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1.1.Function of Respiratory
System
Objectives
Summary
The function of respiration is to provide gas
exchange for an organism. Since most biological organisms require
aerobic metabolism for basic survival function, these metabolic
chemical reactions either produce or consume gases. (Most animals
consume O2 and produce CO2 gases while most
plants consume CO2 and produce CO2 during
photosynthesis.) As a result, gas exchange is needed between the
external and internal environments. The respiratory system provides
a means for the organism to exchange gases efficiently and delivers
the needed gases via the circulatory system.
Q&A
What are the functions of the respiratory
system?
It is used for gas exchange.
Since most living organisms
require oxygen for metabolism (except for anaerobic animals), gas
exchange is vital for the survival of the organisms, both in plants
and in animals. During aerobic metabolism for plants and animals,
O2 is consumed while CO2 is produced as the byproduct. During
anaerobic metabolism (an = no; aerobic = air), O2 is not
required.
Note that plants also consume
O2 and produce CO2 in its metabolism,
especially in the non-photosynthetic parts, such as roots. Of
course, photosynthesis will consume CO2 and produce
O2 as the result.
What gas is needed for aerobic metabolism?
Oxygen is needed for aerobic metabolism.
Aerobic (aero = air)
metabolism requires oxygen as the substrate for chemical reaction
to occur. Thus, the delivery of oxygen to the tissue is essential
for the survival of animals in the process called
respiration.
What gas is released from aerobic metabolism?
Carbon dioxide is produces as a byproduct of aerobic
metabolism.
Thus, the elimination of carbon
dioxide from tissues as the result of metabolic byproduct is also
essential in respiration.
What is anaerobic metabolism?
It is the metabolism, which does not require oxygen
as the substrate.
Anaerobic (an = no; aero
= air) metabolism does not require oxygen for the chemical
reaction to occur. Anaerobic metabolism is not as efficient as
aerobic metabolism. It was evolved before aerobic metabolism. The
earliest metabolism derives energy from heat obtained from
geothermal source at the bottom of ocean.
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1.2.Principles of Gas Diffusion
Objectives
Summary
The principle of diffusion states that gas molecules move from high pressure to low. This is a macroscopic phenomenon of gas movement.
Microscopically, diffusion is resulted from the random motions of gas molecules moving in all directions bombarding each other called Brownian motions. Since high-pressure gas molecules are more energetic than low-pressure ones, therefore gases are more likely to move from high pressure to low. This results in the direction of diffusion – from high pressure to low pressure – at the macroscopic level.
Q&A
What is gas diffusion?
Gas diffusion is the movement of gas molecules often from high to low pressure at the macroscopic level.
The net movement of microscopic particles is from high to low concentration. For gas, the net movement is from high pressure to low pressure by the same principle.
How does gas move from high to low pressure?
It is due to Brownian motion at the microscopic level, resulting in a net movement from high to low pressure at the macroscopic level.
At the microscopic level, diffusion is due to random movement of gas molecules in all directions, bombarding each other. This results in what we called Brownian motion (because it was discovered by the scientist Mr. Brown).
Because high-pressure gases are more energetic, they move much faster than low-pressure gases. As a result, it is more likely for high-pressure gas molecules to move from high to low pressure than the opposite direction. This results in the macroscopic flow of gas from high pressure to low pressure called “diffusion.”
Do gas molecules move from low to high pressure too?
Yes, they do, except that the chance of gas molecules moving from low to high pressure is much lower than the opposite direction.
Gas molecules are more likely to move from high to low pressur...
