Respiratory system

Question 1

Steps in gas exchange

Answer 1

1) ventilation
2) diffusion
3) perfusion

Question 2

carina

Answer 2

point of bifurcation of trachea

- sensitive → anything touch and instantly triggers cough reflex

Question 3

pleura

Answer 3

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

Question 4

-ve pressure b/w pleura

Answer 4

exists to help keep lungs open

- space becomes more -ve with inspiration

Question 5

diaphragm

Answer 5

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

Question 6

larynx

Answer 6

ciliated epithelium → filters dust particles

• protects against entrance of substances
• organ for voice production (vocal cords)

Question 7

trachea

Answer 7

• cartilaginous rings ANT
• trachealis POS → prevents collapse
• cartilage weak in children → prone to bronchoconstriction → asthma significant

Question 8

composition of alveoli

Answer 8

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

• lung infection → disturbs surface tension → shortness of breath

Question 9

inspiration

Answer 9

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

Question 10

expiration

Answer 10

• passive elastic recoil

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

Question 11

conc of gases (PaCO2, PaO2…)

conc of HCO3 and pH level

Answer 11

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

HCO3 → 22-26mmol/L
pH → 7.35-7.45

Question 12

what is the aim of respiration

Answer 12

to maintain normal levels of O2, CO2, HCO3

Question 13

effects of humidifying gases

Answer 13

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

Question 14

3 neurochemical control of vent

Answer 14

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

Question 15

central chemoR

Answer 15

• sensitive to changes in small pH

- change by PaCO2 stimulates both peripheral and central chemoR

Question 16

equation for CO2 into HCO3

Answer 16

CO2 + H2O → H2CO3 → H + HCO3

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

Question 17

peripheral chemoR

Answer 17

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

Question 18

neural innervation of lungs

Answer 18

• SNS b2 → bronchial SM relax

- PNS m3 → bronchial SM contract

Question 19

external resp

Answer 19

ex gas exchange
- b/w alveoli and blood

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

Question 20

internal (cellular) resp

Answer 20

aerobic & anaerobic

Question 21

resp membrane permeability

Answer 21

membrane more permeable to CO2 than O2

Question 22

boyle’s law

Answer 22

p inversely proportional to V at constant temp

*i.e. if can’t change vol → can’t breath)

Question 23

dalton’s law

Answer 23

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

Question 24

fick’s law

Answer 24

rate of diffusion → directly proportional to:

• SA membrane
• pressure gradient
• gas solubility

indirectly proportional to
- thickness of membrane

Question 25

how is O2 transported

Answer 25

binds to hb

~1000ml/min O2 delivered to cell

Question 26

how is CO2 transported

Answer 26

~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)

Question 27

factors affecting oxyhaemoglobin dissociation curve

Answer 27

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

Question 28

tidal vol

Answer 28

normal in out (500ml)

Question 29

inspiratory reserve vol

Answer 29

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

Question 30

expiratory reserve vol

Answer 30

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

Question 31

vital capacity

Answer 31

max in out (4.8L)

Question 32

residual vol

Answer 32

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

Question 33

functional residual capacity

Answer 33

vol remaining at the end of normal in and out

Question 34

total lung capacity

Answer 34

total vol air lung can hold

Question 35

ageing and resp system

premature

Answer 35

inadequate surfact → may lead to resp distress

given steroids

Question 36

ageing and resp system

elderly

Answer 36

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

Question 37

ageing and resp system

changes in resp rate throughout ages

Answer 37

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