Cleanse Protect Moisten Lubricate the eye

Lesson 2 Final Flashcards by katrina daz

Special senses include:

*Smell
* Taste
* Sight
*Hearing
* Equilibrium

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How many percent of all sensory receptors are in the eyes

70 percent

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Anatomy of the eye

Accessory structures include the:

*Extrinsic eye muscles
* Eyelids
* Conjunctiva
* Lacrimal apparatus

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Meet at the medial and lateral commissure (canthus)

Eyelids

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Tarsal glands produce an oily secretion that lubricates the eye

Eyelashes

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Membrane that lines the eyelids and eyeball

Conjunctiva

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Connects with the transparent cornea

Conjunctiva

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Lacrimal gland+ ducts

Lacrimal Apparatus

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Produce lacrimal fluid (tears); situated in lateral end of each eye

Lacrimal gland

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Tears drain across the eye into the lacrimal canaliculi, then the lacrimal sac, and into the nasolacrimal duct, which empties into the nasal cavity

Lacrimal Apparatus

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Tears contain:

*Dilute salt
* Mucus
* Antibodies
* Lysozyme (enzyme that destroys bacteria)

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Function of tears:

Cleanse
Protect
Moisten
Lubricate the eye

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Six muscle attach to the outer surface of the eye

Extrinsic eye muscles

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Produce gross eye movements

Extrinsic eye muscles

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Three layers, or tunics, form the wall of the eyeball

fibrous layer
Vascular layer
Sensory layer

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Outside layer

Fibrous layer

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Middle layer

Vascular layer

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Inside layer

Sensory layer

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Two types of fibrous layer

*Sclera
* Cornea

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Two types of fibrous layer

*Sclera
* Cornea

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White connective tissue

Sclera

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Seen anteriorly as the “white of the eye”

Sclera

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Transparent, central anterior portion

Cornea

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Allows for light to pass through

Cornea

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Choroid is a blood- rich nutritive layer that contains a pigment (prevents light from scattering)

Vascular layer

Regulates the amount of light entering eye

Iris

Rounded opening in the iris

Pupil

Signals leave the retina toward the brain through the optic nerve

Sensory layer

Retina contains two layers:

* Outer pigmented layer * Inner neural layer

Where the optic nerve leaves the eyeball

Optic disc (blind spot)

Most are found toward the edges of the retina

Rods

Allow vision in dim light and peripheral vision

Rods

Allow for detailed color vision

Cones

Densest in the center of the retina

Cones

Lateral to blind spot

Fovea centralis

Sensory layer Types of inner neural layer:

*Rods * Cones

Three types of cones

Cone sensitivity

Flexible, biconvex crystal-like structure

Lens

Held in place by a suspensory ligament attached to the ciliary body

Lens

Lens divides the eye into two chambers:

* anterior (aqueous) segment * Posterior (vitreous) segment

Anterior to the lens

Anterior (aqueous) segment

Contains aqueous humor, a clear, watery fluid

Anterior (aqueous) segment

Posterior to the lens

Posterior (vitreous) segment

Contains vitreous humor, a gel-like substance

Posterior (vitreous) segment

Watery fluid found between lens and cornea

Aqueous humor

Gel-like substance posterior to the lens

Vitreous humor

Prevents the eye from collapsing

Vitreous humor

Instrument used to illuminate the interior of the eyeball and fundus (posterior wall)

Ophthalmoscope

Can detect diabetes, arteriosclerosis, degeneration of the optic nerve and retina

Ophthalmoscope

Pathway of light through the eye and light refraction

Physiology of vision

is bent, or refracted, by the cornea, aqueous humor, lens and vitreous humor

Light

The eye is set for distant vision over?

Over 20 feet away

The lens must change shape to focus on closer objects (less than 20 feet away)

Accommodation

Bundle of axons that exit the back of the eye carrying impulses from the retina

Optic nerve

Location where the optic nerves cross

Optic chiasma

Contains fibers from the lateral side of the eye on the same side and the medial side of the opposite eye

Optic tracts

Axons from the thalamus run to the occipital lobe

Optic radiation

Summary of the pathway of impulses from the retina to the point of visual interpretation

1. Optic nerve 2. Optic chiasma 3. Optic tract 4. Thalamus 5. Optic radiation 6. Optic cortex in occipital lobe of brain

Each eye "sees" a slightly different view

Visual fields

Binocular vision results and provides:

Depth perception (three-dimensional vision)

Eye focuses images correctly on the retina

Emmetropia

Distant object appear blurry

Myopia (nearsightedness)

Near objects are blurry, whereas distant objects are clear

Hyperopia (farsightedness)

Images are blurry

Astigmatism

Types of closer look:

*Emmetropia * Myopia (nearsightedness) * Hyperopia (farsightedness) * Astigmatism

Types of eye reflexes:

* Convergence * Photo pupillary reflex * Accommodation pupillary reflex

Reflexive movement of the eyes medially when we focus on a close object

Convergence

Bright light causes pupils to constrict

Photo pupillary reflex

Viewing close objects closes pupils to constrict

Accommodation pupillary reflex

Ear houses two senses:

* Hearing * Equilibrium (balance)

The ear is divided into three areas:

* External (outer) ear * Middle ear * Internal (inner) ear

Auricle (pinna)

External (outer)ear

Air-filled, mucosa lined cavity within the temporal bone

Middle ear cavity (tympanic cavity)

Links middle ear cavity with the throat

Pharyngo tympanic tube (auditory tube)

Three bones (ossicles) span the cavity:

1. Malleus (hammer) 2. Incus (anvil) 3. Stapes (stirrup)

Includes sense organs for hearing and balance

Internal (inner) ear

Bony labyrinth (osseous labyrinth) consists of:

* Cochlea * Vestibule * Semicircular canals

Equilibrium receptors of the inner ear are called?

Vestibular apparatus

Vestibular apparatus has two functional parts:

* static equilibrium * Dynamic equilibrium

Static equilibrium - receptors in the vestibule

Maculae

Hair cells are embedded in the otolithic membrane

Anatomy of the maculae

Dynamic equilibrium - responds to angular or rotational movements of the head

Crista amullaris

Hearing - located within the cochlear duct

Spiral organ of corti

Pathway of vibrations from sound waves

Hearing

Location of taste buds:

* most are on the tongue * Soft palate * Superior part of the pharynx * Cheeks

Covered with projections called papillae that contains taste buds

Tongue

Papillae that contains taste buds:

* vallate (circumvallate) papillae * Fungiform papillae * Filiform papillae

Five basic taste sensations:

* sweet receptors * Sour receptors * Bitter receptors * Umami receptors

Lesson 2 Final Flashcards

(88 cards)