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Coordination and Irritability

Osmoreceptors Proprioceptors
They detect the changes in osmotic These are internal sensory receptors that
pressure. The osmoreceptors are primarily monitor the degree of stretch of muscles and
found in the hypothalamus and kidney of tendons around the body. This information
most homoeothermic organisms. They gives an individual a sense of balance and
contribute to regulate fluid balance in awareness of the position of various parts of
FOR ONLINE READING ONLY
the body (osmoregulation) and modulate the body in relation to each other (Figure 4.26).
osmolarity in the kidney.

Electroreceptors
Electroreceptors detect natural electrical
stimuli. They are almost found in aquatic
or amphibious animals because salt water Motor
neurons
is a better conductor of electricity than air. Sensory neurons
The ampullae of Lorenzini found in sharks
are an example of electroreceptors. Some
terrestrial organisms such as arachnids, Muscle
cockroaches and bees are known to have Muscle spindle
electroreceptors. Tendon

Classification of sensory receptors
based on the location of the stimuli
they detect Figure 4.26: Structure of the proprioceptors
Based on the location of stimulus they
detect in the environment, there are three 4.2.2 Mammalian eye
types of receptors. These are interoceptors, Task 4.6
exteroceptors, and proprioceptors. Search for information from the library

Interoceptors and internet sources on the structure of
These receptors detect stimulus that retina including the structural differences
between rods and cones. Write short notes
originates from the inside of the body;
especially from internal organs and the on the searched information.
gut. For example, stomach pain stimulus is The eye is a sense organ which receives
detected by pain receptor (nociceptor) and light of various wavelengths, reflected from
blood pressure change stimulus is detected objects at varying distances in the visual
by pressure receptor (baroreceptor). field and converts it into electrical impulses

Exteroceptors (Figure 4.27). Optic nerves transmit these
These are receptors that detect external impulses to the brain where an image of
remarkable precision is perceived. The
stimuli such as light, temperature, principal functions of the eye include:
olfactory and tactile. For example, the controlling the amount of light entering it,
skin thermoreceptors detect temperature focusing images from the external world
changes of the external environment. by means of a lens system, and processing
Ear, eye and nose also detect stimuli that the captured image into a pattern that can
originate from external environment. be seen.

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