Chapter 19 Heart Anatomy
To initiate a cardiac muscle cell contraction, calcium
binds to troponin.
For the repolarization phase of an SA nodal cell action potential,
calcium channels close and potassium channels open.
The AV valves close in response to the ________________________.
contraction of the ventricles and the resulting rise in ventricular pressure
Vagal tone refers to the
decreasing of the heart rate below its inherent rhythm by parasympathetic stimulation
A first degree block is caused by ________________.
delay of the action potential between the SA and AV nodes
At the AV node of the conduction system, the action potential is
delayed due to the cells being small and having few gap junctions.
As with action potentials in other types of cells, the repolarization of cardiac muscle cells involves the
exit of potassium through voltage-gated channels.
The membrane of a contractile cardiac muscle cell contains
fast voltage-gated sodium channels and slow voltage-gated calcium channels.
The atrioventricular (AV) node is located in the
floor of right atrium
Cardiac output equals the
heart rate multiplied by stroke volume.
The foramen ovale of the fetal heart is an opening in the
interatrial septum.
Positive inotropes allow the heart to pump ____________ blood with fewer heart beats. They do this by _____________________ the end-systolic volume (ESV).
more; decreasing
The papillary muscles attach to the cusps of the atrioventricular valves by means of the
tendinous cords.
Cardiac reserve is
the increase in cardiac output an individual is capable of demonstrating during vigorous exercise.
The rate of ventricular conduction is best determined by _______________________ on an ECG.
the number of QRS complexes present within a specific unit of time
During ventricular contraction
the semilunar valves open and the AV valves close
The internal wall surface of each ventricle displays large, smooth, irregular muscular ridges called
trabeculae carneae.
Which feature permits the compression necessary to pump large volumes of blood out of the ventricles?
Arrangement of cardiac muscle in the heart wall
Which of the following is not one of the three main factors influencing stroke volume?
Chronotropic agents
Action potentials received directly from ________________ stimulate the papillary muscles to contract, allowing for the proper _______________ of the AV valves.
Purkinje fibers; closing
What are the cell-to-cell contacts of the cardiac muscle fibers called?
Intercalated discs
From which view is the connection between the pulmonary veins and the heart most visible?
Posterior view
Which segment of the ECG reflects the plateau phase of ventricular muscle cells' action potentials?
S-T segment
What part of the cardiac conduction system is located in the posterior wall of the right atrium, adjacent to the entrance of the superior vena cava?
SA node
Sympathetic innervation of the heart arises from the ________ segments of the spinal cord.
T1-T5
Someone with a heart block would have
a long P-R interval
Which can be used to characterize blood flow in the human body? a: There is a unidirectional blood flow. b: Arteries always carry oxygenated blood. c: Veins always carry deoxygenated blood. d: Arteries carry blood away from the heart. e: Veins carry blood toward the heart.
a, d, e
Metabolically, cardiac muscle relies on
aerobic metabolism using many mitochondria and a rich supply of myoglobin.
An ECG tracing from someone with a third-degree AV block is best described as a tracing with ______________________.
atrial depolarization occurring 70-100 times per minute and ventricular depolarization occurring 40-50 times per minute
Once an SA nodal cell reaches threshold, the depolarization phase occurs during which
calcium comes in through fast voltage-gated channels.
Occlusion of blood vessels tends to lead to
inadequate blood supply and damage to body tissues
Mitral valve prolapse severe enough to cause regurgitation may directly cause _________________ pressure in the ____________ atrium.
increased; left
An individual with high blood pressure (hypertension) is expected to benefit from the administration of ____________________ inotropic drugs that _______________ the hearts workload.
negative; decrease
Which pair is located more anteriorly in a heart in normal position?
Right atrium and right ventricle
Which region of the ECG image aligns with the electrical changes related to atrial repolarization?
region b
Which circuit of the cardiovascular system includes the left ventricle and aorta?
Systemic circuit
The atria remain in diastole throughout both the _______________________ phases of the cardiac cycle
ventricular systole and ventricular diastole
Which prenatal structure forms the ascending aorta and pulmonary trunk?
Truncus arteriosus
The tetralogy of Fallot is
a developmental disorder that is a cardiac septal defect.
An autorhythmic heart cell is one in which
action potentials fire spontaneoulsy.
Just prior to atrial contraction,
all four chambers are at rest and AV valves are open
Norepinephrine is considered a positive chronotropic agent because it causes
an increase in the firing rate of SA node cells.
According to the Frank-Starling law
as the volume of blood entering the heart increases, ventricular contractions become more forceful.
What is the sequence of events in the transmission of an impulse through the heart muscle? a: AV node b: AV bundle c: SA node d: Through the atria e: Through the ventricles f: Bundle branches g: Purkinje fibers
c, d, a, b, f, g, e
The semilunar valves remain open throughout the ____________________ phase of the cardiac cycle.
late ventricular systole
Cardiac output is usually expressed in
liters per minute
The serous fluid within the pericardial cavity works to
lubricate membranes of the pericardium.
The layer of the heart wall composed of cardiac muscle tissue is the
myocardium.
The opening and closing of the heart valves is caused by
pressure changes of alternating contraction and relaxation during the cardiac cycle.
Coronary vessels are open when the heart is
relaxed
Which heart chambers contain deoxygenated blood?
right atrium and right ventricle
The fossa ovalis appears just above the opening of the coronary sinus within the
right atrium.
The function of the coronary sinus is to
take blood from the coronary circulation to the right atrium
How many half-moon shaped, pocketlike cusps are found in each semilunar valve?
3
Which layer is made of dense irregular connective tissue?
Fibrous pericardium
Which carries oxygenated blood from the lungs to the heart?
Pulmonary veins
During a cardiac cycle, how many of the four chambers contract at any one time?
2
Which valve prevents the backflow of blood into the left ventricle when the ventricles relax?
Aortic semilunar valve
Parasympathetic innervation of the heart occurs via
CN X.
Which action leads to the closure of the right atrioventricular valve?
Contraction of the right ventricle
Which correctly describes the heart's apex?
Projects slightly anteroinferiorly toward the left side of the body
Which of the cardiovascular system's circuits has deoxygenated blood in its arteries?
Pulmonary circuit
Which describes the endocardium? a: Has single layer of epithelium b: Has layer of areolar connective tissue c: Epithelial cells are squamous d: Epithelial cells are cuboidal e: Has layer of adipose connective tissue f: Has patches of myocardium
a, b, c
Which are functions performed by the fibrous skeleton of the heart?a: Separates the atria and ventricles b: Anchors the heart valves c: Provides electrical insulation between the atria and ventricles d: Provides the framework for the attachment of the myocardium e: None of these are true functions of the fibrous skeleton of the heart
a, b, c, d
Which are differences between cardiac muscle tissue and skeletal muscle tissue? a: The sarcoplasmic reticulum in cardiac muscle is less extensive. b: The sarcoplasmic reticulum in cardiac muscle is more organized. c: Cardiac muscle has intercalated discs; skeletal muscle does not. d: Cardiac muscle has 1 or 2 nuclei per cell; skeletal muscle has multiple nuclei per cell. e: Cardiac muscle has more well-defined terminal cisternae.
a, c, d
In an EKG, the P wave is generated when the
atria depolarize
Cardiac output is the amount of blood that is pumped
by a single ventricle in one minute.
Most of the calcium that triggers contraction of cardiac muscle comes
from the sarcoplasmic reticulum of the cell.
The heart valves
permit the passage of blood in one direction.
In an ECG, what does the T wave represent?
repolarization of ventricles
Which type of muscle cell exhibits a longer refractory period?
Cardiac muscle cell
The shutting of the semilunar valves occurs during which phase?
Isovolumetric relaxation
The expected effect of the drug Digoxin is to _________________ ventricular contraction and _________________ stroke volume.
strengthen; increase
