Question

1. Gas Exchange and Transport

(A) Discuss the factors affecting gas exchange in the lungs

(B) Discuss the factor affecting the transport in the blood

C) Discuss the effect of bicarbonate on oxygen transport

(D) Discuss oxygen/carbon dioxide exchange at the tissue level

Answer 1

(A) The factors that affect the rate of diffusion in the lungs:

· The thickness of the membrane- the thinner the membrane, the faster the diffusion rate. The lung diffusion barrier is extremely thin, but some conditions cause the barrier to thicken and thus impair diffusion.

· Surface area of the membrane – the larger the surface region, the higher the rate of diffusion. Because of the alveoli, the lungs usually have a very wide surface area for gas exchange.

· The difference in pressure across the membrane

· Gas diffusion coefficient

(B) The factor affecting the transport in the blood

· The levels of carbon dioxide, blood pH, body temperature, environmental factors, and diseases can all affect the capacity and delivery of oxygen in the blood.

· A reduction in hemoglobin's oxygen-carrying capacity is associated with increased carbon dioxide and temperature, as well as decreased pH within the body.

· Diseases like sickle cell anemia and thalassemia can also affect oxygen-carrying capacity and delivery.

(C) The effect of bicarbonate on oxygen transport

When blood reaches the lungs, the bicarbonate ion in exchange for the chloride ion is transported back into the red blood cell. The H+ ion dissociates and binds to the bicarbonate ion.

(D) Oxygen/carbon dioxide exchange at the tissue level

In the alveoli, gas exchange occurs such that oxygen is pumped into the bloodstream and carbon dioxide is discharged from the bloodstream. Oxygen is then carried through the pulmonary vein to the left side of the heart which pumps it into the systemic circulation.

Red blood cells carry the oxygen into the body's tissue capillaries. Oxygen diffuses in tissue cells, whereas carbon dioxide diffuses out of tissue cells and into the bloodstream.