The Human Breathing System

Question 0

Trachea

Answer 0

Carries air from mouth and nose to bronchi

• held open by rings of cartilage
• trachea is lined with mucus -secreting cells, the mucus catches dirt, dust and bacteria
• cilia are tiny infoldings that move the mucus upwards with a wavelike motion

Question 1

Nose

Answer 1

Warms the air and hair filters dust etc

Question 2

Bronchi

Answer 2

One bronchus goes into each lung from the trachea

Held open by rings of cartilage

Question 3

Bronchioles

Answer 3

Narrow muscular tubes that carry air from bronchioles to alveoli

Question 4

Alveoli

Answer 4

Tiny air sacs that are the sites of gas exchange

Question 5

Intercostal muscles

Answer 5

Move ribs up and out

Question 6

Diaphragm

Answer 6

A sheet of muscle below the lungs

Question 7

Pleural membrane

Answer 7

Are the fluid-containing membranes surrounding the lungs, the reduce friction by lubrication

Question 8

Describe gas exchange

Answer 8

Occurs in alveoli
Carbon dioxide and water vapour are released from the blood into alveoli
Oxygen is absorbed from there inhales air into the blood
Gas exchange occurs by diffusion

Question 9

How are alveoli adapted for gas exchange

Answer 9

There are millions of alveoli
Alveoli have a large surface area
Air is kept moist and warm which helps oxygen absorption
Walls of alveoli are only one cell so diffusion can happen rapidly
Alveoli are surrounded by a network of capillaries to maximise the surface area

Question 10

How are gases transported by blood

Answer 10

Oxygen is carried by haemoglobin in red blood cells

Carbon dioxide is transported by the plasma

Question 11

Describe the mechanism of breathing as for inhalation

Answer 11

Breathing rate is controlled by the hypothalamus in the brain. The hypothalamus monitors carbon dioxide levels in the blood. Signals are sent to the diaphragm and intercostal muscles which contract
1. Intercostal muscles move ribs up and down, diaphragm moves down. Thoracic cavity volume increases
2. Air pressure in the thorax (chest) is lowered
3. There is drawn into the lungs due to difference between a external and internal air pressure
This process occurs in reverse for exhalation