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Respiration
Gas Exchange
- Gas Exchange: taking in O2 and releasing CO2
- Ventilation: movement of air or water over respiratory surface
- Surface must be moist
- Uses diffusion
- Larger surface area = more gas exchange
- Thinner membrane = more gas exchange
Types of Respiratory Systems
Gills
- Aquatic animals often use gills
- Countercurrent exchange: maximizes gas exchange
- Blood and water flow in opposite directions
Tracheal Systems
- Tracheal System: a network of tubes that carry air throughout the body
- Largest tube is the Trachea, which is open to air
- Insects have many trachea that contact every cell directly
- Enables expensive movements (i.e. flight)
- Most mammals use Lungs: a specialized respiratory organ
- Lungs are open to the air
- Have many pockets to increase gas exchange
- Must use circulatory system to transport O2 to the body
Mammalian Respiratory System
- Air enters the Trachea
- The trachea splits into Bronchi which lead into each lung
- Bronchi branch into smaller Bronchioles
- Bronchioles end in Alveoli: air sacs where gas exchange occurs
- Alveoli are covered in Surfactant: which prevents them from collapsing
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Skin Respiration
The phylum Annelids, worms, don't have lungs like humans do, but still require gas exchange with the circulatory system. These organisms use their skin instead!
- Worm skin has many capillary vessels all along the skin
- The thin layer of skin at these capillaries allows oxygen to diffuse into the blood and carbon dioxide out of the blood
- Worms skin is always moist - this allows the diffusion of dissolved oxygen
- The oxygenated blood is carried by the circulatory system to the cells in the worm that cannot undergo gas exchange
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Example: Countercurrent Exchange
Using words and diagrams describe the process of countercurrent exchange in fish gills.
Countercurrent exchange is the process of oxygen accumulation in the blood of fish through the gills.
Fish swim causing water to flow through the gills in one direction, while the circulatory system flows in the opposite direction.
Deoxygenated blood comes into the gills where the water exits, and oxygenated blood flows out of the gills where the water enters.
The deoxygenated blood has a lower concentration of oxygen than the water so oxygen flows into the blood as it passes through the gills.
Practice: Respiratory Elements
What is the order of Respiratory elements from largest to smallest?
Practice: Gas Exchange in Fish
True or False:
The fish circulatory system flows blood in the same direction that water flows through the gills.
Practice: Respiratory Systems
Which of the following animals have respiratory systems?