A comprehensive concept is a foundation builder. It is a short statement that combines the following four essential elements to form a strong base for your complex novel: (1) genre, (2) main character, (3) opposition, and (4) macro setting. You can arrange these elements, in any order.
The main respiratory surface in humans is the alveoli, which are small air sacs branching off from the bronchioles in the lungs. They are one cell thick and provide a moist and extremely large surface area for gas exchange to occur.t is a passive process (no energy is required) affected by factors such as the surface area available, the distance the gas molecules must diffuse across and the concentration gradient. Gases must first dissolve in a liquid in order to diffuse across a membrane, so all gas exchange systems require a moist environment.
Gas exchange takes place in the capillaries for animals with a closed circulatory system such as birds, mammals, reptiles, and some amphibians. Remember that the capillaries are the smallest blood vessel, and they can be found near every cell in the body. With trillions of cells, that is a lot of capillaries. The respiratory apparatus in insects consists of a system of tubes, called tracheae, which directly ventilate the tissues. When an animal actively moves air to the site of gas exchange, it is called ventilation. The tubes act similarly to a closed circulatory system of blood vessels which divide and branch out into smaller and smaller tubes extending into all parts of the insect like plumbing pipes.