Processing Our senses make us aware of changes that occur in our surroundings and also within our body. Sensation [awareness of the stimulus] and perception [interpretation of the meaning of the stimulus] occur in the brain. Receptors are classified based on their location: . Exteroceptors are located at or near the surface of the body.
These are sensitive to external stimuli and receive sensory inputs for hearing, vision, touch, taste and smell. . Interoceptors are located in the visceral organs and blood vessels. They are sensitive to internal stimuli.
Proprioceptors are also a kind of interoceptors. They provide information about position and movements Table: . Types of receptors Receptors Stimulus Effector organs Mechano receptors Pressure and vibration Mechano receptors are present in the cochlea of the inner ear and the semi circular canal and utriculus Chemoreceptors Chemicals Taste buds in the tongue and nasal epithelium Thermoreceptors Temperature Skin Photoreceptors Light Rod and cone cells of the retina in the eye XI Std Biology-Zoology Chapter- The conjunctiva is a thin, protective mucous membrane found lining the outer surface of the eyeball (Figure . ).
Lacrimal gland Pupil Sclera Iris Eyelid Superior lacrimal canal Lacrimal sac Lacrimal puncta Inferior lacrimal canal Lacrimal duct Figure. . The human eye The eye has two compartments, the anterior and posterior compartments . The anterior compartment has two chambers, first one lies between the cornea and iris and the second one lies between the iris and lens.
These two chambers are filled with watery fluid called aqueous humor . The posterior compartment lies between the lens and retina and it is filled with a jelly like fluid called vitreous humor that helps to retain the spherical nature of the eye. Eye lens is transparent and biconvex, made up of long columnar epithelial cells called lens fibres . These cells are accumulated with the proteins called crystalline .
The Eye Ball The eye ball is spherical in nature. The anterior one- sixth of the eyeball is exposed; the remaining region is fitted well into the orbit. The wall of the eye ball consists