Respiratory Flashcards
Cartilage and goblet cells extend to which point?
Up until the end of brochi
What is the end of the conductive zone in the respiratory system?what is its epithelium?
The terminal bronchi.
Pseudostratified ciliates columnar cells
What is the epithelium in the respiratory zone?
Respiratory bronchi>cuboidal
Alveoli>squamous cells
What is the explanation of the low pressure in the terminal bronchioles,considering their small radius?
They are large in number ,in parallel architecture>least airway resistance
What does pulmonary surfactant consists of?when does the synthesis begins?
It is a complex of lecithins,–>dipalmitoyphosphatidylocholine(DPPC)
Surfactant synthesis :week 26>35
❗️lecithin/sphingomyelin ratio>2.0 in amniotic fluid indicate fetal lung maturity
What’s the purpose of Clara cells?
They are nonciliated ,low columnar with secretory granules. #secrete components of the surfactant #degrade toxins #act as reserve cells
What’s the determination of physiologic dead space.?
ANATOMIC dead space of conductive airways PLUS alveolar dead space
Vd=Vt*(Paco2-Peco2)/Paco2
TacoPacoPecoPaco
How much is the ANATOMIC dead space approximately ?
150mL
How is minute ventilation determined?Ve
Ve=Vt*RR(respiratory rate)
How is alveolar ventilation determined?Va
Va=(Vt-Vd)*RR
What is FEV1?
How do lung diseases affect it?
It is the volume of air that can be expired in the first second of a forced maximal expiration.
Normally=80% of the FVC
FE1/FVC=0,8
In obstructive lung diseases>ratio is decreased
In restrictive lung diseases >ratio is in increased
How is the amount of dissolved O2 estimated?
Dissolved O2=Po2*solubility of O2in the blood
What is the transmural pressure?
It is alveolar pressure minus intrapleural pressure.
How does the compliance of the lungs change during respiratory circle?
Inflation(inspiration) of the lungs follow a different curve than deflation(expiration)>this is called HYSTERISIS:due to the need to overcome surface tension forces when inflating.
Compliance of the lungs-wall system is less than that of the lungs alone or the chest wall alone
How does the compliance of the lungs change in several lung diseases?
Emphysema :
low elastic tissue>high compliance>low tendency of collapsing,higher tendency of expanding»new higher FRC>barrel shaped chest
Fibrosis:
More elastic tissue>low compliance >high tendency of collapsing>lower tendency of expanding>new lower FRC
How is collapsing pressure on alveoli determined?
P=2T/r
What are the two factors that determine airflow???
#pressure difference(Q=DP/R) #resistance(R=8ηl/πr4)
There are three factors that change airway resistance.which are they?
contraction of bronchial smooth muscle
Sympathetic>β2>relaxation Parasympathetic >^R
Deep sea dive>high air density>high R
He>low R
Patients with asthma learn a certain style of breathing.what is that??
Patients with asthma experience high airway resistance>they learn to breath in ⬆️high volumes to offset high airway resistance associated with their disease
Patients with COPD learn a certain style of breathing.what is that??
They learn to expire slowly in pursed lips in order to prevent positive P intrapleural pressure>no collapsing of the airways>less difficult expiration
What is the partial pressure equation?
PP=total pressure*fraction gas concentration
In humidified air at 37•C>760-47mmHg
How is gas diffusion across the alveolar-pulmonary capillary determined?what are the factors that affect it?
Give 3examples
Vx=Dl*dP
It is proportional to: #partial pressure difference #diffusion coefficient of the gas #surface area
Inversely proportional to: #thickness of the barrier
Exercise:more open capillaries>more surface>^diffusion
Emphysema:loss of membrane>decreased surface area>low diffusion
Fibrosis/edema:increased thickness>low diffusion
What are the perfusion limited gases?
O2 (normal)
CO2
N2O
Gas equilibrates early along the length of the capillary
Diffusion can ONLY BE INCREASED by blood flow
What are the diffusion limited gases?
CO
O2 in exercise/fibrosis/emphysema
Gas does not equilibrates by the time blood reaches the end of the capillary
What is the effect of low PAo2 in the pulmonary capillaries?
It causes an hypoxia vasoconstriction (unlike all the other systems)>shifts blood away from poorly ventilated regions of the lungs to well-ventilated regions of lung
Fetal hemoglobin has higher affinity for O2 than the adult hemoglobin.why is that?
HbF consists of α2γ2 chains and 2,3-BPG binds less avidly to the taut γ chain>higher affinity with O2(left shift)>less release of O2.
(Movement from mother to fetus is facilitated
What is O2content?how is it measured?
The total amount of O2 carried in blood including bound and dissolved O2
O2content=[Hb]O2binding capacity%saturation+dissolved O2
Capacity=the max amount of O2 bound to hemoglobin at 100% saturation
How is O2delivery to the tissues measured?
o2delivery ti tissues=CO*O2content of blood
How is the sigmoid shape of Oxygen-Hb dissociation explained?
It is due to the positive cooperativity >higher affinity of hemoglobin as each successive O2 molecule binds to a heme site
The curve is almost flat toward the end of the O2-hemoglobin curve.why is that?
It is flat when the Po2is between 60 and 100mmHg>humans can tolerate changes in atm pressure an Po2 without compromising the O-carrying capacity of hemoglobin
Name the factors that cause right shift of the O2-hemoglobin curve.
ACE BAT: Acid(>^H+>low pH) CO2 Exercise 2,3-BPG Altitude Temperature
Affinity to Hb is lower/^P50/lower O2content
How does methemoglobin lead to tissue hypoxia ?
Methemoglobin has Fe3+ instead of Fe2+>it connects less readily with O2 and has ^affinity to cyanidine>low saturation and low O2content
It presents with cyanosis and chocolate-colored blood
It is treated with methylene blue
How does carboxyhemoglobin lead to hypoxia?
- It binds competitively to Hb with x200 greater affinity than O2
- it causes low O2-binding capacity >left shift>low O2 unloading in the tissues
Treatment=100%O2 and hyperbaric O2
Causes of hypemia.
#low Po2(hypoventilation or ^altitude=low Pβ) ->NORMAL A-a GRADIENT #diffusion defect #V/Q defect. INCREASE A-aGRADIENT>10mmHg #right to left shunt
Causes of hypoxia.
#low CO>low blood flow #hypoxemia #low [Hb]>anemia #CO poisoning>low content of blood #cyanidine poisoning >low utilization by tissues
Pulmonary vascular resistance equation.
PVR=(Ppulm.art-Pl.atrium)/CO
Alveolar gas equation.
PAo2=Pio2-Paco2/R
R=CO2production/CO2consumed
Causes of ischemia.
#impaired arterial flow #low venous drainage
What are the two forms of adult hemoglobin Hb?
- T(taut )form>deoxygenated>low affinity for O2>Tissues
- R(relaxed) form>oxygenated>high affinity for O2(300x)>Respiratory tract
In what forms does CO2 transfers in blood?
#free dissolved(5%) #bound to hemoglobin(HbCO2)5% #HCO3-(90%)
How are H+ molecules buffered in blood?
Via deoxyhemoglobin
In the RBV>carbonic anhydrase:H+ and HCO3-(:counter transport with Cl)
Why is the blood flow through the fetal lungs very low(blood surpasses pulmonary circulation)?
There is a generalized hypoxia vasoconstriction >fetal pulmonary vascular resistance is very high
With the first breath:alveoli of the neonatal are oxygenated ,pulmonary vascular resistance decreases>pulmonary blood flow increases=equal to the cardiac output
How does the distribution of pulmonary blood flow change according to the position of the body?
#supine=uniform blood flow throughout the lungs #standing=gravity>lowest at the apex(zone1) , highest at the base(zone 3)
What changes of V ,Q, V/Q do we come across at the different regions of the lungs?
apex(zone1)=
- very low Q>gravitational effect of AP
- low V>gravitational effect of the upright lung BUT the regional differences for ventilation are not as great as for perfusion
- –> ^V/q
- ^^ Q
- ^V
- —>Low V/Q
What is the effect of airway obstruction in the V/Q ratio?
With the airway obstruction>V=0 >V/Q=0 > SHUNT #no gas exchange #Po2,Pco2 of pulmonary capillary =venous blood #^A-a gradient
100%O2 DOES NOT improve Po2❗️
What is the effect of pulmonary embolism in the V/Q ratio?
When there is embolism>Q=0 >V/Q= infinity >DEAD SPACE #no gas exchange #Po2,Pco2 of the alveolar gas=inspired air
100%O2 improves Pao2(assuming<100%dead space)❗️
Which shunt results in a decrease in arterial Po2.
Which shunt is me most common?
List the changes that occur in the pulmonary system during the response to exercise…
#early activation of the joint and muscle receptors. #^demand of O2in the tissues>high ventilation rate! #Po2,Pco2:no change! #Pco2 venous:a little higher #pH:May be lower:^lactic acid #V/Q:evenly distributed
List the changes that occur in the pulmonary system during the response to high altitude..
#low Pb>low Po2>hypoxemia #hyperventilation>low HCO3- #respiratory alkalosis(augment with acetazolamide) #^EPO #^2.3-BPG>right shift>^P50>low affinity #chronic hypoxic vasoconstriction>^resistance>^work>Right ventricle hypertophy
