A&P 2: Chapter 19 Heart Part 2

action potentials fire spontaneoulsy

An autorhythmic heart cell is one in which _?

pushes against the semilunar valves and opens them.

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

calcium channels close and potassium channels open.

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

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

At the AV node of the conduction system, the action potential is ______?

3

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

aerobic, mitochondria, myoglobin

Metabolically, cardiac muscle relies on __________ metabolism using many ___________ and a rich supply of _________.

calcium comes in through fast voltage-gated channels

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

internal walls of the right and left atria

Pectinate muscles are found on the ?

ensure that blood flow is "one-way"

The heart valves ________.

trabeculae carneae

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

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

The membrane of a contractile cardiac muscle cell contains ______________.

chordae tendineae

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

intercalated discs

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

c: SA node d: Through the atria a: AV node b: AV bundle f: Bundle branches g: Purkinje fibers e: Through the ventricles

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

contraction of the ventricles

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

a: The sarcoplasmic reticulum in cardiac muscle is less extensive 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.

Which are differences between cardiac muscle tissue and skeletal muscle tissue?

• Separates the atria and ventricles • Anchors the heart valves • Provides electrical insulation between the atria and ventricles • Provides the framework for the attachment of the myocardium

Which are functions performed by the fibrous skeleton of the heart?

2

Typically, there are __________ papillary muscles that project from the wall of the left ventricle and attach to the tendinous cords that support the left AV valve.

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

Vagal tone refers to the ______.

Arrangement of cardiac muscle in the heart wall

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

somewhat susceptible to heart attack, because it relies so exclusively on aerobic metabolism.

The metabolic pathways of cardiac muscle make it

aortic semilunar valve

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