Chapter 10 - Respiration in Organisms (Overview) - CBSE Class 7 Science Video Lecture

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respiration in organisms
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all organisms are made of microscopic
units called cells a cell is the
smallest structural and functional unit
of an organism every cell of an organism
performs certain functions such as
nutrition transport excretion and
reproduction to perform these functions
the cell needs energy all living
organisms respire to get energy from
food when we breathe we breathe in air
which contains oxygen and breathe out
carbon dioxide the air we breathe in is
transported to all the parts of our body
and ultimately to each cell in the cells
the oxygen helps in breaking down the
food the process of breakdown of food in
the cell is called cellular respiration
through a process called glycolysis
glucose is converted to pyruvic acid
which breaks down into water and carbon
dioxide with the help of oxygen
when breakdown of glucose happens with
the help of oxygen it is called aerobic
respiration food can also be broken down
in the absence of oxygen which is known
as anaerobic respiration this happens
mostly in case of prokaryotes
which are single-celled organisms living
in environments devoid of oxygen
our muscles can also respire
anaerobically during high exercise like
cycling or weightlifting the demand for
energy is high but the supply of oxygen
is limited that is when anaerobic
respiration takes place in the body to
satisfy the demand of energy this
results into the production of lactic
acid from pyruvic acid a high
concentration of lactic acid might
impair the muscles leading to cramps in
the process of breathing we take the
oxygen present in the air through our
nostrils which is called inhalation
giving out air rich in carbon dioxide
which is called exhalation it is a
continuous process that goes on
throughout the life of an organism the
respiratory system moves the air through
the nose pharynx larynx trachea and
bronchi to the alveoli where the gas
exchange between oxygen and carbon
dioxide occurs
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nares are the opening to the north
through which the air passes to the
nasal cavity the air then continues to
move into the pharynx or throat the
common passageway for food and air the
air then moves on to the larynx the
epiglottis a tissue in front of the
larynx closes of the larynx when
swallowed to prevent food from entering
the larynx or voice box contains the
vocal folds
the trachea or windpipe connects the
larynx to the bronchi tree the
cartilaginous rings of the trachea
prevent it from collapsing lungs are
spongy tissues with alveoli and blood
capillaries breathing occurs because of
the expansion and contraction of the
lungs the primary muscle of respiration
is the diaphragm the diaphragm is a thin
dome shaped layer of muscle and tendons
that separates the abdominal cavity from
the chest cavity the diaphragm attaches
along the lower ribcage high in front of
the sternum and deeply in the back along
with the spine
it also attaches to itself by an
essential tendon the diaphragm uses its
central tendon and its attachments as a
leverage to flatten during inhalation
the expansion of the ribs comes from the
resistance of the internal organs to
downward movement as the internal organs
are slow to move the ribs expand to make
room for the lungs
the bronchi carrying the s sub divided
into smaller branches or bronchioles at
the end of each bronchial are the
alveolar sacs which are surrounded by
blood capillaries and contain millions
of single layer as we lie cells where
the gas exchange takes place the
oxygenated air passes through the nose
and reaches the alveoli by the process
of diffusion oxygen in the air moves the
alveoli to the capillaries carbon
dioxide moves from the capillaries to
the alveoli and is exhale bringing the
process of respiration to an end unlike
the other animals which have chest
cavities like human beings insects like
cockroaches have a different respiratory
system a cockroach has small openings on
its body called spiracles insects have a
network of air tubes called trachea for
gas exchange earthworms are one of the
few insects that breathe through their
skin the skin of an earthworm is
extremely moist and slimy unlike animals
living on land fish breathe or get their
oxygen from water instead of using lungs
the fish breathe with the help of organs
called gills most fish have four pairs
of gills enclosed in a gilt chamber on
each side of the head on the outside of
the body a flap of bone called the Gill
cover protects the gills of bony fish
to get oxygen fish got water through the
mouth and pump it over the gills in many
fish the breathing process begins when
the gill covers closed and the mouth
opens the walls of the mouth then move
inwards in the mouth
partially closes and the gill covers
open this action forces the water from
the mouth into the gill chamber in case
of plants the roots transport the
minerals and water to the leaves carbon
dioxide is taken in through the tiny
pores on the surface of the leaves known
as toe matter in this process plants
release oxygen with the help of which we
breathe in order to survive
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