Structures

Question 1

Role of ciliated epithelium

Answer 1

Line trachea to bronchi. Each cell has tiny projections called cilia which sweep mucus up and away from the lungs to the mouth where they are swallowed and digested by stomach acid

Question 2

Goblet cells

Answer 2

Embedded throughout ciliated epithelium and are mucus-producing cells. The mucus they produce traps dust, bacteria and microorganisms

Question 3

Cartilage

Answer 3

Rings of cartilage line the trachea. Strong but flexible (C shaped) tissue and essential for keeping trachea open. Because of its flexibility, cartilage is able to move and flex as we breathe

Question 4

Smooth muscle

Answer 4

Found in walls of bronchi and bronchioles. Helps to regulate the flow of air into and out of lungs by dilating and widening when more air is needed
- constricts the bronchus

Question 5

Elastic fibres

Answer 5

Found in squamous epithelium of the alveolar walls. Critical component of alveoli- allows tiny alveoli to recoil to help expel air. It is the elastic abilities of alveoli which enables them to have such a large SA. (Cases like COPD- alveoli lose elastic properties)

Question 6

Squamous epithelium

Answer 6

Consists of flat thin cells in the alveolar walls. Thinness means that oxygen and carbon dioxide have short diffusion pathway meaning efficient gas exchange

Question 7

Trachea

Answer 7

Airway that leads from mouth and nose to bronchi. Lined with mucus- secreting goblet cells and cilia. Cilia sweep microorganisms and dust away from lungs

Question 8

Bronchi

Answer 8

Located at the bottom of trachea and are similar in structure to trachea but narrower. Leads to bronchioles

Question 9

Alveoli and adaptations

Answer 9

Tiny sacs that are main site of gas exchange in lungs
Adaptations:
- 2 cells thick made of squamous epithelium and elastic fibres enabling short diffusion pathway for efficient gas Exchange
- large capillary network which maximises surface area for efficient gas exchange
- good blood supply- blood constantly takes oxygen away from alveoli and brings more carbon dioxide- maintains concentration gradient
- ventilated lungs so that air in each alveolus is constantly replaced- maintain concentration gradients

Question 10

Bronchioles

Answer 10

Barrier tubes which carry air from bronchi to alveoli. As they are so narrow, they have no supporting cartilage (most is in larger bronchiole but only a little) so can collapse