Biology - The respiratory system / gas exchange

What is the function of the respiratory system

To obtain sufficient oxygen for respiration and to remove the equivalent volume of waste gases, carbon dioxide and water

What is the trachea?

Brings air into the lungs , supported by the rings of cartilage that prevent it from collapsing

What is the bronchus

Branches off the trachea to bring air into the lungs

What is the bronchiole

Branch off the bronchi

What the lungs

The organ where gas exchange occur

What is the diaphragm

Sheet of muscle that separates the chest cavity from the rest of the body

What is the ribcage

protects internal organs of the thorax

Intercostal muscles

Muscles between ribs and controls rib movement

Features of inspiration

• Intercostal muscles contract

• Ribs lift up and out

• Diaphragm contracts and flattens

• Chest cavity increases in volume and decreases in pressure

Features of expiration

• Intercostal muscles relax

• Ribs move down and in under their own weight

• Diaphragm relaxes and domes up

• Chest cavity decreases in volume and increases pressure

What is gas exchange?

The alveoli are surrounded by capillaries so oxygen and carbon dioxide diffuse between the air in the alveoli and the blood in the capillaries.

What is diffusion

Movement of gas from an area of high concentration to an area of low concentration.

Where does oxygen and carbon dioxide diffuse?

As the blood moves through the capillaries in the alveoli, oxygen diffuses into it and carbon dioxide diffuses out of it

ADAPTATIONS - Large surface area

to enable more diffusion of oxygen into the blood from the alveoli, and more carbon dioxide out of the blood into the alveoli

ADAPTATIONS - Thin walls

Short diffusion distance.

ADAPTATIONS - Moist walls

Gases dissolve in the moisture helping them to pass across the gas exchange surface.

ADAPTATIONS - Permeable walls

Allow gases to pass through.

ADAPTATIONS - Good blood supply

Ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.

ADAPTATIONS - Large blood supply

the oxygen concentration in the alveoli is higher than in the capillaries so oxygen moves from the alveoli to the blood. Carbon dioxide diffuses in the opposite direction.