COM 4 Physiology

Question 1

Where does oxygen diffuse from and to where

Answer 1

Diffuse from alveoli to the pulmonary blood

Question 2

Where deos carbon dioxide diffuse from and why

Answer 2

Pulmonary blood to the alveolar

Question 3

What is diffusion driven by

Answer 3

• Kinetic energy

Question 4

What is gas pressure + what is it proportional to

Answer 4

Force from molecular collisions with surfaces
-Porporitonl to :
-No of molecules
-Their kinetic energy

Question 5

What is atmospheric air composed of

Answer 5

Nitrogen + oxygen

Question 6

What is the notion for partial pressure of oxygen and carbon dioxide

Answer 6

PO2= partial pressure of oxygen
PCO2 is for carbon dioxide

Question 7

Name 2 factors that partial pressure depends on

Answer 7

• Concentation of dissolved gas
  -Solubiity coefficient of the gas

Question 8

What is Henrys law equation partial pressure + when does partial pressure increase

Answer 8

Partial pressure = Concentration of dissolved gas/ solubility coefficient

• It increases when Concentration of dissolved gases increases and solubility coefficient decreases

Question 9

Which is more soluble

Answer 9

Co2 is x20 more soluble

Question 10

Name the 6 factors that determine the rate of gas diffusion

Answer 10

• Partial pressure difference
  -Solubility of gas
  -Cross sectional area
  -Diffsuin distance
  -Moleular weight
  -Temperature

Question 11

What is the diffusion equation + what does everything stand for

Answer 11

D∝ΔP×A×S​/ d x R/MW

D = diffusion rate
ΔP = partial pressure difference
A = cross-sectional area
S = solubility
d = diffusion distance
MW = molecular weight

Question 12

Gas properties determines which 2 factors + what does those 2 factor together form + what is the equation for that

Answer 12

• Solubiity
  -Molecular weight
  They form the diffusion coefficient
• Diffusion coefficient∝ S/ R/MW​ ( root)

Question 13

Give 2 characteristics of respiratory gases

Answer 13

• Higly Lipid soluble
• Freely permeable through the cell membranes

Question 14

Why does alveolar air differ from atmospheric air =

Answer 14

= Because Alceolar air has different gas composition due to 4 reasons

• Alveolar air is partially replaced
  -Continous absorption of oxygen
  -Continous diffusion of CO2
  -Inspired air is humidified

Question 15

What is teh phsyioogical importance of slow alveolar renewal
- What does it prevent + make

Answer 15

• Prveents sudden changes in :
  -Blood oxygen
  -Blood CO2
  -Tissue pH
• Makes respiratory control more stable

Question 16

Alveolar oxygen concentration and alveolar PO2 depend on the balance between betwen what 2 FACTORS

Answer 16

• Rate of oxygen absorptiom into blood
  -Rate of oxygen entry by alveolar ventilation

Question 17

Explain the principle of the determinants of alveolar Po2

• in realtion to absoprtion

Answer 17

↑ O₂ absorption → ↓ alveolar PO₂

↑ alveolar ventilation → ↑ alveolar PO₂

Question 18

Explain what is the continous process of CO2

Answer 18

• Constantly produced by metabolism

Question 19

What is alveolar PCO2 depend on (partial pressure)

Answer 19

• Rate of CO2 excretion
  -Rate of alveolar ventilaton

Question 20

Explain relationships between Alveolar PCO2
-What does it increases with + DEcreases with

Answer 20

Alveolar PCO2 increases directly with CO2 excretion

• Decreases inversly with ventilation ↑ ventilation → ↓ PCO₂

↓ ventilation → ↑ PCO₂

Question 21

What is expired air (formuka)

Answer 21

• Dead space Air+ alveolar Air

Question 22

What is the determinants of expired air composition

Answer 22

-Amount of dead space air
-Amount of alveolar air

Question 23

Explain the composition of expired air / its components

• Early expiration
  -Mid expiration
  -End of expiration

Answer 23

• Early expiration- Air from anatomical dead space

-Mid expiration- Mixture of dead space and alveolar air

-End of expiration - Pure alveolar air only

Question 24

Name the 4 major factors that determine gas diffsuion

Answer 24

• Thickness of the respiratory membrane
  -Surface area of the membrane
  -Diffsuion coefficent
  -Partial pressure difference across the membrane

Question 25

Increased thickness of the respiratory membrane occurs due to which 2 diseases

Answer 25

-Pulmonary edmea -Pulmonary fibrsos

Question 26

Name 2 conditions/disease that reduce the surface area of the membrane

Answer 26

-Pneumonectomy -Emphysema

Question 27

What does the diffsuion coefficient of gas depend on

Answer 27

- Solubiltiy of the gas in the membrame -Inversely porportional to molecular weight

Question 28

What is partial pressure difference defined as

Answer 28

Alveolar partial pressure - pulmonary capillary partial pressure

Question 29

What is the symbol for diffusing capacity

Answer 29

-DL

Question 30

What is diffusing capacity + formuka

Answer 30

Volume of gas that diffuses acros the respiratory membrane - DL= Gas transfer rate/ Partial pressure difference