Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Clin Phys 1 > Clin Phys Week 4 E > Flashcards

Clin Phys Week 4 E Flashcards

1
Q

What are the AP generating capabilities of the different cardiac cells?

A

SA: 60-100bpm

AV: 40-60bpm

Purkinje fibres: 20-40bpm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the order of electrical activity in the myocardium?

A

1) atria begin to depolarise
2) atria depolarise
3) ventricles begin to depolarise from the apex. Atria repolarise.
4) ventricles depolarise
5) ventricles begin to repolarise from the apex

.6) ventricles repolarise.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is there a delay in the AV node?

A

Size of the fibres

Less negative resting membrane potential

Fewer gap junctions connecting successive muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What can affect the rate of action potentials from pacemaker cells?

A

Nervous system

Electrolyte extracellular fluid concentration

Hormones and chemicals

Mechanical forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What balances the heart rate?

A

Sympathetic cardio acceleratory centre (sympathetic nerves from the cortex)

Parasympathetic cardioinhibitory centre (vagus nerve)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What inputs come to the cardiac centre that can affect heart rate?

A

Higher brain centre (eg sensory and emotional stimuli)

Peripheral sensory input proprioceptor, baroreceptors, chemoreceptors, drugs (caffeine, nicotine etc) hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Sympathetic nervous system: noradrenaline and it’s impacts on heart rate

A

Distributed to all parts of the heart.

Mediates by Beta 1 receptors (SA and AV Node)

Release of noradrenaline which increases the hearts permeability to Na + and Ca+.

This results in increase of conduction of the impulse and strength of contractions called the Ionotropic effect.

Increases sinus rhythm = chronotropic effect. Can increase heart rate by up to 3x resting level.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Parasympathetic nervous system: acetylcholine and it’s impacts on heart rate

A

Mainly due to stimulation of SA and AV nodes.

Release of ACh increases the membrane permeability to K+.

Stops the heart beat for a few second and then beats at 40% of the resting level.

Vagal control decreases the rate of SA firing and decreases excitability of AV junctional fibres.

Mediated via M2 (muscarinic ACh receptors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens to heart rate with an increase in K+ ion concentration?

A

Is causes the heart to dilate, become flaccid and decreases heart rate.Large quantities also block conduction of the nervous impulse through the AV bundle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to the heart and heart rate with an increase in Ca2+ ion concentration?

A

Causes the heart to undergo a continuous spastic contraction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is sinus rhythm?

A

Set by the SA node, in adults at rest it is 70-80bpm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is tachycardia?

A

SA node fires at a higher rate (eg sympathetic nervous system stimulation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is bradycardia?

A

SA node fires at a lower rate (less than 50bpm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is arrhythmia?

A

Abnormal cardiac rhythm.

Heart block: failure of conduction system. bundle branch block total heart block (damage to AV node)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is ectopic foci?

A

A region of spontaneous firing (not SA node)

  • nodal rhythm = rhythm set by AV node of 40-60bpm
  • intrinsic ventricular rhythm = 20-40bom(Any cell in the heart outside the conduction system can generate the action potential)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an electrocardiogram

A

A recording of the electrical activity of the heart (not mechanical). The graphic record produced by an electrocardiograph.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an electrocardiograph?

A

A galvanometric device that detects, amplifies and records the minute differences in electric potential caused by the heart cells

18
Q

What does each axis of the ECG mean?

A

The x axis is time. The y axis is mV.

One small square of 1mm by 1mm = 0.04 (40ms) seconds and 0.1m .

One large square of 5 1mm by 1mm squares = 0.2 seconds (200ms) and 0.5mV

19
Q

On an ECG what is a flatline also called?

A

Isoelectric line

20
Q

If part of an ECG record contains waves and isoelectric lines what is it called?

A

Interval

21
Q

What is no electrical activity on an ECG called?

A

It is presented as an isoelectric line or flatline. Also called a segment.

22
Q

On an ECG what are electrical activities presented as?

A

Deflections or waves

23
Q

What are the 4 characteristics of waves on an ECG?

A
  1. Rate
  2. Rhythm
  3. Amplitude
  4. Contours
24
Q

Describe the wave characteristic: rate

A

How often a wave is recorded per unit of time

25
Q

Describe the wave characteristic: rhythm

A

Is the recording of the same wave in the same intervals

26
Q

Describe the wave characteristic: amplitude

A

Are all the waves the same height?It depends on the strength of electrical activity.Is measured in millivolts.

27
Q

Describe the wave characteristic: contours

A

Are the waves originating from the same source?Do they present a similar shape?

28
Q

In an ECG the P wave represents what?

A

Depolarisation of the atria

29
Q

In ECG the PQ interval represents what?

A

Time of atrial contraction

30
Q

In an ECG the PR Interval is what?

A

The time it takes for the impulse to reach the ventricles (0.12-0.2s)

31
Q

In an ECG the QRS complex is what?

A

Depolarisation of the ventricles

32
Q

In an ECG the ST segment is what?

A

Time of ventricular contraction

33
Q

On an ECG the T-wave is what?

A

Re-polarisation of the ventricles

34
Q

What are the two types of ECG recordings?

A

Bipolar

Unipolar

35
Q

Describe bipolar recordings

A

Biopotentials are recorded between two active leads

36
Q

Described unipolar recordings

A

Bio potentials are recorded between one active electrode and a zero potential (earth) on the skin.

37
Q

Three lead ECG

A

Looks at the heart in vertical plane between two points.Limb leads look at the heart from the sides and feet.Right wrist (anterior)Left wrist (anterior)Left leg (medial surface just above muscles)

38
Q

What is Einthovens triangle?

A

An imaginary triangle formed by active electrocutes and flow of current.

39
Q

What is the order of leads on a 3 lead ECG and where are the positive and negative charges placed?

A

Lead 1:+ve left arm -ve right arm

Lead 2:+ve left leg -ve right arm

Lead 3+ve left leg -ve left arm

40
Q
A

Clin Phys 1 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions