Insect Respiration's outline ....

1. PHYSIOLOGY OF INSECT
RESPIRATION

2. General vs. Insect Respiration
• A process in living
organisms involving the
production of energy,
typically with the intake of
oxygen and the release of
carbon dioxide from the
oxidation of complex
organic substances.
• It is a complex network of
tubes (called a tracheal
system) that delivers
oxygen-containing air to
every cell of the body. Air
enters the insect's body
through valve-like openings
in the exoskeleton.

3. Basics of the Respiratory System
General Functions
• Exchange of gases
• Directionality depends on gradients!
– Atmosphere to blood
– Blood to tissues
• Regulation of pH
– Dependent on rate of CO2 release
• Protection
• Vocalization
• Synthesis

4. Mainly two types of Respiration occur
for Insect
Insect Tracheal Respiration in short
O2 from spiracles --> tracheae --> tracheoles --
> cells
Terrestrial Respiration
Aquatic Respiration

5. Mechanism of respiration
Inspiration:
Air enters the spiracles during inspiration and
comes to the tracheae, then it comes to the
tracheoles which contain fluids, the O2 gets
dissolved in these fluids and reaches the tissue
cells.
Expiration:
In expiration some carbon dioxide may pass out
through the spiracles but the major part of it
diffuses out through the cuticular covering of
the body.

7. Figure Showing Inspiration & Expiration

8. Amount of Oxygen Resting and Active
Tissue in Tracheal Respiration

9. Respiration For Insect
Terrestrial: Open system (siphon, physical gill,
etc.)
Aquatic: Closed tracheal system (gills,
cutaneous) with exceptions

11. MECHANISMS OF GAS EXCHANGE
 Oxygen molecules first enter the insect via the spiracle,
then proceed down the branching tracheae to the
tracheoles
 The terminal tips of the tracheoles are sometimes
fluid-filled, so at this point gas transport may occur in a
liquid medium rather than air
 Diffusion
Diffusion is the passive movement of molecules down
their concentration gradient, driven by random
molecular motions.
The insect tracheal system is capable of high rates of gas
exchange by diffusion

12. Convection
Convection is the bulk movement of a fluid (gas or liquid)
driven by pressure. Differential air pressures can drive
gas movement through the tracheae and spiracles at
much higher rates and over longer distances than
diffusion.
OXYGEN-BINDING PROTEINS AND OXYGEN SENSING
Oxygen-binding pigments such as hemoglobin have been
thought to be unimportant in gas exchange for most
insects, due to the high capacity of tracheal systems.
However, it is becoming apparent that oxygen-binding
pigments are very important for gas exchange in a
variety of insects.

13. Aquatic Insect Respiration
• One problem that aquatic insects must overcome is how to
get oxygen while they are under water. All aquatic insects
have become adapted to their environment with the
specialization of these structures.
• Aquatic adaptations Simple diffusion over a relatively thin
integument
 Temporary use of an air bubble
 Extraction of oxygen from water using a plastron or physical
gill
 Storage of oxygen in hemoglobin molecules in hemolymph
 Taking oxygen from surface via breathing tubes (siphons)

14. Aquatic Insect Respiration Using Deferent type of
Modified Organ