INHALATION IN MAMMALS

this is a process whereby living organisms respire]
Every cell in an animal requires oxygen to perform cellular respiration which gives off carbon dioxide and water as waste products. Respiration is the process by which animals exchange these gases with their environment. Animals have specialized systems of structures that help them to do this successfully and efficiently. Even a fish will drown if it cannot successfully breathe underwater.

Gas Exchange

The actual exchanging of the gases is dependent upon important structures such as lungs or gills, and the principle of diffusion. Diffusion says that the molecules or particles will move from an area where they are very concentrated into an area where they are less concentrated.

As shown below in a liquid model, the red dots start with a high concentration on the left, but after time they have spread out into the area on the right. This is relevant during respiration because oxygen and carbon dioxide are often highly concentrated in opposite places, and simultaneous diffusion is how gas exchange occurs.
The chief organ in mammalian respiration is the lungs. The lungs are actively ventilated via a suction-pump mechanism of inhalation and exhalation. Breathing is dependent upon the rib muscles and the diaphragm, which is a structure located just beneath the lungs like a dome-shaped floor (or a dome-shaped roof for the intestinal cavity). Check this site out for how to make a lung model.

Inhalation happens when the rib cage opens up and the diaphragm flattens and moves downward. The lungs can then expand into the larger space that causes the air pressure inside them to decrease, and the drop in air pressure inside the lung makes the outside air rush inside.

Exhalation is the opposite process. The diaphragm and the rib muscles relax to their neutral state that causes the lungs to contract. The squashing of the lungs increases their air pressure and forces the air to flow out.


A diagram of ventilation in most mammals. The left image shows inhalation with a flattened diaphragm. The right side shows the dome shaped diaphragm forcing the air out during exhalation.

In most mammals, the first place that air enters upon inhalation is the nose. It gets warmed, moistened, and filtered by cilia and mucus membranes which can trap dust and pathogens. Air then reaches the epiglottis, which is the tiny leaf shaped flap at the back of the throat. The epiglottis regulates air going into the windpipe and closes upon swallowing to prevent food from being inhaled. It is the gatekeeper to the lungs. If the epiglottis is the gatekeeper, who's the key master?