We need to breathe in oxygen in order to release energy
through aerobic respiration. Sugar reacts
with oxygen in cells to release energy.
Make
sure you learn the word and balanced symbol equations for aerobic
respiration:
In order
to carry out aerobic respiration we need to breathe in oxygen
from the air. Oxygen diffuses from the alveoli
(air sacs) in the lungs into the blood because there is a concentration
gradient (oxygen moves from an area of high concentration to
an area of lower concentration). Carbon Dioxide also moves out
of the blood into the alveoli for the same reason.
The
air we inhale contains:
21%
Oxygen
0.03
to 0.04% Carbon Dioxide
The
air we exhale contains
16%
Oxygen
4%
Carbon Dioxide
Most
of the remainder of the inhaled and exhaled air (approx 78%)
is made up of Nitrogen gas which is not used in respiration.
Anaerobic
Respiration
When
you exercise hard, not enough oxygen gets to the muscles to
be able to release sufficient energy by aerobic respiration.
In order to make up the shortfall in the energy release required
you body performs anaerobic respiration as
well as aerobic respiration.
Anaerobic
respiration releases much less energy than aerobic respiration
and lactic acid is toxic to muscle cells and must be removed
as quickly as possible. Once you stop exercising you continue
to breathe deeply to oxidise lactic acid to carbon dioxide and
water. When you are panting after heavy exercise your body is
paying back the 'oxygen debt' - the oxygen breathed in is needed
to break down the lactic acid which has accumulated.
Differences
between aerobic and anaerobic respiration
Aerobic
Respiration
Anaerobic
Respiration
Uses oxygen
Does not use
oxygen
Does not make
lactic acid
Makes lactic
acid
Makes carbon
dioxide
Does not make
carbon dioxide
Makes Water
Does not make
water
Releases a large
amount of energy
Releases a small
amount of energy
Carbon
Dioxide
Carbon
Dioxide is a toxic and excess carbon dioxide must be removed
from the blood. Increased amounts of carbon dioxide are detected
by the brain and a nerve signal is sent to the lungs to increase
the breathing rate. More carbon dioxide is then able to diffuse
from the blood into the air.
