Role of the intercostal Muscles and Diaphragm

How does inhalation work?

external intercostal muscles contract, pushing ribs up and out, diaphragm contracts, pulling downwards. This increase volume in the lungs, which decreases the pressure, causing air to be drawn into the lungs

How does exhalation work

the external intercostal muscles relax, allowing ribs down and in, diaphragm relaxes, moving upwards, volume decreases, pressure increases, pushing air out of the lungs

What does the body do when we need to increase the rate of gas exchange, for example during heavy activity

the internal intercostal muscles will also pull the rubs down and in, forcing air out more quickly, which is called forced exhalation. this allows for a greater volume of gases to be exchanged

What must gases do before being exchanged

be dissolved in an aqueous solution, which is why all gas exchange surfaces are moist

Explain an adaption of a gas exchange surface : large surface area

many alveoli gives a large surface area to volume ratio for diffusion

Explain an adaptation of a gas exchange surface : thin walls

alveoli and capillaries are 1 cell thick creating a short diffusion distance

Explain an adaptation of a gas exchange surface : good ventilitation (concentration gradient)

there is always a high conc of oxygen in the alveoli to be diffused into the blood