Sensory systems Flashcards
What is the pupil?
It is the opening in the middle of the eye which is often black. Light passes through this
What is the iris?
the visible coloured ring at the front of the eye
Why does the iris adjust?
To control the amount of light entering the eye through the pupil
What are tear glands?
AKA lacrimal glands
produce tears to clean and lubricate the front of the eye
What does the fluid found in tear glands contain?
Salt and natural antiseptic properties which defend against infection
What are aqueous and vitreous humours (fluids)?
Watery, jelly like fluids that fill the eye.
What do aqueous and vitreous humours do?
They keep the eye in shape and nourish it
What is the conjunctiva?
A thin membrane that protects the cornea
What is the cornea?
A transparent film through which light rays pass into the retina of the eye.
Where is the cornea found ?
At the front of the eye
What is the retina?
The inner lining of the eye which contains light sensitive cells called rods and cones
macula
Has a very high concentration of photoreceptor cells
What do macula detect?
It detects light and sends signals to the brain which interprets them as images.
What is the optic nerve?
It is where the nerve cells exit the eye.
Why is the optic nerve known as the blind spot?
Because there are no rods or cones
What is the ciliary muscle?
A muscle that enables the lens to change shape for focusing
How does the cilliary muscle stretch the lens?
By contracting
By contracting, what does the ciliary muscle become?
Flatter and thinner
What do suspensory ligaments do?
Attach the lens to the ciliary muscle
What does the lens do?
It focuses the light entering the eye
What is the eardrum known as?
tympanic membrane
What is the eardrum and what does it do?
It’s a thin layer of tissue that receives sound vibrations and transmits them to the middle ear cavity
What are the following also known as?
Stapes
incus
malleus ear bones
stirrup
anvil
hammer
What are the stapes incus and malleus ear bones?
Small bones
What do the stapes incus and malleus ear bones do?
Amplify sound waves and transmit the vibrations across the middle of the ear to the cochlea
What is the cochlea?
Coiled tube that contains jelly like fluid. Vibrations pass through the fluid and are converted to neural messages. The vibrations are then passed on to the brain via the auditory nerve.
Where is the organ of Corti located?
In the cochlea
What is the organ of Corti sometimes called and why?
Sometimes called the body’s microphone and is lined with rows of hairs that convert sound vibrations into nerve impulses
What is the Eustachian Tube?
A tube that connects the middle of the ear to the throat
What is the Eustachian Tube’s role?
It ensures that the pressure in the middle of the ear is equal to that outside of thee ear
What is the round window?
A drum like membrane
What happens to the vibrations from the oval window?
Vibrations pass through the round window to the cochlea
What is the auditory nerve?
It is a bundle of nerve fibres
What is the role of the auditory nerve?
It carries hearing information between the cochlea and the brain
What are semi-circular canals and ampullae?
They are tiny fluid filled tubes in the inner ear that help with balance
What are the semi-circular canals and ampullae lined with and what do these act as?
They are lined with cilia. The movements of these cilia are communicated to the brain. As they do this they act as a motion sensor allowing you to keep your balance.
What do semi-circular canals and ampullae have nothing to do with?
Hearing
Name four malfunctions of the eye…
Glaucoma
Age related macular degeneration
Cataracts
Retinopathy
Name the three different types of hearing loss….
Gradual hearing loss
Conductive hearing loss
Sensorineural hearing loss
What is glaucoma caused by?
A build up of pressure in the eye when fluid from the aqueous humour is unable to drain properly.
What does a build up of pressure in the eye lead to?
Damage to an optic nerve
What can increase the risk of getting glaucoma?
Age - more common as you get older
Ethnicity - people of African, Caribbean or Asian origin are at higher risk
Family history - more likely to develope it if a parent or sibling has the condition
Other medical conditions like diabetes make you more susceptible to having glaucoma
What is the cause of age related macular degeneration?
Exact cause = unknown however it is linked to... - smoking - high blood pressure - Being overweight - Family history of the condition
What are the possible causes of cataracts?
- Diabetes
- Exposure to ultraviolet light in sunlight
- Taking particular medications like corticosteroids or statins, for a long time
- Smoking and drinking too much alcohol
- A family history of cataracts
What is the possible cause of retinopathy?
It is a complication of diabetes caused by high blood sugar levels which damages the retina.
Even in well controlled diabetes what can cause blood vessels to narrow and leak?
High blood sugar levels
What do high blood levels cause to happen for those with retinopathy?
Damage to the cells in the retina due to the abnormal blood flow that results from a leaky blood vessel.
What can cause gradual hearing loss?
Ageing or exposure to loud noises over many years
What causes conductive hearing loss?
Due to a blockage by earwax or infection because of a build up of fluid or due to a perforated ear drum
Possible to be caused by changes of oestrogen levels in women, in pregnancy or through genetic disposition.
