pigmented portion of the eye that has muscles that control pupil size.
What is the pupillary dilator muscle and what is its function?
it increases the size of the pupil, (radial muscle) to allow more light in (dark room, sympathetic stimulation)
What is the pupillary constrictor muscle and what is its function?
it decreases the size of the pupil in a bright room (parasympathetic) (anular muscle)
What order would aqueous humor flow after being secreted by the ciliary body?
1. ciliary body
2. posterior chamber
4. anterior chamber
5. absorbed at the canal of Schlem
What maintains the intraocular pressure?
the constant secretion and reabsorption of aqueous humor
increase of intraocular pressure
the formation of functional microvascular networks with red blood cell perfusion
layer of cells that absorb photons of light that photoreceptors cannot absorb (that we don't see)
(prevents vision echoes)
has 3 sub layers of cells
1. photoreceptors=absorb photons in visible spectrum (the ones we see)
2. bipolar cells=1st order neurons
3. ganglion cells=axons exit the eye at the optic disc / nerve
is damage to the eyes retina caused by complications of diabetes mellitus, which can eventually lead to blindness
spot on the retina that contains the highest density (concentration) of photoreceptors
spot on the retina where all ganglion cell axons exit the eye to the optic nerve it contains 0 (zero) photoreceptors
fibers that make up the lens of the eye, very elastic
are proteins that are clear, refracts light, magnify things
a change in the direction of a ray of light as it passes from one medium to another (bending of light)
What are the four refractive media of the eye?
2. aqueous humor
4. vitreous humor
the lens loses its transparency of the cornea or lens
a change in the shape of the lens to focus light on the retina
abnormal curvature of the lens or cornea
normal vision 20/20
being far sighted due to a loss of elasticity of the lens
What are Photoreceptor cells and what do they do?
1. are an elongated outer segments that contain membranous discs with visual pigment (rhodopsin)
2. do black/white vision (night vision)
1. are a tapered outer segments (conical) with membraneous folds that contain visual pigments (Iodopsins)
2. color vision and detail (sharp vision)
What is the process of accommodation?
Viewing a near object
(need lens to be "more round")
1. ciliary muscle contracts
2. suspensory ligaments go slack
3. lens becomes more round
What is the process of accommodation?
Viewing a distant object
(need the lens to be "less round")
1. ciliary muscle relaxes
2. suspensory ligament light
3. lens is more flat
any substance that can hold on to a photon of light and holds on to it or catches it
What is the function of the pigmented epithelium?
absorbs photons that are not absorbed by visual pigments
What are the four visual pigments?
2. Iodopsin I
3. Iodopsin II
4. Iodopsin III
What are Rod and Cones?
photoreceptor cells that are found in the retina of the eye
What are the five steps of a chemical reaction involved in photoreception in a rod?
1. 11-cis-retinal is struck by photons of light and converted 11-trans-retinal. The change in shape of retinal activates an enzyme called Opsin.
2. Activated Opsin then interacts with and activates many Transducin molecules.
3. Activated Transducin molecules then interact with and activate many PDE (Phosphodiesterase) molecules.
4. Activated PDE molecules then breakdown many cyclic guanosine monophosphate(cGMP) molecules.
5. Breakdown of cGMP results in closing of Na+ channels and hyperpolarization of the rod cell. This decreases neurotransmitter release on the bipolar cell which then sends a signal to a ganglion cell that communicates to the brain that we have seen something.
the maze of bone in the inner ear
the fluid between the bony and membranous labyrinth
How is the sense of equilibrium detected?
by hair cells found in the vestibule (vestibular complex)