Physiology Flashcards

1
Q

4 steps of respiration?

A

Ventilation
Gas exchange (alveoli and blood)
Gas transport
Gas exchange (at tissue)

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2
Q

What is Boyle’s Law?

A

As the volume of a gas increases the pressure exerted by the gas decreases

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3
Q

Structure of cardiac muscle?

A

Striated with gap junctions for communication and desmosomes for adhesion

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4
Q

How does ventilation occur?

A

Chest wall stretches
The Increase in the size of the lungs make the intra-alveolar pressure to fall
The air then enters the lungs down its pressure gradient

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5
Q

What is alveolar surface tension?

A

Attraction between water molecules at liquid air interface- present in alveoli- stop COLLAPSE

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6
Q

What produces surfactant, and why?

A

Produced by type 2 alveoli

Lowers alveolar surface tension- prevents collapse

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7
Q

What is alveolar interdependence?

A

If an alveolus start to collapse the surrounding alveoli are
stretched and then recoil exerting expanding forces in the
collapsing alveolus to open it

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8
Q

Major muscle of inspiration?

A

Diaphragm and external intercostals

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9
Q

Accessory muscles of inspiration?

A

Sternocleidomastoid, scalenus, pectoral

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10
Q

What does parasympathetic innervation cause the bronchus to do?

A

Constrict

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11
Q

What does sympathetic innervation cause the bronchus to do?

A

Dilate

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12
Q

What is tidal volume?

A

Volume of air entering or leaving lungs during a single breath

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13
Q

What is residual volume?

A

Minimum volume of air remaining in the lungs even after a maximal expiration

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14
Q

What is functional residual capacity?

A

Volume of air in lungs at end of normal passive expiration

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15
Q

What is vital capacity?

A

Maximum volume of air that can be moved out during a single breath following a maximal inspiration

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16
Q

What is total lung capacity and how is it calculated?

A

Maximum volume of air that the lungs can hold

Vital Capacity + Residual Volume

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17
Q

Is actin thick or thin?

A

Thin

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18
Q

Is myocyin thick or thin?

A

Thick

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19
Q

How is muscle tension produced?

A

By sliding of actin filaments on myocin filaments

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20
Q

In cardiac muscle, where is the calcium released from?

A

Sarcoplasmic reticulum

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21
Q

What does inotropic mean?

A

Increase force of contraction

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22
Q

What does chronotropic mean?

A

Increase heart rate

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23
Q

Why is alveolar ventilation less than pulmonary ventilation?

A

Anatomical dead space

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24
Q

Causes of metabolic acidosis?

A

Lactic acidosis
Renal failure
Sepsis

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25
Q

Cause of metabolic alkalosis?

A

Vomiting

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26
Q

Causes of respiratory alkalosis?

A

Hyperventilation:
Anxiety
Pain
early sepsis

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27
Q

What is partial pressure?

A

The pressure that gas would exert if it occupied the total volume for the mixture in the absence of other components

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28
Q

Which part of the brainstem modifies respiration?

A

Pons

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29
Q

Which part of the brainstem generates the rhythm of respiration?

A

Medulla

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30
Q

What do central chemoreceptors respond to?

A

H+ level of CSF (increased H+ causes hypercapnia)

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31
Q

3 important pressures in ventilation?

A

Atmospheric
Intra-alveolar
Intrapleural

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32
Q

What is lung compliance?

A

Compliance is measure of effort that has to go into stretching or distending the lungs

33
Q

When might lung compliance decrease?

A

pulmonary fibrosis, pulmonary oedema, lung collapse, pneumonia, absence of surfactant
(restrictive)

34
Q

When might lung compliance increase?

A

COPD- hyperinflation of lungs

obstructive

35
Q

How do emphysema and pneumothorax affect gas exchange?

A

Decreased surface area

36
Q

How do pulmonary fibrosis, pulmonary oedema and pneumonia affect gas exchange?

A

Increased thickness

37
Q

How does pulmonary embolism affect gas exchange?

A

Decreased perfusion

38
Q

What does left-sided heart failure cause?

A

Pulmonary capillary
congestion and pulmonary oedema
(SOB, orthopnea, PND)

39
Q

What shifts oxygen dissociation curve to the right (Bohr effect)?

A

Increase PCO2
Increase H+ conc
Increase temp
Increase 2,3-biphosphoglycerate

40
Q

In anaemia, what would be the arterial PO2 sensed by peripheral chemoreceptors?

A

Normal!

41
Q

Examples of investigations for SOB?

A
CXR
ECG
FBC
ABG
Troponin T
\+ many others (e.g. spirometry, ECHO, VQ scan etc.)
42
Q

What is FVC?

A

Forces vital capacity- maximum volume that can be forcibly expelled from the lungs following a maximum inspiration

43
Q

What is FEV1?

A

Forced expiratory volume in one second

44
Q

In obstructive disease, what are the results of FVC, FEV1 and FEV1/FVC?

A

FVC- normal
FEV1- low
FEV1/FVC- low

45
Q

In restrictive disease, what are the results of FVC, FEV1 and FEV1/FVC?

A

FVC- low
FEV1- low
FEV1/FVC- normal

46
Q

Mechanism of AF?

A

Multiple wavelets of re-entry

47
Q

What is paroxysmal AF?

A

Paroxysmal and lasting less than 48 hours

48
Q

What is persistent AF?

A

An episode of AF lasting greater than 48 hours, which can still be cardioverted to NSR

49
Q

What is permanent AF?

A

Inability of pharmacologic or non-pharmacologic methods to restore NSR

50
Q

Causes of AF?

A
Hypertension
Heart Failure
Obesity
Familial
Valve disease
Alcohol abuse
COPD
Pericarditis etc.
51
Q

What is idiopathic AF?

A

Absence of any heart disease and no evidence of ventricular dysfunction

52
Q

Symptoms of AF?

A
Palpitations
Pre-syncope
Chest pain
Dyspnea
Sweatiness
Fatigue
53
Q

ECG features of AF?

A

Irregularly irregular
atrial rate >300
ABSENT P WAVE

54
Q

What does a ventricular rate of >60bpm suggest in AF?

A

AV conduction disease

55
Q

Principles of AF treatment?

A

Rate or rhythm control
+
Anti-coagulation

56
Q

Name some drugs to control rate in AF?

A

Digoxin
Beta blockers
Verapamil

57
Q

How can normal sinus rhythm be restored in AF?

A

Direct current cardioversion or pharmacologically

58
Q

How can normal sinus rhythm be maintained in AF?

A

Anti-arrhythmic drugs
Catheter ablation
Radiofrequency ablation

59
Q

What is used to assess stroke risk in AF?

A

CHA2DS2-VASc score

60
Q

Criteria of CHA2DS2-VASc score?

A
Heart failure
Hypertension
>75 years
Diabetes
Stroke
Vascular disease
Female
61
Q

Name some anti-arrhythmic drugs used in AF?

A
Lignocaine
Flecainide
Propranolol
Amiodarone
Dronedaron
Verapamil
62
Q

Name some anti-coagulants used in AF?

A

Warfarin
Rivaroxaban
Apixaban

63
Q

What can be used to assess major bleeding risk when on anti-coagulation?

A

HAS-BLED

64
Q

What is atrial flutter?

A

Rapid and regular form of atrial tachycardia

65
Q

Mechanism of atrial flutter?

A

Macro-reentrant signals in right atrium ONLY

66
Q

ECG features of atrial flutter?

A

SAW-TOOTH

67
Q

What can atrial flutter cause?

A

Progression to AF

Thromboembolism

68
Q

Treatment of atrial flutter?

A

RF ablation
Cardioversion
Warfarin

69
Q

62 year old smoker with SOB. Barrel shaped chest and hyper-resonant percussion note. What will happen to his total lung capacity, lung diffusion capacity and FEV1/FVC ratio?

A

Increased total lung capacity
Decreased lung diffusion capacity
Decreased FEV1/FVC ratio

70
Q

Man in hospital post MI. Wakes up at night with SOB. He’s now sitting with high flow O2 but has mild tachycardia and chest crackles posteriorly. What do you prescribe?

A

Probably got pulmonary oedema

IV furosemide + start nitrate infusion

(venous dilation to reduce preload- decrease work of heart and backload on lungs)

71
Q

Longterm treatment of heart failure?

A

Diuretics
ACE inhibitor
Beta blockers

72
Q

74 year old woman with SOB on exertion for weeks. Weight loss, irregularly irregular pulse at 110bpm, tremor and normal cardiac auscultation. What investigation is diagnostic?

A

Thyroid function tests

73
Q

28 yo tall thin woman with sudden right sided chest pain, worse on breathing. Has insomnia + taking diazepam at night. On oral contraceptive. RR 20, HR 90, no added sounds in chest. What is the mechanism of her shortness of breath?:
A- loss of transmural pressure gradient across the lung wall
B- ventilation perfusion mismatch
C- respiratory muscle paralysis

A

B- ventilation perfusion mismatch

74
Q

pH 7.34 pCO2 6.5 HCO3 38 pO2 6.1-

what is this ABG classic of?

A

Compensated resp acidosis- in COPD (longterm CO2 retention)

75
Q

56 yo farmer with SOB on exertion. History of hypertension. What will happen to his total lung capacity, lung diffusion capacity and FEV1/FVC ratio?

A

Decreased total lung capacity
Decreased lung diffusion capacity
Normal/increased FEV1/FVC ratio

76
Q

pH 7.06 pCO2 2.9 pO2 12.8 HCO3 9.2

What are these results suggestive of?

A

Metabolic acidosis with respiratory compensation

E.g. diabetics with DKA

77
Q

65 yo with SOB after prescribed painkiller for knee. Stool black and tarry. Tired, chest and heart sound normal. Mechanism of SOB?

A

Reduced oxygen carrying capacity of the blood

could have been prescribed NSAIDs- cause gastric ulcer and bleeding

78
Q

What is transmural pressure?

A

The transmural pressure gradient is the difference between intrathoracic (or ‘intrapleural’) and alveolar pressure
(P in alveolus > P surrounding interstitial tissue)

79
Q

How can DKA be compensated?

A

With Kussmaul breathing (deep, signing breaths)