The Eye Flashcards
What composes the inner tunic (retina)?
Pigmented epithelium
Neural retina
What are the components of the outer fibrous tunic?
Sclera
Cornea
What are the components of the middle vascular tunic (uvea)?
Iris
Ciliary body
Choroid
What causes jaundice?
Bilirubin in the blood
What reabsorbs the aqueous humor in the eye?
It is reabsorbed though the trabecular mesh work into the canal of schlemm
What is retinoblastoma?
White reflection in the pupil
Most Common malignancy in children
It runs in family
Where do the lens and cornea come from?
Ectoderm
What comes from the diencephalon in eye development?
Optic stalk
Pigmented epithelium
Neural retina
What is the most Important part of the cornea?
Limbus (where the stem cells hang out)
What does the cornea do?
Accommodation of light
The first thing to come in contact with light
What are the layers of the cornea from superficial to deep?
- Corneal epithelium
- Bowman’ layer
- Storms
- Descemet’s membrane
- Corneal endothelium
What is aqueous humor made of?
Water, amino acids and glucose
What are the characteristics of the corneal epithelium?
Squamous stratified cells
Attached with hemidesmosomes
Innervated by unmyelinated axons
What are the characteristics of bowman’ layer?
Type 1 collagen
Barrier to trauma and bacterial invasion
- does not regenerate
What are the characteristics of the stroma?
Collagen Lamellae at angle to one another (this is the reason you can see through it)
Transparency depends on arrangement and affinity to water
What are the characteristics of decemet’s membrane?
Thick basement membrane
Thick type 4 collagen
Note: 4th layer and type 4 collagen :D
What are the characteristics of of the corneal endothelium?
Permeable to air
Regulates hydration of stroma
Vital to transparency of stroma
Metabolically active
When does bowman’s layer stop?
When it reaches the sclera
What causes Kayseri flesher ring?
Copper deposit is desminous (desmosome) membranes (in Wilson’s disease)
Where is aqueous humor made?
In the ciliary body
What does the ciliary body do?
Participates in the blood aqueous barrier
Makes aqueous humor and viscous humor
Anchors zonular fibers ( change lens shape)
What is the other name of the canal of schlemm?
Sclera venous sinus
Where is the canal of schlemm located?
Angle of the iris
In what location is the aqueous humor deposited?
Posterior chamber (it then travels along the lens and in between the iris into the anterior chamber)
What divides the anterior and posterior chamber?
The iris
Where does the photosensitive part of the retina begin and end?
At the ora serrata
How do the layers of the cornea receive nutrients?
The cornea receives nutrients from the aqueous humor via endocytosis at the endothelium and diffusion to the outer layers
Note: this tissue is avascular
What are the boundaries of the anterior chamber of the eye?
The cornea and the iris in front of the lens
What are the boundaries of the posterior chamber of the eye?
Bound by the lens, iris, ciliary body, and zonale fibers
What creates aqueous humor and what path does it take within the eye?
The ciliary process. It passes from the posterior chamber to the anterior chamber
Note: it passes through the center of the iris to reach the anterior chamber which divides the two
What features of the cornea allows light transmission?
The lower water composition, the avascularity and the collagen fiber arrangement
The zonular fibers (suspensory ligaments) are important for what function?
Focusing of the lens (accommodation)
For close vision what occurs? (Muscle/body/lens)
The ciliary muscle contracts
The ciliary body with zonular fibers move closer to the lens
Tension is reduced and the lens rounds
Note: whenever the muscle contracts it becomes a ball making the distance between the muscle and lens closer (ball is round)
For distant vision, what occurs? (Muscle/body/lens)
The ciliary muscle relaxes
The ciliary body with zonular fibers moves away from the lens
Tension increase and the lens flattens
Note: when the ciliary muscle relaxes it becomes flatter again the wall of the eye and pulls the lens causing it to flatten (flat to flat)
How do cataracts occur?
Excess of sorbitol reduces solubility of crystallins leading to opacity
Note: glucose is the major metabolite of the lens. High glucose levels (diabetes) cause sorbitol to accumulate in the lens fibers.
What are the 10 layers of the retina? (Deep to superficial)
“In New Generations It Is only Ophthalmologist Examining Patients Retina”
- Inner Limiting membrane
- Nerve fiber layer
- Ganglion cell Layer
- Inner plexiform layer
- Inner nuclear layer
- Outer plexiform layer
- Outer nuclear layer
- Outer limiting membrane (external)
- Photoreceptors inner and outer segments
- Retinal pigment epithelium
Note: the layers might be referred by number and are ordered superficial to deep
What cells are found in the Inner nuclear layer?
Amacrine
Bipolar
Horizontal
Muller cells
Note: Muller cells span almost all layers but cell body is here
What are muller cells?
Supportive cells that helps structurally and to clean the layers
What cells are found in the ganglionic cell layer of the retina?
Ganglion cell nuclei (conducting cells)
Where are the photoreceptor nuclei found?
Outer nuclear layer
Note: the rest of the cell are within the outer limiting membrane and photoreceptors inner and outer segments
What pigment is associated with rods?
Rhodopsin
What pigment is associated with cones?
Iodopsin
Blue,red, green
What part of the photoreceptor makes the signal in a reversible manner?
Membranous disk
When light enters the eye, opsin is activated and turns retinal into retinol. What other process occurs that is not done in the dark?
Phosphodiesterase is activated by transducin
Note: this decreases cGMP to close the sodium pump (NA+) causing the cell to become hyper polarized
What are the layers of the choroid?
- Bruch’s membrane
- Choriocapilaris- layer of capillaries
- Sattler’s layer- medium diameter blood vessels
- Haller’s layer- large diameter blood vessels
Where does the ciliary body begin and end?
Begins posteriorly at the ora serrata and extends anteriorly to wears the root of the iris
*be able to distinguish this in a picture
What do amacrine cells do in the eye?
The shift information in the layer
What are the components of the lens?
Capsule
Epithelium
Substance
Zonule
Describe the capsule of the eye.
It forms an elastic collagenous membrane around the lens
Lens epithelium is only present on the anterior surface of the lens. What happens as cells migrate?
As cells migrate posteriorly they become lens fibers at the equator
What is the substance of the lens?
The substance of the lens is composed of 6 sided prism fibers derived from the epithelium at the equator
What is the zonule of the lens?
Zonule suspensory ligaments
-from the ciliary proceses of the ciliar body to the equator and are continuous with the lens
What are the components of rhodopsin?
Retinal and opsin
What activates phosphodiesterase when light hits the rhodopsin?
Transducin
What does the fovea contain ?
Only cones
Note: area of greatest visual acuity because the nuclear layers do not obstruct path resulting in accurate color vision
