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BMB G Lab Underline Terms > Lab 7: Vision, Eyeball Movement And Balance Systems I > Flashcards

Lab 7: Vision, Eyeball Movement And Balance Systems I Flashcards

1
Q

3 Concentric Coats of the Eyeball

A

External or fibrous coat: sclera posteriorly and cornea anteriorly

Middle or vascular coat: choroid, ciliary body, and iris

Internal or retinal coat: outer layer of pigmented cells and inner layers of neural elements posterior to the ora serrata

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2
Q

4 Refractive Media of the Eye

A
  1. Cornea
  2. Aqueous Humor
  3. Lens
  4. Vitreous Body
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3
Q

Conjunctiva

A

Covers the anterior surface of the eyeball (corneal epithelium) and is attached near the edge or limbus of the cornea

Edge is also called corneoscleral junction.

Lines the inner surface of the eyelids (palpebral conjunctiva) and reflects onto the eyeball (bulbar conjunctiva)

Epithelium: 2 layers of stratified columnar cells which become more squamous closer to the limbus

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4
Q

Cornea

A

Transparent disk-like anterior portion of the eyeball and has 5 layers

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5
Q

Suspension Ligament

A

Composed of zonular fibers

Holds lens in position

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6
Q

Lens

A

Has an outer capsule of hyaline material

Lens epithelium (outside the capsule): which is a layer of cuboidal epithelial cells;

Center region: composed of tightly packed cells, which have lost their nuclei and are, chock full of special transparent proteins (crystalline)

New cells from the lens epithelium are added to the margin of the lens throughout life. Cells are the center do not undergo replacement and are the oldest cells in the body

Avascular and nourished by diffusion

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7
Q

Ciliary Body

A

Extends from base of the iris to the ora serrata (saw-toothed, black margin) at which point it’s continuous with the choroid (pigmented, vascular middle layer)

Contains ciliary muscle (smooth muscle) which you will see in microscopic views. Contraction of this muscle decreases the tension on the suspensory ligament of the lens and allows the lens to round up and become more spherical

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8
Q

Iris

A

Sheet-like diaphragm anterior to the lens and separates the anterior and posterior chambers of the eyes

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9
Q

Pupil

A

Circular aperture, which can be constricted or dilated by the actions of the circular fibers of the constrictor pupillae (parasympathetic innervation) and radial fibers of the dilator pupillae (sympathetic innervation) muscles respectively

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10
Q

Aqueous Humor

A

Resembles CSF in composition and is secreted by epithelial cells of the ciliary processes in posterior chamber

It flows from there to the anterior chamber through the pupil and provides nutrients to neighboring structures.

After filtering through a network of spaces (space of Fontana) lined by endothelium, the trabecular mesh work, which runs around the circumference of the root of the iris at the peripheral of the anterior chamber, the aqueous humor enters the CANAL OF SCHLEMM.

T

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11
Q

Canal of Schelmm

A

Runs around the whole circumference of the limbus within the sclera and drains into veins

There’s normally resistance to the flow of aqueous Humor through the trabecular mesh work

Consequently, continued secretion and resorption of the aqueous humor is responsible for the normal intraocular pressure of 10-22 mg Hg

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12
Q

Glaucoma

A

Results from abnormal drainage of the aqueous humor and is characterized by a rise in intraocular pressure. If not treated, blindness can result from damage to the nerve cells of the retina

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13
Q

Vitreous Body

A

Fills the space between the lens and the retina

Has a volume of about 4 mL and is considered a specialized support tissue. It’s composed of a few scattered spindle-shaped cells, fine highly dispersed collagen fibers and an extracellularly matrix rich in hylauronic acid

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14
Q

Retina

A

Attached at the back of the eye at the optic disc

The innermost layer of the eye and is composed of a non-neural layer pigment epithelial cells which absorb light and prevent distracting back scatter into the retina and a neural layer of photoreceptors cells, retinal support cells and nerve cells

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15
Q

Optic Disc (also called the blind spot)

A

Axons of the retinal ganglion cells all collect here where they penetrate the sclera (lamina cribosa) to form the optic nerve

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16
Q

Choroid

A

Middle layer of the posterior 2/3 of the eyeball

Extends from the ora serrata, the anterior margin of the neural retina, to the optic nerve and contains blood vessels and lymphatics supporting the retina.

Appears as a dark brown sheet which blends with the sclera in it’s outer portion, while in the inner portion it’s attached to the pigmented epithelium of the retina at Bruch’s Membrane.

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17
Q

Separation of the Retina

A

Occurs between the rods and cones and pigment epithelium

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18
Q

Tapetum Lucidum

A

Special reflective surface portion of the choroid layer, which reflects light within the eye and is found in the eyes of animals that liver under conditions of low-intensity light

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19
Q

Ophthalmic Artery

A

Blood supply to the neural retina

Gives 2 branches: central artery of the retina and ciliary arteries.

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20
Q

Central artery of the retina

A

Branches out from the region of the optic disc to serve inner portions of the retina

4 branches go to the 4 quadrants of the regina

These branches are end arteries and if occluded, will result in death of the ganglion cells and therefore total blindness from that quadrant of the eye

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21
Q

Posterior Ciliary Arteries

A

penetrate the sclera around the optic disc and form the choroidocapillary plexus in the choroid

Materials from this plexus provide nutrients to the outer portions of the neural retina, the rods and cones

22
Q

Anterior Chamber Location

A

Between the iris and cornea

23
Q

Posterior Chamber

A

Posterior to the iris

24
Q

Iris

A

Contains the constrictor and dilator pupillae muscles

25
Q

Optic Disc and the Optic Nerve

A

Consists of axons of ganglion cells

Note the general location of the meninges surrounding the optic nerve

26
Q

Ciliary Muscles

A

Regulate shape of lens

27
Q

Ciliary Processes

A

Connected to suspensory ligaments

28
Q

Suspensory Ligament

A

Connected to lens by zonule fibers

29
Q

5 layers of the cornea (we look at 3)

A

Corneal epithelium

Corneal stroma

Corneal endothelium

30
Q

Corneal Epithelium

A

Lines the outer surface

Stratified squamous non-keratinized epithelium

31
Q

Corneal Stroma

A

The main layer of the cornea and consists of some 70 broad sheets of tightly bound, parallel collagen fibers embedded in an extraocular matrix

  • the direction of the collagen fibers differs in each layer for maximal mechanical strength
  • the absence of blood vessels in the cornea and the regular arrangement of the collagen fibers make the cornea translucent, allowing it to transmit light
32
Q

Corneal Endothelium

A
  • single layer; lines the inner surface
  • adapted for ion-pumping
  • pumps fluid from the corneal stroma, prevents corneal opacification from excessive hydration
33
Q

Lateral Geniculate Body

A

At end of the optic tract

  • termination (synapse) of axons of the ganglion cells of the eyeball
  • thalamic nucleus for vision
34
Q

Brachium of superior colliculus

A

Passes dorsal to the medial geniculate body

-contains optic tract fibers en route to pretectal area and superior colliculus

35
Q

Superior Colliculus

A

Receives fibers for visual reflexes

36
Q

Calcarine fissure

A

Medial occipital lobe

37
Q

Cuneus

A

Superior to calcarine fissure

38
Q

Lingual Gyrus

A

Inferior to calcarine fissure

39
Q

Calcarine Cortex

A

Primary visual cortex (area 17), along the banks of the calcarine fissure

40
Q

Secondary and Tertiary Visual Cortex

A

Surrounds primary visual cortex

41
Q

Optic Radiation (geniculocalcarine tract)

A
  • pass posterior to the lentiform nucleus as retrolenticular fibers from the lateral geniculate nucleus
  • pass posteriorly, lateral to the inferior horn and atrium of the lateral ventricle
42
Q

Path of Optic radiation

A

Passes deep or subcortical to the temporal cortex and receives arterial supply mainly from cortical branches of the middle cerebral artery

43
Q

Optic Chiasm

A

Contains crossing of ganglion cell axons from the nasal half of each retina

44
Q

Loop of Meyer

A

Inferior fibers of the optic radiations that loop around the inferior horn of the lateral ventricle

45
Q

Visual Acuity

A

Test for near versus distant vision; deficits often the result of inappropriate shape of refractive media of eyeball

46
Q

Scotoma

A

Loss of part of a visual field of an eyeball

47
Q

Hemianopsia

A

Half loss (loss of half a visual field)

48
Q

Quadrantic Anopsia

A

Quarter loss of a visual field

49
Q

Homonymous

A

Loss in same part of visual field for both eyeballs

50
Q

Heteronymous

A

Loss in different part of visual field for 2 eyeballs

BMB G Lab Underline Terms (15 decks)

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