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Distinguish between ventilation, gas exchange and cell respiration
Explain the need for a ventilation system
Describe the features of alveoli that adapt them to gas exchange
Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercoastal muscles, the diaphragm and abdominal muscles
Respiratory System Diagram
Hand drawn diagram of the ventilation system
Why do we need a ventilation system?
The ventilation system allows for oxygen into the lungs and the excretion of CO2.
It ensures that the concentration of the respiratory gases within the lungs encourages the diffusion of each gas in a direction that is beneficial to the body.
There has to be more CO2 in the blood than the alveoli and more oxygen in the alveoli than blood.
Ventilation, Gas Exchange and Cell Respiration
is the flow of air in and out of alveoli in 2 stages - respiration and expiration
Breathing in (Inspiration) - increases concentration of oxygen between alveoli and blood
Breathing out (Expiration) - removes CO2
Depends on muscles - intercostal muscles and diaphragm
Its the diffusion of gases in the alveoli
2 locations where the gas exchange occurs
Lungs - oxygen moves from the air of the lung into the bloodstream. The carbon dioxide moves in the opposite direction
Capillary Bed - opposite gas exchange occurs: oxygen diffuses out of the bloodstream and into a body cell. CO2 diffuses out of the body cell into the capillary bed.
There are two types of cell respiration: Aerobic and Anaerobic
Aerobic - uses oxygen in the mitochondria and produces carbon dioxide
Anaerobic - does not use oxygen to produce carbon dioxide
Alveoli and Gas Exchange
ADAPTATION OF THE ALVEOLI
ADVANTAGE TO GAS EXCHANGE
spherical shape of alveoli
provides large surface area for respiratory gases to diffuse through
flattened single cell-thick
prevents respiratory gases from diffusing through more cell layers
moist inner lining
allows for efficient diffusion
associated capillary bed nearby
respiratory gases do not have to diffuse far to reach single thick capillaries
The fact that there are also millions of alveoli within the lung contributes to the increase in overall surface area for gas exchange.
Mechanism of Ventilation
Diaphragm contracts and flattens downwards
Abdominal muscles relax
external intercostals muscles contract
ribs goes up
pressure in lungs decreases
diaphragm relaxes and moves upwards
abdominal muscles contract
external intercostals muscles relax
air flows out
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