Respiration
-Respiration is a life process involving intake of
oxygen from surroundings
- Oxidation of food
-Release of energy
-Elimination of CO2 produces as a by-product
-Respiration----- Exchange of gases + Oxidation of
food
- Oxidation of assimilated molecules releases their bond
energy.
- Simplest form of food is formed with the process of
digestion (Glucose)
C6H12O6 + 6O2---- 6Co2 + 6H2O+ Energy (ATP)
Is
Respirat
ion same
as
Breathin
g?
Types of Respiration
-Aerobic Respiration
- Presence of oxygen
-Anaerobic Respiration
- Absence of oxygen
• In all cases, the first step is the break-down
of glucose, a six-carbon molecule into a three-
carbon molecule called pyruvate. This process
takes place in the cytoplasm and some energy is
released during this process.
Anaerobic respiration
• Breakdown of food to release energy in absence of oxygen
• Stepwise process
- Glycolysis (1st step)
. Occurs in cytoplasm
. No need of oxygen (common step in aerobic & anaerobic
respiration)
. 1 molecule of glucose (6C)-- 2 molecules of Pyruvate
(3C)
. Total ATP yield 2 ATP molecules
C6H12O6 -------------- 2(C3H3O3) + 2 ATP
- Anaerobic respiration (in yeast)
. Occurs in cytoplasm
. Termed as “Fermentation”
. Pyruvate--- Ethanol (C2H5OH) +Carbon dioxide + Energy
(3 C)
Aerobic respiration
• Breakdown of food to release energy in presence of oxygen
• Stepwise process
- Glycolysis (1st step)
. Occurs in cytoplasm
. No need of oxygen (common step in aerobic & anaerobic
respiration)
. 1 molecule of glucose (6C)-- 2 molecules of Pyruvate
(3C)
. Total ATP yield 2 ATP molecules
C6H12O6 -------------- 2(C3H3O3) + 2 ATP
- Aerobic respiration
. in presence of oxygen
. Occurs in mitochondria
. Pyruvate--- 3 molecules of Carbon dioxide + Water +
Energy
(3carbon molecule)
• The release of energy in this aerobic process is a lot greater
than that in anaerobic process.
Anaerobic respiration
• Anaerobic respiration (in some bacteria, parasitic worms,
human muscle cells)
- Occurs in cytoplasm
- Pyruvate--- Lactic acid + Energy
(3-carbon molecule) (3-carbon molecule)
- Overall, 2 Molecules of ATP are produced.
Note- During exercise humans produce energy anaerobically,
which also produces lactic acid in our body which gets
accumulated in our muscles, hence we feel pain in muscles.
Different pathways of glucose breakdown to
release energy
Aerobic vs Anaerobic
respiration
Where do we use the energy released in
Respiration?
• Allowing endothermic chemical reactions to take place
inside body.
• Growth & repair of cells.
• Maintain body temperature for warm blooded animals like
mammals & birds.
• Message transfer through nerves.
• Muscle movements during vigorous exercise.
Respiration in Plants
• Gaseous exchange takes place through Diffusion.
• Gases exchanged: O2 & CO2
• Diffusion takes place through:
- stomata
-small pores present on the leaves
- Lenticels
- Porous tissues present in plants(having large
intercellular spaces)
- Root hairs
- Hair- like branches of roots having direct
contact with the soil to diffuse O 2 from soil.
Respiration in plants: Direction of Diffusion
The direction of diffusion depends upon:
- Environmental conditions (day or night)
- requirements of the plant
Day time Night time
• Photosynthesis: • Respiration:
6CO2 + 12H2O--------> C6H12O6 + C6H12O6 + 6O2------ 6CO2 + 6H2O + 36 ATP
6O2 + Energy Carbon di oxide released is a major
Oxygen released is a major event event in night time.
in day time.
Respiration in Plants
- During night, CO2 diffuses out from the plants to the
environment.
- During day, O2 diffuses out from the plants to the
environment.
- Exchange of gases between plants & environment occur
through stomata, lenticels & root hairs.
- Internal transport of O2 & CO2 occurs through the
intercellular spaces in plant tissues.
- Food breakdown is not seen in plants unlike animals
as plants prepare their food in the simplest form
(Glucose) already.
Respiration in animals
• Aquatic animals:
- Fishes have gills for absorption of dissolved oxygen.
- Oxygen is present in water in less amount compared to air.
- Rate of breathing of aquatic animals is higher than the
terrestrial ones.
• Terrestrial animals:
- Terrestrial organisms use the oxygen in the atmosphere for
respiration.
- Specialized organs for oxygen absorption are present in many,
like: Lungs.
- Unicellular organisms perform gaseous exchange through their
surface is called Respiratory surface, like Amoeba, Paramecium.
Respiratory surface should be thin to provide maximum gaseous
exchange and the surface should be exposed to air.
- Insects have tube-like structures to perform gaseous exchange
called tracheal system.
- In many amphibians gaseous exchange takes place either through
skin or lungs.
Respiration in Human beings
• Respiratory system consists of :
- Nostrils
- Nasal cavity
- Pharynx
- Trachea
- Lungs
- Bronchi
- Bronchioles
- Alveoli
Respiration system: Nostrils &
nasal cavity
- Nostrils
- Openings through which air is taken in.
- Fine hairs present filters the air taken in.
- Nasal cavity
- Central septum separates the left & right air
passages dividing the two nostrils.
- Nasal passages are lined with ciliated epithelium &
mucus. Mucus helps in blocking the germs, dust
particles, microbes etc.
- Air enters through nostrils, get warmed & moistened
at nasal cavity.
Respiration system: Pharynx
and Epiglottis
Pharynx
- Common passage for food & air
- Food goes to oesophagus
- Air goes to Trachea.
Epiglottis
- Small flap of skin
- Prevents food from entering respiratory tract
Respiration system: Trachea
- Trachea
- Wind pipe
- C shaped rings of cartilage present,
cartilage gives a strengthened tube-like
structure to trachea.
- Internally lined by cilia & mucus
- Runs from throat till thoracic cavity
Respiration system: Lungs
- Lungs
- Spongy, elastic organs
- Located in thoracic cavity
- Right lung: 3 lobes
- Left lung: 2 lobes
- Enclosed by a 2-layered membrane, called Pleura,
it lubricates the both layers & reduces the friction
between 2 layers.
Respiration system: Bronchi
-Bronchi
- Trachea divides into thinner tubes
called Bronchi as it enters thoracic cavity
- Left bronchus divides into 2 bronchi
- Right bronchus divides into 3 bronchi
Respiration system:
Bronchioles & Alveoli
- Each bronchus further divides into finer branches
called Bronchioles.
- Each bronchus ends in cluster of tiny air chambers
called Alveoli.
- Alveoli provide a surface where the exchange of gases
can take place.
- Walls of alveoli contain an extensive network of blood-
vessels (capillaries).
- Alveoli are called as the functional units of lungs.
Respiratory system: Quick
recap
Air-- Nostrils---Nasal cavity--Pharynx---Trachea--
Bronchi--- Bronchioles---- Alveoli----
Capillaries---- Rest of the body
Rest of the body Capillaries---- Alveoli----
Bronchioles---- Bronchi--- Trachea-- Pharynx---
Nasal cavity-- Nostrils--- Air--
Breathing: The physical
process
- Inhalation
- Taken in good air
- Diaphragm muscles contract due to its muscular structure
- Diaphragm is pulled down
- Thoracic cavity expands
- Lungs expand
- Air pressure inside decreases due to increase of volume
- Hence the movement of air takes place from outside to inside
our body
- Exhalation
- Releasing out foul air
- Diaphragm muscles expand
- Diaphragm is pulled up
- Thoracic cavity contracts
- Lungs contract
- Air pressure inside increases due to decrease of volume
Hence the movement of air takes place from inside to outside of
Respiration: Overview
• Air (inside)-- Nostrils---Nasal cavity--Pharynx---
Trachea--Bronchi--- Bronchioles---- Alveoli----
Capillaries--- Blood-- Tissues--- Cells (O2) --
(Oxidation)
Aerobic respiration
Glucose + O2-- Co2 + H2O + Energy
• (Co2) Tissues-- Blood-- Capillaries--- Alveoli----
Bronchioles---- Bronchi--- Trachea-- Pharynx--- Nasal
cavity-- Nostrils--- Air (outside)
