The senses Flashcards
All sense organs contain what ?
Receptor cells
A receptor
A cell that can detect a stimulus
A stimulus
Any change in your environment
Eyelids
Protects eye blinking squeezes tears over surface of the eye
Conjunctiva
Transparent lining on inside of eye lids that also travel across the cornea to protect it
Sclera
White tough part of eye
for attachement if muscles
Holds shape of eye
Cornea
Transparent part of sclera
Bends light for it to focus on retina
Choroid
prevents internal reflection
Brings food and oxygen to cells of eye
Retina
Contains light receptor cells
Two types -
rod for black and white -cone for coloured
Blind spot
Part where the optic nerve leaves the eye
No rods or cones in this area
Optic nerve
Carries impulse from eye to brain
Iris
in dim light iris expands and allows more light in
In bright light the iris contracts and reduces light into eye
Ciliary body
Thickened edge of choroid
Has muscle fibres that control the shape of the lens by pulling on the ligaments that hold it in place
Fovea
Point of most accurate vision
Aqueous humour
water liquid at front of eye
helps maintain shape of the eye
Vitreous humour
maintains shape of eye
Acomodation
Is the ability of the lens to change its shape to form a clear image
(lens changes to convex for close objects)
(lens changes to concave for further objects)
Pinna
Sticks out of from side of head
funnels sound into ear
Eardrum
membrane of skin and fine protein fibres stretched across the inner part of our ear canal
vibrates when sound waves hit it
3 small bones
Hammer, Anvil, Stirrup
amplify sound
Eustachian tube
connects back of throat and ear
Why should air pressure in and outside the eardrum be equal ?
so that the eardrum is free to vibrate
What happens if air pressure outside eardrum drops ?
eardrum is stretched outwards and cannot vibrate
How do our ears pop?
Eustachian tube opens
How do we hear?
sound travels to eardrum through pinna
eardrum vibrates
hammer anvil and stirrup vibrate this amplifies sound
stirrup pushes on oval window of cochlea
liquid is moved by oval
hairs on receptor cells detect movement and send a signal to brain along the auditory nerve
brain interprets sound
How does the ear balance?
The three semicircular canals are filled with fluid
head movement detected by nerves in these canals notifies brain
brain sends message to cerebellum which triggers reflex action in our muscles
