Respiratory Physiology

Front 1

According to Boyle's Law, how do pressure and volume relate?

Back 1

P and V are INVERSELY PROPORTIONAL when T remains constant
--ONLY APPLIES TO CLOSED CIRCUITS!!!

Front 2

According to Charles' Law, how do volume and temperature relate?

Back 2

V and T are DIRECTLY PROPORTIONAL when P remains constant

Front 3

According to Gay Lussac's Law, how do pressure and temperature relate?

Back 3

P and T are DIRECTLY PROPORTIONAL when V remains constant

Front 4

According to Dalton's Law, how does the pressure exerted by one gas in a gas mixture affect the pressure exerted by another gas in that same gas mixture?

Back 4

the P exerted by one gas in a gas mixture is INDEPENDENT of the pressures exerted by the other gases within that same gas mixture

Front 5

According to Dalton's Law, what is the total pressure of a mixed gas?

Back 5

the sum of each of the partial pressures of each gas within a gas mixture

Front 6

According to Henry's Law, how does the partial pressure of a gas in a solution relate to the partial pressure of a gas above the air-liquid interface at equilibrium?

Back 6

the partial pressure of the gas in the solution will equal the partial pressure of the gas above the air-liquid interface
EXAMPLE: if alveolar air have a PO2 of 100mmHg, then at equilibrium, capillary bld will also have a PO2 of 100mmHg

Front 7

If there is a higher PCO2 in the capillary bld than the alveoli, which way will CO2 diffuse?

Back 7

into the alveoli

Front 8

According to Graham's Law, how does the rate of diffusion of a gas in the gas phase (in air) relate to the size of the gas?

Back 8

the smaller the MW of a gas, the faster it will diffuse

Front 9

According to Graham's Law, when is a gas unable to diffuse?

Back 9

when the gas is insoluble in a solution

Front 10

According to Fick's Law of Diffusion, the volume of a gas that can diffuse across a barrier is directly proportional to what?

Back 10

1. the surface area available for diffusion
2. the diffusivity of the gas (depends on MW and solubility of the gas)
3. the difference in partial pressures on either side of the pulmonary endothelial capillary barrier

Front 11

According to Fick's Law of Diffusion, the volume of a gas that can diffuse across a barrier is inversely proportional to what?

Back 11

the thickness of the pulmonary endothelial capillary barrier

Front 12

how thick is the pulmonary endothelial capillary barrier

Back 12

only 2 cell layers thick:
1. alveoli
2. capillary
...so actually very thin
-1 cell layer=

Front 13

According to Poiseuille's Law, the R to airflow is directly proportional to what?

Back 13

1. the viscosity of the liquid or gas
2. the length of the path

Front 14

According to Poiseuille's Law, the R to airflow is inversely proportional to what?

Back 14

the FOURTH power of the radius
--has the biggest effect on R and deals with bronchoconstriction and bronchodilation

Front 15

What is the primary mm of inspiration? what other mm's of inspiration are there?

Back 15

-inspiration is primarily mediated by the diaphragm
-other mm's of insp:
1. external intercostals
2. SCM
3. ant serratus
4. scalene

Front 16

primarily, what kind of process is expiration? sometimes we use what 2 mm's during expiration?

Back 16

exp is primarily a passive process
1. abdominal rectus
2. internal intercostals

Front 17

at the end of expiration, what is the airflow into the lungs? why?

Back 17

0,b/c
alveolar pressure=Patm
Ohm's Law:
-change in P=0
-therefore, Q=0

Front 18

are the respiratory mm's contracted or relaxed at the end of expiration?

Back 18

relaxed

Front 19

at the end of expiration, the lung and chest wall are acting on each other in opposite direction.
1. what is happening to the lung (alveoli)?
2. what is happening to the chest wall?

Back 19

1. the lung (alveoli) decreases its volume b/c of inward elastic recoil of the distended alveolar walls--> acts, by its elastic recoil, to hold the chest wall in
2. the chest wall increases its volume b/c of its outward elastic recoil-->
acts to hold alveoli open in opposition to their elastic recoil

Front 20

at the end of expiration, the lung and chest wall are acting on each other in opposite direction.
--what does this do to the intrapleural space?

Back 20

the opposite pull of the chest wall(out) and the alveoli(in) pulls the visceral and parietal pleura apart creating a larger volume within the intrapleural space
-Boyles law: inc V, dec P
-such opposing forces create a negative intrapleural pressure (-5)=inrapleural P is established

Front 21

what is the transmural pressure?

Back 21

-the difference in pressure across the alveolar wall
=(alveolar P)-(intrapleural P)
-->transmural P across alveoli at end of expiration=(0)-(-5)=5cmH2O

Front 22

what is transmural P equal to?

Back 22

the alveolar elastic recoil pressure
--> a P of +5 pulls in (intramural P or alveolar elastic recoil P) and a P of -5 pulls out (intrapleural P)
-therefore, P=0 inside alveoli

Front 23

when is the only time there is air movement in respiration?

Back 23

when there is a difference in Patm and Palveolar
-->MUST HAVE A PRESSURE DIFFERENCE TO HAVE AIRFLOW
-the only time airflow exists is DURING inspiration and expiration

Front 24

during inspiration what does the diaphragm (primarily) and the other mm's of inspiration do? what does this do to the intrapleural pressure?

Back 24

they contract to increase the volume of the thoracic cavity (diaphragm moves down)
-this increases the outward stress on the lung
-the intrapleural P decreases even more (becoming more negative: dec from -5to-8) d/t an increase in V (boyle's law)

Front 25

what happens to the diaphragm at the end of expiration?

Back 25

the diaphragm moves up passively d/t elastic recoil of chest wall which pulls the chest out

Front 26

as air comes into alveoli, it expands...what does this do to the elastic recoil of the alveolus?

Back 26

elastic recoil P increases b/c alveoli become larger
(>alveolar volume=>inward elastic recoil)-->THE PASSIVE TENSION EFFECT

Front 27

what happens to alveolar and transmural P during inspiration?

Back 27

-transmural P, which distends alveolar wall, increases b/c intrapleural P decreases
-alveoli enlarge passively: increasing alveolar volume lowers alveolar P(from 0to-1)=air flows in b/c Palveoli<Patm

Front 28

when does airflow stop coming into alveoli?

Back 28

when Palveoli=Patm

Front 29

what is FRC?

Back 29

functional residual capacity: the amount of air left in lungs at the end/beginning of a normal eupnic breath

Front 30

what is TV?

Back 30

tidal volume:
-the amount of air inhaled during a normal eupnic breath OR the amount of air exhaled during a normal eupnic breath
--amnt air inhaled=amnt air exhaled

Front 31

does inspiration or expiration last longer? why?

Back 31

expiration b/c air flows slower out of the lungs than into the lungs but the amount of air inhaled and exhaled is equal

Front 32

during a normal eupnic breath when do FRC and TV occur?

Back 32

1. FRC (volume at beginning of insp)
2. TV (volume at end of insp/beginning exp)
3. FRC (volume at end of expiration)

Front 33

why is the decrease in intrapleural pressure during insp and increase in intrapleural pressure during exp not a linear relationship?

Back 33

b/c there is a R to air flowing into the alveoli
-if R=0, there would be a linear relationship

Front 34

during insp, pressure work must be done for air to flow into the lungs...why?

Back 34

the diaphragm contracts and causes the thoracic volume to increase as chest expands out
-this creates a more negative intrapleural P, which increases transmural P gradient, which expands alveoli= decreases R to flow
-->this is the pressure work that must be generated to overcome the resistance to airflow

Front 35

what happens if a pt has asthma? how will pt respond?

Back 35

the resistance to Q increases d/t bronchoconstriction
-response: gasp for air which is conscious/active/forced inspiration and decreases intrapleural P to an even greater degree
--the higher the R to airflow goes, the more negative intrapleural P must go inorder to overcome R to Q

Front 36

what is Q at FRC and TV?

Back 36

Q=0 at
-beginning insp
-end insp
-beginning exp

Front 37

when is airflow the highest?

Back 37

during the first 1/2 of insp and exp and reaches max in the middle of each phase then rate decreases

Front 38

what is the slope of a pressure-volume curve known as?

Back 38

Compliance=dV/dP=1/elasticity=1/elastic recoil
-high compliance=steep slope
-->a small change in distending pressure will cause a large change in volume

Front 39

what is the difference btwn compliance and elasticity?

Back 39

-compliance: the ease with which something can be stretched or distorted
-elasticity: the tendency for something to oppose strectch or distortion and ability to return to original configuration after the distortin force is removed

Front 40

what is the pressure-volume curve of respiration called? why?

Back 40

hysteresis curve: there is a difference between the pressure-volume curve for inspiration and expiration

Front 41

Does TV or FRC have a greater volume?
Does TV or FRC have a greater intrapleural pressure?

Back 41

-TV has a greater lung volume than FRC (greater volume of air brought into the lungs than left in the lungs)
-since TV has a greater volume than FRC, it has a lower pressure than FRC

Front 42

during inspiration, how does the compliance of the alveoli change?

Back 42

1. at FRC or beginning of insp, compliance is low and the alveoli are hard to expand
2.in the middle of insp, alveoli are the most compliant--easiest to expand b/c elastic recoil is the lowest
3.compliance is low again at end of insp and hard to expand b/c high elastic recoil

Front 43

what is atelectasis and when does it occur?

Back 43

alveolar collapse: occurs at very low lung volumes (under FRC) and high intrapleural P

Front 44

how do you get a collapsed alveoli to open back up?

Back 44

1. inflate the normally compliant alveoli that are not collapsed until they are at maximal V(TV)
2. at TV, the normal alveoli will decrease in compliance
3. when the normal alveoli reach a compliance lower than the collapsed alveoli, then air will flow to the atelectic alveoli

Front 45

why is it bad to have a atelectasis?

Back 45

an atelectic lung cannot participate in gas exchange

Front 46

It is hypothesized that we prevent atelectasis by________.

Back 46

yawning/deep breaths

Front 47

what is surfactant?

Back 47

a very thin fluid layer that lines the inside of the alveolus
-functions to decrease surface tension
-therefore, the walls of an atelectic alveoli do not stick together when collapse

Front 48

what are the affects of surface tension and elasticity on alveolus?

Back 48

works in conjxn with elasticity in alveolus and both cause alveolus to passively collapse
-surfactant dec surface tension=alveoli < likely to collapse
-absence of surfactant=alveoli more likely to collapse

Front 49

who is most likely to have insufficient surfactant?

Back 49

premies--put them on ventilator b/c their lungs will be atelectic b/c can't decreases surface tension
-when they are born they exhale and alveoli snap to atelectic postition and have to generate lots of P to open alveoli

Front 50

what is the avg total compliance of both lungs in the normal adult?

Back 50

~200mL of air/cmH2O transmural P
=every time transmural P increases 1cmH20, the lung volume after 10-20sec, will expand 200mL

Front 51

what are the 2 types of elastic forces of the lung?

Back 51

1. tissue elastic forces of air filled lung: greatest in middle and end respiration where compliance is the lowest
-1/3 of tot lung elasticity
2. elastic forces caused by surface tension of fluid that lines inside walls of alveoli and other lung air spaces=fluid-air surface tension forces
-2/3 of tot lung elasticity

Front 52

what is the TV?

Back 52

tidal volume is the volume of air inspired or expired with each normal breath

Front 53

what is IRV?

Back 53

inspiratory reserve volume is the extra volume of air that can be inspired over and above TV when the person inspires with full force

Front 54

what is ERV?

Back 54

expiratory reserve capacity is the maximum extra volume of air that can be exerted by forceful expiration after the end of a normal tidal expiration

Front 55

What is RV?

Back 55

residual volume is the volume of air remaining in the lungs after teh most forceful expiration

Front 56

what is the IC?

Back 56

inspiratory capacity is the amount of air a person can breathe in, beginning at the normal expiratory level and distending the lungs to the maximum amount
IC=TV + IRV

Front 57

what is FRC?

Back 57

functional residual capacity is the amount of air that remains in the lungs at the end of normal expiration
FRC=ERV+RV

Front 58

what is VC?

Back 58

vital capacity is the maximum amount of air a person can expel from the lungs after the first filling the lungs to their maximum extent and then expiring to the maximum extent

Front 59

what is TLC?

Back 59

total lung capacity is the maximum volume to which the lungs can be expanded with the greatest possible effort
TLC=VC+RV=IRV+TV+ERV+RV

Front 60

what can a spirometer measure?

Back 60

volume of air entering or leaving the lungs

Front 61

Can you use the spirometer to measure FRC?

Back 61

NO, FRC=RV+ERV, and RV is never exhaled from the lungs

Front 62

what method must you use to measure FRC?

Back 62

the He dilution method
FRC=([Hei]/[Hef]-1)(Vispir)

Front 63

How does the He dilution method work?

Back 63

1. a spirometer of known volume is filled with air mixed with He at a known concentration
2. pt expires normally and at the end of this expiration, the remaining volume in the lungs is equal to the FRC
3. at this point, the pt begins to breathe into the spirometer and the gases of the spirometer mix with the gases of the lungs until their concentrations are equal
4. use equation to calculate FRC

Front 64

with the He dilution method, what would be measured if the pt took a deep breath then started breathing into spirometer?

Back 64

TLC

Front 65

with the He dilution method, what would be measured if the pt had forced expiration then started breathing into spirometer?

Back 65

RV

Front 66

with the He dilution method, what would be measured if the pt breathed into spirometer at beginning of normal eupnic breath?

Back 66

FRC

Front 67

TLC, FRC, and RV all contain what?

Back 67

residual volume=what we have to measure with the He dilution method

Front 68

what is the displacement of the diaphragm a reflection of?

Back 68

the amount of air moving into and out of the lungs

Front 69

what will happen to the diaphragm when in the supine position? why?

Back 69

-the dia will be pushed toward the apex of the lungs b/c
1. diaphragm not pulled as much by gravity
2. guts not pulled down by gravity and now push up against diaphragm toward apex--diaphragm sits higher up

Front 70

what happens to TV when in the supine position?

Back 70

it does not change b/c can still take normal insp and exp

Front 71

what happens to IRV when in the supine position?

Back 71

diaphragm starts off higher but when tell pt to take a maximal forced insp, the diaphragm can push down and move the guts out of the way and is back down to the same level as it was when standing
-dia has > displacement
-therefore, IRV increases

Front 72

does the VC change when in the supine position? why?

Back 72

the VC is set and does not change
-IRV becomes largers
-ERV becomes smaller

Front 73

what happens to FRC when in the supine position?

Back 73

FRC=ERV+RV
-RV does not change
-ERV becomes smaller
-therefore, FRC becomes smaller

Front 74

does body position effect lung volume?

Back 74

Yes-lung volumes are altered by altering body position

Front 75

Do alveoli ever have outward recoil?

Back 75

NO-they always have (+) inward elastic recoil regardless of volume

Front 76

after a forced expiration, at RV (0% VC), what happens to the chest wall and alvoli?

Back 76

-chest wall is at maximal outward recoil and pulls out
-alveoli are at minimum inward elastic recoil and are very compliant

Front 77

after a forced inspiration, at TLC (100% VC), what happens to the chest wall and alveoli?

Back 77

-chest wall is expanded too far out and wants to collapse in=inward elastic recoil
-alveoli are at maximal inward elastic recoil and have a very low compliance

Front 78

at FRC, what happens to the chest wall and alveoli?

Back 78

-the inward elastic recoil of the alveoli=the outward recoil of the chest wall
--equal and opposite forces
--expend no energy b/c forces are balanced

Front 79

when you move from standing to supine position, what happens to the elastic recoil of the alveoli? why?

Back 79

it does not change b/c the elastic recoil in the alveoli are dependent upon:
1. surface tension and volume of surface tension will not be altered
2. elastic fibers and the amount of elastic fibers in the alveoli will not change

Front 80

when you move from standing to supine postion, what happens to the elastic recoil of the chest wall? wht does this cause?

Back 80

the elastic recoil will decrease and this causes FRC to decrease
-at FRC there is still equal and opposite elastic recoil forces BUT volume at which FRC occurs drops from 40%VC to 25%VC

Front 81

why does FRC decrease when you move from standing to supine position?

Back 81

FRC=ERV+RV
ERV gets smaller b/c gravity can not act on the diaphragm and guts to pull them down so the guts push up against the diaphragm