Respiration and Breathing

Respiration

Adaptation of the respiratory tract

-nasal cavity, trachea, and bronchi are line with cilia, which traps dusts and microbes from entering the lungs. Goblet cells along the tract produce mucus that also traps dusts and microbes.

-air entering tract is moistened

- Alveoli, found at the end of bronchioles, are one cell thick to allow quick diffusion of gases

-alveoli are covered with a dense network of capillaries

-each lungs have millions of alveoli to increase surface area

- if too much dust enters the tract, a sneeze occurs, to force the dust particles out of respiratory tract

 Movement of air

Nose /mouth --> trachea--> bronhus (two bronchi present)--> bronchole --> alveolus (air sac)

Breathing

Inhalation

-intercostal muslces contract causing the rib cage to move upwards and outwards

-the diaphragm muscles contract causing the diaphragm to flatten

-this causes the volume in the lungs to increase, while the pressure decreases. Air then enters into the lungs.

Exhalation

-Intercostal muscles relax, causing the rib cage to move downwards and inwards

-diaphragm muscles contact, causing the diaphragm to move upwards (domed shaped)

-as such the volume of the lungs decrease, while the pressure increases. Air then is force out of the lungs.

Gas Exchange in the Alveoli

-Oxygen dissolves in the fluid lining of the alveoli surface

https://y12hb.wordpress.com/category/unit-1/lungs-and-gas-exchange/

-Diffusion gradient is created, where high concentration of oxygen in the alveolus diffused onto the capillaries with low concentration of oxygen. Carbon dioxide diffuses in the opposite direction.

-in the capillaries, dissolved oxygen will combine with the hemoglobin found on red blood cells-RBC to form oxyhaemoglobin