copy of respiratory part1

8/8/2019 Copy of Respiratory Part1

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RESPIRATORYPHYSIOLOGY

PART I


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RESPIRATIONprocess of taking up oxygen andremoving carbon dioxide from

cells of the bodyGAS EXCHANGE


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R espiration

External respiration :

ventilation and exchange of gases in the lungs

I nternal respiration :

ventilation and exchange of gases in the tissues


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E xternal R espiration

P ulmonary ventilationE xchange between lungs and bloodT ransportation in bloodE xchange between blood and bodytissues


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O ther R espiratory S ystem

Functions

HOST DEFENSE

METABOLISM


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M etabolic R oles


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STRUCTURE AND FUNCTIONS O F THE RESPIRATORY SYSTE M


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R espiratory S ystem


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S tructures of the T horacicC avity

P leura membrane lining of lu ngs and ch est wa llPle ura l sa car ou nd ea chlung


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P leura

pr oduc e a lubr icat ing fluid (15 ml) that fills the ga p bet ween them. This he lps the

lungs to mov e sm oo thly in the ch est when the y are inflat ing and de flat ing as we breat he.


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CLINICAL:

Lung can cer can s pread to the p le ura. Th e can cer irr itates the p le ura pr oduci ng p le ura l e ffus ion.

P ne umotho raxEm pyema


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Respiratory System: Anatomical division


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Huge increase in cr oss se ctiona l area

Branching of A irways


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C onducting Zone

Air passage wa y- 150 mL volu me = dead s pa ce volu me

warms and hu midifies ins p ired a ir.filters and cleans:

Mucu s se creted to tra p part icles in the

ins p ired a ir.Mucu s moved by cilia to be ex pe ctorated


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F iltrat ion of Air

Nasa l ha irs ser ve as filtersMuco sa l lining tra ps part icles and ba cter ia

Large part icles:


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R espiratory Zone

Reg ion of gas ex ch ange bet ween a ir and bloo d


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S tructures of the R espiratoryZone

R espiratory bronchiolesA lveolar ducts

A lveoliA lveolar sacs


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ALVEOLI

~ 300 million air sacs (alveoli)L arge surface area ( 6 080 m 2)E ach alveolus is 1 cell layer thick.


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R espiratory M embrane

Th e area where gas ex ch ange bet ween a ir and bloo d occu rsIt is the fused a lve olar and ca p illar y wa lls (3la yers )

1. Alve olar e p ithe lium

2. Fused basa l lam inae3. Ca p illar y e p ithe lium


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The R espiratory Membrane


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CELLS O F THE AIRWAY


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CILIATED CELLS

- line the res p irat or y tra ctbr onchiol es


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CELLS PRODUCING M UCUS

1. s ur f a ce se cret or y c e lls (goblet ce lls )2. s ubm uco sa l glands

- p resent where ver there is cart ilage3. Clara ce lls

- fou nd at the le ve l of br onchiol es- ma in se cret or y c e ll type in the dista l co nd uc ting a ir wa ys- ma y p la y a r ole in e p ithe lia l

regenerat ion a f ter injur y


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MUCOCI LIARY ELEV ATOR

Ciliated ce lls + goblet ce llsImpa ired by toxins f r om cigarette sm oking


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ALVEOLAR CELLS

A lveolar type I

A lveolar type II

> Rou nd t o cu be -s ha pedse cret or y c e llsP r oduc e s ur f a ctantRegenerat ive ca pa city

> thin sq uam ou s e p ithe lia l ce lls

> form 90% of s ur f a ce of a lve olu s

> Gas ex ch ange


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SUR FACTANT

Thin film lining the a lve olar s ur f a ceCo mp lex mixture of pho s pholip ids , ne utra l

lip ids , f att y a cids and pr ote insMa in co mponent: DPPCP r oduc tion starts at 24 wks gestat ion


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3 main functions of SUR FACTANT:

1. lowers s ur f a ce tens ionhas ant i-st ick pr opert y

2. pr omotes stab ility am ong a lve oli of diff erent s izes by de creas ing the tenden cy of sma ll a lve oli to

colla pse (interde penden ce )3. red uc es ca p illar y filtrat ion for ces


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CELLS IN THE ALVEOLI

D ust cells (phagocytes)

Alve olar ma cr ophagesPh ag ocy tize inha led part icles and ba cter ia

Impa ired by sm oking


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PUL M ONARY BLOOD FLOW

is the card ia c ou tput of the r ight heart

eje cted f r om the r ight ventr icle and is de livered to the lungs via the pulmonar yarter y


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Th e pulmonar yarter ies bran ch i ntoincreas ing ly sma ller arter ies and tra ve lwith the br onchitoward the res p irat or yzo nes. Th e sma llest arter ies divide intoarter ioles and then into the pulmonar yca p illar ies , which fo rm dense net wor ks ar ou nd the a lve oli.


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UNEVEN LY distr ibuted be ca use of gra vitat iona l e ff e ct

On stand ing , bloo d flow is lowest at the a pex (top) of the lungs and highest at the base (bottom) of the lungs.

Wh en the pers on is s up ine (lying down),these gra vitat iona l e ff e cts disa pp ear


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REGULATION of PUL M ONARY BLOOD FLOW

a cco mp lis hed by a lter ing the res istan ce of the pulmonar y arter ioles

Ch anges in pulmonar y arter iolar res istan ce are co ntr olled by loc a l f a ctors ,ma inly O 2

a in P a O 2 ca uses a hypoxic v as oco nstr iction that s hif ts blood a wa y f r om poo r ly vent ilated reg ions of lu ng to w e ll-vent ilated areas


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BLOOD SUPPLY TO THE LUNGS:

1. PULMONARY CIRCULATION

- brings deoxygenated blood fromthe RV to the gas exchanging units

- largest vascular bed in the body

2 . BRONCHIAL CIRCULATION

- the bloo d s upp ly to the co nd uc ting a ir wa ys (which do not part icipate in gas ex ch ange ) and is a ver y sma ll f ra ction of the tota l pulmonar y bloo d flow.


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T he lungs low vascular resistanceis due to

1 . L ow vascular tone

2. L arge capillary compliance


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P ulmonary C irculation D iffersFrom

S ystemic C irculationthinned walled arter ies and its bran ch es

co nta in less e last in and sm oo th mus cle than s ystem ic v esse ls , highlycompliant

ca p illar ies form a dense capillary bed

high flow, high compliance, lowresistance, and a low pressure

system


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C haracteristics of the P ulmonary C irculation


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P ulmonary lymphatics

Two ly mphat ic s upp lies: s uper ficia l and dee p lymphat ic vesse ls. Ex it f r om hilus

No lymphat ics dra in a lve olirem ove p lasma filtrate , part iculate matter abs orbed f r om a lve oli, and es ca ped pr ote in f r om the vas cul ar s ystemhe lps to ma inta in negat ive interst itia l press ure which pulls a lve olar e p ithe lium aga inst ca p illar yend othe lium.


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INNERVATION O f theRESPIRATORY SYSTE M

1. nervous c ontrolsympatheti c c ontrol

- activation of 2 receptors- causes dilatation

parasympatheti c c ontrol

- activate muscarinic receptors- causes constriction


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INNERVATION O f theRESPIRATORY SYSTE M

2. L ocal control> exerted by substances released in the

lungs by mast cells

histaminebinds to H1 re ce p tors co nstr ictionbinds to H2 re ce p tors dilat ion

SRS -A : co nstr iction-a llerg ic res ponse to pollenP rostaglandins E ser ies dilat ionP rostaglandins F ser ies co nstr iction


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M ucociliary C learance S ystem

a ka mucociliary elevator Mucu s co nt inua lly

se creted by goblet ce llsMucu s blan ket co nta ins im pa cted part icles and debr is

Imm unoglobulin A (Ig A)pr ote cts aga inst ba cter ia and vir uses


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SNEE ZE RE FLEX

Functions to dis lodge fore ign s ubstan ces f r om the nasa l ca vity

S timulu s: irr itat ion in the nasa l passage wa ys Aff erent impulses pass in CN V to the med ullaDur ing the re flex , uvul a and s of t pa late are

de pressed s o that ra p idly flowing a ir f r om the lungs is dire cted thr ou gh the nasa lpassage wa ys


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COUGH RE FLEX

Fr om tra ch ea to a lve olisens itive to irr itants

Aff erents utilize CN X

P rocess :2. 5 L of a ir ra p idly ins p iredEp iglottis clo ses and voc a l co rds clo se tightlymus cles of ex p irat ion co ntra ct for ce fully whichca uses press ure in lungs to r ise to 100 mm HgEp iglottis and voc a l co rds s udden ly o pen wide lywhich res ults in ex p los ive ou tpou r ing of a ir toclear larger a ir wa ys at s peed of 75 1 00 miles

per hr


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Re flex Br onchoco nstr iction

Res ponse to inha led irr itants

Ast hma ca uses br onchoco nstr iction in res ponse to col d a ir , per fumes , et c.


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T he H eimlich M aneuver C an S ave L ives


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2 ways by which lungs can beexpanded and contracted :

1. by downward and upward movement of the diaphragm to lengt hen and s ho rten the ch est ca vity

2. by elevation and depression of the ribsto increase and de crease the A-P diameter of the ch est ca vity


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M uscles of R espiration

Inspiratory musclesDia phragm.Externa l inter co sta ls.

Acc ess or y m us cles. Include stern omast oids ,

s ca lene mus cles

E xpiratory muscles Abd om ina l m us cles. Interna l inter co sta ls.


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DIAPHRAG M

dur ing quiet ins p irat ion, its co ntra ction a ccou nts for 2/3 (75%) of increase in s ize of tho ra cic volu me

inner vated by phren ic ner ve (C3,C 4,C5)


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DIAPHRAG M

Dur ing quiet breat hing mov es 1 c m

Dur ing dee p breat hing mov e as much as 10c m


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N ormal quiet breathing

D uring inspiration : co ntra ction of the dia phragm , pulls the lower s ur f a ces of

the lungs downward

D uring expiration : by re laxat ion of the dia phragm and e last ic re coil of the lungs , ch est wa ll, and abd omina lstr uc tures co mp resses the lungs


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M ECHANICAL PROPERTIES O F THE LUNG and CHEST

WALL

STATIC LUNG VOLU M ES


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Pul monar y Volu mesT idal volume

Volu me of a ir ins p ired or ex p ired dur ing a norma lins p irat ion or ex p irat ion (500 ml)

Inspiratory reserve volume Amou nt of a ir ins p ired for ce fully a f ter ins p irat ion of norma l tida l volu me (3000 ml)

E xpiratory reserve volume Amou nt of a ir for ce fully ex p ired a f ter ex p irat ion of norma l

tida l volu me (1200 ml)R esidual volume

Volu me of a ir rema ining in res p irat or y passages and lungs a f ter the most for ce ful ex p irat ion (1200 ml)


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Pul monar y C a pa citiesInspiratory capacity

Tida l volu me p lus ins p irat or y reser ve volu me

Functional residual capacityExp irat or y reser ve volu me p lus the res idua l volu me

V ital capacityS um of ins p irat or y reser ve volu me , tida l volu me , and ex p irat or y reser ve volu me

T otal lung capacityS um of ins p irat or y and ex p irat or y reser ve volu mes p lus the tida l volu me and res idua l volu me


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A i d h P l S


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Aging and the Pul monar y S ystem


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O bstructive P ulmonaryD iseases

Associated with increased airwayresistanceR esidual volume increases (harder to

expire)Functional residual capacity increasesT otal lung capacity increases


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R estrictive P ulmonaryD iseases

M ore difficult for lungs to expandT otal lung capacity decreasesV ital capacity decreases


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FACTORS A FF ECTING PUL M ONARY VENTILATION:

1 . CO M PLIANCE

2. AIRWAY RESISTANCE


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L ung C ompliance

Th e greater the co mp lian ce , the eas ier it is for a ch ange in p ress ure

to c a use ex pans ion

A low er -than -norma l co mp lian ce means the lungs and tho rax are harder to ex pand


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LUNG CO M PLIANCE

de pends on lung volu me s lightly greater when meas ured dur ing de flat ion than when meas ured dur ing inflat ion


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CHANGES IN LUNG CO M PLIANCE (pathologic states)

E M PHYSE M A ( increased lung co mp lian ce )- loss of e last ic fibers

F IBROSIS (de creased lung co mp lian ce )- st iff en ing of lu ng tiss ues


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L aw of L aplace states that press ure in a lve olu s is dire ctly pr oportiona l toS T; & inverse ly to rad ius of a lve oli

Thu s , press ure in sma ller a lve oli woul d be greater than in

larger a lve oli, if S Twere same in both

Insert fig. 16.11

S urface T ension


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Downloaded from: StudentConsult (on 23 August 2009 05:14 PM) 2005 Elsevier


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S ur f a ctant

Lowers S ur f a ce tens ion by gett ing bet ween H20 mole cul es , red uci ng the ir ab ility to attra ct

ea ch o ther via hydr ogen bond inghas ant i-st ick p r opert yIncreases lung co mp lian ce

De creases wor k of breat hing


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Factors T hat D iminish L ung C ompliance

S car tiss ue or fibr os is that red uc es the nat ura l res ilien ce of the lungs ex. pulmonar y fibr os is , TB

Block age of the sma ller res p irat or ypassages with mucu s or fluid ex. Pul monar y edema

Red uc ed p r oduc tion of s ur f a ctant ex.

HMDDe creased flex ibility of the tho ra cic c age or its de creased ab ility to ex pand ex. De form ities , mus cle para lys is


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Factors T hat INCREASE L ung C ompliance

Emphysema destruction of elastic

fibers in alveolar walls

Old age


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AIRWAY RESISTANCE

determ ined by rate of gas flow (ve locityof gas mole cul es multip lied by c r oss

se ctiona l area ) and diameter of a ir wa ys

G as flow is inversely proportional to

resistance with the greatest resistancebeing in the medium -sized bronchi


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AIRWAY RESISTANCE

Fr om tra ch ea to a lve olar duc ts , tota l cr oss se ctiona larea of a ir wa ys p r ogress ive lyincreasesVe locity of a ir flow de creasesra p idlyIn tra ch ea and ma in br onchi,a ir flow is turbulent

In sma ll a ir wa ys , a ir flow is lam inar Highest res istan ce to a ir flowis in med ium s ized br onchi


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AIRWAY RESISTANCE

Air wa y rad ius is the most important determ inant of res istan ce

(POI S EU ILLES L AW)R =8 l

r 4

S ma ller a ir wa y means higher res istan ce for

an y flow rateCOP D narr ows sma ll a ir wa ys

high a ir wa y res istan ce


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Factors that change airwayresistance :

1. Co ntra ction or re laxat ion of br onchi a l sm oo th mus cle

2. Lung volu me3. Vis co s ity o r dens ity of the

ins p ired gas


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airway resistanceVaga l st imulat ion br onchoco nstr iction Noncholi nerg ic ex citat or y med iat ors ( s ubstan ce P, ne ur okinins ) br onchoco nstr ictionVIP re lax sm oo th mus cleHistam ine

airway resistanceS ympat het ic st imulat ion br oncho dilat ion

1. Contraction or relaxation

of bronchial smooth muscle


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2. LUNG VOLU M ES

High lu ng volu mesMore tra ction and de creased a ir wa yres istan ce

Low lu ng volu mesLess tra ction and a ir wa y res istan ce


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3. V iscosity or density of theinspired gas

Dur ing a dee p sea dive , there is res istan ce due to gas dens ity

be ca use of increased p ress ure

Breat hing a low-dens ity gas like he lium

red uc es res istan ce to a ir flow

N e roh moral R eg lation of


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N eurohumoral R egulation of A irway R esistance

INCR E AS E AIRWAY R ES IS TANCES timulat ion of e ff erent vaga l fibersInha lat ion of sm oke , dust , col d a ir Histam ine , Ach, thr omb oxane A2, P r ostag land in F2,le uko tr ienes

DECR E AS E AIRWAY R ES IS TANCES ympat het ic st imulat ione p ine phr ine


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DYNA M IC LUNG VOLU M ES


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P l F i T


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P ulmonary Function T ests :Forced V ital C apacity (F VC )

M aximum volume inhale followedby exhale as fast as possible

L ow F VC indicates restrictive pulmonarydisease

P l F i T


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P ulmonary Function T ests :Forced E xpiratory Volume (F EV )

P ercentage of F VC that can be exhaledwithin certain time frame

FEV 1 = percent of F VC that can be exhaledwithin 1 second


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F EV 1 & F VC

F orced expiratoryvolume in 1 second y oung trained athletes:

4.0 L

F orced vital capacity y oung trained athletes:

5.0 L

F EV 1 / F VC = 80%

FEV1

FVC


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N ormal F EV 1 = 80%( If F VC = 4000 ml, should expire 3200 ml in1 sec)

FEV 1 < 80% indicates obstructive pulmonarydisease


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Wo r k of B reat hing

Co mp lian ce wor k (e last ic wo r k)- req uired to ex pand the lungs aga inst its e last ic

for cesTiss ue res istan ce wor k- Wo r k req uired to ov er co me vis co s ity of the lung

and ch est wa ll str uc tures Air wa y res istan ce wor k- Req uired to ov er co me a ir wa y res istan ce dur ing

the movement of a ir into the lungs

WORK ENERGY REQUIRED


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WORK ENERGY REQUIRED FOR RESPIRATION

Only 3-5% of the tota l wo r k energ yex pended by the body is req uiredDur ing hea vy exer cise , c an increase 50 fol d

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