Topic 6.4.1 – 6.4.5Gas ExchangePage 228 - 232

What will we learn?

-the difference between respiration, ventilation and gas exchange-why we need these systems, and how they work-names (labeling) of the basic structures involved

How will we learn it?

-interpreting diagrams-investigating models-watching an animation-designing a lab

Most organisms must absorb oxygen from the environment and release carbon dioxide in order to survive. This process is called gas exchange.

Rate of gas exchange depends on amount of available surface area, and concentration of gas on the exchange surface.Which organism below has more gas exchange surface area?

The oxygen that is absorbed is used in cellular respiration.

Investigate model. Are our lungs as big as you though?

What happens when you puncture a lobe?

1. Moist because the O2 and CO2 must be in solution to be absorbed.

2. In contact with an environmental source of O2.

3. Thin-walled so that diffusion across it occurs rapidly.

4. In close contact with the system that transports dissolved materials to and from the cells of the organism.

The gas exchange membrane must be:

In humans gas exchange happens in the alveolus (alveoli). They are 200um in diameter and arranged into bundles.

Endothelial – cells that make the outside of blood vessels

Epithelium – cells that cover surfaces of structures within the body (0.15um)

Basement membrane – a layer of protein gel (0.1um)

Alveolus give us a total area of 80m2 for gas exchange.

Healthy alveolus Alveolus with emphysema

Respiration 3D Medical Animation

http://www.youtube.com/watch?v=HiT621PrrO0&feature=related

The Ventilation System

Exhalation: The diaphragm relaxes and curves beneath the lungs. The volume decreases, the pressure outside the lung increases and forces the lungs to get smaller and squeeze out the air.

Inhalation: The diaphragm contracts, moves down, and increases the volume of the chest cavity. When the volume increases, the pressure inside the chest cavity decreases, causing air to rush into the lungs equalizing the pressure

*see balloon bell jar demo

Gas Exchange and Transport

Dalton’s law of partial pressure – each gas in a mixture (air) exerts its own pressure, or partial pressure.The percent of each gas present in the mixture can help us calculate this partial pressure.

Ex: Air is 21% oxygen. Atmospheric pressure at sea level is 101 kPa. Therefore: 21% x 101kPa = 21.21 kPa.(Carbon dioxide exerts 0.03 kPa)

Gas naturally wants to flow from an area of high pressure to an area of low pressure.

Review Syllabus Details

Homework: Page 232 # 1-7, “?” Boxes on page 229

Lung Volume LabCome up with a procedure that will help us determine if

exercise causes an increase in lung volume. Remember to clearly state the problem and your independent, dependent and control variables.

Keep in mind that this experiment is nearly impossible to control fully – think about what you might expect to see in a “professional fitness lab”.