firing of the SA node excites atrial cardiomyocytes and stimulates the 2 atria to contract almost simultaneously
- in the AV node the signal slows down to about 0.05 m/sec because the cardiomyocytes have fewer gap junctions over which the signal can be transmitted
- the delay at the AV node is essential because it gives the atria time to fill with blood before they begin to contract
which of the following are found on the surface of the heart
- coronary sulcus
- marginal sulcus
the pulmonary circuit is supplied by both right and left sides of the heart
false
systemic circuit contains oxygen-rich blood only
false
which carry oxygen-poor blood
venae cava and pulmonary arteries
which belongs to the pulmonary circuit
pulmonary arteries and pulmonary veins
the heart is enfolded within a space called
pericardial cavity
the apex of the heart is found _____ of the midline of the body
to the left
which is the most superficial layer enclosing the heart
fibrous pericardium
pericardial fluid is found between the _____ and the _____
parietal layer of the serous pericardium; visceral layer of the serous pericardium
the fibrous skeleton of the heart serves as electrical insulation between the atria and the ventricles
true
the ___ performs the work of the heart
myocardium
the _____ are superior chambers of the heart and the ______ are the inferior chambers of the heart
atria; ventricles
the ventricles are the thicker more powerful chambers of the heart, they pump blood to the lungs and body
true
the shallow depression seen on the external surface of the heart between the left and right ventricles is called the
interventricular sulcus
the area where the major vessels lead to and from the heart’s chambers is called the _____ of the heart. the pointy, inferior portion is called the _____
base; apex
the right atrioventricular valve regulates the opening between the ________ and the ________
right atrium; right ventricle
oxygen-poor blood passes through the
right AV and pulmonary valve
the ______ valve regulated the flow of blood between the right ventricle and the vessels leading to the lungs
pulmonary
the chordae tendineae of the AV valves are anchored to the _____ of the ventricles
papillary muscles
the ______ carry blood toward the lungs
pulmonary trunk and arteries
after entering the right atrium the furthest a RBC can travel is the ______
superior vena cava
opening and closing of the heart valves is caused by
pressure gradients
which of the following blood vessels receives blood directly from the right ventricles
pulmonary trunk
which of the following directly stems from the ascending aorta before it branches into the circumflex branch and anterior interventricular branch
left coronary artery
an obstruction in which of the following will cause the most severe myocardial infarction (MI)
left coronary artery (LCA)
blood in the heart chambers provides most of the myocardium’s oxygen and nutrient needs
false
cardiac muscle can only use glucose as a source of organic fuel
false
which is a feature shared by cardiac muscle and skeletal muscle
muscle fiber striations
which is NOT a feature of cardiac muscle
they have about the same endurance as skeletal muscle fibers
desmosomes form channels that allow each cardiomyocyte to electrically stimulate its neighbors
false
electrical signals pass between cardiomyocytes through the
gap junctions
the _____ is the pacemaker that initiates each heart beat
sinoatrial (SA) node
which is NOT part of the cardiac conduction system
tendinous cords
which is the correct path of an electrical excitation from the pacemaker to a cardiomyocyte in the left ventricle (LV)
- sinuatrial (SA) node
- atrioventricular (AV) node
- subendothelial branches
- atrioventricular (AV) bundle
- cardiomyocyte in LV
the pacemaker potential is a result of
Na+ inflow
if the sinoatrial (SA) node is damaged the heart will likely beat at ____ bpm
40 to 50
if the SA node is damaged nodal rhythm is sufficient to sustain life
true
cells of the sinuatrial node ____ during the pacemaker potential
depolarize slow
papillary muscle prevent the AV valves from prolapsing (bulging) excessively into the atria when the ventricles contract
true
parasympathetic stimulation reduces heart rate
true
the cardiac plexus and cardiac nerves dominate the innervation of the heart and contain both parasympathetic and sympathetic fibers
true
