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Cardioresp > 3 > Flashcards

3 Flashcards

1
Q

how are cardiac and skeletal muscle similar

A

both have striations

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2
Q

how are cardiac and skeletal muscle different

A

skeletal: each fibre is separate and innervated by nerve from spinal cord
cardiac: fibres are connected
mechanically: intercalated discs
electrically: gap junctions in intercalated discs

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3
Q

what are some ribosomes found in the cardiac muscle fibre

A 
mitochondria
sarcoplasmic reticulum 
sarcomere
T tubules
bands
sarcolemma (PM)
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4
Q

what’s the sarcolemma

A

equivalent of plasma membrane but for muscle cells

barrier…

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5
Q

are there any intrinsic nerves in the heart

A

no

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6
Q

what vessel supplies the AV node

A

RCA, so if there’s MI there, no beat unless good enough anastomosis from LCA

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7
Q

where is the SA node found

A

right atrium near entry of SVC

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8
Q

are nodes nerves?

A

no, they’re modified cardiac cells

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9
Q

where is the AV node found

A

inter atrial septum near tricuspid valve

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10
Q

how are AP initiated=

A

by opening of sodium and calcium channels

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11
Q

what’s the funny current

A

mixed sodium–potassium current that activates upon hyperpolarization
after each AP, potassium channels close and Na channels open
it dictates pacemaker potential

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12
Q

when is a new AP generated

A

when there’s enough Na and Ca channels open (above threshold)

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13
Q

what ion Chanel maintains the resting potential enter -70 et -90 mv

A

K channels

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14
Q

what systems can alter the speed and rhythm of firing of SA node

A

sympathetic and parasympathetic NS

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15
Q

explain the effect of the PNS on the SA node

A

slows down pacemaker cells
vagus nerve actus via interneurones to inhibit closure of K channels via MUSCARINIC receptors
(depolarisation takes longer)

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16
Q

explain the effect of the SNS on the SA node

A

increase HR pacemaker cells
adrenaline increase rate of closure of K channels via beta adrenoreceptors
(depolarisation takes shorter)

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17
Q

explain the effect of the PNS SNS on the AV node

A

they have an effect bas weaker

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18
Q

what is sinus arrhythmia and why does it happen

A

decrease in HR during expiration (respiratory sinus arrhythmia is normal)
happens bc parasympathetic outflow to vagus nerve increases during expiration and decreases during inspiration

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19
Q

what drug blocks parasymp? what can it be used for

A

atropine blocks PNS and can be used to treat sinus arrhythmia.

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20
Q

how long after SA node stimulation does AP reach both atria and AV node

A

60ms

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21
Q

how long after SA node stimulation does AV node transmit AP to ventricles papillary muscle and bundle of his

A

120 ms

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22
Q

how long is the delay at AV node

A

60ms

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23
Q

where does AV node transmit AP

A

to ventricles PAILLARY MUSCLE and bundle of His

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24
Q

why is there a delay at AV node

A

to allow atria to contract and fill ventricles

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25
Q

are Purkinje fibres nerves

A

no they are fast conducting cardiac muscle

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26
Q

what two branches come off the bundle of his

A

right bundle branch and left bundle branch

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27
Q

what are the fibres that branch out from the bundle branches

A

Purkinje fibres

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28
Q

where do the right and left bundle branches connect

A

bundle of His

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29
Q

what’s one unique feature of the AV node

A

Decremental conduction. the more its stimulated the slower it conducts, so that in atrial fibrillation the ventricles don’t contract too quickly and still have time to fill

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30
Q

what part of the ventricle first contracts

A

papillary muscles

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31
Q

how long after SA stimulation is the base of the heart stimulated

A

180ms

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32
Q

how do valves close

A

papillary muscles pull on chordate tendinae

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33
Q

what pathologies result from poor conduction?

A

bundle branch blocks. can be a result of ischemia of septum (bc it causes poor conduction)

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34
Q

dos branch block necessarily mean CESSATION of conduction

A

no it can just be a decrease in conduction

35
Q

in terms of AP, what is one key difference between cardiac and skeletal muscle

A

cardiac muscle needs to contract longer so there’s a plateau with a prolonged Ca entry to cell.

36
Q

explain the process of ventricular muscle action potential initiation

A 
Na channels open. na influx.
k and cl out
prolonged and delayed ca entry (PLATEAU)
k out
k rectified
37
Q

what channels do calcium enter from

A

L type calcium channels on cardiac cells

38
Q

what drugs can be given to reduce strength of contraction and so work of the heart and o2 demand

A

calcium Chanel blockers.

39
Q

strength of contraction of ventricular muscle depends on what

A

calcium concentration intracellylary

40
Q

Na Chanel blockers (CLASS 1)

A

weak: lidocaine phenytoin
moderate: quinidine proquanindaine
strong flecavidine, propafenone

41
Q

ca Chanel blockers (CLASS 4)

A

verapamil, dilfiazen

42
Q

k Chanel blockers (CLASS 3)

A

amiodanone sotalol

43
Q

beta blockers (CLASS 2)

A

BLOCK K rectifier
propanolol
metaprolol

44
Q

why is a refractory period important

A

prevents premature muscle contraction and so allows everything to beat in synchonry

45
Q

what tool can be used to override refractory period

A

defibrillator

46
Q

what are the 6 limb leads and what area do they measure

A 
lead 1: Left --> Right axillae
lead 2: Right axillae --> leg
lead 3: Left axillae --> leg
aVL
aVR
aVF
47
Q

what is one downside of limb leads

A

it only gives you an image on the frontal plane.

48
Q

what leads make up eiahovens triangle

A

lead 1: Right –> Left axillae
lead 2: Right axillae –> leg
lead 3: Left axillae –> leg

49
Q

standard ECG is recorded from which lead and why

A

lead 2 because it gives off the largest signal

50
Q

PR interval normal duration

A

120-200ms

51
Q

QRS complex normal duration

A

60-100ms

52
Q

which wave on an ECG is not always visible

A

Q

53
Q

P wave normal duration

A

100 ms

54
Q

what does the P wave correspond to?

positive/negative?

A

START of atrial depolarisation

positive in leads 1, 2 and sometimes 3

55
Q

what does the PR interval correspond to

A

delay at AV node

56
Q

what does the QRS complex correspond to

positive/negative?

A

electrical activity in ventricles

polarity depends on lead, can be pos, neg, bipolar.

57
Q

what does the R wave correspond to?

positive/negative?

A

ventricle depolarization
ALWAYS POSITIVE
present on leads 1,23

58
Q

what does the ST segment correspond to?

what is one unique feature of the ST segment

A

the interval between ventricular depolarization and repolarization
its isoelectric 0mV can be raised in MI

59
Q

what does the T wave correspond to

positive/negative?

A

repolarisation of ventricles.
base of ventricle depolarises depolarises before apex so upward wave
pathological T wave for septum injuries
normally same polarity as QRS

60
Q

how many seconds in one big square?

A

0.2 seconds

61
Q

how many seconds in one small square?

A

0.04s

62
Q

how many small square for 1 mV

A

10

63
Q

how many mm for 1 second

A

25

64
Q

when is the ECG large

A

when depolarisation is changing

65
Q

what does the Q wave correspond to

positive/negative?

A

earlier depolarisation of left side of intervenrticalr septum
NEGATIVE
lead 1, aVL, V5, V6

66
Q

what does the S wave correspond to?

positive/negative?

A

spread to depolarisation to base of ventricle

negative ALAWYS

67
Q

what are the 3 augmented leads

A

aVR from middle to right axillae
aVL from middle to left axillae
aVF from middle to groin

68
Q

how are the augmented leads oriented

A

aVR upside down
aVL v small
aVF variable bas normally like lead 2

69
Q

what is one benefit of augmented leads over the three standard ones

A

help better identify locus of abnormality

70
Q

how many chest leads are there and what are their names

A

6 (V1-V6)

71
Q

what is one benefit of chest leads over limb leads

A

gives you a 3D picture

72
Q

what are pericardial leads

A

chest leads

73
Q

location of V1

A

4th ICS left sternal edge

74
Q

location of V2

A

4th ICS right sternal edge

75
Q

location of V3

A

Rib 5 entre V2 and V4

76
Q

location of V4

A

5th ICS midclavicular

77
Q

location of V5

A

5th ICS anterior axillar

78
Q

location of V6

A

5th ICS midaxilla

79
Q

where an apex beat be heard

A

v4

80
Q

chest leads measure from what

A

from an imaginary reference point in the heart to the position of electrode

81
Q 
what degree are the following in
v1
v2
v3
v4
v5
v6
A 
v1 100
v2 80
v3 75
v4 60
v5 30
v6 0
82
Q

V leads can also be called

A

c leads

83
Q

what is the normal polarity of leads v1 to v6

A 
v1  negative (small R large S)
v2 negative (small R large S)
v3 bipolar
v4 bipolar
v5 positive (large R small S)
v6 positive (large R small S)
84
Q 
what parts of the heart is each lead best at
I II III
aVL 
aVR
aVF
V1-V6
A 
v1 view septal
v2 view septal
v3 view anterior heart wall
v4 view anterior heart wall
v5 v6 I aVL lateral wall
II III aVF inferior

Cardioresp (23 decks)

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