3.1.1 exchange surfaces Flashcards
Do prokaryotes need specialised exchange surfaces?
No, they are small enough to get the resources they need via osmosis and diffusion etc.
Why do larger, eukaryotic organisms need specialised exchange surfaces?
Because they have greater metabolisms so they need more resources. They have lower SA:Volume ratios so cannot get all of their resources via simple diffusion, osmosis etc as the substances need to travel further to the internal cells.
How does having a large surface area aid exchange surfaces?
This allows more substances to travel across at a time which increases the exchange rate.
Why do mammals need excellent exchange surfaces?
Because they have large metabolisms.
Why does the trachea have c-shaped rings of cartilage?
To prevent it from collapsing due to the pressure changes in the lungs.
What two types of cells is the trachea lined by?
Goblet cells and Ciliated Epithelial cells.
What is the purpose of the Ciliated Epithelial cells in the trachea?
These cells sweep mucus, dust and bacteria away from the lungs and into the throat.
What is the purpose of the Goblet cells in the trachea?
They secrete mucus which traps dust and microbes which prevents them from reaching the lungs. The mucus is swept along by the cillia of the ciliated epitelial cells upwards and is swallowed.
Which cells line the alveoli?
Squamous epithelial cells (Very thin and permable so allow the diffusion of gases)
Where is smooth muscle found in the human exchange system?
In the bronchi and bronchiole walls.
What is the purpose of the smooth muscle walls of the bronchi and bronchioles?
This helps to regulate the flow of air into the lungs by dialating when more air is needed and constricting when less air is needed.
Which tissues in the lung are elastic fibres present in?
All lung tissues.
What are the purpose of elastic fibres in the tissues of the lungs?
Elastic fibres enable the lung to stretch and recoil which makes expiration a passive process.
What is the difference between the cartilage in the trachea and the cartilage in the bronchi?
The trachea has C-shaped cartilage rings whereas the bronchi has full rings of cartilage.
What is the trachea?
The airway that leads from the mouth and nose to the bronchi.
What do the bronchioles do?
These are narrow tubes that carry air from the bronchi to the alveoli.
What is the purpose of the alveoli.
These tiny sacs are the main site of gas exchange in the lungs.
Describe the process of inhilation in mammals.
- External intercostal muscles contract 2. Ribcage moves up and out
- Diaphragm contracts and flattens
- Thorax volume increases
- Thorax pressure decreases relatie to atmospheric pressure
- Air is drawn in down a PRESSURE gradient from a high to a low concentration.
Is inhilation an active or passive process?
Inhilation is an active process which requires ATP.
Why does breathing out technically occur?
Due to the recoil of the lungs as they have been stretched.
Explain the process of exhilation in mammals.
- External intercostal muscles relax. 2. Ribs move down and in 3. Diaphragm relaxes and curves upwards (dome shape) 4. Thorax volume decreases 5. Thorax pressure increases relative to atmospheric pressure 6. Air moves out down a PRESSURE gradient from a high to low pressure.
What is the function of the rib cage?
To protect the lungs.
What is the function of the diaphragm?
Contracts and relaxes to facilitate ventilation.
What is the function of the pleural fluid?
This reduces friction between the ribcage and lungs during inflation and deflation.