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Bio 22-Lab Test 2 > Lab 9 > Flashcards

Lab 9 Flashcards

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1
Q

? are striated and joined to adjacent cells by ? that appear as dark staining lines (?) when viewed with a light microscope.

A
  • Myocardial cells
  • gap junctions
  • intercalated discs
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2
Q

Since the myocardial cells are electrically coupled, the mass of myocardial cells joined together by the intercalated discs acts as one unit, a ? known as a ?.

A
  • functional syncytium

- myocardium

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3
Q

In a normal heart, (1) cells in the (2) initiate action potentials that allow the heart to beat. This (3) or (4) rhythm is brought about without nervous system input, but can be modified by the ANS or by increased venous return to the heart chambers.

A
  1. autorhythmic
  2. sinoatrial (SA) node
  3. automatic
  4. intrinsic
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4
Q

The autorhythmic cells initiate (1) that allow the myocardium to function as a unit. The cells have an (2), causing them to (3) to threshold.

A
  1. action potentials
  2. unstable resting membrane potential
  3. spontaneously depolarize (pacemaker potential)
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5
Q

The spontaneous depolarization to threshold is caused by channels (?) that open in response to a hyperpolarization or an increase in cyclic nucleotide second messengers.

A

HCN, hyperpolarization cyclic nucleotide channels

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6
Q

The ? involve a slow influx of Ca2+ which will trigger the excitation contraction coupling events for cardiac muscle to contract.

A

myocardial action potentials

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7
Q

The ? of the heart consists of ? that distribute impulses in a coordinated fashion so that the atrial and ventricular contractions are controlled.

A
  • intrinsic conduction system

- nodal tissues

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8
Q

nodal tissues include

A

the SA node, three internodal tracts, the atrioventricular (AV) node, the atrioventricular
bundle (AV bundle or bundle of His), right and left bundle branches, and Purkinje fibers.

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9
Q

The SA node is the ? of the heart, discharging at about 70-80 times per minute; the characteristic rhythm of the heart is thus called ?.

A
  • primary pacemaker

- sinus rhythm

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10
Q

The AV node (?, 40-60 beats per minute) will become the primary pacemaker should something happen to the SA node.

A

secondary pacemaker

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11
Q

The junction between the atria and the ventricles is associated with an interval between atrial and ventricular activity (?).

A

A-V delay

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12
Q

junctional fibers propagate excitation at velocities as low as 5 cm/sec. This slow propagation accounts for the interval of “A-V delay”, but is important in allowing the atria to contract fully (?) before the ventricles contract.

A

atrial systole

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13
Q

The Purkinje fibers are also capable of their own intrinsic pacemaker rhythms
(?, 30-40 discharges per minute).

A

tertiary pacemakers

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14
Q

Ventricular contraction (?) immediately follows the depolarization of the ventricles.

A

ventricular systole

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15
Q

? of the myocardium signifies the relaxation of the heart muscle and is termed ?.

A
  • Repolarization

- diastole

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16
Q

continual cycling of the electrical conduction (and thus systolic contractions followed by diastolic relaxation) is termed the ?.

A

cardiac cycle

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17
Q

A ventricular rate that is slower than 60 beats per minute is referred to as ?.

A

bradycardia

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18
Q

A ventricular rate that is faster than 100 beats per minute is termed ?.

A

tachycardia

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19
Q

a graphic recording of the electrical currents generated by the cardiac cycle.

A

electrocardiogram (ECG or EKG)

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20
Q

During a cardiac cycle, three distinct waves can be seen on the ECG:

A

the P wave, the QRS complex, and the T

wave.

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21
Q

represents the depolarization of the atria.

A

The P wave

22
Q

represents depolarization of the ventricles.

A

The QRS complex (0.08 sec)

23
Q

represents repolarization of the ventricles.

A

The T wave

24
Q

Critical measurements in an electrocardiogram are

A
  • the P-R interval
  • the S-T segment
  • the Q-T interval
25
Q

less than 0.2 sec, represents atrial depolarization and systole as well as depolarization throughout the rest of the system

A

the P-R interval

26
Q

the plateau of the action potential when all of the myocardium is depolarized

A

the S-T segment

27
Q

0.31-0.43 seconds, the period from ventricular depolarization through ventricular repolarization

A

the Q-T interval

28
Q

can be positioned at various locations on the body to record the ECG.

A

Recording electrodes (leads)

29
Q

record the voltage difference between electrodes on the wrists and legs in ECG

A

Bipolar limb leads

30
Q

records electrical potentials between the right arm and left arm in ECG

A

Lead I

31
Q

records right arm to left leg in ECG

A

Lead II

32
Q

records left arm to left leg in ECG

A

Lead III

33
Q

serves as the ground in ECG

A

right leg

34
Q

exploratory electrodes that use a built in ground in the electrocardiograph machine.

A

Unipolar leads

35
Q

The unipolar limb leads are the ? (right arm), ? (left arm), and ? (left leg) in ECG.

A

AVR, AVL, AVF

36
Q

The ? are numbered V1-V6 and begin at the midline of the chest (4th intercostal space) to the right of the sternum in ECG

A

unipolar chest leads

37
Q

a total of ? that are used to monitor the electrical

activity of the heart from different perspectives.

A

12 standard ECG leads

38
Q

? are caused by irregular heart rhythms called ?. They can occur when there is a defect in the intrinsic conduction system.

A
  • Abnormal ECG patterns

- arrhythmias

39
Q

At times, abnormal beats develop in the myocardia as a result of the formation of an ?. In the atria, this develops in addition to the SA node, and can lead to atrial flutter or fibrillation.

A

ectopic pacemaker

40
Q

characterized by rapid atrial waves (sawtooth appearance), with the AV node beating to every third or fourth wave it receives.

A

Atrial flutter

41
Q

characterized by an absence of P waves that are replaced by a wavy baseline.

A

Atrial fibrillation

42
Q

Ectopic foci in the ventricles result in a rapid discharge called ?. With this, the ECG will show a widened and distorted QRS complex that obscures the P waves.

A

ventricular tachycardia

43
Q

the most serious arrhythmia. It results in uncontrolled contractions which do not allow the ventricles to adequately pump blood. No definable waves are seen.

A

Ventricular fibrillation

44
Q

Electrically shocking the heart depolarizes the entire myocardium, hopefully allowing the natural sinus rhythm to be restored by the SA node. This technique is called ?.

A

defibrillation

45
Q

At times, ectopic foci appear when the heart is functioning normally. Impulses are generated even
more quickly than the normal sinus rhythm of the SA node. These ? result in ?.

A
  • premature ventricular contractions (PVCs)

- extrasystoles

46
Q

extra contractions of the ventricles, a QRS complex

without a preceeding P wave

A

extrasystoles

47
Q

There are also times when delays occur between the atria and ventricles. These are known as ?, and they interfere with pacing signals to the ventricles.

A

AV blocks

48
Q

In a ?, the ECG looks normal but the P-R interval is greater than 0.20 seconds.

A

first degree AV block

49
Q

In a ?, two or more P waves are seen before a QRS complex is recorded. This looks like a “dropped” beat on the ECG recording.

A

second degree AV block

50
Q

? or ? occurs when no signals from the atria reach the ventricles. The P wave is normal but not related to the QRS. The ventricles are freed from the SA
node and ectopic pacemakers appear in the ventricles. The rhythm is slowed to 20-40 beats per minute.

A
  • Third degree AV block

- complete AV block

Bio 22-Lab Test 2 (4 decks)

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