It deals with the structure and function of sensory organs in organisms. The five sensory of vertebrates, the mechanism of sense reception, kinds of information, the information process and dealt in brief. It may be useful for the post graduate students studying animal physiology as their core paper.

1. ANIMAL PHYSIOLOGY
SENSE AND INFORMATION
part-1
Dr. Nagabhushan Charantimath Ph.D
Asst. Professor,
VSK University, Ballari, India.
nagabhushancm@vskub.ac.in
1

2. how
• How animals obtain INFORMATION from the
surroundings.
1. What kind of information is available?
2. How the information is processed and passed to
the CNS?
3. How the information is used for controlled and
integrated physiological functioning.?
2
Dr. Nagbhushan CM

3. the way
• Virtually all the animals depend on
INFORMATION from the nature / surroundings
for finding the MATES, ESCAPE from predators.
• It is obtained through SPECIALIZED SENSES.
3
Dr. Nagbhushan CM

4. classification
• SENSE ORGANs receiving information from
externals are EXTEROCEPTORS, and from
internals are PROPRIOCEPTORS.
• Traditional classification is based on senses:
1. Sense of vision (sight)
2. Sense of hearing (auditary)
3. Sense of smell (olfactory)
4. Sense of taste (gustatory)
5. Sense of touch (thigmatic)
4
Dr. Nagbhushan CM

5. Source of information/ sensory
perception
1. Electromagnetic and thermal energy
2. Mechanical energy and force
3. Chemical agents.
5
Dr. Nagbhushan CM

6. Details (environment stimuli
significant in sensory perception)
1. Electromagnetic and thermal energy:
1. LIGHT 2. IR 3. HEAT / COLD
4. ELECTRIC 5. MAGNETIC.
2. Mechanical energy and force:
1. SOUND AND SONAR 2. TOUCH AND VIBRATION
3. PRESSURE 4. GRAVITY 5. INERTIA
3. Chemical agents:
1. TASTE 2. SMELL 3. HUMIDITY
Dr. Nagbhushan CM
6

7. the right way
• Nerve impulses carried in the different sensory
nerves are all of the same fundamental nature.
• Sensory neurons are the TRANSDUCERS ( a device
that translates one form of energy to another) that
receive the STIMULUS and ENCODES as impulses
in the sensory nerves. Later in the CNS nerve
signals are again DECODED and the pertinent
information is integrated and utilized.
Dr. Nagbhushan CM
7

8. Sequence of events in light perception
1 • Stimulus (light)
2 • Accessory structures (eye)
3 • Sensory neuron (retina)
4 • Nerve transmission (optic nerve)
5
• Central nervous system (visual cortex-brain)
6 • Storage as memory / motor response
Dr. Nagbhushan CM
8

9. vision
• It is the DIRECTIONAL SENSE OF VISION to
majority of animals.
• As the light rays travel in a straight line.
• THERE ARE 3 WAYS TO OBTAIN DIRECTIONAL
INFORMATION:
1. Bipolar neuron (receives and sends signals)
2. Comparing the similar senses received from a
pair of sense organs.
3. Signals can be compared in space and time.
Dr. Nagbhushan CM
9

10. vision
• Information about the DISTANCE is more
difficult and the superior organ is EYE.
• With the aid of two eyes and the differences
in the images received, DISTANCE CAN BE
EVALUATED (binocular vision).
Dr. Nagbhushan CM
10

11. Light and vision
• Information obtained with the aid of light
depends on differences in INTENSITY,
WAVELENGTH / COLOUR, PLANE OF
POLARIZATION can give highly precise
information.
• Transmission of light is 3 x 106 kmps, the
change in the environment is perceived
spontaneously.
Dr. Nagbhushan CM
11

12. Image formation
• Sensitivity to light is widespread among
organisms.
– Eye spots
– Compound eyes
– Single lens multifaceted vertebrate eyes.
• Man receives light in 380 – 760 nm wavelength
band so as majority of animals including plants.
FOR energy carried by each quantum of radiation
is inversely related to wavelength.
• (longer wavelength rays donot carry required
energy and shorter wavelength rays can destroy
the organic matter of the organisms)
Dr. Nagbhushan CM
12

13. Insect eye
Dr. Nagbhushan CM 13

14. Dr. Nagbhushan CM 14

15. Annelid eye
Dr. Nagbhushan CM
15

16. Mammalian eyes
Dr. Nagbhushan CM
16

17. acknowledgement
• Cephalov
• Slideshare
• Researchgate
• Wikipedia
• Open resource journals
• Animal physiology book by Neilson
• Google.com
17
Dr. Nagbhushan CM

18. End of part - 1
18