Specialised Exchange Surfaces Flashcards
What are the characteristics of a specialised exchange surface?
- Large surface area
- Thin layers
- Good blood supply
- Ventilation
Why is ventilation important?
1) Maintains a concentration gradient
2) More efficient process
Why is a good blood supply important?
Ensures substances are constantly being removed and delivered to the exchange surface which maintains a steep concentration gradient for diffusion.
What are the features of the nasal cavity?
- Large SA
- Good blood supply
- Moist surfaces
- Hairy lining
Why does the nasal cavity need a good blood supply?
Warms the air to body temperature
Why does the nasal cavity need moist surfaces?
Increase humidity of the incoming air, reducing evaporation from exchange surfaces.
Why does the nasal cavity need a hairy lining?
Secretes mucus to trap dust and bacteria, protecting the lug tissue from infection.
What is the pathway of air into the body?
Nasal cavity, trachea, bronchus, bronchioles, alveoli
What is the structure of the trachea?
Wide tube supported by incomplete rings of strong, flexible cartilage, which stops it from collapsing.
Why are the rings in the trachea incomplete?
So food can move easily down the oesophagus behind the trachea.
What lines the trachea?
Ciliated epithelium with goblet cells between and below epithelia cells.
What is the purpose of goblet cells in the trachea?
Secrete mucus to trap dust and microorganisms.
How does the structure of the bronchus differ to that of the trachea?
It is smaller but still has the rings of cartilage.
What is the structure of bronchioles?
No cartilage.
Walls contain smooth muscle, so can control the amount of air reaching the lungs.
Lined with a thin layer of flattened epithelium.
What tissue allows the alveoli to stretch and recoil?
Elastic
What is it called when alveoli return to their resting size to squeeze air out?
Elastin recoil
What are the adaptations of the alveoli?
- Large SA
- Thin layers
- Good blood supply
- Good ventilation
What is the inner surface of the alveoli covered in?
A thin layer of a solution, water, salts and lung surfactant.