resp theory Flashcards
(138 cards)
1
Q
4 steps of inspiration
A
- ventilation
- gas exchange (alveoli)
- gas transport
- gas exchange (tissues)
2
Q
internal vs external inspiration
A
internal - cells converting O2
external - breathing
3
Q
passive vs active movements
A
lungs - passive
inspiration - active
expiration - passive
4
Q
forces keeping alveoli open
A
transmural pressure gradient
pulmonary surfactant
alveolar interdependence
5
Q
forces prompting alveolar collapse
A
elastic recoil
alveolar surface tension
6
Q
transmural pressure gradient
A
intrathoracic pressure is lower than alveolar pressure
7
Q
intrapleural fluid cohesiveness
A
pleural membranes stick together - water molecules in pleural fluid attracted to each other
8
Q
pneumothorax
A
air in pleural space
abolishes transmural pressure gradient - lung collapses
9
Q
boyle’s law
A
increased volume of gas = decreased pressure
10
Q
inspiratory muscles
A
diaphragm (down)
external IC (ribs up)
11
Q
inspiration mech
A
inspiratory muscles increase volume of lungs -> intra-alveolar pressure falls -> air from atmosphere IN
12
Q
expiration mech
A
muscles relax -> chest wall + lungs recoil -> intra-alveolar pressure rises -> air dips to atmosphere
13
Q
alveolar surface tension
A
attraction of water molecules on surface
14
Q
resp surfactant
A
produced by type 2 alveoli
lowers surface tension by getting between water
more important in smaller alveoli
15
Q
respiratory distress syndrome of the newborn
A
lack of surfactant (premes)
16
Q
alveolar interdependence
A
one alveoli starts to collapse -> surrounding stretched + recoil -> expanding forces open collapsing alveoli
17
Q
accessory muscles of inspiration
A
(during forceful insp)
maj + min pectorals
sternocleidomastoid
scalenus
18
Q
active expiration muscles
A
abdominal
internal IC
19
Q
tidal volume (TV)
A
volume of air entering / leaving lungs in a single breath (0.5L)
20
Q
inspiratory reserve volume (IRV)
A
extra volume that can be manually inspired (3.0L)
21
Q
expiratory reserve volume (ERV)
A
extra volume that can be manually expired (1.0L)
22
Q
residual volume (RV)
A
min volume remaining in lungs after max expiration (1.2L)
cannot be measured by spirometry
increases when elastic recoil is lost
23
Q
inspiratory capacity (IC)
A
max volume of inspiration (3.5L)
24
Q
IC =
A
IRV + TV
25
functional residual capacity (FRC)
volume of air in lungs after normal expiration (2.2L)
26
FRC =
ERC + RV
27
vital capacity (VC)
max volume of air that can be expired in a single breath (4.5L)
28
VC =
IRV + TV + ERV
29
total lung capacity (TLC)
total volume lungs can hold (5.7L)
30
TLC =
VC + RV
31
forced vital capacity (FVC)
max volume that can be forcibly expired (= VC)
32
forced expiratory volume in one second (FEV1)
volume of air expired in the first second
(should be >75%)
33
obstructive spirometry
FVC - low or normal
FVC1 - low
ratio % - low
34
restrictive spirometry
FVC - low
FVC1 - low
ratio % - normal
35
sympathetic broncho
bronchodilation
36
parasympathetic broncho
bronchoconstriction
37
dynamic airway compression (active ex)
pressure on alveoli pushes air out, pressure on airways not great
fine in normal, can cause lung collapse in obstructive
38
peak flow meter
gives an estimate of peak flow rate
39
pulmonary compliance
measure of the effort that goes into stretching lungs
less compliance = more work
40
pulmonary ventilation (PV)
volume of air breathed in / out per minute
41
PV =
TV X RR
42
alveolar ventilation
volume of air exchanged between atmosphere + alveoli per minute
43
AV =
(PV - anatomical dead space) x RR
44
alveolar dead space
ventilated alveoli that arent properly perfused
very small in normal lungs
45
V/Q matching
apex - V/q
base - v/Q
46
CO2 accum (v/Q)
bronchodilation
vasoconstriction
47
O2 accum (V/q)
bronchoconstriction
vasodilation
48
factors affecting rate of gas exchange
1. partial pressure gradient
2. diffusion coefficient
3. surface area
4. thickness of membrane
49
dalton's law of partial pressures
total pressure exerted by gas mixture = sum of partial pressure of components
50
partial pressure
pressure that one gas in a mix would give off if it was the only one there
51
PA02 =
PiO2 - (PaCO2/0.8)
52
diffusion coefficient
solubility in membranes
53
PP gradient offset
O2 higher PP gradient, CO2 higher diffusion coefficient
54
O2 transport in blood
1. haemoglobin bound
2. physically dissolved (not much)
55
oxygen delivery index (DO2I) =
CaO2 X CI (cardiac index)
56
foetal haemoglobin
higher affinity for O2
57
myoglobin
present in SkM + cardiac M
releases O2 at v low PO2
short-term storage of O2 (for anaerobic conditions)
58
henry's law
higher pressure of gas = more dissolved
59
transport of CO2 in blood
1. solution - henry's law
2. bicarbonate - RBC, carbonic anhydrase
3. carbamino components - CO2 + anime (globin)
60
haldane effect
removal of O2 increases affinity for CO2
61
bohr effect
affinity for O2 is decreased in high CO2 concentration
62
major rhythm generator
medulla
63
pre-botzinger complex
generates breathing rhythm - firing contracts inspiratory muscles
DORSAL neurons
upper end of medullary resp centre
64
ventral group neurons
activated by increased dorsal firing (hypervent)
cause active inspiration (active ex muscles)
65
pneumotaxic centre
stimulated when dorsal neurons fire - terminates inspiration
located in pons
66
apneustic centre
impulses excite dorsal neurons - prolong inspiration
located in pons
67
involuntary modifications of breathing
1. pulmonary stretch receptors (large TV)
2. joint receptors (moving limbs increases - exercise)
68
peripheral chemoreceptors
carotid + aortic bodies
sense tension of O2 + CO2 in blood
69
central chemoreceptors
near surface of medulla
respond to [H+] of CSF
CSF separated by BBB, permeable to CO2 - less buffered than blood
70
hypoxaemic drive
peripheral chemoreceptors (H+ doesnt cross BBB)
increase causes hyperventilation -> ditches CO2 more (acidosis)
71
XR views
PA - posterior -> anterior
AP - anterior -> posterior
(lateral (replaced by CT))
72
asthma triad
reversible airflow obstruction
T2 airway inflammation
airway hyper-responsiveness
73
asthma cytokines
IL-5 - eosinophils
IL-4 - IgE
IL-13 - FeNO
74
COPD components
chronic bronchitis
emphysema
75
inflammatory cascade
inherited / acquired factors -> eosinophilic inflammation -> mediators + TH2 cytokines -> twitchy SM (AHR)
76
gas transfer test (TLCO)
asthma - normal
emphysema - low
restrictive - low
77
SM contraction pharma
myosin light chain (MLC) phosphorylated (Ca2+ and ATP)
relaxation - dephosphorylated (myosin phosphatase)
78
asthma pathological changes
1. increased SM mass (hyperplasia / hypertrophy)
2. ISF accum (oedema)
3. mucus secretion
4. epithelial damage (exposes nerve endings)
5. sub-epithelial fibrosis
79
asthma stages
immediate (type l hyp)
- mast cells
delayed (type lV hyp)
- TH2, eosinophils
80
rhinitis types
1. allergic (same mech as allergic asthma)
2. non-allergic
3. mixed (occupational)
81
allergic broncho-pulmonary aspergillosis (ABPA)
NOT aspergillosis (infection)
allergic resp to aspergillus
82
mMRC dyspnoea scale
0 - strenuous exercise
1 - hurry on level / slight hill
2 - walks slower, stop for breath on level
3 - stop for breath 100m / few mins (level)
4 - cant leave house / dressing or undressing
83
GOLD square (COPD)
Y axis - exacerbations
up - 2 / 1 + hospital
down - 0 or 1
X axis - mMRC scale
left - 0-1
right - 2
84
resp failure types
1 - low O2
2 - low O2 AND high CO2
85
type 2 resp failure pathway
1. acute resp acidosis
- bicarbonate comp -
2. compensated resp acidosis
- trigger / infection -
3. decompensated resp acidosis
86
resp acidosis ABGs
acute - low O2, high CO2, normal HCO3
compensated - low O2, high CO2, high HCO3
decompensated - low O2, very high CO2, high HCO3
87
normal lungs hypoxaemia adjustments
increase TV or RR
88
dangers of liberal O2
cannot see sats drops due to oxy sat graph curve
89
type of hypoxia
1. circulatory
2. anaemic
3. toxic
4. hypoxaemic
90
circulatory hypoxia
global - HF
local - obstruction
91
anaemic hypoxia
iron deficiency
blood loss
sickle cell
92
toxic hypoxia
CO poisoning
cyanide
fava-ism (beans + drugs)
93
hypoxaemic hypoxia
1. alveolar hypoventilation (opiates, laryngeal ob, obesity, bronchial ob, anaesthesia, kyphoscoliosis)
2. impaired diffusion (interstitial thickening / vascular dysfunction)
94
CO2 retainers
chest deformities
COPD (some)
CF
obesity
neuromuscular
95
causes of CO2 retention
V/Q mismatch
- O2 tricks vessels into matching V/Q, CO2 stuck due to poor V, into blood
haldane effect
- CO2 displaces O2
96
O2 guidelines
MI / stroke - ≥90% is good
CO2 retention risk - 88-92%
everything else - 94-98%
96
unrestricted O2 access
cluster headaches
toxic hypoxia
sickle cell crisis
pneumothorax (no chest drain)
97
bacteraemia
viable bacteria in blood
98
URT colonisers
gram positive -
strep pneumoniae
strep pyogenes
staph aureus
gram negative -
haemophilus influenzae
moraxella catarrhalis
99
whooping cough micro
bordetella pertussis
100
viral pneumonia
RF for invasive aspergillus
101
strep throat
exudate, pus, sore throat, dysphagia, dysphonia
mostly viral, some strep
no need for swab / abx
102
tonsillitis
swollen tonsils, erythematous, dysphagia, dysphonia
tonsillectomy (grows back)
typically not treated
103
feverPAIN score
sore throat abx rating
Fever (24h)
Purulence
Attended rapidly (3d onset)
Inflamed tonsils (severely)
No cough / coryza
0/1 - 13-18%
2/3 - 34-40%
4-5 - 62-65%
104
quinsy
complication of tonsillitis - life threatening
peri-tonsillar abscess
can be drained (beware ICA)
105
epiglottitis
children - crit emergency
histoically H influenzae, now bacterial (strep/staph)
secure airway (one shot!)
IV antibiotics
106
coryza
self limiting
viruses
107
sinusitis
frontal headache, retro-orbital pain, maxillary sinus pain, toothache, discharge
self limiting
fungal BAD (im comp, enters brain)
acute - follows coryza, purulent nasal discharge, self limiting
108
diphtheria
life threatening (toxin)
characteristic pseudo-membrane
vaccinated (not for long)
109
acute bronchitis
cold that 'goes to chest', preceded by coryza
self limiting
productive cough, fever, normal exams, potential transient wheeze
110
pneumonia definition
Sx + SGx of LRI w/ new infiltrate on CXR
111
CURB65
Confusion (new onset)
Urea >7
Resp rate >30
BP sys <90 / dias <60
65 (age)
112
pneumonia path types
lobar - whole lobe (strep)
bronchopneumonia - patchy consolidation (varies, pre-existing disease)
113
effusion -> empyema progression
simple pleural effusion
- pH >7.2, high glucose, high LDH, clear fluid
complicated pleural eff
- pH <7.2, low glucose, low LDH, positive gram stain
- requires chest drain
empyema
- frank pus, chest tube
114
chronic bronchial sepsis / persistent bacterial bronchitis
hallmarks of bronchiectasis, NONE on CT scan
115
pleural fluid colours
straw - cardiac failure, hypoalbuminaemia
bloody - trauma, malignancy, infection, infarction
milky - empyema, chylothorax
foul smelling - anaerobic empyema
food particles - oesophageal rupture
bilateral - LVF, PE, drugs
116
pleural effusion types
transudates - protein <30
HF
cirrhosis
hypoalbuminaemia
atelectasis
peritoneal dialysis
exudates - protein >30
malignancy
infection
pulmonary infarction
asbestos
117
cystic fibrosis trans-membrane conductance regulator (CFTR)
actively transports chlorine out of cells
lost in CF - Na+ flows in, lost osmotic gradient
118
resp epithelium
pseudostratified columnar epithelium + goblet cells
119
UNDER resp epi
lamina propria !
seromucous glands + thin-walled venous sinuses
120
NOT resp epithelium
start of nose (keratinised) + pharynx + vocal folds = squamous stratified
roof of nasal cavity = olfactory epithelium
121
trachea histology
C shaped cartilage rings (open part fibroelastic tissue + SM)
shape allows oesophagus space to move (god has made the things in such a way to make the life easy)
LP = CT
122
bronchi his changes
cartilage rings -> irregularly shaped cartilage plates
becomes more discontinuous distally (lost in bronchioles)
123
bronchioles histology
lack cartilage + glands
epithelium - columnar -> cuboidal
LP = SM
terminal (no resp) -> respiratory (yes resp)
124
terminal bronchiole histology
contain non-ciliated club (clara) cells
- stem cells, detox, immune modulation, surfactant
125
alveoli histology
type 1 - discontinuous squamous
type 2 - polygonal + microvilli +surfactant (lamellar bodies exocytosis)
present - alveolar macrophages (dust cells) -> migrate up tree + to pharynx (swallowed / move into CT)
126
visceral pleura histology
1. simple squamous epithelium (mesothelium)
2. fibrosis + elastic CT
127
TB infection mech
1. pathogen inhaled -> alveoli
2. phagocytosis, carried to hilar lymph nodes
3. granulomatous response -> caseous necrosis
128
lung cancers
SCLC - 25%
central, worst prognosis
NSCLC
adenocarcinoma - 35%
non-smokers, asbestos, peripheral
squamous cell - 30%
smokers, central
large cell - 10%
second worse prognosis, peripheral
129
pancost tumour
lung apex -> shoulder pain, arm weakness etc
130
SVC local invasion
puffy eyelids, headache, JV + chest vein distension
131
IPF pathology
fibrosis (foci) + honeycombing
lymphocytes
132
pneumoconiosis
fibrosis + evidence of inhaled substance
133
sarcoidosis
well formed + non-caseating granulomas, hilar node involvement
134
hypersensitivity pneumonitis
loose non-caseating granulomas
lymphocytes + fibroblastic foci
135
adult respiratory distress syndrome (ARDS)
also diffuse alveolar damage syndrome (DADS)
ALSO shock lung
injury ->
1. fibrous exudate lines alveolar walls
2. cellular regeneration
3. inflammation
135
neonatal RDS
lack of surfactant
136
cor pulmonale
RH hypertrophy / dilation caused by pulmonary hypertension
