Special Senses part 1 Flashcards
General senses of touch
Temperature
Pressure
Pain
The Special senses are
Smell
Taste
Sight
Hearing
Equilibrium
70 percent of all sensory receptors are in the
Eyes
How many percent of sensory receptors does the yes have?
70%
Each eye has over a million
Nerve fibers
2 Protection for the eye are
bony orbit & fat cushion
Most of the eye is enclosed in a
bony orbit
A cushion of ____ surrounds most of the eye
fat
a fold of skin that closes over the eye to protect it
Eyelids
protect the eye from debris, dust, and small particles
Eyelashes
modified sebacious glands produce an oily secretion to lubricate the eye
Meibomian glands
The purpose of oily secretions in the eye is to
Lubricate it
modified sweat glands between the
eyelashes
Ciliary glands
A Membrane that lines the eyelids. It Connects to the surface of the eye and secretes mucus to lubricate the eye.
Conjunctiva
4 subparts of the Lacrimal apparatus are
Lacrimal gland
Lacrimal canals
Lacrimal Sac
Nasolacrimal Duct
It produces lacrimal fluid
Lacrimal gland
I drains lacrimal fluid from eyes
Lacrimal canals
It provides passage of lacrimal fluid towards nasal cavity
Lacrimal sac
It empties lacrimal fluid into the nasal cavity
Nasolacrimal duct
lacrimal fluid is composed of
Dilute salt solution (tears)
antibodies
lysozyme
The lacrimal fluid has an __________ property
antibacterial
It Protects, moistens, and lubricates the eye. It also Empties into the nasal cavity
Lacrimal Apparatus
Muscles attach to the outer surface of the eye which Produce eye movements
Extrinsic Eye Muscles
The wall of the eye has three tunics which are
Fibrous tunic
Choroid
Sensory tunic
The outer layer wall of the eye
Fibrous tunic
The middle layer wall of the eye
Choroid layer
The inside layer wall of the eye
Sensory tunic
The two fibrous Tunics are
Sclera
Cornea
A fibrous tunic which is a White connective tissue layer. It is Seen anteriorly as the “white of the eye”
Sclera
Sclera is Seen ___________ as the “white of the eye”
anteriorly
A Transparent, central anterior portion which Allows for light to pass through.
Cornea
It is the only human tissue that can be transplanted without fear of rejection and could also repairs itself easily
Cornea
A Blood-rich nutritive tunic which has
Pigment to prevent light from scattering
Choroid Layer
Choroid Layer has interiorly has 2 structures
Cilliary body
Iris
An interior smooth muscle of the choroid layer
Cilliary body
A Pigmented layer that gives eye color which is a part of the choroid layer
Iris
A rounded opening in the iris
Pupil
Sensory Tunic is also known as
Retina
The receptor cells in the Retina are called
Photoreceptors
The two types of receptor cells in the Retina
Rods
Cones
The Signals pass from photoreceptors via a __________ ________
two-neuron chain
the 2 neurons involved inthe 2-neuron chain are
Bipolar neurons
Ganglion cells
Signals leave the retina toward the brain through the
Optic Nerve
This photoreceptors are Mostly found towards the edges of the retina which Allow dim light vision and peripheral vision. Its Perception is all in gray tones
Rods
It Allow for detailed color vision
Cones
The cones are Densest in the center of the
Retina
An area of the retina with only cones
Fovea centralis
No photoreceptor cells are at the ____ ___ or ______ ____
optic disk, or blind spot
There are three types of cones which are
Red-sensing cones (60 percent)
Green-sensing cones (30 percent)
Blue-sensing cones (10 percent)
is the result of lack of one cone type
Color Blindness
A Biconvex crystal-like structure
that Held in place by a suspensory ligament attached to the ciliary body.
Lens
The 2 Internal Eye Chamber Fluids are
Aqueous humor
Vitreous humor
A Watery fluid found in chamber between the lens and cornea
Aqueous humor
Aqueous humor is Similar to
Blood Plasma
Aqueous humor Helps maintain
Intraocular Pressure (IOP)
Aqueous humor Provides nutrients for the
Lens and Cornea
Aqueous humor can be Reabsorbed into venous blood through the ______ ___ _________
canal of Schlemm
deoxygenated blood that flows from tiny capillary blood vessels within the tissues into progressively larger veins to the right side of the heart.
venous blood
A Gel-like substance behind the lens
ehich Keeps the eye from collapsing. It Lasts a lifetime and is not replaced
Vitreous humor
Light must be focused to a point on the ______ for optimal vision
retina
The eye is set for distance vision of over
20 ft away
It must change shape to focus for closer objects
Lens accomodation
the passageway of light
visual pathway
Too much IOP
Glaucoma
each of the second pair of cranial nerves, transmitting impulses to the brain from the retina at the back of the eye
Optic Nerve
Optic nerve crosses at the
Optic Chiasma
the part of the brain where the optic nerves cross and is therefore of primary importance to the visual pathway.
Optic Chiasma
a bundle of nerve fibers that serves to carry visual information from the optic chiasm to the left and right lateral geniculate bodies as a part of the visual pathway.
Optic tracts
It is where the axons form optic radiation
Thalamus
the primary cortical region of the brain that receives, integrates, and processes visual information relayed from the retinas
Visula cortex
The lobe wherein receives, integrates, and processes visual information
Occipital lobe
Internal muscles are controlled by the
autonomic nervous system
Bright light causes pupils to constrict through action of
radial and ciliary muscles
Viewing close objects causes
accommodation
External muscles control eye movement to
follow objects
Viewing close objects causes ________. It is where the eyes move medially
Convergence
