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Flashcards in Respiratory system Deck (37)
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1

Steps in gas exchange

1) ventilation
2) diffusion
3) perfusion

2

carina

point of bifurcation of trachea
- sensitive → anything touch and instantly triggers cough reflex

3

pleura

parietal → surrounds lung tissues
visceral pleura → connects to parietal pleura
pleural space → serous fluid to dec friction and adhesion

4

-ve pressure b/w pleura

exists to help keep lungs open
- space becomes more -ve with inspiration

5

diaphragm

pulls down → pull lungs down → visceral layer stuck to the viscera → creates -ve pressure

6

larynx

ciliated epithelium → filters dust particles
- protects against entrance of substances
- organ for voice production (vocal cords)

7

trachea

- cartilaginous rings ANT
- trachealis POS → prevents collapse

- cartilage weak in children → prone to bronchoconstriction → asthma significant

8

composition of alveoli

squeamish tissues
- type 2 → secretes surfactant (dec surface tension → prevent aveoli collapse)

- lung infection → disturbs surface tension → shortness of breath

9

inspiration

- dia + ex IC contract
- chest walls and lungs expand
- accessory muscles (SCM and pec minor) contracts

10

expiration

- passive elastic recoil
- accessory muscles (int IC and abs) contract for active expiration

11

conc of gases (PaCO2, PaO2...)

conc of HCO3 and pH level

PaCO2 → 35-40
PvCO2 → 46
PaO2 → 80-100
PvO2 → 40

HCO3 → 22-26mmol/L
pH → 7.35-7.45

12

what is the aim of respiration

to maintain normal levels of O2, CO2, HCO3

13

effects of humidifying gases

gas enter lungs → humidified → dec PO2 to 100mmHg (from atmospheric pressure)

14

3 neurochemical control of vent

1) central chemoR → bathed by CSF close to resp center
2) peripheral chemoR → in carotid A and aorta
3) lung stretch R

H+ cannot diffuse through BBB, but CO2 can

15

central chemoR

- sensitive to changes in small pH
- change by PaCO2 stimulates both peripheral and central chemoR

16

equation for CO2 into HCO3

CO2 + H2O → H2CO3 → H + HCO3

- ↑PaCO2 → ↑diffusion of CO2 into CSF → ↑H+ in CSF → ↑signals to central chemoR → ↑ventilation

17

peripheral chemoR

- near baroR
- primary response to changes in O2 blood levels
- not as sensitive to changes in central chemoR (only when O2

18

neural innervation of lungs

- SNS b2 → bronchial SM relax
- PNS m3 → bronchial SM contract

19

external resp

ex gas exchange
- b/w alveoli and blood

int gas exchange
- exchange of O2 and CO2 b/w blood and tissues

20

internal (cellular) resp

aerobic & anaerobic

21

resp membrane permeability

membrane more permeable to CO2 than O2

22

boyle's law

p inversely proportional to V at constant temp
*i.e. if can't change vol → can't breath)

23

dalton's law

total pressure exerted by mixture of gases = sum of pressure of each individual gas
(p1+p2+p3=Ptot)

24

fick's law

rate of diffusion → directly proportional to:
- SA membrane
- pressure gradient
- gas solubility

indirectly proportional to
- thickness of membrane

25

how is O2 transported

binds to hb
~1000ml/min O2 delivered to cell

26

how is CO2 transported

~200ml/min prod by tissues
1) dissolved in plasma (PCO2) - 10% (20x more soluble than O2)
2) as a carbaminohaemoglobin - 20% (hb-co2 complex)
3) as a bicarbonate - 70% (as hco3 dissolved in plasma)

27

factors affecting oxyhaemoglobin dissociation curve

CO → takes up Hb subunit → remaining subunits ↑affinity for O2 → BUT saturation of Hb with O2 is lowered

- temp/2,3DPG/CO2 (dec pH) → all shifts curve right

28

tidal vol

normal in out (500ml)

29

inspiratory reserve vol

max vol breathed in over normal insp (~3.3L)

30

expiratory reserve vol

max vol breathed out over normal exp (~1L)