Human Breathing System

Human breathing system

Diagram

How are alveoli adapted?

Have a large surface area. There is a large number too. Therefore more diffusion takes place

The surface is moist allowing for diffusion of gases

Alveoli are very thin - only one cell in thickness and so is the capillary. Only 2 cells separating the lungs from the blood

Pulmonary and systemic circuits

Diagram

Why is the heart known as a double pump

For one circuit the blood enters the heart twice - keeps blood pressurised

Alveolus

Diagram

Oxygen comes from …..

Red blood cells

What shape is a red blood cell

Biconcave disc

O2+haemoglobin

Oxyhaemoglobin

CO2

Carried by the plasma

Controls the rate of breathing

Monitored by the brain “medulla oblongata”

Steps of Inhaling

Intercostal muscles contract, the ribs move up and out

Diaphragm contracts, it moves down

The thoracic cavity volume increases

Air pressure decreases

Air is pulled into the lungs “inhaled”

Steps of exhaling

Intercostal muscles relax, the ribs move down and in

Diaphragm relaxes, it moves up

The thoracic cavity volume decreases

Air pressure increases

Air is breathed out “exhaled”