respiration - lecture 2

Question 1

what is spirometry

Answer 1

measuring lung volumes

Question 2

what is total lung capacity

Answer 2

very deep breath
around 7l
total amount of air in lungs

Question 3

what is vital capacity

Answer 3

diff between tlc and residual volume

Question 4

what is tidal volume

Answer 4

breathing at rest ~1L in/out

Question 5

what is functional residual capacity

Answer 5

around 3L left in lungs
during quiet breathing = do not breathe out all the air

Question 6

what is residual volume

Answer 6

breathe out at max effort
expire air, still some left in lungs tho
if make too much effort = lungs collapse, need some air always to keep open

Question 7

describe spirometer

Answer 7

upside down cannister floating above water
nose clip
breathe into cannister so pen goes upwards

Question 8

what cant you measure with spirometer

Answer 8

what you breathe in = pen goes ip
cannot measure tlc and cannot measure functional residual capacity

Question 9

what is inspiratory reserve vol

Answer 9

tidal volume to total

Question 10

what is expiratory reserve volume

Answer 10

functional residual capacity to residual vol

Question 11

what is vital capacity

Answer 11

functional to total

Question 12

describe measurement of frc - helium dilution - gen

Answer 12

dissolved in air that subject breathes in
measures functional residual capacity

Question 13

describe measurement of frc - helium dilution - experiment

Answer 13

breathe through spirometer with dissolved helium - concentration c1 known
also know volume
breath out to frc and then open valve and takes a few. breaths and equilibrates helium between canister and lungs
have new concentration and helium less concentrated = diluted in lungs
total vol = at beginning + frc

Question 14

describe measurement of frc - helium dilution - math

Answer 14

c1 x v1 = c2 x (v1 + frc)
so
frc = (c1 x v1 / c2) -v1

Question 15

what is minute ventilation

Answer 15

amount of air inspired or expired over one minute = VE
VE = VT x f
VT = tidal vol and f = number of breaths per min
(dot above VE = per min)

Question 16

what is anatomical dead space

Answer 16

not all the air inhaled into the lungs reaches the gas exchange area
some of air remains in conducting airways = anatomical dead space

Question 17

describe volumes of air

Answer 17

tidal = 450ml
dead space = 150ml ish - wasted in terms of gas exchange
around 450ml useful inside alveolar region

Question 18

how to know how much anatomical dead space is

Answer 18

around 150ml in adult
hard to measure but close approx = subjects weight in pounds

Question 19

describe volumes - formulas

Answer 19

healthy adult male VT=500ml and f=12 breaths/min
so VE = 6000ml/min = 6L/min
anatomical dead space = 150ml
alveolar ventilation = VA = (500-150ml) x 12/min = 4200ml/min = 4.2L/min

Question 20

what is alveolar dead space

Answer 20

under some pathological conditions
certain amount of inspired air reaches respiratory zone but does not take part in gas exchange
can be due to decrease blood supply or no blood supply at alls

Question 21

describe alveoli during alveolar dead space

Answer 21

ventilated region not perfused=wasted air
occluded blood vessel by blood clots = little blood flow
so no gas exchange since no blood flow

Question 22

describe pressure formulas

Answer 22

P = total pressure
Px = partial pressure of gas x
Fx = fractional concentration in dry gas
Px = P (Fx)

Question 23

what is physiological dead space

Answer 23

VD = (alveolar + anatomical) dead space
usually equal but sometimes under pathological conditions alveolar greater

Question 24

describe pressure formulas - ex

Answer 24

Barometric P = 760mmHg
FO2 = 21% *
FCO2 = 0.03% *
(percent of O2 in air ~2% - fractional concentration)

Px = (P-47mmHg)Fx (in a gas with a water vapor pressure of 47mmHg)
PO2 = (760mmHg – 47mmHg)(21/100) = 150mmHg
PCO2 = (760mmHg – 47mmHg)(0.03/100) = 0.2mmHg
(must subtract 47 bc of water vapour pressure)

Question 25

describe fractional concentrations

Answer 25

generally given as the fraction of dry gas volume that is occupied by the gas in question. Because of that convention, barometric pressure has to be corrected for the contribution from water vapor

Question 26

describe partial pressures of air vs alveoli

Answer 26

air po2 = 160mmhg, pco2=0.3mmhg
alveoli po2 = 105mmhg, pco2 = 40 mmhg
avg values = as inspire, fresh air mixes with old air and diffuses and co2 diffuses into alveoli

Question 27

describe partial pressures of left heart

Answer 27

in pulmonary veins - po2 = 100mmhg, pco2 = 40mmhg
in systemic arteries = po2 = 100mmhg, pco2=40mmhg

Question 28

describe partial pressures of tissue capillaries

Answer 28

o2 diffused into cells and co2 into capillaries
in cells p02<40mmhg (mitochondrial po2 <5mmhg), pco2 > 46mmhg

Question 29

describe partial pressures of right heart

Answer 29

systemic veins po2=40mmhg, pco2=46mmhg
pulmonary arteries - po2 = 40mmhg, pco2 = 46mmhg

Question 30

describe the components important for partial pressures

Answer 30

pressure gradient
other components important like solubility in blood co2 diffuses better - more soluble

Question 31

describe normal alveolar ventilation

Answer 31

alveolar ventilation keeps p arterial co2 at a constant level of 40mmhg
arterial co2 keeps ventilation proper
in systemic blood

Question 32

what is A and what is a

Answer 32

A = alveolar
a = arterial
see ventilation increase and decrease as measure of arterial co2

Question 33

describe alveolar hyperventilation

Answer 33

ventilation exceeds needs of body
more o2 supplied and more co2 removed than metabolism needs

Question 34

describe alveolar hyperventilation - pressures

Answer 34

p alv o2 and p arterial o2 rise
palv co2 and p arterial co2 decrease

Question 35

describe alveolar hyperventilation - metabolism

Answer 35

all with respect to metabolism so not during exercise (which increases metabolism and ventilation)
there are limits to increase in p arterial o2

Question 36

describe alveolar hyperventilation - how to fix

Answer 36

in paper bag = arterial co2 goes down and in brain = artery constricts= leads to fainting but bag build co2 and then you breath in and reestablish co2 levels

Question 37

describe alveolar hypoventilation

Answer 37

decrease in alveolar ventilation below metabolic requirements
less o2 supplied and less co2 removed than metabolism requires

Question 38

describe alveolar hypoventilation - pressures

Answer 38

palv o2 and parter o2 decrease
palv co2 and parter co2 rise

Question 39

describe alveolar hypoventilation - disorders

Answer 39

chronic obstructive lung disease
damage to respiratory muscles
rib cage injuries
cns depression
pneumothorax
drugs

Question 40

describe pressures when breathe air with low po2

Answer 40

alveolar po2 decreases
no change in alveolar pco2

Question 41

describe pressures when increase alv ventilation and unchanged metabolism

Answer 41

palv o2 increases
palv co2 decreases

Question 42

describe pressures when decrease alv vent and unchanged metabolism

Answer 42

palv o2 decreases
palv co2 increases

Question 43

describe pressures when unchange alv vent and increase metabolism

Answer 43

palv o2 decreases
palv co2 increases

Question 44

describe pressures when unchange alv vent and decrease metabolism

Answer 44

palv o2 increases
palv co2 decreases

Question 45

describe pressures when proportional increases in metabolism and alv vent

Answer 45

no change in palv co2 or o2

Question 46

describe diffusion rate

Answer 46

transfer of gasses across alveolar capillary membrane = by passive diffusion
diffusion v efficient in lungs bc of huge surface area and v thin membrane

Question 47

what is diffusion governed by

Answer 47

ficks law

Question 48

describe diffusion rate - mayth

Answer 48

proportional to surface area (50-100m^2)
proportional to partial pressure gradient
inversely proportional to thickness (~0.2mm)

Question 49

describe diffusion pathway

Answer 49

o2 flows from alveolus through fluid layer inside alveolus and surfactant through alveolar epithelium and bm through interstitial space then capillary bm then capillary endothelium then plasma and rbc
co2 = opp dir - passive
gasses must be liquid soluble and plasma - also has to be soluble in liquid
gas dissolved = proportional to partial pressure

Question 50

what is henrys law

Answer 50

to diffuse through a liquid, a gas must be soluble in the liquid. The amount of gas dissolved is proportional to its partial pressure
more diffusion = more pressure

Question 51

what diffuses faster

Answer 51

co2 diffused 20 times faster than o2 bc co2 is more soluble in water

Question 52

describe time required for equilibrium between alveolar air and capillary blood

Answer 52

same for 2 gases
pco2 between 2 sides of alveolar capillary membrane is 10 times smaller than for po2

Question 53

describe transit time

Answer 53

~0.75s in capillary
po2 = 105mmhg

Question 54

describe transit time - po2

Answer 54

as flow in through pulmonary cap = po2 increases v fast
~0.35s = o2 saturated

Question 55

describe transit time - pco2

Answer 55

same thing = ~0.25 sec - decrease co2 to same level of lungs = desaturate

Question 56

describe transit time - athlete

Answer 56

increase blood flow - goes faster
transit time ~0.3s
still enough time to be saturated

Question 57

describe transit time - edema

Answer 57

fluid in interstitial alveolar cap membrane = thicken so takes longer
can still have enough time but if exercise = wont saturate and desaturated = diffusion problem