Respriration and Gas
exchange
Respiration is the process by which living organisms
obtain energy from food. It involves breaking down
glucose (a type of sugar) into energy that the cells
can use.
Gas exchange refers to the process of swapping
gases—oxygen (O₂ ) is taken into the body, and
carbon dioxide (CO₂ ) is expelled. This happens in
the lungs for humans and other animals with lungs.
Gas exchange refers to the process of swapping
gases—oxygen (O₂ ) is taken into the body, and
carbon dioxide (CO₂ ) is expelled. This happens in
the lungs for humans and other animals with lungs.
By Ahnas Bashir
And Ahmed Fahad
Aerobic Respiration: Requires oxygen to
break down glucose, producing a large
amount of energy, water, and carbon
dioxide as by-products.

Equation: Glucose (C₆ H₁ ₂ O₆ ) +
Oxygen (O₂ ) → Carbon dioxide
(CO₂ ) + Water (H₂ O) + Energy
Anaerobic Respiration: Does not
use oxygen and produces less energy.
In animals, it results in lactic acid,
while in plants and yeast, it produces
ethanol and carbon dioxide.


Equation (in animals): Glucose →
Lactic acid + Energy.
Equation (in yeast/plants): Glucose →
Ethanol + Carbon dioxide + Energy.
Uses of Energy
1. Contracting muscles
2. Making protein molecules
3.cell division
4. active transport
5.growth
6. transmitting nerve impulses
7.producing heat inside body
Importance of Respiration:

It provides the necessary energy for vital
functions such as muscle contraction, cell
division, and maintaining body temperature
in warm-blooded animals.
Gas Exchange:
The Role of Lungs:

In humans, gas exchange occurs in the alveoli (tiny air sacs)
of the lungs. These sacs have very thin walls surrounded by
capillaries (small blood vessels), allowing gases to pass
through.
Oxygen and Carbon Dioxide Transport:

When we inhale, oxygen moves from the alveoli into the
blood, and carbon dioxide moves from the blood into the
alveoli to be exhaled.

Red blood cells transport oxygen from the lungs to the rest
of the body and bring carbon dioxide back to the lungs to be
exhaled.
Diffusion:

The movement of gases (oxygen and carbon dioxide)
occurs through diffusion. This means that gases move from
areas of high concentration to areas of low concentration
(oxygen moves from high concentration in the alveoli to
lower concentration in the blood, and carbon dioxide moves
from high concentration in the blood to lower concentration
in the alveoli).
Breathing vs. Respiration:

Breathing is the physical process of inhaling
and exhaling air, while respiration refers to
the chemical process in cells where glucose
and oxygen are used to produce energy.
Adaptations for Gas Exchange:

The alveoli are specialized for efficient gas
exchange:
o
o
o
o
Large surface area: Many alveoli increase
the surface area for gas exchange.
Thin walls: Alveoli and capillary walls are
just one cell thick to allow quick diffusion
of gases.
Moist surface: This helps gases dissolve
and pass through the membranes more
easily.
Good blood supply: The alveoli are
surrounded by capillaries that constantly
refresh the blood supply, ensuring
efficient gas exchange.