Ch19.

Someone with a heart block would have:

a long P-R interval

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 A: c,d,a,b,f,g,e

Sympathetic innervation of the heart arises from the ... segments of the spinal cord

a: T1-T5

Large doses of certain stimulants can lead to dangerous increases in heart rates. Such a stimulant is a:

a: a positive chronotropic agent

An autorhythmic heart cell is one in which:

a: action potentials fire spontaneously

Just prior to atrial systole:

a: all four chambers are at rest and AV valves are open

Which type of muscle cell exhibits a longer refractory period?

a: cardiac muscle cell

Vagal tone refers to the:

a: decreasing of the heart rate below its inherent rhythm by parasympathetic stimulation

During the plateau phase of a cardiac muscle cell's action potential, the membrane stays:

a: depolarized as potassium exits and calcium enters

What describes the endocardium?

a: has single layer of epithelium b: has layer of areolar CT c: epithelial cells are squamous d: epithelial cells are cuboidal e: has layer of adipose CT f: has patches of myocardium A: a,b,c

Sympathetic innervation of the heart:

a: increases the heart rate b: decreases the heart rate c: increase the force of contractions d: decreases the force of contractions e: has no effect on contraction force A: a,c

Blood moves into and then out of a heart chamber because:

a: it moves along its pressure gradient, and that gradient depends on contraction and relaxation during the cardiac cycle

The serous fluid within the pericardial cavity works to:

a: lubricate membranes of the pericardium

Which correctly describes the heart's apex?

a: projects slightly anterioinferiorly toward the left side of the body

Which of the cardiovascular system's circuits has deoxygenated blood in its arteries?

a: pulmonary circuits

As blood is pumped out of the heart and into the major arteries leaving the heart, it:

a: pushes against the semilunar valves and opens them

Which functions performed by the fibrous skeleton of the heart?

a: seperates the atria and ventricles b: anchors the heart valves c: provides electrical insulation between the atria and ventricles d: provided the framework for the attachment of the myocardium e: none of these are true functions of the fibrous skeleton of the heart D: a,b,c,d

Someone with tacharrhythmia would be expected to show an abnormally:

a: small Q-T interval

The metabolic pathways of cardiac muscle make it:

a: somewhat susceptible to heart attack, since it relies so exclusively on aerobic metabolism

Which are the 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 per cell e: cardiac muscle has more well defined terminal cisternae A: a,c,d

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

The epicardium is another name for the:

a: visceral layer of the serous pericardium

The resistance in arteries to the ejection of blood by the heart is known as

afterload

The inferior, conical end of the heart is called the

apex

The pulmonary trunk receives blood from the right ventricle and conducts it toward the lung. The pulmonary trunk is a(n)

artery

The layer of the heart wall composed of cardiac muscle tissue is the:

b. myocardium

During a cardiac cycle, how many of the four chambers contract at any one time?

b: 2

Typically there are......papillary muscles that project from the wall of the left ventricle and attach to the chordae tendineae that support the left AV valve

b: 2

Which analogy fits the human heart?

b: It is like a double pump, each working side by side with the other

Which segment of the ECG reflects the plateau phase of ventricular muscle cells' action potentials?

b: S-T segment

Metabolically, cardiac muscle relies on:

b: aerobic metabolism using many mitochondria and a rich supply of myoglobin

Which of the following would cause a decrease in cardiac output?

b: an increase in afterload

Which valve prevents backflow of blood into the left ventricle when the ventricles relax?

b: aortic semilunar valve

According to the Frank-Starling law:

b: as the volume of blood entering the heart increases, ventricular contractions become more forceful

In an EKG, the P wave is generated when the:

b: atria depolarize

To initiate a cardiac muscle cell contraction, calcium:

b: binds to troponin

Once an SA nodal cell reaches threshold, the depolarization phase occurs during which:

b: calcium comes in through fast voltage-gated channels

The membrane of a contractile cardiac muscle cell contains:

b: calcium pumps that move calcium out of the cell

Which of the following is NOT one of the three main factors influencing stroke volume?

b: chronotropic agents

As with action potentials in other types of cells, the repolarization of cardiac muscle cells involves the:

b: exit of potassium through voltage-gated channels

The membrane of the contractile cardiac muscle cell contains:

b: fast voltage-gated sodium channels and slow voltage-gated calcium channels

Which layer is made of dense irregular CT?

b: fibrous pericardium

The atrioventricular (AV) node is located in the:

b: floor of the right atrium

The heart valves:

b: permit the passage of blood in one direction

From which view is the connection between the pulmonary veins and the heart most visible?

b: posterior view

The opening and closing of the heart valves is caused by:

b: pressure changes of alternating contraction and relaxation during the cardiac cycle

Which carries oxygenated blood from the lungs to the heart?

b: pulmonary veins

Cardiac reserve is:

b: the increase in cardiac output an individual is capable of demonstration during vigorous exercise

Cardiac output is the amount of blood that is pumped:

by a single ventricle in one minute

How many half-moon shaped, pocketlike cusps are found in each semilunar valve?

c: 3

The plateau phase of an action potential:

c: allows cardiac muscle cells to contract and then relax without locking up

Norepinephrine is considered a positive chronotropic agent since it causes:

c: an increase in firing rate of SA node cells

Which feature permits the compression necessary to pump large volumes of blood out of the ventricles?

c: arrangement of cardiac muscle in the heart wall

Which action leads to the closure of the right atrioventricular valve?

c: contraction of the right ventricle

At the AV node of the conduction system, the action potential is:

c: delayed due to the cells being small and having few gap junctions

The shutting of the semilunar valves occurs during which phase?

c: early ventricular diastole

Most of the calcium that triggers contraction of cardiac muscle comes:

c: from the sarcoplasmic reticulum of the cell

Cardiac output equals the:

c: heart rate multiplied by stroke volume

Pectinate muscles are found on the:

c: internal walls of the right and left atria

The posterior interventricular sulcus:

c: is a groove between the ventricles on the back of the heart

The base of the heart faces in the:

c: posterior and superior

In an ECG, what does the T wave denote?

c: repolarization of the ventricles

The fossa ovalis appears just above the opening of the coronary sinus within the:

c: right atrium

Which heart chambers would contain deoxygenated blood?

c: right atrium and right ventricle

The internal wall surface of each ventricle displays large, smooth, irregular muscular ridges called:

c: trabeculae carneae

The pericardial cavity is between the:

c: visceral and parietal layers of the serous pericardium

A chemical that alters heart rate is known as ...... agent

chronotropic

Parasympathetic innervation of the heart occurs via:

d: CN X

For the repolarization phase of an SA nodal cell action potential:

d: calcium channels close and potassium channels open

The papillary muscles attach to the cusps of the atrioventricular valves by means of the:

d: chordae tendineae

The atria are separated from the ventricles externally by the:

d: coronary sulcus

Atrial systole occurs just before:

d: early ventricular systole

A drug that decreased calcium levels in a muscle cell and thereby lowered the number of crossbridges formed during the heart's contractions would be a:

d: negative inotropic agent

Which pair is located more anteriorly in a heart in normal position?

d: right atrium and right ventricle

Each of the receiving chambers of the heart has a wrinkles flaplike extension; the one that is more visible from an anterior view is the:

d: right auricle

The left ventricle and aorta are part of which circuit of the cardiovascular system?

d: systemic circuit

Which circuit of the cardiovascular system is responsible for sending blood to the kidneys, stomach, and pelvic regions?

d: systemic circuit

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 cavae?

e: SA node

During ventricular systole:

e: the semilunar valves open and the AV valves close

Arteries carry blood toward the heart, while veins carry blood away from the heart

false

Cardiac reserve is greater in a nonathletic individual than in a highly trained athlete.

false

The hearts nodal cells have a more negative resting potential than neurons do, because nodal cells lack leak channels for sodium and potassium ions

false

Occlusion of blood vessels tends to lead to:

inadequate blood supply and damage to body tissues

What are the cell-to-cell contacts of the cardiac muscle fibers called?

intercalated discs

Cardiac output is usually expressed in:

liters per minute

The units for perfusion of blood are typically:

milliters per minute per gram

The time that starts when a muscle cell is depolarized and ends when it is able to be restimulated is the ......period

refractory

Deep to the interventricular sulci is the think muscular wall that divides the left and right ventricles, known as the intervemtricular

septum

The period of time when ventricles begin to contract is early ventricular.....

systole

Cardiac muscle is able to use a variety of fuel types for cellular respiration

true

Immediately prior to atrial systole, blood continues to enter the atria from the venae cavae and pulmonary veins

true

Like skeletal muscle cells, cardiac muscle cells have an absolute refractory period prior to repolarization

true

Myofibrils within cardiac muscle cells are aligned in sarcomeres?

true

Nodal cells contain fast voltage-gated calcium channels

true

Parasympathetic innervation influences the heart rate, but generally tends to have no direct effect on the force of contractions

true

Preload is the stretch of the heart wall as determined by the amount of blood returned by the veins

true

SA nodal cells are autorhythmic

true

The main functions of the cardiovascular system are the transport and exchange of respiratory gases, nutrients, and wastes throughout the body

true

The pericardium helps prevent overfilling of the heart and it lessens the friction of movements during heartbeats

true

The receiving chambers of the heart are the atria, and the forcefully pumping chambers of the heart are the ventricles

true