gas exchange

Question 1

what is daltons law

Answer 1

total pressure of a mix of gases is equal to the sum of the partial pressures of the individual component gases

Question 2

what is the composition of dry air

Answer 2

21 oxygen
78 nitrogen
.1 argon

Question 3

what is henrys law

Answer 3

explains how gasses dissolve across the alveoli-capillary membrane

-amount of gas absorbed by a liquid is directly proportional to the partial pressure and solubility of the gas in the liquid

altitude=less pressure

when you have a lot of atmospheric pressure, it will force more molecules to diffuse from capillary to blood= dissolution of O2 into blood due to pressure gradient

Question 4

what is ficks law of diffusion

Answer 4

passive exchange of gas between lung and blood and blood and tissues/organs is dependent on:

• concentration gradient/partial pressures of gases
• solubility of gases
• surface area available for diffusion
• membrane thickness

diffusion of oxygen is better w more surface area

supplemental O2 change pressure gradient of O2

Question 5

when is diffusion less likey to occur

Answer 5

when the interstitial is wider and thicker

Question 6

what provides surface area for gas exchange with pulmonary blood

Answer 6

alveoli

Question 7

how does lung disease impair diffusion

Answer 7

-during exercise, pulm blood flow is quicker which shortens time available for gas exchange
-lung disease are unable to oxygenate the pulm blood fully and have a limited ability to exchange gases fully
=impaired ADLS and exercise

Question 8

talk about CO2 and the membrane

Answer 8

it diffuses across the alveolar-capillary membrane 20x faster than oxygen so less likely to compromise co2 transfer from blood to alveoli

Question 9

what is oxygen transport

Answer 9

amount of o2 delivered to tissues

Question 10

what is o2 content of blood dependent on

Answer 10

• PaO2

- hemoglobin concentration

Question 11

how is o2 transported

Answer 11

2 forms:

• dissolved in plasma
• reversibly bound to hemoglobin

Question 12

what is the bohr effect

Answer 12

promotes unloading (muscle)

• increases co2
• decreases ph
• decreases Hb affinity for o2

Question 13

how is co2 transported

Answer 13

3 ways:

• bicarbonate in RBC and plasma
• carbaminohemoglobin
• dissolved gas

Question 14

what is the haldane effect

Answer 14

-deoxyhemoglobin can carry more o2

Question 15

what happens in pulm circulation with low oxygen

Answer 15

vasoconstriction

Question 16

explain pulm circulation

Answer 16

• rate of BF through pulm circulation = flow of rate through systemic circulation
• pulm vascular resistance (afterload) low
• autoregulation: hypoxic vasoconstriction that is when pulm arterioles constrict when alveolar po2 decreases…matches ventilation and perfusion ratio

Question 17

what are local factors for vasodilation

Answer 17

• low ph
• high co2
• nitric oxide
• decreased oxygen

Question 18

what part of the lung does the majority of BF and ventilation go?

Answer 18

base

Question 19

are ventilation and perfusion evenly matched across the lung?

Answer 19

no

Question 20

what is a low v/q?

Answer 20

shunt

Question 21

what is a high v/q?

Answer 21

dead space

Question 22

what is a physiologic shunt

Answer 22

VV 
#1 reason people desaturate
-pulse ox here is lower than normal
-blood flow without air flow
-blodo has low o2 and high co2
poorly oxygenated

Question 23

what is physiologic deadspace

Answer 23

V>Q or Q

Question 24

what is perfusion

Answer 24

heterogenous

• gravity effect
• cardiac output
• pulm vascular resistance

Question 25

what is zone I ventilation and perfusion

Answer 25

alveoli > arterial> venous

-airflow > BF (deadspace )

Question 26

what is zone II ventilation and perfusion

Answer 26

arterial <> alveoli > venous

-airflow <> BF

Question 27

what is zone III ventilation and perfusion

Answer 27

arterial > venous> alveoli

-BF > airflow (shunt)

Question 28

what is the cause of desaturation

Answer 28

ventilation or perfusion issue

Question 29

what happens to V and Q during exercise?

Answer 29

both increase with workload

at rest, V/Q mismatched but during exercise they are matched

breathing more deeply because as workload increases , CO2 must be blown off

CO2 values stay the same until anaerobic threshold is hit which = Co2 dropping