Respiratory system

What is the function of the respiratory system?

To exchange oxygen and carbon dioxide between the body and the environment

What is gas exchange?

The movement of oxygen into the blood and carbon dioxide out of the blood by diffusion

Where does gas exchange occur?

In the alveoli in the lungs

What are alveoli?

Tiny air sacs in the lungs where gas exchange happens

How are alveoli adapted for gas exchange?

Large surface area, thin walls (one cell thick), moist surface, good blood supply

Why is a large surface area important in alveoli?

Increases rate of diffusion

Why are alveoli walls thin?

Short diffusion distance

Why is a good blood supply important in alveoli?

Maintains a steep concentration gradient

What is ventilation?

The movement of air into and out of the lungs

What happens during inhalation?

Diaphragm contracts and flattens, ribs move up and out, volume increases, pressure decreases, air moves in

What happens during exhalation?

Diaphragm relaxes and domes, ribs move down and in, volume decreases, pressure increases, air moves out

What muscles are involved in breathing?

Intercostal muscles and diaphragm

What do intercostal muscles do?

Move the ribcage up and down during breathing

What is the concentration gradient in the lungs?

High oxygen in alveoli, low oxygen in blood

What happens to oxygen in the alveoli?

Diffuses into the blood and binds to haemoglobin

What happens to carbon dioxide in the blood?

Diffuses into the alveoli to be exhaled

What is tidal volume?

The volume of air moved in and out during normal breathing

How does exercise affect breathing rate?

Increases to supply more oxygen and remove carbon dioxide

What does smoking do to the lungs?

Damages alveoli, reduces surface area, causes inflammation

What is the effect of smoking on cilia?

Damages cilia so mucus builds up

What is the role of cilia?

Move mucus and trapped pathogens out of the lungs

What is mucus?

Sticky substance that traps dust and pathogens

What is lung cancer?

Uncontrolled cell division in the lungs forming tumours