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Senses by Nicole Hennen Sec 31 (Gross and microscopic anatomy of the eye…
Senses
by Nicole Hennen
Sec 31
Sensory receptors based on stimulus origin
Exterocepters
stimulus from the environment.
Located in skin & some special senses
Interoceptors
stimulus from inside of body
location: internal organs
Proprioceptors
stimulus coming from your muscle or tendons, ligaments &joints
Sensory receptors based on type of stimulus
Thermoreceptor
sensitive to temperature
Cold and warm each have own thermoreceptor
Photoreceptor
sensitive to light
Chemoreceptor
sensitive to chemicals
example smells in the air, tastes
also in blood vessels
Nociceptor
sensitive to pain
Mechanoreceptor
sensitive to pressure, touch, vibration, stretch
Baroreceptor
larger category of mechanoreceptor. Sensitive to blood pressure
Gross and microscopic anatomy of the eye
Tunics of eye
Fibrous layer
Sclera
white outer layer. Dense C.T., protective
anchors for muscles
gives shape
Cornea
transparent, allows light into eye
helps focus light
Vascular layer
choroid
black layer, very pigmented, lots of blood vessels to nourish other tunics especially retina
absorbs light, prevents from scattering
choroid is continuous with the ciliary body-muscle-changes shape of lens
Inner layer
contains photoreceptors
tan in color
very thin and delicate
axons from photoreceptors converge to become optic nerve
Rods
more than cones. sensitive to light; darkness + light
works best in dim light
Cones
for color
works best in bright light
lens
thick, transparent, bioconvex disc
changes shape to allow precise focusing of light on retina
iris
visible, colored part of eye.
contains sphincter and dilator muscles to change size of pupil
optic disc
circular elevation where the axons of ganglion cells converge to exit the eye as the optic never
macula lutea
"yellow spot" at eyes posterior pole
fovea centralis
tiny pit in the macula lutea
contains only cones
provides maximum visual acuity
posterior segment
filled with clear jelly like substance containing collagen and ground substance: vitreous humor
transmits light
supports posterior surface of lens and holds neural retina firmly in place
helps maintain normal pressure within eye
anterior segment
divided into anterior(between cornea and iris) and posterior (between iris and lens) chambers
filled with aqueous humor (clear, fluid similar to blood plasma)