Cardiovascular Physiology

Front 1

Which ventricle pumps the blood into the pulmonary circulation?

Back 1

Right ventricle

Front 2

Three major types of cardiac muscle

Back 2

1- Atrial muscles.
2- Ventricular muscles.
3- Excitatory and conductive muscle fibers.

Front 3

The difference between the contraction of skeletal muscle and atrial, ventricular muscle

Back 3

the atrial and ventricular muscle have a longer contraction duration than the skeletal muscle.

Front 4

the intercalated disks are

Back 4

cell membranes

Front 5

How does the action potential travel from the atrial syncytium to the ventricular syncytium?

Back 5

Through the AV bundle.

Front 6

The action potential of the ventricular muscle averages

Back 6

105 millivolts

Front 7

The plateau of the ventricular muscle action potential lasts for about

Back 7

0.2 seconds

Front 8

In the cardiac muscle, the action potential is cause by which type(s) of channels

Back 8

1- Fast sodium channels.
2- Slow calcium channels.

Front 9

What's the difference between the cardiac muscle and the skeletal muscle in the source of calcium driving the contractile process.

Back 9

Skeletal muscle: Sarcoplasmic reticulum.
Cardian muscle: Extracellular calcium.

Front 10

The plateau observed in the action potential of the heart muscle is caused by

Back 10

1- The presence of the slow calcium channel.
2- The fivefold decreased permeability of the cell membrane to sodium after the onset of action potential.

Front 11

What's the duration of the refractory period of the atria and the ventricles?

Back 11

Atria: 0.15 second
Ventricles: 0.25-0.30 second

Front 12

Why is there a need for the extracellular calcium for the contraction of the cardfiac muscle to take place?

Back 12

because the sarcoplasmic reticulum is less well developed than that of the skeletal muscle

Front 13

Waht's the difference between the skeletal t tubules and the cardiac t tubules?

Back 13

The cardiac t tubules have a diameter 5 times as that of the skeletal t tubules, they also have a large quantity of negatively charged mucopolysaccharides to concentrate calcium ions needed for the contraction.

Front 14

Why can the heart function without any atrial contraction?(percents)

Back 14

80% of the blood flowing into the atria goes to the ventricles without any contraction, the 20% left is pumped to the ventricles when the atria contract.

Front 15

Thwe papillary muscles attach to the cusps by the

Back 15

Chordae tendinae

Front 16

The incisura in the aortic pressure curve occurs due to

Back 16

a short period of backflow of blood then sudden cessation of the backflow as the valve closes

Front 17

The first heart sound is caused by

Back 17

the closure of the A-V valves

Front 18

The second heart sound is caused by

Back 18

The closure of the semilunar valves

Front 19

Stroke work output(definition)

Back 19

the amount of energy the heart converts to work every heartbeat

Front 20

Definition: Minte work output

Back 20

The amount of energy the heart converts to work in 1 minute

Front 21

The Frank-Sterlingh mechanism

Back 21

the greater the heart muscle is stretched during contraction, the greater is the force of contraction, and the greater the quantity of the blood pumped into the aorta

Front 22

Normal heart rate

Back 22

70 beats/minute(60-100)

Front 23

The sinus node is connected to the A-V node through the

Back 23

internodal pathways

Front 24

The location of the sinus node is

Back 24

the superior posterolateral wall of the right atrium

Front 25

The RMP of the sinus node is

Back 25

-55 to -60

Front 26

The channels responsible for the APs in the sinus node are

Back 26

The slow calcium channels

Front 27

Why don't the sodium channels contribute to the AP of the sinus node

Back 27

because when the membrane potential is less negative than -55 the inactivation gate remains closed

Front 28

The threshold for the SA node

Back 28

-40 mv

Front 29

What's the location of the A-V node?

Back 29

posterior wall of the right atrium directly behind the tricuspid valve

Front 30

What's the delay caused by each potion of the AV node?

Back 30

1- 0.09 s A-V node.
2- 0.04 s Penetrating A-V node.
3- 0.03 s conduction delay threough the internodal pathways.
= 0.16 s of delay.

Front 31

What's the cause of the slow conduction in the A-V node?

Back 31

The diminished number of gap junctions between successive cells

Front 32

The velocity of the transmission of the purkinje fibers is:

Back 32

1.5-4.0 m/sec

Front 33

What are the rhythmic rate of the following:
1- Sinus node.
2- A-V node.
3- Purkinje fibers

Back 33

1- 70-80 times/minute.
2- 40-60 times/minute.
3- 15-40 times/minute.

Front 34

What's an ectopic pacemaker?

Back 34

A pacemakes elsewhere than the sinus node

Front 35

What's stokes-adam syndrome

Back 35

The delay between the blockage of the normal conduction pathway and the rhythmatical activity of the purkinge fibers

Front 36

Ventricular escape

Back 36

The purkinje fibers start generating their own APs after the AV and SA nodes are inhibited by the acetylcholine released from the vagi

Front 37

What's the time interval between ventricular depolarization and repolarization

Back 37

0.25-0.35 s

Front 38

Define P-R interval

Back 38

The time between the beginning of the P wave and QRS complex. It's the time between atrial excitation and ventricular excitation(0.16 s), it shows the delay shown in the A-V node.

Front 39

Define Q-T interval

Back 39

The interval from the beginning of the QRS complex to the end of the T wave(0.35 s), this is the duration of the ventricular contraction.

Front 40

What's the configuration of the lead 1?

Back 40

The negative terminal is connected to the right arm and the positive terminal is connected to the left arm

Front 41

What's the configuration of lead two?

Back 41

The negative terminal is connected to the right arm and the positive terminal is connected to the left leg

Front 42

What's the configuration of lead III?

Back 42

The negative terminal is connected to the left arm and the positive terminal is connected to the left leg

Front 43

What's Einthoven's law?

Back 43

If the electrical potentials of two of the leads are known at a given instant then the third one can be determined mathematically by summating the first two.

Front 44

What are the precordial leads that have negative recordings, and why?

Back 44

V1 and V2
Because they're near to the base of the heart which is the direction of electronegativity during most of the ventricular depolarization.

Front 45

Which one of the augmented unipolar limb leads is inverted?

Back 45

The aVR

Front 46

The first part to be polarized in the ventricles after the impulse travels through the A-V bundle is

Back 46

the left endocardial surface of the septum

Front 47

What's the first area to repolarize in the atria?

Back 47

The area around the sinus node

Front 48

Give another name for the A-V bundle

Back 48

Bundle of His

Front 49

What's the normal P-R interval?

Back 49

0.12 - 0.2 second

Front 50

What's the normal duration of the QRS complex?

Back 50

0.12 s (three squares)

Front 51

What does each of the chest leads look at?

Back 51

V1 & V2: Right ventricle.
V3 & V4: Ventricular Septum.
V5 & V6: anterior and lateral walls of the left ventricle.

Front 52

What's the normal range of the degree of the cardiac axis?

Back 52

-30 to +90