3.1.1 - Exchange surfaces Flashcards
Why do single-called organisms not need specialised exchanges surfaces ?
- Due to their small size, they have a large surface area : volume ratio. This maximises surface area for absorbable/ removal of substances and results in a short diffusion distance so rate of diffusion is sufficient
- They have low metabolic demands so Ov2 demands/ COv2 production is low
Why do multicellular organisms require specialised exchange surfaces ?
- Due to their large size they have a small surface area : volume ratio. Diffusion distance is too large so the rate of diffusion is insufficient to supply cells with all required nutrients/ molecules ( ie. Ov2 )
- They have high metabolic demands due to large size and mobility so cells have greater Ov2 demands / COv2 production
What is the relationship between size and surface area : volume ratio ?
As the size of an object increases, tippets surface area to volume ratio decreases
Do you know how to calculate surface area : volume ratio ?
Yes
What are features of efficient exchange surfaces ?
- Increased surface area
- Thin layers
- Good blood supply
- Ventilation to maintain gradient
Explain how increased surface area is a feature of efficient exchange surfaces ?
Provides a larger surface area over which diffusion can occur increasing rate/ overcoming the limits of surface area to volume ratio
Name an example of specialised exchange surfaces with an increased surface area ?
Root hair cells lining roots of the plant
Explain how thin layers is a feature of efficient exchange surfaces ?
This results in a shorter diffusion distance increasing the rate of diffusion / making it more efficient
Name an example of specialised exchange surfaces with thin layers ?
Alveoli in the lungs
Explain how a good blood supply is a feature of efficient exchange surfaces ?
This results in a steeper concentration gradient which increases the rate of diffusion
Name an example of specialised exchange surfaces with a good blood supply ?
- Alveoli in the lungs
- Gills of fish
Explain how ventilation to maintain diffusion gradient is a feature of efficient exchange surfaces ?
Ventilation system helps maintain concentration gradient which increases the rate of diffusion
Name an example of specialised exchange surfaces with a ventilation to maintain diffusion gradient ?
- Alveoli in the lungs
- Gills of fish where ventilation means a flow of water carrying dissolved gases
What are the components of the respiratory system ?
- Nasal cavity/ passage way
- Lungs
- Trachea
- Bronchus
- Bronchioles
- Alveoli
What are the adaptations of the nasal cavity ?
- Large surface area with good blood supply ( warms air to body temperature )
- Hairy lining ( secretes mucus to trap dust and bacteria )
- Moist surfaces ( increases humidity of incoming air )
What is the role of the nasal cavity ?
It ensures air that passes through the nasal cavity is a similar temperate and humidity than air already in the body/ lungs
What is the trachea ?
The main airway carrying air from the nose down into the chest
What are features of the trachea ?
- It is a wide tube supported by incomplete rings of strong/ flexible cartilage
- Trachea and branches are lined with a ciliated epithelium with goblet cells between/ below epithelial cells
What is the function of the incomplete rings of strong/ flexible cartilage in the trachea ?
- They prevent the trachea from collapsing
- Since the rings are incomplete, this allows food to be easily moved down the oesophagus
What is the role of goblet cells in the trachea ?
Goblet cells secrete mucus onto trachea lining to trap dust and microorganisms
What is the role of cilia in the trachea ?
Cillia beat and move the mucus, along with any trapped dirt/ microorganisms away from the lungs to the throat were it is swallowed and digested
What is the bronchus/ bronchi ?
Trachea divides in the chest into a left branch in the left lung and a right branch into the right lung which are bronchi
What are the functions of bronchi ?
- Similar to trachea with rings of cartilage but they are smaller
What are bronchioles ?
In the lungs, bronchi divide into many small bronchioles