Nervous System, Includes Eye Flashcards
what does the CNS consist of
brain and spinal chord
what does the PNS consist of
sensory and motor neurons
steps in responding to a stimulus
1.receptors detect a stimulus
2.the impulse is sent along the sensory neuron to the spinal chord
3.the CNS integrates the information and, if necessary, sends it to the brain for processing prior to initiating a response
4.the impulse is sent from the CNS along the motor neurons to the effector
5.the effector generates the response
what do sensory neurons do in the PNS
they conduct impulses from sensory receptors in the skin and other locations
what do motor neurons do in the PNS
they cause muscles to contract, and other organs to function. They transmit impulses from the CNS to the muscles and other organs
what do the interneurons do in the CNS
transmit impulses between sensory and motor neurons within the brain or spinal chord
what do chemoreceptors do
detect the presence of chemicals
what do thermoreceptors do
detect changes in the temperature
what do mechanoreceptors do
detect mechanical changes in the environment
what do photoreceptors do
detect the presence of light
auditory receptors (mechanoreceptors)
hair cells in the inner ear vibrate according to the pitch and volume of sounds. they send impulses via the auditory nerve to the brain for processing
gustatory receptors (chemoreceptors)
the tongues of many animals are covered with papillae which contain taste buds.
visual receptors (photoreceptors)
photoreceptors in the retinal layer of the eye respond to light
somatosensory (mechanoreceptors)
skin contains a variety of receptors which respond to temperature, touch or pressure
olfactory(chemoreceptors)
receptors in the nasal cavity respond to odour molecules in the air
description of the eyelid
fold of skin which covers the eye
function of the eyelid
cleaning and protecting the eye
description of the cornea
transparent covering on the eye
function of the cornea
protecting the eye, helping bend light rays that enter the eye
description of the sclera
white part of the eye made of tough collagen fibres
function of the sclera
providing protection and support
description of the retina
layer of light-sensitive cells at the back of the eye
function of the retina
detecting light rays
description of the choroid
layer of blood vessels with a black pigment
function of the choroid
nourishing the eye and absorbing the light
description of the iris
ring of muscles around the pupil, coloured which provides eye colour
function of the iris
controls the amount of light entering the eye
description of the lens
transparent, flexible and can change shape due to the ciliary muscles
function of the lens
focusing the light onto the retina and focuses on objects
description of the pupil
hole in the middle of the iris
function of the pupil
allowing light to enter the eye
description of the ciliary body
attached to the underside of the lens
function of the ciliary body
producing aqueous humour and helping with focusing by altering the shape of the lens
where is the aqueous humour found
found behind the cornea
function of the aqueous humour
helping to keep its rounded shape, providing nutrients to the cornea and lens
where is the vitreous humour found
behind the lens
function of the vitreous humour
gives the eyeball its shape
where is the lateral rectus muscles found
on the lateral side of the eye
function of the lateral rectus muscle
helping orientate the pupil away from the centre of the body
where is the medial rectus muscle found
on the medial side of the eye
function of the medial rectus muscle
helping orientate the pupil towards the centre of the body
description of the optic disc
blind spot where there are no photoreceptors
function of the optic disc
where the optic nerves leave the eye
description of the optic nerve
bundle of fibres
function of the optic nerve
relaying information from the retina and fovea to the brain
description of the fovea
spot located ion the macula, which has a high density of cone cells
function of the fovea
gives sharp central vision, light is focused onto this spot by the lens