Respiratory System and Environmental Physiology — the first-year Physiology chapter on breathing, here and elsewhere

You breathe all day without deciding to. Now think of someone climbing in the high Himalaya, or a diver going deep under the sea. Their bodies are breathing too, but in air that is not like the air in your classroom. This chapter covers both: ordinary breathing, and breathing in unusual places.

The NCH syllabus gives “Respiratory System and Environmental Physiology” chapter seven of Physiology and Biochemistry (HomUG-PB). “Respiratory” means to do with breathing. “Environmental physiology” means how the body works in different surroundings. The sheet lists nine topics. They fall into two halves.

The first half: how breathing works

Physiological anatomy of respiratory tract. The respiratory tract is the path air takes, from the nose down to the lungs. “Physiological anatomy” means you study the structure only as far as you need it to understand the function. You do not relearn all of Anatomy here.

Mechanism of respiration: Ventilation, diffusion of gases. Two ideas in one line. Ventilation is moving air in and out of the lungs. Diffusion of gases is the movement of oxygen and carbon dioxide across a thin barrier, from where there is more to where there is less. You met diffusion in Bio-Physical Sciences. Here you see it at work in the lungs.

Transport of respiratory gases. Once oxygen enters the blood, how is it carried to the tissues? And how does carbon dioxide come back? That is this topic.

Regulation of respiration. “Regulation” means control. Who decides how fast and how deep you breathe? The body has its own control system for this. Your textbook will explain its parts.

Pulmonary Function Test. “Pulmonary” means to do with the lungs. A pulmonary function test measures how well the lungs are working. Your teachers will show you what is measured and what the values mean.

A tip for this half: draw one long flow chart. Air in through the nose, down the tract, into the lungs, across into the blood, carried to the tissues, and carbon dioxide back out. Then pin each topic onto the chart where it belongs.

The second half: breathing in other places

High altitude and space physiology. High up, the air is thinner. In space, there is no air to breathe at all, and there is little gravity. This topic asks how the body is affected and how it adjusts.

Deep sea physiology. Deep under water, the pressure is much higher. This topic asks what that does to the body and to the gases in it.

Artificial respiration. This means helping or taking over breathing for a person who cannot breathe well enough on their own. The sheet gives only the name. Learn the methods your textbook and teachers describe. Learn them as physiology, for the exam. Practical first-aid skills are taught separately, by trained people, with hands-on practice.

Effects of exercise on respiration. When you run, you breathe faster and deeper. This topic asks what changes, and why.

There is an Indian link worth noticing. India has high mountain regions and a long coastline. The questions in this half are not only for astronauts and divers in far-off places. They are about real people in real parts of our own country.

How the chapter sits in the year

This is chapter seven. It comes right after the Cardio-Vascular System, and the two chapters are a pair. The heart moves the blood. The lungs fill it with oxygen and take away carbon dioxide. Notice that both chapters end with exercise. When you study one, keep the other open beside it.

It also draws on earlier chapters. Diffusion comes from Bio-Physical Sciences. The blood that carries the gases comes from Body Fluid and Immune Mechanism.

What to take from it

1. Know the parts of the respiratory tract, as far as function needs.
2. Explain ventilation and diffusion of gases, and the difference between them.
3. Explain how oxygen and carbon dioxide are carried.
4. Know what controls breathing, and what a pulmonary function test measures.
5. Explain what changes at high altitude, in space, and deep under the sea.

The sheet names the topics and stops. It does not give values, pressures or methods. Those come from your textbook and your teachers.

Where to go next on the platform

This piece sits in the first-year Physiology and Biochemistry room. “Cardio-Vascular System — the first-year Physiology chapter on the heart and the blood’s journey” is its partner chapter. “Bio-Physical Sciences — the first-year Physiology chapter on the physics inside the body” explains diffusion, which this chapter uses.