The Principals of Exchange and Transport Flashcards
What is the surface area of an organism?
The total number of cells in direct contact with the surrounding environment.
What is the volume of an organism?
The three-dimensional space occupied by metabolically active tissue.
What are some features of exchange surfaces that aid passive and active transport into and out of organisms?
- Increasing the Surface area of the exchange surface
- Thin separating surface
- Large concentration gradients
How does increasing the SA of the exchange surface aid active and passive transport?
Decreases distance substances have to diffuse to reach any cell in the body.
How does a thin separating surface aid active and passive transport?
Rate of diffusion is maximised, as there is few layers to diffuse through.
How does large concentration gradients aid active and passive transport?
Diffusion will only occur across an exchange surface if there is a concentration gradient.
How is Mass flow brought about?
Pressure differences existing within the organism.
Why is Gaseous exchange necessary?
To ensure sufficient oxygen reaches all cells in an organism.
What features do gas exchange surfaces have to maximise the rate of exchange.
- Large surface area
- Moist surface
- Diffusion gradient
- Permeable
- Short diffusion path
What is Fick’s Law?
When the rate of diffusion equals the surface area multiplied by the difference in concentration, and divided by the thickness of membrane.
What are the two processes involving gas exchange in plants?
Respiration and Photosynthesis
What is respiration?
Plants carry out respiration to produce energy and it is a process which takes place all the time. This involves the use of oxygen and the production of carbon dioxide as a waste product.
What is Photosynthesis?
Requires light energy, uses carbon dioxide and oxygen is produced as a waste product.
Where does Photosynthesis occur in the plant?
The palisade mesophyll cells.
What are some leaf adaptation for gas exchange?
- Large moist gas exchange surfaces
- Intercellular air spaces of the spongy mesophyll
- Stomata
- Thin body/Large surface area
How are mammals adapted for gas exchange?
- Small surface area to volume ratios
- Impermeable body covering
- Millions of alveoli in lungs
Where are surfactant secreting cells found?
The alveolar wall.
What does the surfactant secreting cells produce, and what does it do?
A surfactant that reduces the surface tension and prevents the collapse of the alveoli.
What other cell is present in alveoli?
Macrophages.
What does breathing mean?
The process involved in ventilating the lungs in the alveoli.
What is Inspiration?
The process of breathing in. The external intercostal muscles contract and ribs are pulled upwards and outwards. The diaphragm muscle contracts causing the diaphragm to flatten. Both these actions increase the volume of the thorax which reduces the pressure around the lungs. The pressure differential between the atmosphere and lungs cause air to enter the lungs until an equilibrium is reached.
What is Expiration?
Breathing out. The external intercostal muscles relax causing ribs to move downwards and inwards. The diaphragm returns to original shape. These cause a reduce of volume in the thorax therefore increasing the pressure around the lungs. As the thorax has a high pressure that the atmosphere air is forced out of the lungs.
What is Tar?
The general name given to toxic chemicals in cigarette smoke.
What does Tar do?
Tar damages the DNA in the epithelial cells lining the lungs and cause cancer.
