Special Senses Flashcards
What are the functions of the ear
The ears are responsible for hearing and balance
What are the structures in the outer ear
The auricle collects sound waves from the atmosphere
The auditory meatus is the ear canal that delivers sound waves to the skull and ear drum. It contains ceruminous glands which produce earwax
What is the function of earwax
Earwax is an antimicrobial substance that protects against infection. More is produced in pregnancy and the use of cotton buds can compact it and cause hearing deficiency.
What are the structures of the middle ear
The middle ear is an air filled drum connected to the throat by the eustachian tube which ensures air pressure is the same on both sides of the drum. However is can be infected by bacterial throat infections.
Eardrum vibrates and carries waves through the malleus, incus and stapes bones to the inner ear.
What are the structures of the inner ear
The cochlea contains hair cells which detect sound waves and relay them along the auditory nerve to the brain.
The semi circular canals are fluid filled canals containing hair cells responsible for the sense of equilibrium (balance)
How are hair cells associated with deafness
Hair cells are very fragile and can be snapped off due to loud noises
What are the accessory structures to the eye
Eyelashes bat away dust and debris
Eyebrows are used in facial expression and direct sweat from the eye
Eyelids are used for blinking and keeping the eye moist by distributing tears from lacrimal glands
What is the conjunctiva
The conjunctiva is the thin protective membrane over the eye which can become infected cause cause conjunctivitis. Babies exposed to chlamydia during labour can have chlamydial conjunctivitis.
What are the two chambers of the eye
The anterior chamber is filled with watery aqueous humour
The posterior chamber is filled with jelly like vitreous humour
What is the cornea
The cornea is the front transparent part of the eyeball that allows light to enter and begins to focus it
What is the iris
The iris is the ring of smooth muscle that colours and controls how much light enters the eye.
What is the lens
The lens is behind the iris and focuses light onto the retina
What are the layers of the eye
The sclera is the tough protective white layer
The choroid is the black layer behind the sclera that stops light reflection in the eye
The retina is the photosensitive part that focuses images
What are the two types of cell in the retina
Rods detect light in low light vision where colour is hard to see
Cones are found in the fovea in high numbers and are responsible for coloured vision. Can be red, green or blue.
How does vision work
Rods and cones generate action potentials
These leave through the optic nerves
They then relay information to the visual cortex in the occipital lobes
There they decode information into a recognisable picture
