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Histology > Eye and Ear > Flashcards

Eye and Ear Flashcards

1
Q

Structure of the eye

A

3 layers

  1. Outer layer (CT layer) = Tunica Fibrosa
    - Sclera = CT
    - Conea
  2. Uvea
    - Choroid - vascular layer which provides nutrients to the retina
    - ciliary body
    - Iris
  3. Retina (innermost part)
    - consists of rods and cones and neruons that will become the optic nerve
    - mainly nerual (5/6)
    - non neural retina lines the ciliary body and the iris
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2
Q

Tunica Fibrosa

A
  • outermost layer
  • fibrous layer
  • Sclera - covers most of the back of the eye
  • Cornea - in contact with air on one side and fluid on the other
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3
Q

Sclera

A
  • CT layer
  • acting as a capsule to hold the eye in place
  • has typical CT materials - fibroblasts, amorphous components, etc.
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4
Q

Cornea

A
  • Has 5 layers
    1. corneal epithelium (outermost layer)
  1. Bowman’s membrane
    - thick layer of extracellular material
    - noncellular
  2. Stromal layer
    - thickest layer
  3. Descemel’s membrane
  4. Endothelium Layer
    - squamous

Light must pass through all 5 layers of cornea before it gets inot the anterior chamber

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5
Q

Canal of Schlemn

A
  • Facilitates equilibrium of pressure within the eye
  • Equilibrates the pressure in the anterior chamber
  • if you have pressure that builds up in the anterior chamber, it can drain out through this canal
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6
Q

Uvea

A

3 layers

  1. choroid - vascular
  2. ciliary body
  3. iris
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7
Q

Choroid

A
  • Blood vessels providing nutrients to the sclera (CT) and the retina

Choriocapillary layer - close to the retina

  • subdivision of choroid
  • blood vessels are much smaller - filled with capillaries
  • immediately adjacent to the retina
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8
Q

Ciliary Body

A
  • contain muscle that can contract and change shape of lens for visual accommodation
  • folds of epithelium = ciliary processes
  • from the processes, you have zonule fibers
  • by changing the shape of the muscle, you will pull or relax on the lens to change its shape for visual acuity
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9
Q

Ciliary Processes

A
  • Contain a double layer of low columnar to cuboidal epithelium
  • Inner layer is pigmented with melanin granules
  • outer layer is non pigmented
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10
Q

Iris

A
  • Double layer of epithelium continues from the ciliary processes to line the posterior iris
  • eye color is due to amount of pigment in the epithelium
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11
Q

Zonule Fibers

A
  • from the ciliary processes, you get zonule fibers attached to the lens
  • oxytalin fibers - first component of elastic fibers
  • bridge between ciliary body and lens
  • Pull on the lens - change lens shape
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12
Q

Vitreous Chamber

A
  • like a sponge
  • a lot of hyaluronic acid
    • glycosaminoglycans - hyrophobic - absorb a lot of water
  • -holds a lot of water
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13
Q

Retina

A

5/6 of the back of the eye ball is neural retina

forward 1/6 is non neural
- double layer epithelium that projects forward to line the ciliary body and iris

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14
Q

3 Layers of the Retina

A
  1. Outer most/ deepest layer
    - consists of rods and cones embedded in pigmented epithelium
    - receive photons of energy in the form of light
    - stimulate some visual stimulus
  2. Bipolar neurons
    - one side on the rods and cones
    - the other on a ganglian cell
    - Muller cell - sustantacular cell (support cell)
  3. Ganglain Cell layer
    - one end attaches to the bipolar neuron layer
    - the other end forms axons and project to become the optic nerve
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15
Q

Ora serrata

A
  • Transition form the neural retina to the non neural retina

- non neural is double layer epithelium that lines the ciliary body and back of the iris

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16
Q

Rods

A
  • most sensitive to light
  • only give you black, white and shades of grey
  • Rhodopsin - responsible for perceptions of black, white and grey
  • under low light conditions, the rods are able to pick up light that the cones cannot
17
Q

Cones

A
  • give you color vision
  • have iodopsin - gives perceptions of color
  • cones need a good bit of light to be stimulated
  • in the light they are able to pick up more photons of light
18
Q

Fobea Centralis

A
  • macula
  • only cones
  • located at the back of the eyeball
  • responsible for central vision and visual acuity
19
Q

Optic Nerve

A
  • blind spot
  • central artery of the retina runs through the optic nerve
  • no rods or cones
20
Q

Lens

A
  • outermost layer is lens capsule - CT, non cellular
  • lens epithelium - simple cuboidal to columnar
  • Differentiating lens fibers
  • mature lens fibers
  • light has to go through all of these layers plus the anterior chamber before reaching the rods and cones
21
Q

Eyelid

A

Innermost layer is the conjunctiva

  • in contact with the eye ball
  • layer of epithelial cells

Tarsal plate gives rigidity to the eye
- so you can move your eye

Meibomian Gland
- sebaceous glands

Orbicular Muscle
- contract to allow movement of the eye

Eyelashes
- prevents things from getting in the eye

22
Q

Conjunctiva

A
  • Layer in contact with part of the eyeball

- predominantly stratified columnar to stratified squamous

23
Q

Lacrimal Apparatus

A

Lacrimal Gland

  • produces tears
  • secretes fluid onto the eye
24
Q

Extraocular Muscles

A
  • Pull on the eye to that it can move around and to focus
25
Q

Structure of the Ear

A

3 Layers

  1. Outer ear
    - eardrum
  2. Middle ear
    - articulating bones
    - create a sound wave for inner ear
  3. Inner ear
    - cochlea (hearing)
    - vestibular apparatus (balance and motion)
26
Q

Pinna

A
  • Contains a lot of CT and elastic fibers
27
Q

External Auditory Meatus

A
  • ear canal
  • lined by epidermis
  • Continuous with the ear lobe
  • contains the ceruminous glands - gives rise to ear wax
28
Q

Tympanum

A
  • Tympanic membrane (eardrum)
  • 3 layers
    1. Epidermis continuous with the canal
    2. middle layer of fibrous CT
    3. Inner layer of simple cuboidal and/or squamous
29
Q

Middle Ear

A

Malleus, incus, and stapes

  • articulating bones
  • transmit a sound wave from eardrum to the oval window
  • when they articulate, they amplify the signal of sound
  • stapes has a pad that pounds on the oval window of the inner ear
30
Q

Bony and Membranous Labyrinth

A

Bony Labyrinth
- bone “shell” around the membranous labyrinth

Membranous labyrinth
- the tissue within the bony labyrinth

  • nerves are quite large and attach to the three components of the inner ear
31
Q

Inner Ear Sensory Regions

A

Vestibular Apparatus

  • utricle and the saccule
  • maculae is the sensory structure within - responsible for the perception of motion

Semicircular canals

  • 3 of them in different orientations (x,y,z)
  • cristae ampullares - responsible for 3D orientaion and motion

Cochlea
- Oran of Corti - responsible for hearing

32
Q

Cochlea

A
  • sea shell shaped
  • Oval window is being baned on by the stapes
  • pressure wave passes down through cochlea
  • causes the organ of Corti to vibrate, causing sensation of sound
  • pressure goes back down and pushes on the round window
  • vibration of the tectorial membrane is responsible for stimulating the hair cells of the of the organ of corti
33
Q

Middle Duct of Cochlea

A
  • called scala media
  • organ of corti is on the scala media
  • one the back of the scala media, there is a layer of cells called the scala vascularis - secrete endolymph (maintains the viability of the cells of the organ of corti)
  • surrounded by vesibular membrane
34
Q

Organ of Corti

A
  • As the fluid within the canal is pushed by a pressure wave the tectorial membrane rubs against the hair cells
  • vibrating due to sound creating a pressure wave
  • the hair cells perceive the movement of tectorial membrane
  • projects that on the cochlear nerve which then goes to the auditory nerve which is how you hear
35
Q

Stereocilia Bundles

A
  • Hair cells - in a v shaped row

- Tectorial membrane rubbing on the hair cells transduces a signal perceived as sound

36
Q

Vestibular Apparatus

A
  • within the utricle and the saccule there is a sensory structure called the macula
37
Q

Macula

A
  • contains stereocilia and one long true cilia
  • embedded in a gelatinous layer - has calcium carbonate crystals on top of it - otoliths or otoconia
  • otoliths provide for inertia
  • cilia and stereocilia bend with the movement of the gelatinous layer which provides for perception of linear acceleration
  • sensory cells containing stereocilia and one true cilia at the end of the escalating ramped up bundle of stereocilia
38
Q

Cristae Ampullares

A
  • at the base of semicircular canals perceive rotation
  • The gelatinous layer rubs against the other side of the canal
  • inertia is provided by the rubbing against the other side of the canal
39
Q

Semicircular canals

A
  • canals are in X, Y, Z orientation allowing for perception of rotation

Histology (25 decks)

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