Nervous system: sensory function vision and olfaction Flashcards
what are the 5 special senses?
- olfaction
- gustation (taste)
- vision
- hearing
- equilibrium
where are the olfactory neurons located?
offactory epithelium = roof of nasal cavity
what happens when you sniff?
swirling air currents created by nasal conchae of ethmoid bone when you sniff
what layer do odor molecules dissolve?
mucus layer
what do the odor molecules bind to?
bind to chemoreceptors on cillia of olfactory neurons which leads to depolarization
what happens after depolarization of odor molecules?
mitral cells integrate input and convey to olfactory nerve which leads to temporal lobe, frontal lobe, amygdala, and hypothalamus
what membrane covers the inner surface of the eyelid and outer surface of the eye
mucous membrane the conjunctiva which protects/moistens
what does the fibrous tunic consist of?
sclera=white of eye
cornea= transparent covering continuous with sclera which bends light rays
cornea is avascular and is easily transplanted
what is the vascular tunic (uvea)consist of?
choroid= contains extensive capillary network
isis= pigmented c.t smooth muscle here constricts/dilates pupil
ciliary body= ring of smooth muscle anchored to lens by suspensory ligaments
functions of ciliary body?
changes shape of lens to focus: lens become more rounded when ciliary muscle contracts: secretes aqueous humor
what does the neural tunic consist of?
retina= contains bipolar sensory
photoreceptors= rods+cones
Macula= highest concentration of cones
fovea= area within macula where vision is sharpest images are focused here when you directly look at an object
optic disc= blind spot where optic nerve emerges has no photoreceptors
what are the two cavities of the eye?
anterior cavity and posterior cavity
what does the anterior chamber consist of?
anterior chamber and posterior chamber
aqueous humor
what is aqueous humor?
secreted by ciliary body and is recycled into blood via scleral venous sinus
what does the posterior cavity consist of?
vitreous humor/body which is gelatinous which stabilizes the eye shape and supports the retina
what is the function of the lens?
to focus an image on the retina
how does the lens focus the image on the retina?
accommodation (changing the shape off the lens by contraction of smooth muscle in ciliary body )
lens made of special fibres called lens fibres
how does the shape of the eye corelate to how we see?
lens becomes more rounded to focus on near objects
lens is convev in shape bends the light rays to converge at focal point (focuses image on retina)
what do lens fibres contain?
transparent proteins called crystallins
what does the cornea do?
bend light rays to focus image on retina
what does the anterior cavity contain?
fluid called aqueous humor
what is the suspensory ligaments?
attaches ciliary muscles to the lens
what is the iris
contains melanin which is coloured part of eye
what is the posterior cavity?
contains jelly-like vitreous body
what is the ciliary body?
smooth muscles here contracts to make lens more rounded
what is the cornea?
transparent part of the fibrous tunic
what is the sclera?
white part of the eye
what is the optic disc?
part of the retina which contains no photoreceptors
what is the retina?
contains photoreceptors rods and cones and sensory neurons
what is the fovea?
highest concentration of cones in the eye
what are the extraocular muscles?
moves the eye in the orbit of the skull
what is the choroid?
part of vascular tunic that supplies retina with oxygen and nutrients
where are photoreceptors found?
rods and cones
what types of light detection do rods and cones let in?
rods= dim light
cones= bright light and colours
how do cones respond differently?
respond to different wavelengths and colours of light
blue cones
red cones
and green cones
where are cones concentrated?
fovea which lies in neural tunic
how does the fovea help us see?
when you look directly at something it is projected onto the fovea and you see colours and detail most clearly
what do rods and cones contain?
photopigments
what are photopigments?
pigments in photoreceptors that absorb light energy
what are the two photopigments?
rhodopsin= in rods
iodpsin= in cones
what does rhodopsin contain?
contains protein apsin and molecule retinal made from vitamin A
what does retinol do?
absorbs light energy and changes shape from cis-retinal to trans-retinal
what does opsin do?
activates a g protein transducen
what does the activated transducen activate?
activates a second messenger which causes na channels to close stopping the release of the neurotransmitter
what do the photoreceptors synapse with?
synpase with bipolar sensory neuron in the retina
what is the neurotransmitter at synapse?
it is glutamate and it is inhibitory