Sensory Systems III - Eye Flashcards
What is the cavity in the skull where the eye is housed called?
orbit
What are the three main components of the eye?
1) optical apparatus
2) neural apparatus
3) supportive tissues
What are some of the components of the optical apparatus?
- cornea
- aqueous humor
- iris
- lens
- vitreous body
What does the neural apparatus consist of?
retina and optic nerve
What do the supportive tissues of the eye consist of?
sclera and conjunctiva
What are the three main layers of the eye?
1) fibrous layer
2) vascular layer
3) inner layer
What does the fibrous layer (tunica fibrosa) consist of?
sclera (white of the eye) and cornea
What kind of tissue does the sclera consist of?
collogenous connective tissue
What pole of the sclera is the thickest and what is it perforated by?
posterior pole
blood and lymphatic vessels and nerves
What is the posterior zone of the sclera where the optic nerve exits the eye called?
lamina cribrosa
What is the zone of transition between the sclera and cornea called?
limbus
Which surface of the eye does the cornea cover?
anterior (exterior) surface of the eye
What are the three components of the cornea?
- corneal epithelium
- corneal stroma
- endothelium
In the cornea, what is a thin stratified squamous epithelium five or six cells thick, with a basement membrane called Bowman’s membrane?
corneal epithelium
In the cornea, what is the middle layer constituting about 90% of the corneal
thickness, composed of lamellae (layers) of collagen fibers and fibroblasts?
corneal stroma
In the cornea, what is a simple cuboidal epithelium lining the inner face of the cornea, with a basement membrane called Descemet’s membrane?
endothelium
What gives the corneal stroma its transparency?
- parallel arrangement and tight compression of its fibers within each lamella
- gel of glycosaminoglycans (GAGs) between lamellae
What are the components of the vascular layer (tunica vasculosa)?
- choroid
- ciliary body
- iris
What layer of the eye has the most blood vessels packed in?
vascular layer
Which portion of the vascular layer is deeply pigmented and appears in dissection as a spongy brown membrane between the retina and sclera, thinner than either of those?
choroid
What is an outer layer of loose collagenous and elastic fibers that connect the
choroid to the sclera, bridging a gap called the perichoroidal space?
epichoroid
What cells are located within the epichorid?
melanocytes—pigment cells that produce melanin
What is the thickest layer of the choroid, consisting of a dense mass of veins and arteries amid loose connective tissue and melanocytes?
vessel layer
What is a layer of blood capillaries that nourish the retina?
choriocapillaries
What happens with a detached retina?
the retina become detached from the chorid, resulting in blindness
What is the basement membrane of the innermost layer
of the retina, the pigment epithelium? It is the boundary between choroid and retina.
lamina vitrea
What is a reflective, mirrorlike layer between the vessel layer and the choriocapillaris? It occurs in animals that must be able to see in low-light conditions, ranging from wolf spiders and fish to your pet cat and that classic “deer in the headlights” look.
tapetum lucidum
the reflective sheen seen in animal’s eyes in the dark
What is an advantage and disadvantage to having a tapetum (sheen that some animals have on their eyes)?
advantage: ability to see in low-light (dark)
disadvantage: the image they see is not very clear/sharp
At its anterior margin, the tunica vasculosa thickens and forms a ring, the ____ ____, that supports the lens and iris and secretes the aqueous humor.
ciliary body
What is the wavy or serrated line in the posterior margin of the ciliary body called?
ora serrata
What are the two zones of the cilary body called?
- pars plana (flat part)
- pars plicata (pleated part)
What is a smooth zone constituting the posterior two-thirds of the
ciliary body, consisting mostly of smooth muscle fibers? Contraction of these fibers relaxes tension on the suspensory ligament that connects to the lens, allowing the lens to relax into a more convex shape.
pars plana
On the ciliary body, what is the region with 70 to 80 ciliary processes arranged radially like wheel spokes?
pars plicata
What is composed of a radially striated pupillary zone that immediately
surrounds the pupil, and a more peripheral ciliary zone?
iris
What are the three tissue layers of the iris?
1) anterior layer
2) fibrous layer
3) pigment epithelium
In the anterior layer of the iris, what are the pigment cells called?
chromatophores
In the iris… The ____ ____ is a circular smooth muscle that constricts and
narrows the pupil. The ____ ____ is musclelike, although composed of contractile myoepithelial cells rather than true muscle cells.
pupillary sphincter; pupillary dialator
Which part of the nervous system is the pupillary sphincter apart of?
parasympathetic nervous system
Which part of the nervous system is the pupillary dialator apart of?
sympathetic nervous system
What is a layer of deeply pigmented cells at the posterior surface of the iris? These serve to absorb light and prevent any light from passing any farther into the eye except that which passes through the pupil.
pigment epithelium
What fluid is both the anterior and posterior chamber of the eye filled with?
aqueous humor
What is the large portion of the eye, the posterior segment, filled with?
vitreous body (a gel-like mass)
The aqueous humor has a canal which helps to remove metabolic wastes from the anterior segment and it maintains the roundness of the cornea, which is important to the focusing of light… what is this called?
scleral venous sinus (canal of Schlemm)
