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Physiology BRS > Respiratory > Flashcards

Respiratory Flashcards

0
Q

Cartilage and goblet cells extend to which point?

A

Up until the end of brochi

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1
Q

What is the end of the conductive zone in the respiratory system?what is its epithelium?

A

The terminal bronchi.

Pseudostratified ciliates columnar cells

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2
Q

What is the epithelium in the respiratory zone?

A

Respiratory bronchi>cuboidal

Alveoli>squamous cells

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3
Q

What is the explanation of the low pressure in the terminal bronchioles,considering their small radius?

A

They are large in number ,in parallel architecture>least airway resistance

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4
Q

What does pulmonary surfactant consists of?when does the synthesis begins?

A

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

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5
Q

What’s the purpose of Clara cells?

A 
They are nonciliated ,low columnar with secretory granules.
#secrete components of the surfactant
#degrade toxins
#act as reserve cells
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6
Q

What’s the determination of physiologic dead space.?

A

ANATOMIC dead space of conductive airways PLUS alveolar dead space

Vd=Vt*(Paco2-Peco2)/Paco2

TacoPacoPecoPaco

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7
Q

How much is the ANATOMIC dead space approximately ?

A

150mL

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8
Q

How is minute ventilation determined?Ve

A

Ve=Vt*RR(respiratory rate)

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9
Q

How is alveolar ventilation determined?Va

A

Va=(Vt-Vd)*RR

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10
Q

What is FEV1?

How do lung diseases affect it?

A

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

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11
Q

How is the amount of dissolved O2 estimated?

A

Dissolved O2=Po2*solubility of O2in the blood

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12
Q

What is the transmural pressure?

A

It is alveolar pressure minus intrapleural pressure.

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13
Q

How does the compliance of the lungs change during respiratory circle?

A

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

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14
Q

How does the compliance of the lungs change in several lung diseases?

A

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

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15
Q

How is collapsing pressure on alveoli determined?

A

P=2T/r

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16
Q

What are the two factors that determine airflow???

A 
#pressure difference(Q=DP/R)
#resistance(R=8ηl/πr4)
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17
Q

There are three factors that change airway resistance.which are they?

A

contraction of bronchial smooth muscle

 Sympathetic>β2>relaxation
 Parasympathetic >^R

Deep sea dive>high air density>high R
He>low R

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18
Q

Patients with asthma learn a certain style of breathing.what is that??

A

Patients with asthma experience high airway resistance>they learn to breath in ⬆️high volumes to offset high airway resistance associated with their disease

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19
Q

Patients with COPD learn a certain style of breathing.what is that??

A

They learn to expire slowly in pursed lips in order to prevent positive P intrapleural pressure>no collapsing of the airways>less difficult expiration

20
Q

What is the partial pressure equation?

A

PP=total pressure*fraction gas concentration

In humidified air at 37•C>760-47mmHg

21
Q

How is gas diffusion across the alveolar-pulmonary capillary determined?what are the factors that affect it?
Give 3examples

A

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

22
Q

What are the perfusion limited gases?

A

O2 (normal)
CO2
N2O
Gas equilibrates early along the length of the capillary
Diffusion can ONLY BE INCREASED by blood flow

23
Q

What are the diffusion limited gases?

A

CO
O2 in exercise/fibrosis/emphysema

Gas does not equilibrates by the time blood reaches the end of the capillary

24
Q

What is the effect of low PAo2 in the pulmonary capillaries?

A

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

25
Q

Fetal hemoglobin has higher affinity for O2 than the adult hemoglobin.why is that?

A

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

26
Q

What is O2content?how is it measured?

A

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

27
Q

How is O2delivery to the tissues measured?

A

o2delivery ti tissues=CO*O2content of blood

28
Q

How is the sigmoid shape of Oxygen-Hb dissociation explained?

A

It is due to the positive cooperativity >higher affinity of hemoglobin as each successive O2 molecule binds to a heme site

29
Q

The curve is almost flat toward the end of the O2-hemoglobin curve.why is that?

A

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

30
Q

Name the factors that cause right shift of the O2-hemoglobin curve.

A 
ACE BAT:
Acid(>^H+>low pH)
CO2
Exercise
2,3-BPG 
Altitude
Temperature

Affinity to Hb is lower/^P50/lower O2content

31
Q

How does methemoglobin lead to tissue hypoxia ?

A

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

32
Q

How does carboxyhemoglobin lead to hypoxia?

A
  • 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

33
Q

Causes of hypemia.

A 
#low Po2(hypoventilation or ^altitude=low Pβ)   ->NORMAL A-a GRADIENT
#diffusion defect
#V/Q defect.               INCREASE A-aGRADIENT>10mmHg
#right to left shunt
34
Q

Causes of hypoxia.

A 
#low CO>low blood flow
#hypoxemia
#low [Hb]>anemia
#CO poisoning>low content of blood
#cyanidine poisoning >low utilization by tissues
35
Q

Pulmonary vascular resistance equation.

A

PVR=(Ppulm.art-Pl.atrium)/CO

36
Q

Alveolar gas equation.

A

PAo2=Pio2-Paco2/R

R=CO2production/CO2consumed

37
Q

Causes of ischemia.

A 
#impaired arterial flow
#low venous drainage
38
Q

What are the two forms of adult hemoglobin Hb?

A
  • T(taut )form>deoxygenated>low affinity for O2>Tissues

- R(relaxed) form>oxygenated>high affinity for O2(300x)>Respiratory tract

39
Q

In what forms does CO2 transfers in blood?

A 
#free dissolved(5%)
#bound to hemoglobin(HbCO2)5%
#HCO3-(90%)
40
Q

How are H+ molecules buffered in blood?

A

Via deoxyhemoglobin

In the RBV>carbonic anhydrase:H+ and HCO3-(:counter transport with Cl)

41
Q

Why is the blood flow through the fetal lungs very low(blood surpasses pulmonary circulation)?

A

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

42
Q

How does the distribution of pulmonary blood flow change according to the position of the body?

A 
#supine=uniform blood flow throughout the lungs
#standing=gravity>lowest at the apex(zone1) , highest at the base(zone 3)
43
Q

What changes of V ,Q, V/Q do we come across at the different regions of the lungs?

A

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
44
Q

What is the effect of airway obstruction in the V/Q ratio?

A 
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❗️

45
Q

What is the effect of pulmonary embolism in the V/Q ratio?

A 
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)❗️

46
Q

Which shunt results in a decrease in arterial Po2.

Which shunt is me most common?

A
47
Q

List the changes that occur in the pulmonary system during the response to exercise…

A 
#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
48
Q

List the changes that occur in the pulmonary system during the response to high altitude..

A 
#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

Physiology BRS (6 decks)

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