Learning Assessment Quizzes (4,6,7)

Question 1

Under normal conditions, all cardiac electrical activity is initiated in the

Answer 1

SA Node

Question 2

Propagation of an action potential across the intercalated disc is due to _____________ through gap junctions.

Answer 2

the electrostatic attraction of ions

Question 3

The direct propagation of cardiac action potentials between atrial and ventricular myocytes is prevented by

Answer 3

the cardiac skeleton

Question 5

The term _________________ is used to describe conduction velocity.

Answer 5

Dromotropic

Question 6

Control of cardiac function can be regulated or modulated via (select all correct answers):

1. The parasympathetic nervous system
2. Autoregulation
3. The sympathetic nervous system
4. The somatic nervous system

Answer 6

1,2,3

Question 7

Primary control of heart rate in an normal, healthy individual at rest is due to changes in _________________ input to the sinoatrial (SA) node.

Answer 7

Parasympathetic

Question 8

Increased parasympathetic input to the sinoatrial (SA) node results in _______________ of the nodal cells due to an increased permeability of the cell membrane to ____________.

Answer 8

hyperpolarization; potassium

Question 9

The cardiac sympathetic nerve innervates which of the following (select all correct answers):

1. atria
2. atrioventricular (AV) node
3. ventricles
4. sinoatrial (SA) node

Answer 9

All of the above

Question 10

Sympathetic input has a positive chronotropic effect by increasing cell membrane permeability to

Answer 10

Na+/Ca+

Question 11

Sympathetic input to ventricular myocytes has a _____________________ effect.

Answer 11

positive inotropic

Question 12

When stimulated to contract, cardiac myocytes contract as a single unit due to the presence of gap junctions at the intercalated discs. This property is known as a/an:

Answer 12

functional syncytium

Question 13

Propagation of a cardiac action potential down a transverse tubule results in the opening of ____________ channels.

Answer 13

voltage-gated L-type calcium

Question 14

The influx of extracellular calcium following excitation acts as ______________ calcium to open calcium channels on the sarcoplasmic reticulum.

Answer 14

trigger

Question 15

Relaxation of cardiac myocytes occurs with the majority of calcium

Answer 15

being actively pumped back into the sarcoplasmic reticulum.

Question 16

The resting tension on a cardiac myocyte is influenced by

Answer 16

preload and EDV

Question 17

The term used to describe the downstream pressure/resistance that has to be overcome in order for blood to be ejected from the ventricles is know as

Answer 17

afterload

Question 18

In the heart, a positive inotropic effect results in ______________ in a myocyte’s ability to shorten.

Answer 18

increase

Question 19

Cardiac myocyte relaxation is influenced by the re-uptake of calcium by the sarcoplasmic reticulum. Sympathetic input can ____________ relaxation by leading to the phosphorylation of __________________.

Answer 19

increase; phospholamban

Question 20

In addition to increasing the relaxation rate of cardiac myoctes, sympathetic input can shorten the absolute refractory period

Answer 20

by increasing cell membrane permeability to potassium via delayed rectifier channels.

Question 21

One complete cycle of the cardiac cycle includes (select all that apply)

1. cardiac muscle excitation
2. cardiac relaxation
3. ejection of blood from ventricles
4. cardiac filling

Answer 21

all of the above

Question 22

Following the ejection phase, as a result of blood moving away from the heart:

Answer 22

aortic pressure decreases

Question 23

During the majority of diastole, filling of the ventricles is

Answer 23

passive

Question 24

Isovolumetric contraction of the left ventricle occurs until

Answer 24

the aortic valve opens

Question 25

The isovolumetric relaxation phase starts

Answer 25

when the aortic valve closes

Question 26

During the ejection phase

Answer 26

ventricular myocytes shorten

Question 27

The volume of blood ejected from the ventricles in relation to the starting volume is known as

Answer 27

ejection fraction