Respiration 3

Question 1

What is movement of gas proportional to

Answer 1

Pressure gradient

Solubility of gas in liquid

Temp

Question 2

What is Dalton’s law of pressure

Answer 2

Pressure from a mix of gases = sum of the partial pressure from 1 gas

Question 3

What is partial pressure of gas dependent on

Answer 3

It’s abundance in the atmosphere

Question 4

If 78% of atmosphere is nitrogen what is the pp N

Answer 4

78%

Question 5

What needs to be taken into account with alveolar air when measuring partial pressures of o2, co2 and nitrogen

Answer 5

The water vapour / h20

Need to measure dry gases only

Question 6

What is solubility in liquid dependent on

Answer 6

Temp and partial pressure

Question 7

In a partial pressure gradient , what happens to o2

Answer 7

It will move to liquid and only some will dissolve

It isn’t as soluble as co2

Question 8

Why does o2 need carriers in blood

Answer 8

It’s lack of solubility in liquid

Question 9

Why would oxygen move to the blood because of partial pressure and co2 out into alveoli

Answer 9

Pp o2 is lower in the blood than alveoli so moves into blood

Ppco2 higher in blood so moves into alveoli

Question 10

Why can co2 easily move into alveoli

Answer 10

It is more soluble in liquid

Question 11

Why doesn’t temp impact diffusion

Answer 11

It’s always at body temp

Question 12

Why is large perfusion/ blood flow to the lungs better for diffusion

Answer 12

They run parallel to the bronchioles and close capillary to alveoli type 1 cells = reduces diffusion pathway

Question 13

What is ficks law of diffusion

Answer 13

Flux = permeability x Conc gradient / distance

Question 14

Which ficks diffusion variable can change

Answer 14

Concentration gradient (permeability and distance doesn’t change in blood and alveoli)

Question 15

Explain the pressures which allow o2 to diffuse from alveoli into tissues

Answer 15

100 mmhg at alveoli vs 40 mmhg at the capillaries

O2 moves in

Capillaries now have 100mmhg compared to tissues with 40mmhg = diffusion into tissues

Question 16

Explain how co2 gets from tissues due to partial pressures

Answer 16

46 mmhg at tissues vs 40 in blood system = diffusion into blood

46 now in blood = diffusion into alveoli due to it being 40mmhg

Question 17

What is the effect of pp02 and co2 and ventilation

Answer 17

Hypoventilation = increased PPc02 and low ppo2 in the alveoli

Hyperventilation = high ppo2 in the alveoli and low ppco2 (more removed)

Question 18

What is the therapy called used to treat low ppo2 in the lungs eg due to anemia or blood loss

Answer 18

Hyperbaric oxygen therapy

Question 19

What does hyperbaric oxygen therapy allow

Answer 19

More exchange of o2 to the tissues

Question 20

How does emphysema cause lack of exchange due to lack of diffusion

Answer 20

Depletion of alveoli, not many alveoli decreases SA for gas exchange

Question 21

Which 2 ways does restrictive fibrosis decrease diffusion

Answer 21

Reduces alveoli permeability by increasing its thickness (affect in ficks law)

Also lack of elastic on lungs causes lack of lung compliance and ventilation

Question 22

How does edema increase diffusion distance

Answer 22

Produces fluid in the interstitial space

This means there’s a lack of o2 gradient because it’s not as soluble in liquid as co2

Question 23

How does asthma affect gas exchange / diffusion

Answer 23

Obstruction to ventilation decreases ppo2 in the system

Low FEV1

Question 24

Explain the levels of perfusion vs ventilation at the base and top of lungs

Answer 24

At base of lungs there is more blood flow than ventilation

At top of lungs too much ventilation and not enough perfusion

Question 25

What does lack of ventilation at base of lungs cause

Answer 25

Lack of oxygenation to match the large blood flow

Question 26

What does high ventilation and low perfusion st top of lungs cause

Answer 26

Dead space (air removed before exchange)

Question 27

What would affect ventilation at the top of lungs

Answer 27

Posture and rate of ventilation

Upright causes high in top of lungs

Question 28

Ventilation perfusion matching allows levels to be at ….

Answer 28

0.9-1

Question 29

How is lack of ventilation at base meaning lack of oxygenation of blood overcome

Answer 29

Hypoxic pulmonary vasoconstriction

Question 30

What does hypoxic pulmonary vasoconstriction do

Answer 30

If low po2 is sensed eg in base of lungs then vasoconstriction allows redirection of blood to other areas of high p02

Question 31

What happens when po2 is increased in alveoli

Answer 31

Vasodilation of vessels / arterioles

Question 32

What do bronchioles respond to in hypoxic pulmonary vasoconstriction

Answer 32

Pco2 levels in the blood

Question 33

What happens when there is low pco2 in blood

Answer 33

Bronchioles will constrict as exchange doesn’t need to happen

Question 34

When do bronchioles vasodilate

Answer 34

When pco2 is too high in the blood ie 46 mmhg

Needs exchanging out of body

Question 35

What is Henry’s law

Answer 35

At constant temp, the amount of gas dissolved in liquid is dependant on the solubility and the partial pressure of the gas