Class 10 Biology Windows of Knowledge
Eyes:
The eye is the major sense organ for vision.
Aqueous chamber contains a water-like fluid that provides oxygen and nourishment to the eye tissues.
Vitreous chamber contains a jelly-like substance that helps maintain the eye’s shape.
Iris and pupil regulate the amount of light entering the eye.
Curvature of the cornea and lens helps focus light on the retina.
Retina contains photoreceptors – rod cells for dim light and cone cells for color vision.
Photoreceptors contain visual pigments (rhodopsin in rods and photopsin in cones) that dissociate in the presence of light, leading to the formation of impulses for vision.
Deficiency of Vitamin A leads to night blindness.
Glaucoma is caused by the improper reabsorption of aqueous humor, leading to increased pressure in the eye and potential blindness.
Cataract is the opacity of the lens, which can be corrected through surgery.
Conjunctivitis is an infection of the conjunctiva that can be prevented through personal hygiene.
Ear:
The ear serves both hearing and maintaining balance.
The pinna carries sound waves to the auditory canal.
The tympanum is a thin circular membrane that vibrates with sound waves.
Ear ossicles amplify and transmit vibrations to the internal ear.
The Eustachian tube balances pressure on either side of the tympanum.
The internal ear has membranous labyrinths filled with endolymph and perilymph fluids.
Semicircular canals and vestibule maintain body balance, while the cochlea is responsible for hearing.
Sensory hair cells in the Organ of Corti of the cochlea act as auditory receptors, detecting sound waves.
Hearing is enabled through the transmission of impulses from the auditory nerve to the cerebrum.
Movements of the head cause the movement of endolymph, generating impulses to maintain body balance.
Chemoreceptors for Taste:
Taste is detected by chemoreceptors present on the surface of the tongue in taste buds.
Taste buds are stimulated by different tastes: sweet, salt, sour, bitter, and umami.
Substances responsible for taste dissolve in saliva, stimulating chemoreceptors and generating impulses.
Impulses reach the brain through respective nerves, allowing us to experience taste.
