Special Senses

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  • Created by: Jade
  • Created on: 07-01-21 12:05
What are the five special senses?
Smell
Taste
Sight
Hearing
Equilibrium
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What are the accessory structures of the eye?
Extrinsic eye muscles

Eyelids

Conjunctiva

Lacrimal apparatus
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What is the function of the extrinsic eye muscles?
Extrinsic eye muscles aim the eyes for following moving objects and for convergence (coordinated movement of the eyes so that the image of a single point is formed on corresponding retinal areas).
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What is the function of the eyelids?
They protect the eyes.

Also, associated with the eyelashes are the ciliary glands (modified sweat glands) and the tarsal glands (which produce an oily secretion). Both help keep the eye lubricated.
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What is the function of the conjunctiva?
The conjunctiva is a mucous membrane that covers the anterior eyeball and lines the eyelids. It produces a lubricating mucus.
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What is the function of the lacrimal apparatus?
The lacrimal apparatus includes a series of ducts and the lacrimal glands that produce tears, a saline solution that washes and lubricates the eyeball.
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What is the space between the eyelids in an open eye called?
The palpebral fissure
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What occurs when there is inflammation of the conjunctiva?
Conjunctivitis
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What are the six extrinsic eye muscles?
Lateral rectus
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
Superior oblique
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What is the function of the lateral rectus and which cranial nerve controls it?
Moves the eye laterally (away from the nose)

VI (abducens)
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What is the function of the medial rectus and which cranial nerve controls it?
Moves eyes medially (towards the nose)

III (oculomotor)
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What is the function of the superior rectus and which cranial nerve controls it?
Elevates eye and turns it medially

III (oculomotor)
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What is the function of the inferior rectus and which cranial nerve controls it?
Depresses eye and turns it medially

III (oculomotor)
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What is the function of the inferior oblique and which cranial nerve controls it?
Elevates eye and turns it laterally

III (oculomotor)
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What is the function of the superior oblique and which cranial nerve controls it?
Depresses eye and turns it laterally

IV (trochlear)
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What three layers form the eyeball?
The fibrous layer (outermost layer)

The vascular layer (middle layer)

The sensory layer (innermost layer)
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What does the fibrous layer consist of?
The sclera (the white of the eye) forms most of the outer, tough, protective fibrous layer.

The central anterior portion is the cornea, which is transparent to allow light to enter the eye.
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What does the vascular layer consist of?
The choroid (posterior portion).

Moving anteriorly, the choroid is modified to form two smooth muscle structures: the ciliary body and the iris.
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What is the function of the choroid?
The choroid is pigmented and prevents light from scattering in the eye.
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What are the functions of the ciliary body and the iris?
The ciliary body - changes lens shape (helps eye to focus).

The iris - controls the size of the pupil (regulates amount of light)
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What does the sensory layer consist of?
The two-layered retina - the outer pigmented layer, and the transparent inner neural layer.
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What is the function of the outer pigmented layer?
It is composed of pigmented cells that absorb light and prevent light from scattering inside the eye.

They also remove dead/damaged receptor cells and store vitamin A which is needed for vision.
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What is the function of the inner neural layer?
Electrical signals pass from photoreceptors via bipolar cells and then ganglion cells, before leaving the retina via the optic nerve and being transmitted to, and interpreted by, the optic cortex. Resulting in vision.
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What are the types of photoreceptors (receptors which respond to light)?
Rods - allow us to see in gray tones in dim light

Cones - allow us to see in color under bright light conditions
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What is the function of the lens of the eye?
Focuses light on the retina
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What is accommodation?
The resting eye is "set" for distance vision, so accomodation is the ability of the eye to focus specifically for close objects (those less than 20 feet away).
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What is the pathway of light through the eye?
1) Cornea
2) Aqueous humor
3) Through pupil
4) Aqueous humor
5) Lens
6) Vitreous humor
7) Retina
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What are the three major areas of the ear?
External (outer ear)

Middle ear

Internal (inner) ear
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What is the external ear composed of?
The auricle (pinna) - what most people call "the ear"
The external acoustic meatus - auditory canal
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What occurs in the external acoustic meatus?
Sound waves entering the auditory canal eventually hit the tympanic membrane (eardrum) and cause it to vibrate.
The canal ends at the eardrum, which separates the external from the middle ear.
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What is the function of the middle ear cavity (tympanic cavity)?
Normally, the pharyngotympanic (auditory) tube is closed, but swallowing/yawning opens it to equalize pressure in the middle ear cavity with the atmospheric pressure. Enabling the eardrum to vibrate freely.
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What does the internal ear consist of?
Bony chambers called the "bony labyrinth".
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What are the subdivisions of the "bony labyrinth"?
The cochlea

The vestibule

The semicircular canals
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What are the two branches of the vestibular apparatus (the equilibrium receptors of the inner ear) responsible for?
One branch is responsible for monitoring static equilibrium , and the other monitors dynamic equilibrium.
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What is static (gravitational) equilibrium?
The special sense which interprets the position of the head permitting the CNS to maintain stability and posture when static.
Involves the movement of the head with respect to gravity.
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What is dynamic (rotational) equilibrium?
The special sense which interprets balance when moving.
Involves acceleration of the head in rotation, horizontal, and vertical movements.
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What is the spiral organ of corti?
The membranous labyrinth of the cochlea, which contains the hearing receptors.
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List some symptoms of equilibrium apparatus problems.
Involuntary rolling of the eyes

Nausea

Vertigo

An inability to stand erect
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What are olfactory receptors and where are they located?
These are receptors for the sense of smell, which are located in the superior aspect of each nasal cavity.
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What are the five basic taste sensations?
Sweet
Sour
Bitter
Salty
Umami (savoury)
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Other cards in this set

Card 2

Front

What are the accessory structures of the eye?

Back

Extrinsic eye muscles

Eyelids

Conjunctiva

Lacrimal apparatus

Card 3

Front

What is the function of the extrinsic eye muscles?

Back

Preview of the front of card 3

Card 4

Front

What is the function of the eyelids?

Back

Preview of the front of card 4

Card 5

Front

What is the function of the conjunctiva?

Back

Preview of the front of card 5
View more cards

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