Exchanges With The Environment Essay, Research Paper

Gas Exchange in Animals In Humans this occurs in the lungs located in the thorax or

chest cavity. The windpipe or trachea splits at its base into two principal

bronchus these then subdivide into lobes, which in turn subdivide into

bronchioles and then terminate in alveoli. Gas exchange takes place in the

alveoli of which there are seven million. This gives them a large surface area

for the exchange. Air enters when the pressure of the air in the alveoli is

less than that of the atmospheric pressure. Ventilation in insects Air passes into the tracheae then into tracheoles that are

located on the insects? abdomen mostly via diffusion. Abdominal movement e.g.

flying will help with this. Feature Lung Leaf Large surface area Alveoli Big air spaces in the spongy mesophyll Close to transport system Capillaries close to the alveoli Stoma and leaf plans reduce diffusion distances Moist surface aids diffusion Internalisation preserves the moisture and the mucus

layered on the capillaries to aid diffusion Humid atmosphere within the air spaces in a leaf Well ventilated The use of breaths force air to enter the lungs Diffusion from the surrounding atmosphere.