Unit 3 Biology - Substance Exchange Flashcards
What is the insect gas exchange system
called?
The tracheal system.
What is the tracheal system?
A gas exchange surface that consists of small tubes called tracheoles that carry oxygen around the body.
What are spiracles?
Spiracles are openings in an insect’s thorax and abdomen that allow gases to diffuse in and out of their body.
What is a the fish gas exchange system?
Gills are highly branched and folded, large surface area for diffusion.
The gills are also covered in lamellae which further increases the SA.
How does oxygen diffuse in fish?
Oxygen in the water diffuses quickly into the bloodstream of fish because of the counter-current system.
What is meant by counter-current system?
Blood in the lamellae of fish flows in the opposite direction of the flow of water through the gills.
This means there is a maintained steep concentration gradient between the blood and gills.
How does gas exchange take place in plants? Give detail.
Mesophyll cells: large SA for photosynthesis.
Stomata: Carbon dioxide leaves the plant from the stomata on the epidermis.
Guard cells: Open and close the stomata to prevent water loss.
How do insects minimise water loss? Give detail.
Waxy cuticle: Insects have a waterproof waxy cuticle on their body.
Spiracles: Can be closer to prevent water loss.
What is the trachea?
The entrance to the human gas exchange system.
Has cartilage ridges at the front to provide protection.
What are bronchi?
The trachea divides into two bronchi.
Air flows along each bronchus to a lung.
They are made from cartilage and smooth muscle.
What are bronchioles?
Each bronchus divides into bronchioles which branch throughout the lungs into small sacs called alveoli.
What are alveoli?
Sacs that are filled with air when a human breathes in.
Where oxygen exchange takes place.
Millions of them in the lungs.
Large SA
How are capillaries used in the lungs?
Each alveoli is surrounded by a network of capillaries, providing a large surface area for gas exchange.
They also provide a steep concentration gradient.
What are alveolar epithelium cells and why are they good for exchange?
Single layer of cells that lines the walls of the alveoli.
This is good because it provides a short diffusion distance for gas exchange.
