Eye Ear: Special Sense Organs Flashcards
Name the three tunics of the Eye:
- sclera
- cornea form the outer fibrous tunic
- - the middle vascular layer (or uvea) consists of the choroid, ciliary body and iris - retina forms the inner sensory layer which communicates with the cerebrum through the posterior optic nerve.
What type of tissue makes up the Transparent Conrea
- Consists of an anterior stratified squamous
epithelium on Bowman’s membrane - Inner Endothelium & a thick avascular stroma on Descemet’s membrane .
- What is the Aqueous Humor?
- Where is it Aqueous Humor found?
- What is the Aqueous humor secreted by and into what chambers?
- A transparent, watery fluid similar to plasma-containting low protein concentration.
- Located- Anterior/Posterior chambers of the eye.
- Aqueous humor is secreted by ciliary processes into the posterior chamber, flows through the pupil into the anterior chamber, and is drained by the scleral venous sinus in the limbus .
What types of cells make up the Iris Stroma ?
Melanocytes
What type of muscle makes up the Iris Stroma?
posteriorly has smooth muscle fibers of the sphincter pupillae muscle
What type of Cells form the Dialator Pupillae muscle of the Iris Stroma
Myoepithelial cells form the dilator pupillae muscle .
What type of unique tissue makes Lens ?
Unique avascular tissue composed of long lens fibers.
What type of tissues make up the Lens?
Lens is covered on its anterior side by cuboidal lens epithelium, and surrounded by a thick acellular layer called the lens capsule .
What is the location of the lens and what are its cellular structures?
The lens is suspended behind the iris and its central pupil by the ciliary zonule of fibrillin fibers produced by epithelial cells covering the encircling ciliary body .
What are the two major parts make up the retina and where do both parts derive form?
- Pigmented epithelium (outermost layer) next to the vascular choroid layer
- Thicker neural retina
The retina has the two major parts derived from the embryonic optic cup
What are the Pigmented Epithelium Cells responsible for?
pigmented epithelium:
- absorb scattered light
- form part of a blood-retina barrier
- regenerate 11- cis -retinal
- phagocytose shed discs from rods
- support the rod and cone cells.
What are Rod Cells and what are they responsible for ?
- Rod cells are photoreceptors detecting light intensity with short rod-shaped outer segments
- Found in the outer edges of the Retina used in Peripheral vision
What are Cone Cells and what are they responsible for?
- cone cells are less numerous than Rod cells with conical outer segments
- are receptors for the primary colors (light of different
wavelengths).
Responsible for color vision and function best in relatively bright light.
Rod cells (Rods) are characterized as having what type of memebrane formation and what type of Protein makes up the membrane?
Rods have stacked membrane discs in which the membranes are densely packed with the protein rhodopsin with bound retinal .
What is the process when Photos of light convert Cis to Trans?
- Photons of light convert 11- cis -retinal to all- trans -retinal,
- causing rhodopsin to release the retinal ( bleaching ), and activate the adjacent G protein transducin, which causes a nerve impulse.
What projects from the Hair Cell and what is it surrounded by?
- A bundle of rigid stereocilia and one rigid kinocilium project apically from each hair cell
- are surrounded by endolymph containing a
gel-like matrix with mineralized crystals called otoliths.
What types of effects occur within memebranes with head movement ?
Head movements cause endolymph and the otolithic membrane to move, deforming the rigid apical structures of the hair cells, depolarizing them and producing nerve impulses.
What is the orientation of the Semicircular Ducts?
- Each of the semicircular ducts is oriented 90 degrees from one another
- has a terminal ampulla region with a thickened crista ampullaris containing hair cells that contact a gel-like cupola.
What factors contribute to the Sense of Equilibrium?
Head movements displace endolymph (fluid contained in the membranous labyrinth) and stereocilia of hair cells in the utricle, saccule, and semicircular ducts which together produce signals that contribute to the sense of equilibrium.
Where are the Rod and Cone Layer (RCL) found?
- neural retina
- nearest to the retina pigmented epithelium and near the inner nuclear layer (INL) which contains the cell bodies of these photoreceptors.
Define OPL
What does it contain?
- An outer plexiform layer (OPL)
- contains the photoreceptor’s axons connected in synapses with dendrites of various integrating neurons
whose cell bodies form the (INL) inner nuclear layer.
What causes synapses in the inner plexiform?
Axons from cells in the INL form synapses in the inner plexiform layer (IPL) with neurons of ganglionic layer (GL ), which send axons thrugh the nerve fiber layer (NFL ) to the optic nerve .
What causes synapses in the inner plexiform?
Axons from cells in the INL form synapses in the inner plexiform layer (IPL) with neurons of ganglionic layer (GL ), which send axons thrugh the nerve fiber layer (NFL) to the optic nerve .
What lines the Eyelids?
- Eyelids are lined by conjunctiva
- stratified columnar epithelium with goblet cells, which also covers the anterior part of the sclera and is continuous with the corneal epithelium.
- Lacrimal glands produce what?
2. Where does it drain?
- Lacrimal glands continuously produce the tear film
2. drains into the nasal cavity via the ducts of the lacrimal apparatus .
What is conjunctiva?
- a stratified columnar epithelium with goblet cells
What covers the anterior part of the sclera?
- conjunctiva and is continuous with the corneal epithelium.
Define External Acoustic meatus?
The passage leading inward through the tympanic portion of the temporal bone, from the auricle to the tympanic membrane; it consists of a bony (inner) portion and a fibrocartilaginous (outer) portion, the cartilaginous external acoustic meatus.
