How does shape affect diffusion?
Diffusion is like going through a net or sieve. Smaller sizes and shapes pass through more easily than large ones.
What is the relationship between cell size and diffusion?
The surface-to-volume ratio of a sphere is 3/r; as the cell gets bigger, its surface-to-volume ratio decreases, making diffusion less efficient. The larger the size of the sphere, or animal, the less surface area for diffusion it possesses.
How does volume and surface area affect diffusion?
When the cell increases in size, the volume increases faster than the surface area, because volume is cubed where surface area is squared. When there is more volume and less surface area, diffusion takes longer and is less effective.
How does a cells surface area affect diffusion?
When a cell’s surface area increases, the amount of substances diffusing into the cell increases. This is known as the surface area/volume ratio (SA/V ratio). A cell will eventually become so large there is not enough surface area to allow the diffusion of sufficient substances like oxygen and it will die.
What four features should all exchange surfaces have?
Exchange surfaces have a number of adaptations to make them efficient: Thin barriers to minimise the diffusion distance. A high concentration gradient to the substance. A large surface area….Exchange Surfaces
- Carbon Dioxide.
- Oxygen.
- Ammonia.
What four ways can the effectiveness of exchange surfaces be increased?
The effectiveness of exchange surfaces in plants and animals is increased by having: A large surface area: the flattened shape of structures such as leaves. the villi in the digestive system.
What are 4 features of an effective gas exchange surface in an animal?
List the features of gas exchange surfaces in animals.
- They are moist to prevent the cells from drying and to allow gases to dissolve;
- They have a large surface area , so that a lot of gas can diffuse across at the same time;
- They have a high concentration gradient – maintained by the movement of air & blood.
What are the features of an efficient exchange surface?
Common features of exchange surfaces:
- thin – for a short diffusion distance.
- large area – achieved by being long and thin, flat, or folded.
- moist – so that substances can be dissolved for diffusion to happen.
What happens in the alveoli?
The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out. Oxygen breathed in from the air passes through the alveoli and into the blood and travels to the tissues throughout the body.
Should an ideal exchange surface be thick or thin?
Large surface area – many alveoli are present in the lungs with a shape that further increases surface area. Thin walls – alveolar walls are one cell thick providing gases with a short diffusion distance. Moist walls – gases dissolve in the moisture helping them to pass across the gas exchange surface.
Why do lungs work better than gills in air?
Why do lungs work better than gills in air? Much less water is lost via evaporation from lungs than would be from gills suspended in air. Breathing is initiated by neurons in the medulla oblongata. Inhalation occurs as a result of nervous stimulation of the external intercostal muscles and the diaphragm.
Why do alveoli have thin walls?
The alveoli are lined with mucus and are surrounded by a network of blood capillaries. They have very thin walls for gases to be absorbed through. An individual air sac is called an alveolus. The layer of moisture in the alveoli allows gases to dissolve so that they can diffuse quickly.
What is the path of carbon dioxide as it leaves the lungs?
Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.
Which is the correct pathway of oxygen as it travels?
Pathway of air: nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli (site of gas exchange)
How will you describe the sequence of oxygen carbon dioxide and blood flow in your own words?
Oxygen passes quickly through this air-blood barrier into the blood in the capillaries. Similarly, carbon dioxide passes from the blood into the alveoli and is then exhaled. Then the blood is pumped through the pulmonary artery to the lungs, where it picks up oxygen and releases carbon dioxide.