Movement of Molecules

Dissolved Substances
1. Active transport
  1. Goes against concentration gradient and requires energy from respiration.
    1. Enables cells to absorb ions from dilute solutions.
2. Water moves by osmosis
  1. Through a partially permeable membrane from a high concentration to a low concentration.
    1. This is called a concentration gradient.
3. Sports Drinks
  1. Contain waiter, sugar and ions.
    1. The sugars replace sugars lost during energy release while exercising.
    2. The water and ions replace the water and ions lost while sweating.
    3. If not replaced, there is an inbalance and cells cannot work properly.
4. Effectiveness
  1. Large Surface Area
    1. In the lungs; alveoli.
    2. In the small intestine; villi.
      1. Extensive network of capillaries to absorb the products of digestion.
  2. Thin walls
  3. Efficient blood supply
Gaseous Exchange
1. Lungs are protected by the ribcage.
2. Breathing takes air in and out of the body so that oxygen can diffuse into the bloodstream and carbon dioxide out.
  1. Air moves in when the diaphragm contracts and the ribcage expands.
  2. Air moves out when the diaphragm relaxes and the ribcage moves back.

Resource summary

	Created by chattyshannon about 12 years ago