Gas Exchange
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what is gas exchange?

Involves respiration in mitochondria.
O2 enters and CO2 isreleased
How much of the air we breathe is oxygen?

21% of the air we breathe is oxygen
About 76 liters of oxygen per hour consumed at rest
What does the upper respiratory system consist of?
Nose, mouth, and pharnyx.
What happens to lung volume, the ribcage, and diaphram during inhalation?
When breathing in air, lung volume increases as the ribcage is pulled out and the diaphram moves down and contracts.
What happens to lung volume, the ribcage, and diaphram during exhalation?
When breathing out, lung volume decreases as the ribcage is pulled in and the diaphram pulls up and relaxes.
What does the lower respiratory system consist of and how does the air flow through?

Trachea(windpipe which carries air into the lungs), Bronchi, and lungs.
Air flows from pharnyx to the trachea into the bronchi. Each bronchus leads to a lung.
How does the gas exchange happen in the lower respiratory system?

The bronchus divides into bronchioles which leads to the alveoli.
The alveoli are small clusters of sacs, wrapped in a network of capillaries,and filled with air.
Over 150 million tiny alveoli in the human lung creates a large surface area of gas exchange.
How do the gases diffuse?

From high concentration to low concentration.
O2 flows into alveoli and CO2 flows out.
Surface area regulates diffusion rate.
How does the large surface area facilitate diffusion?

The lung surface area is 90 times more than skin.
Oxygen demands depend on size and level of activity.
Ex. More surface area in gill = More active fish.
What is important about the distance of diffusion?

The shorter the distance a gas travels, the faster it can reach its destination.
Oxygen and carbon dioxide need help.
These gases are transferred to the blood which speeds up their delivery to individual cells.
What is the difference between the exchange of gas on land and on water?

Land animals: infolding of body surface to bring air inside
Water animals: Gills are an outfolding of the body surface.
How are the gases transported?

The gases are transported to the blood and the hemoglobin in the blood transports the gases.
Gases are exchanged with cells
What does the hemoglobin do?

The hemoglobin in red blood cells picks up oxygen in lungs and "holds" on to it. Hemoglobin delivers oxygen to cells through diffusion. Around 250,000 hemoglobin molecules per red blood cell.
How do insects breathe?

Air is pumped to trachea.
Trachea delivers oxygen to tracheoles.
Tracheoles diffuse gases directly to cells.

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