Review of pulmonary physiology Flashcards
Main function of Lungs
continuous gas exchange
Metabolic function of Lungs
Angiotensis I -> Angiotensin II
Removal of amines, arachidonic acid metabolites
Metabolic function (PEPTIDES)
Angiotensin I - converted
Angiotensin II
Vasopressin
Bradykinin - 80% inactivated
Metabolic function (Amines)
Serotonin - completely removed
Norepinephrine - 30% removed
Histamine
Dopamine
Metabolic function (Arachidonic acid metabolites)
PG E2 and F2 - almost completely removed
PG A2
Prostacyclin
Leukotrienes - almost completely removed
start of lung development
5th week AOG (Arise from ventral wall of the foregut)
Level of Carina
T5 at expiration and T6 in inspiration
Main bronchus that is prone to aspiration
RIGHT
Boundary of Upper and Lower
Adults - vocal cords
pediatrics - cricoid cartilage
T or F, Lower respiratory tract is sterile
False
Boundaries of pleura and lungs ANTERIORLY
clavicle to 8th rib
Boundaries of pleura and lungs LATERALLY
10th rib l
Boundaries of pleura and lungs Posteriorly
level of T12
ANTERIOR CHEST WALL (PE)
R Lung - UPPER and MIDDLE LOBE
L Lung - UPPER LOBE
Type of airflow in conducting zone
bulk flow
Type of airflow in respiratory zone
diffusion
volume of anatomic dead space
150 ml
no gas exchange
ADS + alveolar dead space
Physiologic dead space
Overall volume that do not participate in ventilation
Physiologic dead Space
Areas with ventilation but poor perfusion
alveolar dead space
Chief sites of greatest resistance
Medium sized bronchi
Part of the conducting zone where glands and cartilage first disappear
bronchioles
cuboidal, non ciliated, secrete surfactants and GAGs
Clara cells
site of gas exchange due to the presence of alveoli
RESPIRATORY ZONE
Most of the lung volume is in the?
Respiratory zone - 3 L
volume that is inhaled and then exhaled with each normal breathing
Tidal volume -500ml
The maximum volume that can be exhaled from the resting end-expiratory level
ERV- 1100ml
The maximum volume that can beinhaled above a normal tidal inspiration
IRV - 3000ml
Volume remaining in lungs after maximum expiration (cannot be measured by spirometry)
RV - 1200ml
Maximum volume that can be inhaled from normal resting end-expiratory level
Inspiratory capacity - 3500ml
Volume remaining in lungs during regular breathing
Functional residual capacity
Maximum volume that may be exhaled following a maximum insiration or inhaled following a maximum expiration
Vital Capacity
Formula for Vital capacity
TLC - RV
Volume contained within the lungs following maximum inspiration
5800ml
Normal pulmonary capillary blood flow
70ml
Histology of bronchi
ciliated pseudostratfied columnar
Histology of bronchioles
cuboidal
Histology of alveoli
squamous
Ratio between thickness of submucosal mucus glands and wall thickness between epithelium and cartilage that covers the bronchi
REID index
Normal : <0.4
Chronic bronchitis >0.4
Innervation of smooth muscle in the airway
parasympathetic
Type of receptor predominantly found in the airway
beta 2
Primary determinant of resting bronchomotor tone
cholinergic system
Decreases vagal tone
M1 and M3
autoinhibitory effect on acetylcholine release and have negative inhibitory effect
M2 receptor
Normal ciliary beating
12-15/sec
Bronchial glands
terminal bronchioles
Parasympathetic control
Gel layer
Mucin +lipids
Sol layer
water + electrolytes
Liquid in Sol layer Regulation
Na channel
cAMP mediated Cl channel
cystic fibrosis transmembrane conductance regulator
Ca activated CL channel
Cystic fibrosis
defective CFTR
sweat gland test
Secretes glycosaminoglycans to protect bronchial lining
clara cells
Blood gas barrier
0.3-0.4 micron
Type I cells
flattend; forms 95% of alveolar wall
Type II cells
cuboidal, secretes surfactants (cytosomes)
moremetabolically active
SUrfactants
Phospholipid Dipalmitoyl Phosphatidyl Choline
multilamellar bodies, precursors to pulmonary surfactants
cytosomes
Laplace Law
lager SA, smaller surface tension
Compliance
P/V
normal lung compliance =
0.15/L cm H2O
Compliance differ on inspiration and expiration for identical volumes
Hysteresis
Keeps airsacs open even in maximum exhalation
hysteresis
Lung is stiffer during?
inflation
Emphysema = high or Low compliance
High (decreased elastic recoil)
Fibrosis = high or Low compliance
LOW
point where pressure outside the airways and pressure inside the airways are equal
Equal pressure point
formula for Alveolar Pressure (Palv)
Pleural Pressure (Ppl) + Elastic Pressure (Pel)
When you inhale = more positive or negative?
more negative
Exhalation is an active or a passive process?
Passive
FEV1/FVC ratio of restrictive pathology
PRESERVED
FEV1/FVC ratio of Obstructive pathology
LOWE
Physiological attributes of COPD
airway obstruction + low elastic recoil
Trapped air due to inability to expel right amount
HYPERINFLATION
Dynamic hyperinflation
Unmasked during exercise
Increased RR
More aair trapped
SPace that lies between the epithelial basement membrane and the vascular basement membrane
Interstitium
Architectural framework of the lung
Interstitium
Cellular components of interstitium
Macrophages
Mesenchymal cells
Lympocytes
Major component of the EC matrix of interstitium
Collagen IV
Controls porosity of interstitium
Perlecan
Controls rigidity of interstitium
Hyaluronan
Diameter of alveolo-capillary membrane
10 um
time for oxgenation of each RBC
0.75 secs
Law governing diffusion of oxygen and carbon dioxide
Fick’s law
Solubillity of CO2
20x than oxygen
Blood supply
Pulmonary arteries and veins
Flow of blood to thelungs/pulmonary capillaries
Perfusion (Q)
Flow of air into alveolar spaces
Ventilation (V)
More perfusion more ventilation (lobe of lung)
Lower lungs
Ventilation is greater where?
base due to lower interpleural pressure
At the upper lungs (Ventilation is __ compared to perfusion)
HIGHER
Bad ventilation, good perfusion
SHUNT
good ventilation, bad perfusion
Dead space
PULMONARY VS SYSTEMIC
Lower pressure in pulmonary
Higher capacitance in pulmonary
Less resistance in pulmonary
Most potent vasoconstrictor
Oxygen (hypoxemia)
Normal PaO2 sustainable for life?
60 mmHg
Increased O2 affinity, decreased O2 release
Shift to the LEft
Decreased O2 affinity, Increased O2 release
Shift to the right
Where do bleeding from hemoptysis comes from?
bronchial circulation
Central respiratory center
Medulla oblongata
Peripheral chemoreceptors
located in carotid artery and aortic arch bifurcation
Connected to the medulla via glossopharyngeal and vagus nerve
5 mechanisms causing hypoxemia
- Low inspired O2
- V/Q mismatch
- Shunting
- Decrease in diffusing capacity
- Hypoventilation
hallmark of alveolar hypoventilation
paCO2 always increased
hallmark of Shunt
Hypoxemia is refractory to supplemental oxygen
ARDS
All the air sacs are filled with liquid Not able to ventilate NOT a vascular shunt No VENTILATION BUT PERFUSION CONTINUES Physiologic dead space is increased