Health and Social Care Unit 4 LO6

The structure of the eye and ear

The eye

• Pupil is the opening in the middle of the eye through which light passes.
• Iris is the visible coloured ring at the front of the eye. It adjusts to control the amount of light entering the eye through the pupil.
• Tear glands (lacrimal glands) produce tears to clean and lubricate the front of the eye. The fluid contains salt and has natural antiseptic properties to defend against infection.
• Aqueous and vitreous humours (or fluids) are the watery, jelly-like fluids that fill the eye. They keep the eye in shape and nourish it.
• Conjunctiva is a thin membrane that protects the cornea.
• Cornea is at the front of the eye and is transparent: light rays pass through the cornea to the retina.
• Retina is the inner lining of the eye: it contains light-sensitive cells called rods and cones.
• Macula has a very high concentration of photoreceptor cells; these detect light and send signals to the brain, which interprets them as images.
• Optic nerve is where the nerve cells exit the eye. There are no rods or cones there and so this is called the 'blind spot'.
• Ciliary muscle enables the lens to change shape for focusing. It contracts to stretch the lens, making it flatter and thinner.
• Suspensory ligaments attach the lens to the ciliary muscle.
• Lens focuses light entering the eye.

The ear

• Eardrum (or tympanic membrane) is a thin layer of tissue that receives sound vibrations and transmits them to the middle ear cavity.
• Stapes/incus/malous ear bones (also known as stirrup, anvil and hammer) are small bones that amplify the sound waves and transmit the vibrations across the middle car to the cochlea.
• Cochlea contains a jelly-like fluid in a coiled tube that resembles a snail's shell. Vibrations pass though the fluid and are converted to…