Grade 7 Respiration in organisms

2. Inhalation and Exhalation
Group discussion on changes happening in the body
during the process of breathing. Students can inflate
balloon to understand the process.

3. Respiration in organisms
Grade 7

4. Breathing Cellular Respiration
Definition
Breathing involves the
process of inhaling oxygen
and exhaling carbon dioxide
Cellular respiration is the process of breaking
down of glucose to produce energy, which is
then used by cells to carry out the cellular
function.
Process Occurrence
Breathing takes place in the
lungs. Also involves the nose,
mouth and pharynx
Respiration takes place in cells

5. Type of Process
Breathing is voluntary as well as an involuntary physical process. (For
example, breathing during sleep is involuntary. Voluntary breathing is
observed when we sing, speak, swim or for relaxation techniques)
Respiration is an involuntary chemical
process.
Production of Energy
There is no production of energy in this process. Energy is produced and released in the
form of ATP.
Cellular Activity
As it occurs outside cells, it is called the extracellular process. (Occurs
between the organism and the external environment)
As it occurs inside cells, it is called the
intracellular process.
Associated Organs
Breathing occurs through respiratory organs, including the nose, lungs,
etc.
Respiration takes place in cells and
cell organelles, including mitochondria,
etc.

6. Why do we respire?
● A cell is a structural and functional unit of living organisms.
● Cells performs functions like nutrition, transport, excretion etc for which it
requires energy.
● The food has stored energy which it releases during respiration.
● During breathing we breathe in air which is rich in oxygen and breathe out air
that is rich in carbon dioxide.
● The air we breathe is transported to all parts of the body and ultimately to
each cell.
● In the cells, oxygen in the air helps in the breakdown of food.
● The process of breakdown of food in the cell with the release of energy is
called cellular respiration

7. See Think share

8. Aerobic Respiration
● In cells, the food (glucose) is broken down into carbon
dioxide and water using oxygen.
● When the breakdown of glucose occurs with the use of
oxygen it is called aerobic respiration.

9. Anaerobic Respiration
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Many organisms ( like yeast)can survive in the absence of
air. They are called anaerobes.
They get energy through anaerobic respiration.
In the absence of oxygen glucose break down into alcohol
and carbon dioxide. It is called anaerobic respiration

10. Anaerobic respiration in humans
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Cramps occurs in muscles due to anaerobic respiration. Accumulation of
lactic acid causes muscle cramps.
Taking a hot water bath or massage improves circulation of blood, due to
which supply of oxygen to muscle cells increases.
This increase in the supply of oxygen results in the complete breakdown of
lactic acid into carbondioxide and water.
Muscles of humans also respire anaerobically, for a short period of time.
During heavy exercise, cycling, walking for many hours etc, the demand for
energy is high but the supply of oxygen produced is limited.
Anaerobic respiration takes place in muscles to fulfil the demand of energy.

12. Breathing
● Breathing is taking in air rich in oxygen and giving out air rich in
carbon dioxide with the help of respiratory organs.
● The taking in of air rich in oxygen into the body is called
inhalation and giving out air rich in carbon dioxide is known as
exhalation.
● The number of times a person breathe in a minute is termed
as the breathing rate.
● A breathe means one inhalation plus one exhalation.
● On an average, an adult human being at rest breathes in and out
15-18 times in a minute (After heavy exercise up to 25 times per
minute)

13. Why do we yawn when we are sleepy or drowsy?
● One is that when we are bored or tired, we just don’t
breathe as deeply as we usually do.
● Our bodies take in less oxygen because our breathing has
slowed.
● Therefore, Yawning helps us bring more oxygen into the
blood and move more carbon dioxide out of the blood.

14. How do we breathe?
● We breathe through our nostrils into our nasal cavity.
● From the nasal cavity, the air reaches our lungs through
the wind pipe.
● Lungs are present in our chest cavity , which is
surrounded by ribs on the sides.
● A large muscular sheet called diaphragm forms the floor
of the chest cavity.
● Breathing involves the movement of the diaphragm and
the rib cage.

15. Human respiratory system

16. ● During inhalation, the ribs move up and outward and
diaphragm moves down.
● This movement increases space in our chest cavity and
air rushes into the lungs.
● The lungs gets filled with air.
● During exhalation, ribs move down and inward, and the
diaphragm moves up to its former position.
● This reduces the size of the chest cavity and the air is
pushed out of the lungs.

17. Mechanism of breathing in human beings

19. ● From the nostrils the air passes into the nasal cavity and
then goes down the windpipe or trachea.
● From here, the air goes through two smaller tubes called
bronchi (singular bronchus), one of which enters each
lungs.
● In lungs each bronchus divides and re divides into finer
tubes called the bronchioles.
● Each bronchiole ends in a number of air sacs, called
alveoli (singular alveolus)
● Alveoli have very thin walls and are supplied with blood
capillaries.

21. Sneezing

22. Model to show mechanism of breathing

23. Breathing in other animals
Cockroach
● A Cockroach has small openings on the side of its body called
spiracles.
● Insects have a network of air tubes called tracheae for exchange of
gases.
● Oxygen rich air rushes through the spiracles into the tracheal tubes,
diffusing into the body tissues, and reaches every cell of the body.
● Carbon dioxide from the cells goes into the tracheal tubes and
moves out through spiracles.
● These air tubes are found only in insects and not in any other
group of animals.

24. Tracheal System
Cockroach Grasshopper

25. Breathing through spiracles.
The trachea is a dense array of a network of air tubes found
in the internal system. Tracheae are known to balance the
pressure inside the system. When oxygen-rich air enters
into the body of the cockroach via spiracles into the
tracheal tubes, it diffuses into various tissues and cells of
the body. Here, oxygen is used up to liberate energy.
Likewise, carbon-dioxide rich air passes into the trachea
and moves to the outwards through the spiracles. Carbon
dioxide is given out as a result of the respiratory process.

27. Earthworms
● Earthworms breathe through their skin
● The skin of the earthworm feels moist and slimy on touching.
● Gases can easily pass through them.
Frogs
Frogs have a pair of lungs like human beings, they can also breathe through their
skin, which is moist and slippery.The frog has three respiratory surfaces on its
body that it uses to exchange gas with the surroundings: the skin, in the lungs
and on the lining of the mouth.

28. Respiration in Earthworm
Have you ever touched an earthworm?
The skin of the earthworms feels moist. That is why they are called slimy
creatures. The reason behind their moist skin is that earthworm’s breathing
organ is their skin. Air can easily pass through the skin of an earthworm. The
exchange of gases usually takes place through its moist skin and capillaries.
In these regions the oxygen gas is picked up by the haemoglobin dissolved in
the blood and carbon dioxide is released out. Earthworms can also use their
skin to move water and salts by active transport.
Interestingly, frogs can also use their skin to breathe. Although frogs have a
pair of lungs to perform respiration, they often breathe through their skin also.

29. Breathing under water

30. Respiration in fish
Respiration in fish takes place with the help of gills. Most fish possess gills on either
side of their head. Gills are tissues made up of feathery structures called gill filaments
providing a large surface area for exchange of gases. A large surface area is crucial
for gas exchange in aquatic organisms as water contains very little amount of
dissolved oxygen. The filaments in fish gills are organized in rows in the gill arch. Each
filament comprises lamellae, which are discs supplied with capillaries. Blood moves
in and out of the gills through these small blood vessels. Though gills in fish occupy
only a small section of their body, the extensive respiratory surface produced by the
filaments renders the whole organism with efficient gas exchange.

31. Fish take in oxygen-rich water via their mouths and pump it over their
gills. When water moves over the gill filaments, the blood within the
capillary network takes up the dissolved oxygen. Then, the circulatory
system supplies oxygen to all tissues of the body and finally to the cells
while taking up carbon dioxide that is eliminated through the gills from
the body. It exits the body of the fish once the water moves past the gills
through the openings provided in the sides of the throat or through the
operculum, a flap, usually found in bony fish, that covers and protects
the fish gills.
Several fish, such as lampreys and sharks, have multiple gill openings.
Rohu, a bony fish, has a single gill opening on either side.

32. Do plants also Respire?
● Plants respire. They take in oxygen and give out
carbon dioxide.
● In cells oxygen is used to break down glucose into
carbon dioxide and water.
● The leaves of plants have tiny pores called stomata
for the exchange of oxygen and carbon dioxide.
● The root cells of plants also need oxygen to
generate energy.
● Roots take up air from the air spaces present between

33. Roots absorb air from the soil

34. Plants do require oxygen to respire, the process in return gives out carbon
dioxide. Unlike humans and animals, plants do not possess any specialized
structures for exchange of gases, however, they do possess stomata (found in
leaves) and lenticels (found in stems) actively involved in the gaseous
exchange. Leaves, stems and plant roots respire at a low pace compared to
humans and animals.Breathing is different from respiration. Both animals and
humans breathe, which is a step involved in respiration. Plants take part in
respiration all through their life as the plant cell needs the energy to survive,
however, plants breathe differently, through a process known as Cellular
respiration.
In this process of cellular respiration, plants generate glucose molecules
through photosynthesis by capturing energy from sunlight and converting it into
glucose. Several live experiments demonstrate the breathing of plants. All
plants respire to provide energy for their cells to be active or alive.

35. The Process of Respiration in Plants
During respiration, in different plant parts, significantly less exchange of gas takes place. Hence,
each part nourishes and fulfils its own energy requirements.
Consequently, leaves, stems and roots of plants separately exchange gases. Leaves possess
stomata – tiny pores, for gaseous exchange. The oxygen consumed via stomata is used up by cells
in the leaves to disintegrate glucose into water and carbon dioxide.

36. Respiration:
oxygen + glucose -> carbon dioxide + water + heat energy
Photosynthesis:
carbon dioxide + water+ light energy -> oxygen + glucose

37. Plants respire all the time, day and night. But photosynthesis only occurs during the
day when there is sunlight.
Depending on the amount of sunlight, plants can give out or take in oxygen and carbon
dioxide as follows1.
Dark – Only respiration takes place. Oxygen is consumed while carbon dioxide is released.
Dim sunlight – Photosynthesis rate equals respiration rate. A plant consumes all the oxygen
photosynthesis generates. It also uses all the carbon dioxide respiration creates. As a
result, no gas exchange takes place with the environment.
Bright sunlight – Photosynthesis uses carbon dioxide and makes oxygen faster than
respiration produces carbon dioxide and consumes oxygen. Extra oxygen is released into
the atmosphere.

38. During daytime, photosynthesis produces oxygen and glucose faster than respiration
consumes it. Photosynthesis also uses carbon dioxide faster than respiration produces it.
Oxygen surplus is released into the air and unused glucose stored in the plant for later use.
This is why plants are so important to human and other animals’ survival. Without
photosynthesis, we wouldn’t have oxygen or food to stay alive.