Chapter 8 Flashcards
Special senses include
Smell
Taste
Sight
Hearing
Equilibrium
Special sense receptors
Large, complex sensory organs (eye and ear)
Localized clusters of receptors (taste buds and olfactory epithelium)
70 Percent of all sensory receptors are in
Eyes
How many nerve fibers in each eye?
Over 1 million nerve fibers per eye
Accessory structures in eye
Extrinsic eye muscles
Eyelids
Conjunctiva
Lacrimal apparatus
Extrinsic eye muscles
Eye movement
Conjunctiva
Cover sclera and cornea (connects w/)
Membrane line eyelids & eyeballs
Palpebra
Eyelid
Eyelids meet in
Commisure or canthus
Lateral commissure
Outer corner of eye
Medial commissure of eye
Inner corner of eye
Sclera
White part
Covered by conjunctiva
Iris
Colored part of eye
Cornea
Clear part of sclera
Pupil
Dark part of eye
Photons of light pass
Meets at medial and lateral commisures
Eyelids
Eyelashes
Prevent injury, keep debris out
Tarsal glands
Produce oily secretion that lubricates eye
Mebum
Oily secretion that lubricates eye
Ciliary glands located
Between eyelashes
What secretes mucus to lubricate the eye and keep it moist
Conjunctiva
Parts of Lacrimal apparatus
Lacrimal gland
Ducts
Lacrimal gland
Lacrimal fluid
On lateral end of each eye
Explain how tears drain
- Drain across eye into Lacrimal canaliculi
- Lacrimal sac
- Nasolacrimal duct
- Empties into Nasal cavity
What is inside tears?
Dilute salt solution
Mucus
Antibodies
Lysozyme (enzyme destroys bacteria)
Function of tears
Cleanse
Protect
Moisten
Lubricate eye
Extrinsic eye muscles
Attach to outer surface of the eye
Make gross eye movement
Name the extrinsic muscles of the eye
Superior, inferior oblique
2 Lateral, superior, inferior rectuses
Trochlea
Anchored superior oblique
Lateral rectus action
Moves eye laterally
Controlling cranial nerve of lateral rectus
VI
Abducens
Medial rectus action
Moves eye medially
Medial rectus controlled by
III (oculomotor)
Superior rectus action
Elevates eye
Turns it medially
Superior rectus controlled by
III oculomotor
Inferior rectus action
Depresses eye
Turns it medially
Inferior rectus controlled by
III oculomotor
Inferior oblique action
Elevates eye and turns it laterally
Inferior oblique controlling cranial nerve
III oculomotor
Superior oblique action
Depresses eye & turns laterally
Controlling cranial nerve superior oblique
IV (trochlear)
Tunics of eyeball
Fibrous
Vascular
Sensory
Humors
Fluids that fill inside of eyeball
Give shape
Lens divides eye into
Two chambers
Anterior posterior chambers
Fibrous layer
Outside layer
Sclera
Vascular layer
Middle layer
Sensory layer
Inside layer
Photoreceptors and pigment layer
Outermost fibrous layer of eye
Sclera
Middle layer or eye
Choroid
Vascular
Retina
Innermost layer
Sensory
rods
Cones
Photoreceptors
Focused light directed to
Fovea Centralis
Fovea Centralis
Higher concentration of photoreceptors
More cones
Higher visual acuity
Parts of fibrous layer
Sclera+ cornea
Cornea
Transparent,
Central anterior portion
Lets light pass through
What repairs itself easily?
Cornea
Only human tissue that can be transplanted w/o fear of rejection
Cornea (lack of blood vessels)
Choroid
Blood rich
Nutritive layer
Pigment that prevents light from scattering
Choroid modified anteriorly into two smooth muscle structures known as
Ciliary body
Iris
Ciliary body
Attached to lens by suspensory ligament called ciliary zonule
Iris
Regulates amount of light entering eye
Function of pigmented layer of iris
Gives eye color
Pupil
Rounded opening in iris
Point where light enters into eye from cornea
Pupil
Light passes from cornea to
Lens and after to retina
Layers of retina
Pigmented layer
Inner Neural layer
Inner neural layer
Has rods and cones
Outer pigmented layer
Absorbs light and prevents it from scattering
Sensory layer
Signals pass from photoreceptors via a
Two neuron chain
Two neuron chain made of
Bipolar cells
Ganglion cells
Signals leave retina towards brain through
Optic nerve
Optic disc
Blind spot
Optic nerve leaves eyeball
Cannot see images focused on
Optic disc
Phototransduction
Specialized outer segment of photoreceptors
Capture light and converts into electrical signals
Photoreceptors (rods)
Pick up photons peripheral vision
Cones
visualize visible light. Different colors
Axons of ganglion cells make
optic nerve
Three major types of neurons that make retina
Rods (photoreceptors)
Cones (visible light)
Bipolar cells
Central artery and vein of retina
Rich blood supply to and from eye
Rods found in
Edges of retina
What allows vision in dim light?
Rods
What allows peripheral vision
Rods
Perception is in grey tones
Rods
Where are cones densest ?
Center of retina
Fovea Centralis location
Lateral to blind spot
Area of retina w/ only cones
Fovea Centralis
Highest visual acuity
Fovea Centralis
No ______ are at the optic disc or blind spot
Photoreceptor cells
Allow for detailed color vision
Cones
Point where optic nerve enters and exits eye
Optic disc
Photopsin 1
Red pigments