General Science Quiz: Sense Organs: Eye, Ear, Nose, Tongue and Skin

The iris is the coloured ring in front of the lens, formed by the front part of the choroid, and the muscles in it widen or narrow the pupil so that the right amount of light reaches the retina; in dim light the pupil opens wide and in bright light…

Gustatory receptors are the receptors of taste, and they lie in the taste buds of the tongue, which sit mostly on small projections called papillae; they are stimulated by chemicals dissolved in saliva and send impulses to the brain.

The stapes, also called the stirrup because of its shape, lies in the middle ear and is the smallest bone in the human body; it passes the vibration received from the eardrum on to the oval window of the inner ear.

The three semicircular canals of the inner ear are set at right angles to one another and are filled with fluid; movement of the head moves the fluid, which stimulates the receptors and tells the brain about the position and motion of the head, so that balance or equilibrium is…

The retina is the innermost coat of the eyeball and it carries the photoreceptor cells, the rods and the cones, which convert light into nerve impulses that the optic nerve carries to the brain; the image formed on the retina is real and inverted, and the brain interprets it as…

Rhodopsin, also called visual purple, is the pigment of the rod cells; it is extremely sensitive to light, which is why rods allow us to see in dim light, though only in shades of black and white.

In myopia the eyeball is too long or the lens too strongly curved, so light from a distant object is brought to a focus in front of the retina and the distant object appears blurred.

The blind spot, also called the optic disc, is the small area of the retina from which the fibres of the optic nerve pass out of the eyeball; it has neither rods nor cones, so an image falling on it is not registered and we do not notice the gap…

The Eustachian tube, also called the auditory tube, runs from the cavity of the middle ear to the nasopharynx, the upper part of the throat behind the nose, and its function is to keep the air pressure on the inner side of the eardrum equal to the pressure outside.

Rhodopsin, the pigment of the rod cells that makes vision in dim light possible, is formed from a derivative of vitamin A, so when the vitamin is lacking the rods cannot work properly and the person is unable to see in faint light, a condition called night blindness or nyctalopia…

The skin is the largest organ of the human body by both surface area and weight, and it is the organ of touch; it is made of an outer epidermis and an inner dermis that carries blood vessels, nerve endings, hair follicles, sweat glands and sebaceous glands.