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Pharmacy Year 2 Semester 1 > Patient - ECG > Flashcards

Patient - ECG Flashcards

1
Q

Which channels, when opened, cause the polarisation of membrane?

A

K+ cationic gated ion channels

Voltage gated can be Ca2+ and Na+

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2
Q

Describe Ca2+ induced Ca2+ release

A

1) Entry of Ca2+ during plateau phase
2) Drives the release of more Ca2+ from internal stores in sarcoplasmic reticulum
3) Ca2+ binds to troponin, exposing actin to myosin
4) Actin/myosin fibres contract, using ATP

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3
Q

Describe how troponin can be a sign of a heart attack (myocardial infarction)

A

If cardiac myocytes are damaged then cells open and leakage of troponin occurs, troponin then is in the blood which is a sign of an MI

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4
Q

What 3 things to contractile myocytes contain?

A
  • proteins actin and myosin make contractile fibres
  • protein troponin regulates the actin-myosin crossbridges
  • Sarcoplasmic reticulum - an organelle which contains stores of Ca2+
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5
Q

What are contractile fibres made of?

A

Actin and myosin

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6
Q

What regulates actin-myosin crossbridges?

A

Troponin

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7
Q

Which organelle contains stores of Ca2+?

A

sarcoplasmic reticulum

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8
Q

Describe how excitation-contraction coupling occurs

A
  • Calcium-induced calcium release during the plateau occurs. Calcium enters the cell (~5%) which triggers sarcoplasmic reticulum to release calcium (~95%)
  • Contraction enabled when cytosolic Ca2+ binds to troponin, making it active and capable of interacting with myosin
  • Repolarisation causes relaxation of actin-myosin fibres. Active transport of Ca2+ back to SR and extracellular fluid
  • Fall in cytoplasmic Ca2+ renders troponin inactive and therefore the fibres relax
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9
Q

In which cell type is the action potential driven by the opening of “fast” Na+ channels?

A

Contractile myocytes

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10
Q

What is an ECG?

A

Electroencephalogram
Non-invasive, information-rich monitoring of cardiac electrical activity
Coordinated electrical currents in the heart create small voltage differences within the body

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11
Q

What do QRS waves correspond to?

A

Ventricular action potentials

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12
Q

The strength of an ECG signal depends on what?

A

direction of depolarisation travel

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13
Q

How many leads in an ECG?

A

12 leads

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14
Q

P, QRS, T shape corresponds to which tissue?

A

Contractile

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15
Q

What does the P wave signify?

A

Atrial depolarisation (start contraction)

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16
Q

What does the QRS complex/wave signify?

A

Ventricular depolarisation (start contraction)

17
Q

What does the T wave signify?

A

Ventricular repolarisation (start relaxation)

18
Q

What factors must one look at to analyse the ECG?

A
  • Identify QRS complex (ventricular contraction)
  • Heart rate - normal? tachycardic?
  • Heart rhythm - look for the P wave - normal excitation cycle? (sinus rhythm?) , does the P wave precede each QRS by a constant interval?
  • Conduction problems
19
Q

How to measure heart rate?

A

Measure R–>R (seconds per beat)
Convert interval to rate (bpm)
Shortcut is 300/number of large squares

20
Q

Name 3 things to look at when checking for conduction problems

A
  • PQ (or PR) interval - May reveal AV block (too long) or Wolff-Parkinson-White syndrome (too short- unwanted pathways)
  • QRS interval - may reveal right or left bundle block
  • Q-T interval - May reveal QT prolongation - failure to repolarise quickly enough
21
Q

PQ (or PR) interval is too long, what can this signify?

A

AV Block

22
Q

PQ (or PR) interval is too short, what can this signify?

A

Wolff-Parkinson-White syndrome

23
Q

Which part of the ECG can reveal right or left bundle block?

A

QRS interval

24
Q

Which part of the ECG can reveal failure to repolarise quickly enough?

A

QT interval that is too prolonged

25
Q

What can an ECG bpm diagnose?

A

sinus tachycardia

sinus bradycardia

26
Q

What does no P wave in an ECG possibly signify?

A

Atrial fibrilation

as artial myocutes are ectopic pacemakers

27
Q

What does a long P-Q interval possibly signify?

A

First degree heart block (AV block)

28
Q

What do missed heart beats possibly signify?

A

Second degree heart block

29
Q

What is STEMI?

A

ST segment elevated above baseline - sign of ischaemic tissue - worst type of myocardial infarction

Pharmacy Year 2 Semester 1 (32 decks)

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