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Physiology > 06-07 - Electrical Activity, Muscular Contraction & Cardiac Cycle > Flashcards

06-07 - Electrical Activity, Muscular Contraction & Cardiac Cycle Flashcards

1
Q

The heart is auto…

A

Rhythmic

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2
Q

The nerve supply to the heart…

A) Regulates
B) Initiates
C) Regulates and initiates

…the heartbeat…

A

A) Regulates

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3
Q

There are two types of myocytes…

A

1) Work cells (that generate force)

2) Conducting cells

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4
Q

Initiation of the heartbeat occurs at the…

A

Sino-atrial Node (SAN)

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5
Q

Action potentials spread through the heart via (3)…

A
  • Gap junctions
  • Specialised conducting fibres
  • Through functional syncytium of work cells
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6
Q

A syncytium is…

A

A multi-nucleic cell formed by fusion of cells

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7
Q

Current flows from the SA node to the AV node via the…

A

Internodal pathways

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8
Q

Current travels from the AV node to the apex of the heart via the…

A

Bundle of His

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9
Q

Current moves from the apex of the heart up and across the ventricles via the…

A

Purkinjie fibres

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10
Q

Heart rate is determined by the…

A

Sino-atrial node (SAN)

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11
Q

Heart rate can be altered by the…

A

Autonomic nervous system

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12
Q

In the event of SAN dysfunction…

A

Other cells can take over (but at a slower rate)

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13
Q

Contractors period occurs:

A) Before
B) After
C) During

…the refractory period…

A

C) During

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14
Q

Cardiac muscle has a long refractory period. This helps prevent…

A

Tetanus

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15
Q

An electrocardiogram (ECG) is…

A

A recording of heart activity made by placing electrodes on the skin

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16
Q

The 3 characteristic parts of an ECG are…

A

1) P Wave
2) QRS complex
3) T wave

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17
Q

The P wave of an ECG corresponds to…

A

Atrial polarisation

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18
Q

The QRS complex of an ECG corresponds to….

A

Ventricular depolarisation

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19
Q

The T wave of an ECG corresponds to…

A

Ventricular repolarisation

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20
Q

The QT interval is…

A) Constant
B) Dependent on stroke volume
C) Dependent on PQ interval
D) Dependent on heart rate

A

D) Dependent on heart rate

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21
Q

There are two types of arrhythmia (abnormal heart rhythm)…

A

1) Impulse propagation defects (heart block)

2) Impulse initiation defects (fibrillation)

22
Q

An action potential from the adjacent heart cell causes voltage-gated channels to open, allowing Ca2+ to enter the cell.

This induces local release of more Ca2+ via…

A

Ryanodine receptor channels (RyR)

23
Q

Local release of Ca2+ leads to Ca2+ spark. The summation of these sparks generates the…

A

Ca2+ signal

24
Q

After the generation of the Ca2+ signal, Ca2+ binds to…

A

Troop in

25
Q

The binding of Ca2+ to troponin initiates muscle…

A

Contraction

26
Q

Muscle relaxation occurs when Ca2+…

A

Unbinds from troponin

27
Q

After muscle contraction and relaxation, Ca2+ is pumped back and stored in the…

A

Sarcoplasmic reticulum (SR)

28
Q

Ca2+ is also exchanged with Na+ by…

A

NCX antiporter

The overall Na+ gradient is maintained by the Na+/K+ ATPase pump

29
Q

Ionic basis for AP in the ventricular muscle cells

  1. Sodium channels open
  2. Sodium channels close
  3. ? / ?
  4. ? / ?
  5. Resting potential reached
A
  1. Calcium channels open / Fast K+ channels close

4. Calcium channels close / Slow K+ channels open

30
Q

The cardiac cycle can be summarised in 4 main steps…

A
  1. Ventricular filling (atrial contraction)
  2. Isovolumic ventricular contraction
  3. Ventricular ejection
  4. Isovolumic ventricular relaxation
31
Q

Systole is ( contraction / relaxation )

A

Contraction

32
Q

Diastole is ( contraction / relaxation)

A

Relaxation

33
Q

EDV stands for…

A

End diastolic volume

34
Q

ESV stands for…

A

End systolic volume

35
Q

The ejection fraction is stroke volume divided by the…

A

End diastolic volume (EDV)

36
Q

End diastolic volume (EDV) - end systolic volume(ESV) =

A

Stroke volume

37
Q

Heart sounds are caused by…

A

The closing of heart valves

38
Q

To hear the AV valve, stethoscope should be placed at the…

A

2nd intercostal space, right sternal margin

39
Q

To hear the pulmonary valve, stethoscope should be placed at…

A

Left sternal margin

40
Q

To hear the mitral valve, stethoscope should be placed at…

A

The heart apex (5th intercostal space in line with middle of clavicle)

41
Q

To hear the tricuspid valve, stethoscope should be placed at…

A

Right sternal margin over 5th intercostal space (varies)

42
Q

Diseases of the valves come in 2 main categories…

A
  1. Stenosis

2. Incompetence

43
Q

Bicuspid valves are prone to calcification. Are there any symptoms, if so what are they?

A

Patients with calcified bicuspid valves may remain asymptomatic. However if a critical point is reached congestive heart failure occurs.

44
Q

Systemic arterial blood pressure is measured where?

A

At the upper arm, level with the heart

45
Q

Systemic arterial blood pressure is recorded as…

A

Systolic (max) over diastolic (min), in mmHg

46
Q

Blood pressure can also be measured by…

A

Auscultation

47
Q

Auscultation involves determining blood pressure using…

A

Sound

48
Q

Auscultation: Pressures of >120mmHg result in…

A) Korotkoff sounds (due to pulsatile blood flow)
B) No sound
C) Poiseuille sounds (due to laminar flow)

A

B) No sound

49
Q

Auscultation: Pressures of 80-120mmHg result in…

A) Korotkoff sounds (due to pulsatile blood flow)
B) No sound
C) Poiseuille sounds (due to laminar flow)

A

A) Korotkoff sounds (due to pulsatile blood flow)

50
Q

Mean arterial pressure (MAP) is the average pressure over…

A

Time

51
Q

MAP =

A

MAP = DP + 1/3 (SP - DP)

Where (SP - DP) = pulse pressure

Physiology (17 decks)

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