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Sensory Receptors & Anatomy of the Eye (Sensory Receptors (based on…
Sensory Receptors & Anatomy of the Eye
Sensory Receptors
structures sensitive to stimuli from their surroundings & sends signal on to CNS via an axon of a neuron
free nerve endings
specialized sensory cells
based on stimulus origin
Exteroceptors
sensitive to stimuli from environment
located in skin & special senses
Interoceptors
sensitive to stimuli from internal organs
Proprioceptors
sensitive to stimuli from muscles, tendons, ligaments, & joints
sensitive to stretching
helps coordinate movement
based on type of stimulus
Thermoreceptor
sensitive to temperature
different sensors for warm & cold
Photoreceptor
sensitive to light
Chemoreceptor
sensitive to chemicals
especially in smell, taste, & blood vessels
Nociceptor
sensitive to pain
Mechanoreceptor
sensitive to touch, pressure, vibrations, & stretching
Baroreceptor
measures blood pressure
General sense receptor
wide spread throughout the body
sensitive to touch
Special sense receptor
located in the head
sensitive to smell, taste, hearing, sight, & equilibrium
Gross & Microscopic Anatomy of the Eye
3 tunics (layers) of the eye
Fibrous layer
helps focus light on retina
allows light in
includes sclera
whites of eye
dense regular connective tissue
protective
anchor for extrinsic eye muscles
gives shape
includes cornea
Vascular layer
nourishes other layers around it especially the retina
has blood vessels
black in color
absorbs light & prevents it from scattering
includes choroid
includes lens & ciliary body
continuous with choroid
smooth muscle
changes shape of lens to focus on distant/near objects
Inner layer
tan in color
very thin
includes retina
location of photoreceptors in axons of retina
rods
most abundant
sensitive to light
cones
sensitive to color
converges to form optic nerve
Function and location of specific pieces of eye
Lens
focuses light on retina
Iris
anterior to lens
colored part of eye
smooth muscle/sphinctor
includes pupil
hole in center of iris
dilates/constricts pupil to allow more/less light to enter eye
Optic disc
has no photoreceptors
blind spot
Macula lutea
posterior pole
Fovea centralis
center of macula lutea
only has cones
light focused here is the clearest vision
Cavities/Segments of the eye
Posterior segment
filled with vitreous humor
viscous (thick) liquid
clear/transparent
supports retina & lens
maintains pressure in eye
Anterior segment
filled with aqueous humor
watery liquid
maintains pressure in eye
nourishes lens & cornea
lens & cornea are avascular
from posterior segment to cornea
anterior chamber
from cornea to iris
posterior chamber
from iris to lens