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Flashcards in Respiratory system Deck (37):
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)

31

vital capacity

max in out (4.8L)

32

residual vol

vol remaining in lungs at the end of exp (~1.2L)

33

functional residual capacity

vol remaining at the end of normal in and out

34

total lung capacity

total vol air lung can hold

35

ageing and resp system

premature

inadequate surfact → may lead to resp distress

given steroids

36

ageing and resp system

elderly

- dec collagen prod → dec lung compliance & airway diameter
- dec # cilia → inc infection rate
- changes in parenchyma → lowers diffusion capacity (dec oxygenation of lungs)

37

ageing and resp system

changes in resp rate throughout ages

newborn: 40-80
5yo: 25
adult: 12-18
elderly: inc