Question

15.. What four factors influence the alveolar rate of gas exchange? For each factor, describe what would happen to gas exchange if it increased/decreased. Give an example (where possible) of something that would cause the factor to increase or decrease. 16.. What is the importance of ventilation perfusion coupling? 17. What is partial pressure? 18..What is the composition of atmospheric air? 19. How does most oxygen travel through the bloodstream (identify two)? 20..How does CO2 travel through the bloodstream(name three)?! 21..What enzyme found in RBCs helps to convert CO2 to this form? 22..In systemic gas exchange, the chloride shift helps to keep the formation of HCO3- and H+ going. How does it do this? 23. What is a COPD? What effects do COPDs have on the body? What are some common examples?

Answer 1

15) Factors influencing alveolar rate of gas exchange:

- membrane thickness: rate of diffusion increases as the thickness of membrane decreases

- Membrane surface area: rare of diffusion is faster as the surface area is larger.

- Pressure difference across the membrane: partial pressure of oxygen is low in alveoli and partial pressure of carbon dioxide is high in the alveoli.

- Diffusion coefficient of gas: Influenced by partial pressure, temperature, viscosity and density.

16) Ventilation perfusion coupling

It is the ratio of ventilation and perfusion which helps to assess the efficiency and adequacy between them.

It is an important factor which affect the alveolar levels of oxygen and carbon dioxide.

17) partial pressure

It is defined as the pressure of an individual gas in the mixture of gases.

18) Composition of atmospheric air

Nitrogen-78.09%

Oxygen-20.95%

Argon-0.93%

Carbon dioxide-0.04%

19) Transportation of oxygen through blood stream

The oxygen transport in the blood by combining with the RBC pigment haemoglobin forming oxyhemoglobin. It is seen in short range of transport like between capillaries and in muscle cells.

Oxygen is also transported via convection method. It is the rapid bulk flow of blood . Done in long range of transport.

20) Transport of carbon dioxide in blood

CO2 is transported by 3 different methods

- Direct dissolution : Despite the solubility only a few portion is soluble and is transported.

- Binding with Haemoglobin:

About 10% of CO2 is transported by this method as carbamate.

- As bicarbonate : About 90% CO2 is transported by this method . It involves formation of bicarbonate ion from carbonic acid.

21) Carbonic anhydrase

22)The chloride shift is the exchange of bicarbonate and chloride across ARBC .It helps to maintain the electric neutrality and no build up of charges.

23)COPD

Progressive disease characterized by airflow limitations that is not Fuly reversible and is associated with an abnormal inflammatory response of the lungs to noxious particles or gases.

Effecs of COPD on body:

Weight loss, nutritional abnormalities, skeletal muscle dysfunction, cardiovascular disease