Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology Kerry > 4. Respiratory physiology - Volumes > Flashcards

4. Respiratory physiology - Volumes Flashcards

1
Q

What is meant by dead space

A

Main lung fxn gas exchnage

cenilation delivery gas - alveoli so available for change

not all inpsired gas useful
some tv in trachea at end inspiration not availabe gas exchange

part inspired voluume - wasteful p desint participtae gas exchnage
dead space gas
volume occupies called dead space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the types of dead space

A

anatomical

physiological

alveolar

apparatus

signif - relate fact vent of space wasted
to and fro breathing 0- some unavoidable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is anatomical dead space

A

Volume of conducting airway

some airway function channell bulk flow gas to tplace gas exhange occurs

dead space - consit total vol contrain in conducting airway

anatom dead space 150mls adult

2.2mls/kr body weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Physiological dead space

A

Some gas might enter alvoeli not perfused / poor
part tv inspiration enter space dead space - not meaure part voulme conductiong airway

volume chagne circ change - more less perfused alveoli

volume conducting airway - unaltered

Phys dead sace part TV diesbt participate gas exchange

Healthy young adult - value anatom & phys dead similar

presence disorder diff signif

difference refer alvoelar dead space

compnent phys dead space dbeyond condctuion airway - not parti gas exhcange

breath mask -a ddit space conduction zone - type apparatus dead large - poorly designer

alveolar dead space- part inspire gas thru anatom dead space mix gas alveol tract - not take part exchange

Defnines alveroly dead as phys minus antom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How measure anatomical dead space adult

A

Folwers method

Tech - breath mouthpeice
-connect pneumotachogrape + sampling line
connect N analyser

Breaths 100% o2 - breathing out
N2 plot against tpye

Curve- page 107 nitrogen conc against time

Anatom dead not detrm curve- no vol axis

curve 108 - plot aginst volume expired
volume determ pneuomatochgraph signal

Vertical line thru rising part curve area a - equal area b

volume of x indicates x - est anatom dead space mid
represent midpoint transition condctuing zone to gas exchange zone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why inita fio2 1 when measure dead space

A

Flush nitrogen co2 out dad space

any now present come from gas exchange area

prior expiration dead space 100% o2 0% nitrogen
co2 used instead N folwer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How measure physiological dead space adult subject

A

Bohr eqn

Vd/Vt = PaCO2-PeCo2/ Paco2

Normal range Vd/Vt .2-.35

Basic pricniple bohr - all expired co2 alveolar gas
dead space part tv - not eliminatite co2
elim used indicator presence gas exchange - function measure phsyological dead space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What value used place alveolar pco2 using Bohr equation

A

Prob Alveolar Pco2 - obtraining suitable value -

not measure prob - no single value alveolar pco2 - varies 28 mmh at epex to 42 at base
need averaged

Ideal valverolar pco2 used in eqn - alerolar pco2 exist if no v/q abnorm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Enghoff modifcation

A

Meaure art pco2 - est ideal alveolar pco2 substituted - use art pco2 boh introduced 1937 enghoff

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Healthy persion room air - how much art pco2 & etco2 differ

A

Diff small - end tidal pco2 2-5mmh lower
size - useful index alveolar dead space

alvceolar dead increase - etpco2 lower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Alveoli constitute alveolar dead space not perfused - no gas exchange
no perfusion no uptake O2 & excretion Co2
what pco2 values

A

Pco2 - avloeli zero is incorrect say

Normal TV - adult

end expiration anatomical dead space - condctuing airway filled gas alveoli - gas pco2 40mmHg

Anatom daed 150 - first 150 enter ventilated alveoli is CO2 contain dead space gas from airway

Resul all dead space alveoli contain some Co2 - comes from airway - no direct delivery CO2 from pum capil - not perfused

actual vlaue pco2 - vary distribu inspiratory gas to different alveoli lung - lower than perfused alveoli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What advantage dead space considder resus

A

End inspiration - antaom dead contain po2 150

mouth to mouth - first gas to alveoli of person ventilated - advant - higher PO2 & 0 Pco2 comp to alveolar gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Lung Volumes draw spirometry trace

Volumes

RV

ERV

IRV

TV

Cap

TLC
VC
IC
FRC

A

Draw trace from page 110

Volumes

RV 15-20ml kg
ERV 15mls kg

VT 7 mls kg

TLC 75-80
VC 60-70
IC 50
FRC 30

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Whats difference between volume and capacity

A

Both represent volumes of gas

Base units volumes

capacity decribe 2 or more bolume

VC - IRV TV ERV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which cant be measured using spirometer

A

RV & Capacity contrains RV - cannot be measured

Prob - residual volume stay n chest - spirometer only measure gas expired lungs

FRC measured He diln / Body plethysmography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

FRC

A

FRC is volume gas - remains lung at end normal expiration

sum of RV + ERV

RV is vol end max expiration

Change FRC _ occur anaes - effect gas exchange

can be meuared in vent pat

FRC is balance betwee tendincey to chest wall spring out and lung collapse in

Muscle tone in diaphgram at end epxiration pull dipahrg away lung
-Important maintaing FRC - higer value than otherwise be in supeine

Admin muscle relax - remove effect FRC - supine paralysed lower

Tendency chest well and diaphragm separate is reason intrapleural pressure negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How large FRC man

Neonate

A

30mls supine adults children

FRC ~ 2100 70 kg man

FRC 30mls kg nearly fully established within 30 mins bith

health 3.3 kg - frc 100 mls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What factors affect FRC

A 
Five maj factors
Height
Weight
position
Disease
Muscle relaxation

FRC increase with

Increase height
change supine to erect 30%
Decrease lung recoil - emphysema

Decreased
Obesity
msle relax
Change erect supine
pulm disease increasing elastic recoil
pregnancy
anaestheisa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Age effects on FRC

A

Doesnt change much w/ inc age in absence conditions alter elastic recoil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How can the FRC be measured

A

Gas dilution - nitrogen washout helium washin

Body pleth

Lung cap - FRC which cont RV - cant measure sirometry

Gas diln - easier explain -

tech helium - rebreathing closed circ w/ known volume V1 & He1 conc
Rebreathing - final heloum conc measure - min uptaken - quan helium circu - consatnt

V1 C He1 = V1 + FRC X He2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why is FRC measured not RV -

A

Method simple
reproducible - quant physiolgy meaninful

Measure commence lung vol end normal expiration
doesnt involve straining, lab can measure rv - same tech - involved ful exp
force exp avoided - not reduce volume gas in lung to true RB - gas trapping d/t dynamic airway closure

FRC more physiologically meaningful quantity - change FRC affect gas exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Diffrence in values obtain diff methods

A

Healthy people usually little difference

Lung disease - body pleth - large value
body plteh measure all gas in lungs -

gas dilution only measure communcating gas volume

Two prob
Gas trapped obstruct - not measured dilution

Gas in PTX measured when body pleth used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Relationship frc & closing capicaty at diff ages

A

Adults - CC normally less FRC
CC increase age - 44 supine 66 erect CC = FRC

Neotates - CC higher FRC - TVent - airwa collaspe depend lung - normal breathing
important cause ineff art oxy in neonates

Functions FRC
Oxygen store
Buffer steady Art Po2
Prevent atelactasis
Minminse WOB - keep lung steep compliance
Min PVR
Min V/Q mismatch
Keep airway resistance low
24
Q

Oxygen store

A

FRC major oxygen sotre body
alveolar po2 100mmhg - frc 2200 - lung contains 290 mls o2
more body cospm 250 mls min - improtnce to anaethetist
- Only oxygen store signif increase
increase occur rapdilky

Breathing 100% Oxygen - close fitting face mask - denitrogenate lungs & increase Oxygen store to 1800

25
Q

Buffer steady arterial PO2

A

Contin presence gas contrain oxygen lung converts intermitten tidal delivery -> continous availbility oxygen for gas exchange

vuffer function = prevent large swin art pO2 during cycle

change with tvidal on 3mmhg

26
Q

Partial inflation = prevention atelactasis

A

FRC - maintain state partial inflation lungs – prevent atelactasis

frc reduced atelactasis more liekly - impairs effeiceny gas exchange arterial Po2 fall

27
Q

Min WOB

A

FRC - lung on steep part compliance curve - that and prevention atelactais - help min WOB

28
Q

Min PVR

A

Varies lung volume high at large and small lung volume

29
Q

Min VQ

A

V/Q 0 erect lung min if volume inspiration commence above CC - min adverse effect basal airway closure gas exchange

FRC above CC - except extemities age - max efficiency gas exchange

30
Q

Keep airways resistance low

A

Airways resitance decrease as lung volume increase

at FRC - resitance low low value decrease further w inspiration as diam increase

31
Q

What blood vessel involved relationship between PVR & Lung VOlume

A

Pulmonary blood vessels 2 groups

1 alveolar vessel - pulmonary capillaries -
exposed alv pressure - high lung vol pulm vap - stretch longitudinally - decrease calibre increase resistance
Resistance increase w increase lung vol

Extra alveolor vessel
not exposed alv pressure - calibre increase high volume - stretch elastic fibrepull out on their walls
resitsance decrease w/ increase vol

32
Q

Lung volume PVR graph page 114

A

PVR - depend resitance alv & extra alveolar vessels some point between extemes high and low vol - PVR at max value - Point FRC
Under normal conditions pulmonaryt capillary - responbile 60% PVR

33
Q

How is work breathing min frc

A

high pulm complaince - steep part presure vol curve - reduced elastic work

Low airways resistance - resitsance work - low

Partial inflation - beng volume above CC - no work open collapsed part lung / open closed airway

If FRC decreased signifcantly - work breathing icnreased

PVR resistance increased gas exchange impair

Hypoxaemia - d/t airway closure - below CC - consequent V/Q mismathc - results

worsened shunt blood thru collapsed lung

34
Q

compliance

A

C = Delta v / Delta P

Volume change in lung per unit pressure change

‘Distensibility’

35
Q

Typical compliance value

How measured

A

200mls cm h2- - normal lung very distensible
high vol - less compliance

Slow of lung pressure volume curve
Curve - expire - steps of given volumes mesure intrapleural pressue

hold lung colume keeping glottis open
intrpleural pressure est as oesophageal pressure
Volume higher during deflation than inflation @ any pressur

Curve - prod join dots
Inspirtation different expiration = hysterisis

Curve not straihgt line - value selected convetion
Slope exp curve

Static compliance - no gas flow at each point measure

36
Q

Is it possible to determine the P-V curve - for lung alone living livng

A

Spirometer - fix point easy determ
bol plot x

Pressure plot on x - pressure gradient across lung
Transpulmonary pressure - / recoil pressure

Difference pressure inside and outside
ie aleolar and outside - intrapleural

TPP = Alovelar - intrapleural

Pressure measure - no flow

alveolar pressure - mouth pressure

Lung col hjeld constant - measure tensing muscle chest wall

Intrapleural - measured indirect - oesophageal pressure at fixed distance lips

Eg figures pg 116

Note - Transpulmonary pressure increase as lung volume increases

37
Q

Curve determ glottis open
-alveolar pressure = atmospheric

Requires tensing chest wall main constant volume

How is effect muscular activity wall elim

A

Pressure gradient across the lung
static TPP - not affected b any chest wall muscle activity

Kybgs - elastic body wall muslce contracted or not gradient constant particular volme

38
Q

Pressure vol curve chest wall - requires measu pressure gradient across chest wall

A

Gradient is recoil pressure of chest wall = equal intrapleural minus outside chest

Recoil pressure of wall = intrapleaural - atmospheric

Recoil pressure = intrapleural pressure

measure require chest muscle fully relax - lung vol sontrant

glottis closed during measurement

intrapleural - oesop baloon

recoil pressure negative all value lung vol ~~75% capacity
means chest wall tending spring outward to reach equilibrium

FRC - recoil pressure chest wall value opposite direction to recoil pressure lung

frc - being equil positing

balance tendency chest wal move out and lung to collapse

39
Q

Draw curve representing pres-vol curve lung - superimpose combined

A

Page 117

X - recoil pressure
Y percent tlc

at FRC - lung +5cms H20
recoil pressure chest wall -5
balances each other - recoil total 0

curve dotted line above pressure tolta system

at 80% TLC recoil presure positive - now exapnded benon equilibrium

40
Q

If someone exhaled to 50% TLC - glottis closed and chest wall muscle relaxed - what would values intrapleural pressure and alveolar pressure

A

Both lung and chest wall - elastic

ballpark from graph
recoil pressure = intrapleural = -3

Recoil lung = alv - intrapleural

alveolar - 5cm

41
Q

What is specific compliance

A

Compliance divied by FRC

Compliance lung depedn size

comparsion compiance diff sub or ages - correcting lung size obrtain standarised value - per unit lung vol

Specific comliance

typical 0.05cm H20

Diff unit spec compliance compared to complaince noted

42
Q

Value Ct compliance

A

1 / Clung + 1/ Chest wall

43
Q

Closing capacity

A

Is the lung volume small first start to close

  • Occurs first in dependent parts lung - erct - base

Airways closre impairs gas exhcange any blood flow non ventilated = shunted blood

CC sum RV & CV

CC = RV+CV

44
Q

How is closing capacity

Why does N2 rise in phase 4

A

Determ of CC - seperate measure RV & CV -

CV - measure single breath n test

Following insp 100% RV Expired N2 during slow epx meausre - rapid anaylser plot volume exp

Late expir - airway closure occus - expired N rises above platue value - volume xpire start of rise to end max expiration - closing volume

rsing n is phase 4

Volume gas remain lung end max exp = RV

RV determ - determ same time as measurement of closing volume - using N washout - immed following max exp used est cc

During initla inspiration RV - first part inspirate preferentially -> upper zones

Dead space gas in arway - high N2
Apex receives less inspire gas - as ventilation lower

apical alveoli - larger - expand less w/ inspiration
n2 in apcial alvoli - less diluted by 100%
effects = higher apical n2

basal closure airway inicdated rise N2 -d/t gas from apical alveoli

45
Q

How does closing capaicty change birth old age

A

CV & CC increase with increasing age

CC = FRC 66 erc
44 supine

Neonates - decreased recoil - less negative value - intrapleaur more airway closure in dependent areas - CC exceeds FRC during TV neonates decrease art po2

46
Q

Oxygen Cascade

WHat is % oxygen lung healthy subject on Room air

A

13-14%

Alveolar pO2 100mmhg (13.3) is over 13%

100/760 x100%

47
Q

What is the oxygen cascade

A

Stepwise decrease in Po2 as o2 moves inspired gas to site consumption
‘hiearachy pp gradients’

As follows

Dry room air 159

Sat room air 149 humidification of dry insp

alveolar gas 100 gas exchange in alveoli

Arterial blood 95 venous admixture

End cap blood 40 diffusion O2 into cells

Mitochondria 4-22 consumption - ox phsopryl

48
Q

What causes drop 149 Sat insp to 100mmHg in alveoli

A

Alveoli depened balance delivery oxgen alvelo in spired gas and uptake by pulmonary capillary

drop not d/t sat inspirared gas w water vapour

dilution of dry - 159 to 149

49
Q

How do you calculate alveolar po2

A

pAo2 = pio2 - PCo2 / R + F

room air fio2 .21

0.21 x 760-47 0 40/.8 = 150-50 = 100mmhG

50
Q

Why is po2 arterial blood slightly lower than alveolar

A

Venous admixture -

True shunt

Lung ratio v/q <1

Usually small amt shunt blood not passed thru gas exchange area - lower Po2 then end cap blood - from capillary with mix

Diffuson oxygen across blood gas membrane never barrier to o2 transfer and doesnt contrib to nromal small A-a grad

51
Q

Hoe does arterial oxygen tension change w/ increasing age

why

A

Po2 decreases from 20
95% values fall +/- 10mmHg of value est formula

Average pO2 = 100 - (1/3 x age in years)

Closing capacity increases with increasing age -

when its greater than FRC - airway closure during normal TV

Blood draining from alveoli has lower Po2 - increase admixture results in lower art Po2

52
Q

Draw diagram show oxygen cascade

What is the pasteur point

A

page 120

Crticical po2 for oxy phosprylation mitochondira

value 1mmhg

if Po2 in mitochondria falls < value - aerobic metabolsim

anaerobic occurs

53
Q

Oxygen transport

How much oxygen taken up into blood in lungs

A

250mls min which = body oxygen consumption

54
Q

What is oxygen flux

A

Amount oxygen delivered periphereal tissue per min

1000mls o2 min
tissue extracts = 250, retuns 750 to right heart

another term total body oxygen delivery

55
Q

What forms carried in blood

flux eqn

A

Chemical oxygne - combine hb

Dissolved oxygen

Flux eqn = {CO x hb x 1.34 x SaO2} + {COx 0.003 X PaO2

56
Q

How much do chemical and dissolved forms contribue

A

50 x 15 x .99 x 1.34 + 50x 100x.003

995 + 15

approx 1000

Breathing room air - 99% oxygen tport combine hb
dissolved carriage small

Not overlook role dissolved - critically important - this form diffuse thru ISF to ICF - use in mitochondria

Physiology Kerry (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions