Biology - Human Respiratory System

A. Figure of human respiratory system

B. Inhale and exhale mechanism

Inhalation:

On inhalation the diaphragm contracts and becomes flatter as it is lowered. In addition, the lower ribs swing upwards and outwards as the external intercostal muscles contract. These movements increase the volume of the thorax and the pressure within it falls to below atmospheric pressure. Consequently, air rushes into the lungs to fill this partial vacuum.

Exhalation:

Relaxation of the external intercostals and the diaphragm allow a set of opposing muscles, the internal intercostal muscles, to return the thorax to its previous size. As the thorax diminishes in size air is expelled from the lungs. All English speech sounds are composed using exhaled air from the lungs, i.e. using a pulmonic air stream.

C. Effect of carbon monoxide from smoking a cigarette on human body  

Carbon monoxide binds to hemoglobin in red blood cells, preventing affected cells from carrying a full load of oxygen.

D. Chemicals in Cigarettes

1. Carsinogens : benzene, formaldehyde, pesticides, TSNAs, and vinyl chloride.

2. Toxic metals : arsenic, and cadmium.

3. Radioactive toxic metals : radioactive cigarette smoke.

4. Poisons : ammonia, carbon monoxide, hydrogen cyanide, and nicotine.