Download Biology and Geology 3. Secondary Education

UNIT
3
Systems of nutrition
WHAT IS BREATHING?
Biology and Geology 3. Secondary Education
UNIT
UNIDAD
3
3
What is breathing?
Most people think that, respiration is
the process where we take air into
our lungs…
…and then expel it. We repeat this process
rhythmically and automatically.
For scientists, this process is not respiration, it is just one part of it:
lung ventilation.
Biology and Geology 3. Secondary Education
UNIT
UNIDAD
3
3
What is breathing?
Respiration is a more complex process:
It starts when,
after we take in
air.
We take in
air
Oxygen
Oxygen passes from the
pulmonary alveoli into
the blood.
Biology and Geology 3. Secondary Education
UNIT
UNIDAD
3
3
What is breathing?
The blood carries the
oxygen collected by
the alveoli to cells
throughout the body.
Oxygen
Biology and Geology 3. Secondary Education
UNIT
UNIDAD
3
3
What is breathing?
The oxygen enters the cells
directly through the membrane…
Oxygen
Oxygen
…and goes into the
mitochondria.
An energy nutrient (called
glucose) also goes into the
mitochondria.
Biology and Geology 3. Secondary Education
Glucose
UNIT
UNIDAD
3
3
What is breathing?
• In the mitochondria, the oxygen (O2) reacts with the glucose in complicated
chemical process, which transform them into simple molecules, such as
carbon dioxide (CO2) and water (H2O) and also releases energy.
O2
ENERGY
Molecules of
glucose
(rich in energy)
CO2 + H2O
This process is cellular respiration.
Biology and Geology 3. Secondary Education
UNIT
UNIDAD
3
3
What is breathing?
• One result of cellular respiration in the mitochondria is the production of
a waste product, CO2, which is expelled from the cell through the
membrane.
CO2
Biology and Geology 3. Secondary Education
UNIT
UNIDAD
3
3
What is breathing?
• The CO2 from the cell activity
is collected by the blood in the
circulatory system.
CO2
Biology and Geology 3. Secondary Education
UNIT
UNIDAD
3
3
What is breathing?
• Finally, the CO2 is
carried by the blood to
the lungs, where it
passes into the air
contained in the
pulmonary alveoly.
CO2
When we breathe
out, we expel the
CO2.
Biology and Geology 3. Secondary Education