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adv. anatomy + physiology > m7 + 8 lab - EKG > Flashcards

m7 + 8 lab - EKG Flashcards

1
Q

what does an ECG do?

ECG

A

electrocardiogram (ECG or EKG) = takes .80 sec per beat = 75bpm
- measures the electrical activity of the nodal system + the myocardium
—> determines activity or inactivity due to damage or ischemia to the myocardium

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2
Q

what is the nodal system?

ECG

A
  • initiated by the intrinsic conduction system —> initiates heart contractions independently of all CNS activity (reason why brain dead patient has a heart beat - bc heart has O2 + nutrient supply)
  • made from autorhythmic cells
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3
Q

what do autorhythmic cells do in the nodal system?

ECG

A
  • spontaneously depolarize to trigger contraction - called pacemaker potential (set @ 100 bpm)
  • some regulation by the ANS
    1. SNS = cardioacceletory —> increased HR
    2. PSNS = cardioinhibitory —> decreased HR
    => thru vagus nerve stim.
    => vagal response - stimulate vagus nerve to decrease HR 1)valsalva
    2) carotid
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4
Q

aspects of the myocardium:

ECG

A
  • connected by gap-junctions
  • two units: atria + ventricles
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5
Q

what happens during isovolumetric time?

valves + filling of blood

A

volume in ventricle is not changing due to valve action
- depo. (right after Q wave)
- repo. (right before T wave)

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6
Q

when do the AV and semilunar valves open + close?

valves + filling of blood

A

AV valves
- closes at beginning of depo. at the Q-wave
- opens at the end of repo. at the T-wave
semilunar valves
- opens at the end of depo. at the Q-wave
- closes at the beginning of repo. at the T-wave

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7
Q

what happens at the beginning of the P-wave?

valves + filling of blood

A
  • SA node initiates atrial depo. leading to contraction (helps fill ventricles)
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8
Q

what happens at the beginning of the Q-wave?

valves + filling of blood

A
  • signal is conducted to purkinje fibers
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9
Q

what happens between the Q-wave (depo.) and the T-wave (repo.)?

valves + filling of blood

A

blood is ejected from the ventricles creating:
- circulation
- pressure

  • BP: systole (120mmHg) = contraction
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10
Q

what happens between the end of the T-wave and the Q-wave?

valves + filling of blood

A

ventricles are refilling (this is occuring durring the SA node initiating atrial contraction)
- 80% is by gravity and circulation
- 20% is by the atrial contraction occuring at the P-wave by the SA node

  • BP: diastole (80mmHg) = relaxation
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11
Q

what happens at the sinoatrial node (SA node)?

cardiac intrinsic conduction

A
  • called the pacemaker
  • largest
  • initiates depolar. leading to contraction of atria @ 100bpm
  • depo. wave starts + spreads out to both atria through intercolated discs –> atria contract at the same time
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12
Q

what happens at the atrioventricular node (AV node)?

cardiac intrinsic conduction

A

delays signal by 0.1 second to allow blood to drain from atria into ventricles

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13
Q

what happens at the atrioventricular (AV) bundle? (bundle of His)

cardiac intrinsic conduction

A
  • carries electrical impulses from the atrioventricular (AV) node to the ventricles
  • bundle of His and Purkinje fibers work together to create ventricular contractions in the heart
    —> descends down the interventricular septum, which separates the right and left ventricles.
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14
Q

what happens at the purkinje fibers?

cardiac intrinsic conduction

A
  • initiates ventricular depo. = then a contraction occurs = ejecting blood = creating pressure and circulation
  • ventricles pump same volume
    —> RV = pumps deoxygenated blood to lungs
    —> LV = pumps oxygenated blood thru the aorta and to the rest of the body
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15
Q

what happens at the P-wave?

electrocardiography

A

initated by SA node - atrial depo. = then atrial contraction

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16
Q

what happens during the QRS complex?

electrocardiography

A

stimulated by purkinje fibers = causes ventricular depo. = then contraction = ventricles eject blood

  • atrial repo. occurs during QRS complex
17
Q

what happens during P-Q interval?

electrocardiography

A
  • point of conduction from SA node to Purkinje
  • atria are depo. = then contracting = filling the last 20% of the the ventricles
  • normal time: .12 - .20 sec
  • > = heart block
  • < = tachycardia or fibrillation
18
Q

what happens during the Q-T interval?

electrocardiography

A
  • ventricles depo. at Q-R wave = causing a contraction
  • during S-T interval, ventricles are ejecting blood = circulation + pressure
  • then ventricular repo. at T-wave
  • normal time: .31 - .41 sec ( < or > = problems w/ circulation)
  • < = dec. filling + ejection = tachycardia
  • > = dec. ejection, dec. flow = long Q-T , genetic condition
19
Q

when do systole and diastole occur?

electrocardiography

A

systole - during Q-T interval (120mmHg)
- blood is ejected from ventricles by contraction
diastole - during T-Q interval (80mmHg)
- ventricles are refilling with blood - relaxation period
- 80% by gravity + circulation, 20% by atrial contraction

20
Q

what is einthoven’s triangle?

standard limb leads

A

lead I = RA - LA
lead II = RA - LL
lead III = LA - LL

21
Q

what is a normal ECG cycle length?

ECG cycle

A

.8 seconds long

22
Q

what are the two divisions of an ECG cycle?

ECG cycle

A

diastole = relaxation
- ventricular filling (passive + active refilling)
- from T-Q wave

systole = ejection
- ventricular contraction + ejection = circulation
- from QRS to end of T-wave

23
Q

what happens during the P-Q interval?

ECG cycle

A
  • AV node delays signal .1 sec to allow ventricular filling
  • normal time: .12-.20 sec
  • > .20 sec = heart block (usually at AV node)
24
Q

what happens at the Q-T interval?

ECG cycle

A
  • all ventricular activity (systole=contraction)
  • normal time: .31-.41 sec
  • stays around the same even during exercise
  • if it elongates, could cause syncope or fibrillation
25
Q

what are the two ways to cause a vagal response?

lower BP

A

1) rectum - straining can cause fainting
2) carotid sinus - massaging can cause fainting

26
Q

how long are each square on a ECG?

ECG examples - sinus rhythms

A

each square = .20 sec
1/5 of the square = .04 sec

find average by adding three sections together / by 3 = average
ex.) .76 + .70 + .76 / 3 = .74
normal sinus rhythm: 60 / average = HR
ex.) 60 / .74 = 81 bpm

27
Q

what indicates sinus bradycardia and sinus tachycardia?

ECG examples - sinus rhythms

A

bradycardia - HR is below 60 bpm
tachycardia - HR is above 100 bpm

28
Q

what indicates atrial fibrillation?

ECG examples - fibrillation

A

no P wave

29
Q

what indicates ventricular fibrillation?

ECG examples - fibrillation

A

no pattern visible

adv. anatomy + physiology (24 decks)

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