A&P Ch 19 Cardiovascular System: Heart

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

artery

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

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

calcium channels close and potassium channels open.

Which type of muscle cell exhibits a longer refractory period?

cardiac muscle cell

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

chordae tendineae.

Vagal tone refers to the:

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

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

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

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

depolarized as potassium exits and calcium enters.

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 atrioventricular (AV) node is located in the:

floor of the right atrium.

Cardiac output equals the:

heart rate multiplied by stroke volume.

Pectinate muscles are found on the:

internal walls of the right and left atria.

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

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

Which chamber of the heart contains pectinate muscles in its walls?

left and right atrium

Which chamber(s) of the heart contains papillary muscles in its walls?

left and right ventricles

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 heart valves:

permit the passage of blood in one direction.

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

During ventricular systole:

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.

About 70% of the ventricle filling is achieved passively without the contraction of the atria.

true

Though the autonomic innervation by autonomic centers in the brainstem cannot initiate a heartbeat, it can increase or decrease the heart rate.

true

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

2

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

An increase in afterload

P wave

Atrial depolarization

QRS wave

Atrial repolarization Ventricular depolarization

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

The right ventricle pumps a smaller volume of blood than the left ventricle.

False

Which layer is made of dense irregular connective tissue?

Fibrous pericardium

Why is it important that cardiac muscle not undergo force summation?

If it did, then the heart would not have enough time to relax and fill up, causing it to stop pumping.

Which analogy fits the human heart?

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

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

Pulmonary circuit

Which carries oxygenated blood from the lungs to the heart?

Pulmonary veins

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

S-T segment

The right ventricle pumps blood at a lower pressure than the left ventricle.

True

T wave

Ventricular repolarization

Sympathetic innervation of the heart: a: increases the heart rate b: decreases the heart rate c: increases the force of contractions d: decreases the force of contractions e: has no effect on contraction force

a, c

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

An autorhythmic heart cell is one in which:

action potentials fire spontaneoulsy.

Just prior to atrial systole:

all four chambers are at rest and AV valves are open.

The plateau phase of an action potential:

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

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

Aortic semilunar valve

Route of blood flow

Right atrium Right AV valve (tricuspid) Right ventricle Pulmonary semilunar valve Pulmonary trunk Pulmonary arteries Lungs Pulmonary veins Left atrium Left AV valve (bicuspid) Left ventricle Aortic semilunar valve Aortic arch

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

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

Systemic circuit

Describe what prevents summation of force in cardiac muscle tissue.

The plateau between depolarization and repolarization extends the absolute refractory period and opens Na+ channels allowing the sarcomeres in cardiac muscle in the heart to fully contract and relax before being stimulated again.

Someone with a heart block would have:

a long P-R interval.

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

Metabolically, cardiac muscle relies on:

aerobic metabolism using many mitochondria and a rich supply of myoglobin.

Norepinephrine is considered a positive chronotropic agent since it causes:

an increase in the firing rate of SA node cells.

To initiate a cardiac muscle cell contraction, calcium:

binds to troponin.

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.

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

The left ventricle walls are typically thicker than the right ventricular wall.

true

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

true

The epicardium is another name for the:

visceral layer of the serous pericardium.