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Z MD1 Respiratory block > Physiology > Flashcards

Physiology Flashcards

1
Q

definition of sleep

A

a behavioural state characterized by decreased awareness of external environment, decreased reactivity to stimuli, but with the capability to return rapidly to wakefulness.

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1
Q

association between sleep deprivation and

A
  • mortality and morbidity - decreased cognitive function
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2
Q

in general, an elevated PCO2 is due to

A

inadequate alveolar ventilation

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3
Q

infective exacerbations of COPD are caused by what

A

bacterial bronchitis increased bronchospasm

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4
Q

how long does oxygen require to fully saturate in the lungs

A

0.25 seconds

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4
Q

mechanical effects of restrictive lung diseases

A
  • breathlessness - increased work of breathing - reduced lung volumes - altered pattern of breath - reduced maximum ventilation
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4
Q

complications of asthma

A
  • death - atelectasis - pneumothorax - airway remodelling - irreversible obstruction - chronic hypoxia –> pulmonary hypertension –> cor pulmonale
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4
Q

brainwave change, EMG change and EOG change from NREM to REM

A

EMG paralysed (inhibited) EEG becomes more desynchoronized EOG - rolling eye movements

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5
Q

clinical signs of pulmonary hypertension and RVH

A
  • right ventricular heave - loud P2 and 4th heart sound - increased JVP with v waves
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6
Q

how does emphysema cause airway obstruction

A

due to loss of elastic recoil

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6
Q

what is the main regulator of breathing during sleep

A

chemical control (central and peripheral chemoreceptors)

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7
Q

what other sensors (other than chemoreceptors) contribute to breathing

A
  • pulmonary stretch receptors - irritant receptors - J receptors - upper airway receptors - joint and muscle receptors - pain
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7
Q

what is the compensatory mechanism elicited by the lungs when there is low ventilation

A

vasoconstriction - directs perfusion away

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7
Q

what does the ventrolateral preoptic nucleus do

A

inhibits the arousal centres - sleep until the arousal centres get the upper hand - inhibit the VLPN - prevents sleep

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8
Q

summary of gas exchange and mechanical effects of restrictive lung diseases

A
  • increased sensation of breathing - increased elastic WOB - reduced lung volumes - altered pattern of breathing - reduced maximum ventilation - abnormal gas exchange, which worsens with exercise
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8
Q

when do we do most of our deep sleep and most of our REM sleep

A

deep sleep - first part of the night REM - second half of the night

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9
Q

volume of CO2 and O2 removed/ produced per minute

A

200 ml/min CO2 250 ml/min O2

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10
Q

what are the physiological effects of disrupting the A-C membrane?

A
  • abnormal gas exchange - abnormal lung mechanics - pulmonary vascular complications
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10
Q

pathogenesis of chronic bronchitis

A

chronic irritation by inhaled substances causes increased mucus production in the larger airways (due to hypertrophy of mucus secreting glands and increased goblet cells) and airway inflammation, scarring and narrowing in the smaller airways

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11
Q

what do central chemoreceptors respond to

A

H+ do not respond to oxygen!

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11
Q

Ventilation and arterial CO2, O2 and pH during metabolic acidosis

A

Ventilation is excessive for oxygen consumption PaO2 >100 PaCO2

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13
Q

What is ficks law

A

the rate of diffusion is proportional to the surface area, the constant, and the difference in partial pressures, and inversely proportional to thickness

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14
Q

in general, elevated PaCO2 is due to

A

inadequate alveolar ventilation

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15
Q

what is the function of orrexin

A

stabilises the arousal system

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16
Q

why does the WOB increase in restrictive diseases

A

because the inspiratory muscles need to generate higher pressures to overcome the reduced compliance of the lungs –> leading to recruitment of accessory muscles, increased oxygen consumption by respiratory muscles and risk of respiratory muscle fatigue if airway obstruction is severe

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18
Q

basal rates of CO2 and O2 (ml/min)

A

CO2 production - 200 ml/min O2 use - 250 ml/min

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19
Q

surface area of alveolar capillary membrane

A

50-100 m2

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19
Q

what drives circadian rhythms

A

the suprachiasmatic nucleus

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20
Q

thought during wake, NREM and REM

A

W - logical, progressive NREM - day dreamy REM - illogical, bizzare

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21
Q

main causes of increased capillary hydrostatic pressure

A

Left ventricular dysfunction mitral stenosis fluid overload pulmonary veno-occlusive disease

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21
Q

what happens to CO2 with sleep

A

at onset - decreased drive - decrease in minute ventilation - leads to increase in CO2 - stimulates breathing - equilibrium reached (but CO2 slightly higher than wakefulness)

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23
Q

what are the forces that inspiration has to overcome

A

resistive - airflow through bronchi elastic - expansion of lungs and chest wall

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24
Q

2 major arousal systems acting on the cerebral cortex and thalamus

A

cholinergic ascending system - affects the thalamus monoaminergic system - innervates the cortex

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25
Q

what happens to ventilatory components during anxiety

A

VE excessive for oxygen consumption PaO2 >100 PaCO2

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27
Q

thickness of alveolar capillary membrane

A

0.5 microns

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28
Q

how does smoking cause emphysema

A
  • draws in inflammatory mediators - neutrophils release proteases that break down elastin - inhibition of anti-proteases
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30
Q

what tells you (from lung function test) that a patient is gas trappin

A

high TLC, RV and RV/TLC

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31
Q

why doesnt the pulmonary artery pressure increase during exercise in a normal person

A

due to recruitment and dilatation of pulmonary vessels

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31
Q

mechanisms to increase pulmonary vascular resistance

A
  • VASOCONSTRICTION = chronic hypoxia –> vasoconstriction (spasm of SM) –> diverts blood through just a few vessels so increases the pressure - OBLITERATION= chronic inflammation –> destruction of alveoli and BVs due to fibrosis –> volume of capillar
32
Q

definition of bronchiectasis

A

irreversible, abnormal dilatation of bronchi/bronchioles

33
Q

how many sleep cycles are typical per night

A

4-6

34
Q

mean pulmonary artery pressure

A

15 mmHg

35
Q

definition of chronic bronchitis

A

clinical definition persistent cough productive of sputum for at least 3 months in 2 consecutive years for which no other cause can be identified

35
Q

how long is a typical sleep cycle

A

90-120 minutes

36
Q

typical sleep requirement of infants

A

up to 18 hours

38
Q

pneumonic for causes of disease and each meaning

A

I DIVINE TIME Congenital/Genetic Acquired: - Infectious - Degenerative - Inflammation/Immune reactions - Vascular - Iatrogenic (drugs, surgery, radiotherapy) - neoplastic - environmental - trauma - idiopathic - metabolic - endocrine

39
Q

whee does laminar and turbulent flows occur

A

laminar - in small airways (poiseulles law applies - 8nl/pi x r4 turbulent - during high flows (large airways)

40
Q

normal lymphatic flow from the lungs

A

20ml/hour

41
Q

definition of asthma and then simplified definition

A
  • increased responsiveness of the airways to various stimuli leading to episodic bronchoconstriction which is at least partly reversible - reversible bronchoconstriction
42
Q

main obstructive lung diseases

A

COPD - chronic bronchitis, emphysema, small airway disease asthma bronchiectasis

43
Q

normal range for HCO3

A

22-28

44
Q

main causes of increased capillary permeability

A

toxins sepsis multiple trauma aspiration of gastric acid

46
Q

complications of chronic bronchitis

A
  • superimposed infective exacerbations - hypoxia, pulmonary hypertension, cor pulmonale - squamous metaplasia –> squamous dysplasia - premalignant
47
Q

reasons for breathlessness (broadly)

A

respiratory cardiac muscle weakness metabolic anaemia psychogenic

48
Q

how long is the Hb in contact with the blood-gas barrier at rest

A

0.75 seconds

49
Q

pathophysiology of asbestosis

A

progressive, diffuse inflammation and fibrosis of lung parenchyma causing disruption and destruction of the A-C membrane

50
Q

Obstructive and restrictive lung diseases are a group of lung diseases which are:….

A

chronic, diffuse and non-infectious

50
Q

what happens at anaerobic threshold

A
  • disproportionate increase in VE for work - causes PaCO2 to decrease and pH to drop slightly due to lactic acid production
51
Q

1 gm combines with how much O2

A

1.3 ml O2

53
Q

What does ARDS cause

A
  • type 1 respiratory failure due to low V/Q units and shunt and stiff lungs
54
Q

diseases that can disrupt the A-C membrane

A
  • inflammation - infection -fibrosis -emphysema -fluid -cancer
56
Q

what do peripheral chemoreceptors respond to

A

reduced oxygen, reduced pH, increased CO2

57
Q

over a long period, people with severe OSA can develop…

A

(chronic hypoxia, chronic hypercapnea, and compensated respiratory acidosis (HCO3- is high) Re-setting of the respiratory centre –> day time hypoventilation)

58
Q

main 2 reasons thought for why we need sleep

A

brain development repair and maintenance

59
Q

what happens to the controllers of breathing during sleep

A

loose higher centres, emotional drive and non-specific inputs other inputs downregulated significantly

61
Q

definition of emphysema

A

abnormal, permanent enlargement of air spaces distal to the terminal bronchiole (from destruction of the alveolar wall without fibrosis)

62
Q

what are the effects of pulmonary oedema

A

-mechanism changes - (decreased compliance, restrictive ventilatory defect, increased airway resistance and increased WOB) - reduced gas exchange - due to shunt, low V/Q and diffusion impairment - increased pulmonary vascular resistance

64
Q

rate of diffusion is determined by

A

Ficks Law

65
Q

symptoms of OSA

A
  • snoring - witnessed apnoeas - arousals - choking - mood change, poor memory, decreased libido - difficult to treat HT, unexplained RF
66
Q

what do you do/feel as a result of increased airways obstruction

A

-increased sensation of breathing - increased respiratory muscle effort - active exhalation - prolonged inspiration and expiration - altered pattern of breathing - reduced maximum ventilation - sometimes gas trapping

67
Q

what defines obstruction via spirometry

A

FEV1/FVC lower than 80% in younger and 70% in elderly

69
Q

compliance of the lungs is effected by:

A
  • tissue composition - surface tension in alveoli
71
Q

5 functions of the lungs

A

1) protect the heart from physical trauma 2) act as a flotation device 3) oxygenate pulmonary arterial blood 4) remove carbon dioxide from blood 5) maintain acid-base balance

72
Q

what causes restrictive lung diseases

A

inflammation and fibrosis of inter-alveolar septa

73
Q

definition of breathlessness

A

RECOGNITION by the subject of an INAPPROPRIATE relationship between RESPIRATORY WORK and TOTAL BODY WORK

73
Q

what does the Suprachiasmatic nucleus do

A
  • receives input from rods, cones and meanopsin - receives input from the intergeniculate leaflet of the lateral geniculate thalamic nulceus - projects to the paraventricular nucleus which connects with the pineal gland which secretes melatonin
74
Q

causes of hypoventilation (5)

A
  • reduced respiratory centre activity - neuromuscular disease - chest wall deformity - gross obesity - SDB
74
Q

main components controlling breathing

A
  • medulla - inflation reflex - peripheral stimuli (pain, touch, temp) - Joint receptors - non-specific drive - central and peripheral chemoreceptors - emotional stimuli
76
Q

how much oxygen in the blood

A

200ml / Litre

77
Q

what is the sleep centre

A

ventrolateral preoptic nucleus

78
Q

brainwave change, EMG change and EOG change from W to sleep

A

EEG more synchornized and lower in amplitude EMG - reduced EOG - slow rolling eye movements

79
Q

pathogenesis of bronchiectasis

A
  • airway gets filled with mucus - infection behind it –> severe destruction of airways and surrounding elastic tissue
81
Q

definition of small airways disease

A

chronic inflammation, fibrosis and obstruction of terminal bronchioles caused by cigarette smoke

82
Q

definition of OSA

A

transient obstruction of the throat during sleep preventing breathing, and disturbing sleep

83
Q

causes of pulmonary hypertension

A
  • increased LA pressure - increased pulmonary blood flow - increased pulmonary vascular resistance
85
Q

MUD reasons for dyspnoea

A

clinical disease diseased or deconditioned psychogenic maximum effort

86
Q

complications of emphysema

A
  • hypoxia (caused by airways obstruction and low DLCO) - pulmonary hypertension –> cor pulmonale - pneumothorax
87
Q

effect of inspiration on cardiovascular system

A
  • decreased venous return to LA - decreased CO - decreased systolic BP on inspiration
89
Q

symptoms of psychogenic breathlessness

A
  • need to take deep inspiration - at rest, but not at exercise - anxiety - tingling in fingers, feet, face or head - oppressive/compressed chest
90
Q

movement during W, NREM and REM

A

W - continuous, voluntary NREM - move alot REM - commanded but inhibited

91
Q

sensation and perception during wake, NREM and REM

A

W - vivid, externally generated NREM - Dull or absent REM - vivid, internally generated

92
Q

How do restrictive lung diseases look on xray

A

ground-glass/reticulo-nodular

93
Q

What are kerley b lines and what are they caused by

A

dilated interlobular septa caused by dilated lymphatics

94
Q

what is the ratio of increasing HCO3 for increase in CO2

A

2-3 mmol/L increase in HCO3- for every 10mmHg increase in CO2

95
Q

how does smoking predispose to pulmonary infection

A
  • inhibition of the muco-ciliary esculator - increased mucus - inhibition of leukocyte function - direct damage to the epithelial layer
96
Q

respiratory causes of dyspnoea

A

airways disease alveolar disease pulmonary vascular disease pleural and chest wall disease respiratory muscle disease

97
Q

effects of sleep deprivation

A
  • cognitive impairment - impaired immune system - risk of diabetes type 2 - increased HRV - risk of heart disease - decreased reaction time and accuracy - tremors -aches - growth suppression - risk of obesity - decreased temp

Z MD1 Respiratory block (11 decks)

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