The small intestine is an organ which is highly coiled and folded which allows a long length of intestine to fit into a relatively small area. This increases the surface area for chemical digestion to occur and for the absorption of nutrients into the bloodstream. The villi are tiny hairlike projections that are surrounded by capillaries and they are extremely thin-walled. Inside there is a lacteal for absorption of fatty acids. Their structure greatly increases surface area for nutrient absorption into the blood and lymph system. The structure of the lungs, allows for gas exchange due to the fact that they contain tiny bunches of grape-like clusters called alveoli. The structure of these air sacs are thin-walled and moist which allows for the exchange of the respiratory gases oxygen and carbon dioxide. They are surrounded by tiny capillaries which can absorb the oxygen and allow the waste carbon dioxide to diffuse into the alveoli to be later exhaled. Any organ in the body is adapted for its function, therefore its structure will reflect this.