Respiration is the process by which organisms break down glucose to release energy in the form of ATP. It can occur aerobically, using oxygen, or anaerobically without oxygen. Aerobic respiration generates more ATP but requires oxygen delivered via the respiratory system. The human respiratory system involves the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and alveoli where gas exchange occurs. Breathing is the process of inhaling and exhaling that delivers oxygen for aerobic respiration and removes carbon dioxide.

1. RESPIRATION
• DEFINITION : - The breaking down of food
( substrate – mainly glucose ) in the presence or
absence of oxygen to release energy in the form of
ATP and carbon dioxide in the cells of the organism is
termed RESPIRATION.
• TYPES :-
a) Aerobic respiration- requires presence of oxygen
b) Anaerobic respiration – does not require presence of
oxygen

2. AEROBIC & ANAEROBIC RESPIRATION
AEROBIC RESPIRATION ANAEROBIC RESPIRATION
• It utilizes oxygen • It occurs in the absence of
oxygen.
• occurs in the mitochondria • It also occurs in the mitochondria
• Involves the process of • It also involves the process of
glycolysis in cytoplasm
‘glycolysis’ where glucose is • Pyruvate then enters different
broken down to ‘pyruvic pathways and forms different
acid’. products .
• 2 types of anaerobic respiration
• Pyruvate is converted to CO2, are:
H2O, and ENERGY by kreb’s • Fermentation - leads to formation
of alcohol in yeast
cycle.
• anaerobic respiration in human
• 38 ATP are generated. muscles - leads to formation of
lactic acid.

3. BREATHING & AEROBIC RESPIRATION
• Aerobic respiration requires the presence of
oxygen which is internalized by the living
system by the process of breathing.
• Breathing in humans involves the rhythmic
intake of oxygen (by inhalation) and release of
carbon dioxide (by exhalation) .
• The terms breathing and respiration are not
synonymous.

4. THE HUMAN RESPIRATORY SYSTEM
Diagram : - The respiratory tract
• nose and nostrils
• nasal cavity
• pharynx
• larynx
• glottis and epiglottis
• trachea
• lungs
• primary bronchi
• secondary bronchi
• bronchioles
• Alveoli/alveolar sac

5. THE RESPIRATORY TRACT
• The nose and the nostrils are the openings
which allow the passage of air in and out of
the body.
• The nostrils are lined with small hair and the
nasal passage is internally covered with a thick
layer of mucus.
• The cavity has the presence of ciliated
columnar epithelium.
• The nasal cavity is separated from oral cavity
with a bony Palate.

6. THE UPPER RESPIRATORY TRACT
• It consists of nasal cavity,
pharynx and larynx.
DIAGRAM • The Pharynx - It is a narrow
opening where the buccal
cavity ends and the trachea
and the esophagus start.
• The end region where the
pharynx joins the trachea has
an opening called GLOTTIS.
• The glottis always remains
open, except during
swallowing it is closed by a
flap like structure called
EPIGLOTTIS.
• The larynx or the voice box
follows the next.

7. larynx
pharynx

8. THE LOWER RESPIRATORY TRACT
• It consists of :
DIAGRAM • Trachea
• Primary bronchi
• Secondary bronchi
• Bronchioles lungs
• Alveoli

9. • The trachea is the organ which
communicates between the upper and the
lower respiratory tract. It is protected by semi
circular cartilageneous rings.
• The trachea further divides into primary ,
secondary and tertiary bronchioles which
connect the alveoli .
• The alveoli are air sacs with thin walls
composed of moist non-ciliated squamous
epithelial cells. They are richly supplied by
blood capillaries.

10. LUNGS
• The organs from primary bronchi to alveoli
are covered up inside the organ called LUNGS.
• The lungs are called the ‘Respiratory organs ’
in the Human body, which has two lungs – The
left and the right lung.
• Different organisms have different organs for
breathing E.g.: Fish – gills, Frog - moist skin
and lungs.

11. • In the humans the Lungs are very delicate
organs located in the “Thoracic Cavity” .
• They are supported by the “Diaphragm” which
is a muscular organ and also separates the
abdominal cavity from the thoracic cavity.
• Externally the lungs are protected by the
ribcage. They are covered by membranes[2]
called ‘PLEURA’

12. Mechanism of Breathing
• BREATHING
INHALATION EXHALATION
breathing in air breathing out air
( rich in oxygen) ( rich in carbon dioxide)
Both inhalation and exhalation are
involuntary processes. It does not require any
energy except to contract and relax the
respective muscles.

13. INHALATION
• The diaphragm lowers down and becomes flat
(contracts) and at the same time the ribs and sternum
are pulled outwards (with the help of intercoastal
muscles) which leads to the enlargement of the
thoracic cavity.
• This leads to the expansion of lungs & hence the air
pressure inside the lungs decreases, to balance the
pressure the fresh air hence moves into the lungs .
• On reaching the alveoli the exchange of gasses occurs
due to difference in the concentration of gasses in the
air and blood. The exchange occurs through diffusion.

14. EXHALATION
• Once the exchange of gasses has occurred the
diaphragm relaxes and returns to it’s original
curved position ( ie it is pushed upwards) and
at the same time the ribs are also pushed
inwards, resulting into decrease in area of
thoracic cavity and increasing the air pressure
inside the lungs.
• This leads to pushing the air out of the lungs
passively.