respiratory system L14-18 Flashcards
respiratory functions
gas exchange
regulation of body pH
pathogen/ irritant protection
vocalisation
conducting systems
upper respiratory tract (nasal cavity/ pharynx/ larynx)
lower respiratory tract (trachea/ bronchi/ bronchioles)
nasal cavity function
debris filtration
antibacterial secretion
olfactory receptors
voice resonance
pharynx functions
soft palate component for swallowing
protection from mechanical stress
larynx function
sound production
prevents food/ liquids entering respiratory tract
epithelial cells of conducting system
goblet
ciliated
mucociliary escalator
goblet cell function
secrete mucus for continuous mucus layer
ciliated cells
produce saline and sweep mucus up to pharynx
mucociliary escalator
removes noxious particles from lungs
NKCC
Na+ K+2Cl- symporter
CFTR
cystic fibrosis transmembrane regulator channel
mucus secretion
- NKCC brings Cl- into epithelial membrane
- apical anion channels allow Cl- into lumen
- ECF Na+ to lumen
- NaCl movement from ECF to lumen
cystic fibrosis
deficient CFTR therefore less liquid component of mucus ^viscosity and colonisation of bacteria as mucus can’t be cleared
c-shaped cartilage support
trachea patence
flexible enough for diameter change in pulmonary ventilation
bronchi to bronchioles
fewer/ irregular cartilage plate
epithelium > columnar cells
^smooth muscle
ventilation mechanics
pressure changes
diaphragm
respiratory muscles
resp system at rest
diaphragm relaxed
intrapulm pressure = atm pressure
no air movement
resp system on inspiration
thoracic volume ^
diaphragm contraction/ flattening
insp muscle contraction
resp system on expiration
thoracic volume decrease
diaphragm relaxation
Boyle’s law
at constant temp/ no. gas molecules, pressure and volume are inversely related
intrapulmonary pressure
pressure within alveoli
atmospheric pressure
pull of gravity on air
intrapleural pressure
pressure in pleural cavity
doesn’t equalise w atm pressure ~4mmHg less than intrapulm and atm pressure due to elastic recoil
pleural sac
2 membranes of elastic tissue/ capillaries around each lung
parietal pleura
outer layer of serous membrane, fused to rib cage/ diaphragm and other local structures
folds in on itself at hilum > visceral pleura
pleural fluid
thin fluid film within cavity
keeps lung and chest wall together
lubricant for lung movement in thorax
maintains lung inflation at rest
physical pulmonary factors
airway resistance
alveolar surface tension
lung compliance
airway resistance
forces of friction causing opposition to flow
airway resistance factors
length of system
airway diameter
laminar/ turbulent flow
gas viscosity
inflammation / mucus secretion effect on airway resistance
increases
alveolar surface tension
reciprocal of elasticity
lung compliance factors
surfactant compliance
distensibility of elastic tissue of the lung
ability of chest wall to move/ stretch in inspiration
alveolar surface tension
surfactant creates gas-water boundary in each alveolus
H-bonds due to partial charges vs no H-bonds in gas
alveolar surface tension factors
increase w decreasing diameter of alveolus
autonomic control of bronchial tone
bronchiole diameter controlled by smooth muscle contraction and relaxation
central control of bronchial tone
para innervation of airways > bronchoconstriction ^resistance
non-neural control of bronchial tone
symp B2 receptors on smooth muscles activated by circulating adrenergic agonists
bronchodilation and decreasing R
law of la Place
pressure = 2T/r
2*surface tension/ radius
atolectasis
collapse of alveolus due to surface tension
surfactant
surface active agent
contains proteins and phospholipids
polar and non-polar end
where’s surfactant produced?
TII alveolar cells
majorly in last 10-12 gestation weeks
surfactant amount with alveoli size
smaller alveoli size ^surfactant
emphysema
alveoli loss and therefore less elastic recoil
fibrosis
elastic tissue replaced w scar tissue
spirometer function
measures lung volumes and capacities over time
tidal volume
volume inspired/ expired with each normal breath
expiratory reserve volume
maximal volume that can be expired over the inspiration of a tidal volume
residual volume
volume that remains in the lungs after a maximal expiration
*only whole body plethysmography can measure
inspiratory capacity
volume of maximal inspiration
functional residual capacity
vol of gas remaining in lungs after normal expiration
vital capacity
vol of maximal inspiration and expiration
total lung capacity
vol of lung after maximal inspiration
forced vital capacity function
assesses respiratory function
max inspiration then expiration fast
measures vital capacity and time
FEV1
forced expiration volume / vol expired in first second of forced expiration
restrictive lung disease
decreasing FVC/ normal FEV1
e.g. pulmonary fibrosis
obstructive lung disease
normal FVC/ decreasing FEV1
e.g. asthma/ bronchitis
dead space
conducting airways not contributing to gas exchange
anatomic dead space
volume of conducting airways
physiologic dead space
anatomic dead space + alveolar dead space
alveolar dead space
non-functioning alveoli
total pulmonary ventilation
ventilation rate * tidal volume
~6L/min
total alveolar ventilation average
~4.2L/min
respiration rate
12-20 breaths / min
alveolar gas exchange influences
PERFUSION
gas diffusion (sa/ distance > thickness/ amount of fluid)
gas movement factors
pressure gradient of gas
gas solubility in liquid
temperature
dalton law
total pressure= sum of pressures exerted by individual gases
Henry’s law
at constant temp, pressure and solubility affects amount of gas dissolved in a liquid
gas movement factors
pressure
temp
solubility
CO2 vs O2 solubility
CO2> O2
pulmonary circulation
low pressure system
high flow
~5L/min
fick’s law
flux= (permeability * conc difference)/distance
hyperventilation
^PO2
hypoventilation
decreasing PO2
hypoxemia
hyperbaric oxygen therapy
^PO2 exposure in chamber
treats anaemia/ severe blood loss/ decompression sickn ess
fibrotic lung disease
thickened alveolar membrane
pulmonary oedema
interstitial fluid ^ diffusion distance
^CO2 solubility in water
asthma
^airway resistance and decreasing alveolar ventilation
alveolar regional variations in inspired air factors
posture
inspiration rate/ amount
lung ventilation variation
base ventilated ~50% more than apex
gravity effects on ventilation
affects p artery hydrostatic pressure/ p vein pressure/ alveolar air pressure
V/Q mismatch
causes L-shunt
hypoxic pulmonary vasoconstriction
blood flow redirection to ventilated alveoli
^gas exchange
% oxygen dissolved in plasma vs Hb
plasma <2%
Hb >98%
PO2 at rest:
arterial blood
tissue level
100mmHg
40 mmHg
% O2 dissociates from HbO4
25-30%
PO2 at exercise:
arterial blood
tissue level
% O2 dissociates from HbO4
100mmHg
15-40mmHg
~85%
effect on O2 saturation curve:
^pCO2
decreasing pH
^temp
shifts right
T-conformations
tense (deoxygenated) > crevice w haem narrows
relax (oxygenated) > easier O2 access
2,3-DPG increase situations
chronic lung disease
anaemia
congestive heart failure
lower atm PO2
diphosphoglycerate production location
erythrocytes
diphosphoglycerate function
interacts w B-chains of Hb
^O2 tissue delivery
shifts dissociation curve to right
anaemia
O2 blood content reduction
less Hb
foetal Hb
efficient gas exchange between maternal/ foetal blood-streams or foetal blood stream to foetal tissue
foetal Hb function
takes up O2 at PO2 values at which maternal Hb is releasing it
2nd month pregnancy> 6 months old
not affected by 2,3-DPG
foetal Hb structure
2 alpha and 2 gamma globins
CO2 transport formula
enzyme used?
CO2+H2O >/< H2CO3 >/< HCO3 + H+
(carbonic anhydrase)
carbaminohaemoglobin production and function
CO2 + Hb
favours T conformation, ^O2 release in high CO2 areas
reversible binding to Hb iron of carbon monoxide
carboxyhaemoglobin
*200 * affin of Hb for O2
carbon monoxide functions
limits O2 carrying capacity
shifts Hb to relaxed conform
carbon monoxide therapy
hyperbaric O2 therapy > facilitates CO dissociation
nitric oxide
signalling molecule causing vasorelaxation (mediate O2 delivery)
O2-diss curve shift to left
binds oxy Hb and Fe2+ of unoxygenated Hb
chemoreceptor ventilation monitoring
control networks in brain stem regulate somatic motor neurones associated w respiratory muscles
pons
site of pontine respiratory group
affects medullary rythmicity centre
apneustic/ pneumotaxic centre
medulla
site of respiratory rythmicity centre
2 respiratory neurone types
dorsal respiratory group
ventral respiratory group
DRG neurone activation
automatic rythmic breathing
apneustic centre
dorsal location
stimulates insp neurones in medulla
pneumotaxic
upper
antagonises/ dominates apneustic centre
decreases inspiration
peripheral chemoreceptor location
aortic arch if aortic bodies
bifurcations of carotid bodies
peripheral chemoreceptor function
samples O2/CO2/H+ content of passing blood
aortic body info transmission via vagus nerve/ carotid bodies via glossopharyngeal nerve
respond to pCO2 changes not pO2 in blood / cerbrospinal fluid
CO2 level effects
^pCO2 >hyperventilation
decrease pCO2 >hypoventilation
metabolic acidosis
H+ ions excluded from CSF entrance by blood-brain barrier > peripheral chemoreceptor
herng breuer reflex
prevents lung over-inflation
stretch receptors in lung smooth muscle
irritant receptors
rapid adaptation to mechanical stimuli w continuous stimulation
myelinated fibres in vagus impulse
cough mechanism
- irritant receptors via vagus
- diaphragm/ external intercostal contraction
- low p in pleural cavity
- abdominal/expiratory muscles contract
- trachea collapse
proprioception
passive movement of limbs> resp stimulation
anticipates ^O2 requirement and CO2 removal`
