Vein because they have valves to prevent back flow of blood.
These alveoli are the smallest types of lung tissue, and one of the most important. In addition to being the primary means by which oxygen enters and carbon dioxide escapes the bloodstream, these small pouches of air are also the reason why the lungs do not totally collapse when a person breathes out. This is because they contain a cell that secretes a special chemical to lower the surface temperature to prevent lung collapse. The alveoli also contain other cells that secrete chemicals to attack and remove any foreign objects in the lungs, such as dust, dirt and other debris.
In addition to making up alveolar sacs, alveoli also form alveolar ducts. It is estimated that there are more than 300 million alveoli in the human lungs, all of which are located in either alveolar ducts or sacs that are found at the end of the smaller passageways, or bronchioles, in the lungs.
SHORT ANSWER:
Alveolar sacs contain tiny pouches called alveoli, whose primary function is gas diffusion. These clusters of alveoli have thin walls that allow oxygen to pass easily from the lungs into the bloodstream and carbon dioxide to flow from the blood to the lungs so it can exit the body.
The uterus, is this for health?
Answer:
Cellulose
Explanation:
trunk is the main axis of a tree that supports the branches and is supported by roots. Cellulose makes it sturdy. Cellulose is the main substance in the walls of plant cells, helping them to remain stiff and upright.
<span>Both isotonic and equilibrium share the same definition; they both carry the meaning “balance” or “equality” – but ultimately, they still have differences. An isotonic solution is a mixture of two or more substances; substances which carry the same salt concentration as the ones that surround the blood cells – while equilibrium is the state of the solution per say.</span>
