3A: Exchange of Substances Flashcards
What is the relationship between size and SA:V?
Smaller size = Larger sa:v
Why do multicellular organisms need specialised exchange organs?
Because they have a small SA:V and they need constant flow substances into their internal and external cells,
Describe the Gas Exchange Structures in fish
Gills:
Each Gill is made up of thin plates called Gill Filaments
The Gill Filaments are covered in Lamellae
What is counter-current flow?
In the Gills of the Fish, blood flows through the Lamellae in one direction and water flows over them in the other direction
Why do Gills have a counter-current flow?
To maintain the concentration gradient across the gill to allow for maximum Oxygen absorbtion
Describe the Gas Exchange Structure in Plants
Stomata on the under side of leaves controlled by Guard Cells (which open an close depending on the water Potential in the leaf) allow gases to diffuse in and out of the leaf
How to Guard Cells open and close?
When there is a higher water potential in the leaf then in the guard cell (water in gaps in spongy mesophyll), water moves into guard cells via osmosis and they become turgid and the stoma opens.
When water potential outside the guard cell decreases, water moves out of the cell via osmosis and the cell becomes flacid and the stoma closes.
Describe the Gas Exchange Structure in Insects
Air moves into Tracheae via Spiracles (pore on the surface), and then into the Tracheoles and then directly into respiring cells.
What is abdominal pumping?
Rhythmic abdominal movements done by insects to move air in and out of spiracles
How are Xerophytic plants adapted to reduce water loss?
- Sunken Stomata to trap water vapor
- hairs to trap water vapor
- curled leaves to protect from wind
- reduced number of stomata so fewer places for water to leave
- thick waxy cuticle to reduce evaporation
Describe the Gas Exchange Structure in Humans
Trachea, Bronchi, Bronchiole, Alveoli
How are Alvioli Specialiased for Gas Exchange?
- 1 cell thin
- large surface area
- lots of capillaries
What are the Intercostal Muscles?
Muscles found between the ribs that contract and relax during ventilation
Describe the process of Inspiration
- External Intercostal Muscles Contract
- Internal Intercostal Muscles Relax
- Diapragm Contracts
- Ribcage moves upwards and outwards
- Increases the volume of the Thoracic Cavity
- Lung Pressure decreases
- Air diffuses from air of higher to an area of lower concentration into the lungs
Describe the process of Expiration
- External Intercostal Muscles Relax
- Internal Intercostal Muscles Contract
- Diapragm Relaxes
- Ribcage moves downwards and inwards
- Decreases the volume of the Thoracic Cavity
- Lung Pressure Increases
- Air diffuses from air of higher to an area of lower concentration out of the lungs
