Special Senses Review Guide

List the main structures (and their functions) of the outer ear.

"sound collection" Auricle = the ear iii. made up of the helix (rigid portion) and lobule (no cartilage) iv. directs sound waves into auditory canal (external auditory meatus) v. canal is short (2.5 cm) and curved and extends to the tympanic membrane vi. Canal is lined with hairs, sebaceous glands, and aprocrine sweat glands called ceruminous glands

e. Ciliary glands

AKA glands of Moll. - modified sweat glands between the eyelashes i. Secrete lipid that adds to the superficial layer of the tear film, slowing evaporation ii. Prone to infection, blockage of its duct with sebum and cell debris = Stye

What does "filling in" refer to in regards to the retina?

ASK

What are the two internal cavities of the eye and what is found in each?

Aqueous humor: watery Vitreous humor: gel-like

Explain why a decibel rating of a sound that jumps from 80 to 90 decibels is a big deal in terms of a mathematical relationship.

Because it's 10 times more intense. Not just 10 numbers, 10 times. (check the intensity!) Example: going from normal convo to vacuum cleaner is 100 times more intense.

What is the name of the structure that acts as the receptor organ for hearing?

Cochlear duct.

Hair cells in the Organ of Corti send action potentials to the temporal lobe via which nerve?

Cochlear nerve

What are cataracts?

Condition where lens has lost its transparency i. No more crystalline protein

Pink eye is an example of an infection of which accessory structure of the eye?

Conjunctiva: inflammation of the conjunctiva

Describe the physiology of the vestibule which enables us to detect gravity and linear acceleration.

Encloses saccule and utricle. Receptors provide sensations of gravity and linear acceleration.

Compare and contrast the locations of endolymph and perilymph in the inner ear.

Endolymph: Located deep within the temporal bone and posterior to the eye socket. Perilymph: fluid between the membranous labyrinth of the ear and bone that encloses it

Identify the name and function of the structure that connects the middle ear with the throat.

Eustachian tube (auditory tube) links middle ear to superiormost part of the throat

List the three different tunics of the eyeball (in order from most superficial to deep) - including the structures (and their functions) found in each tunic.

Fibourous: Cornea - transparent, allowing light to pass through Sclera - White connective tissue layer Vascular: iris Ciliary body- changes the shape of the lens Choroid- Vascular Layer separating the Fibrous Tunic and the Neural Layer (outermost portion of the retina) Neural: Lens- hard disc which creates the image

n. Suspensory ligaments

Fibrous strands that connect the lens of the eye to the cillary body.

The outermost tunic of the eye is the _? The middle tunic of the eye is the_? The innermost tunic of the eye is the _?

Fibrous tunic Vascular tunic Neural layer

Explain the normal flow of aqueous humor.

From the ciliary body processes into the post. chamber and passes between the lens and iris to enter the ant. chamber through the pupil. It flows downward close to the cornea where its cooler and upward near the lens where it is warmer.

Identify where high and low sound frequencies are received in the cochlea.

High: Oval Window (men tend to lose this) Low: Helicotrema (women tend to lose this)

What does the lens do to images as they pass on to the retina?

Image gets flipped upside down and backwards in the retina and the brain flips it right side up.

List AND describe the four functions of the vestibular nuclei.

Integrate sensory information about balance and equilibrium from both sides of head. Relay information from vestibular complex to cerebellum - Why? Relay information from vestibular complex to cerebral cortex - Why? Provide conscious sense of head position and movement - Why? Send commands to motor nuclei in brain stem and spinal cord - Why?

What is the difference between sound intensity and sound frequency? Show this on a graph!

Intensity (Volume) - Determined by number of hair cells stimulated. Frequency of sound - Determined by which part of cochlear duct is stimulated.

List AND describe the functions of the six extrinsic muscles of the eye. Make sure you know which cranial nerve innervates each of extrinsic eye muscle.

LR6 SO4 All others, CN III (Oculomotor) (Lateral Rectus -6; Superior Oblique -4 ) MIRRIOR!!

Describe the composition of a normal lens that allows light to pass through it virtually unobstructed?

Light refraction Focal point Focal distance

Diagram AND label the arrangement of the following regions/cells in the retina: a. Pigmented region b. Rods and cones c. Bipolar cells d. Ganglion cells

MIRROR!!

Diagram how the lens changes shape in order for a person to see an object up close vs. an object far away

MIRROR!!

Draw the effects of how light is focused in a person with an astigmatism

MIRROR!!

Make sure you really, really understand the order of cells that are stimulated when light reaches the retina!

MIRROR!!

Predict the effects of unilateral lesions to cranial nerves III, IV, or VI on the movement of the eyes.

MIRROR!!

Take some time and draw out a flowchart which illustrates the physiology of vision. Yes, this will take you some time. Make sure you relate old concepts like action potentials, second messenger systems, and inhibitory vs. excitatory postsynaptic potentials in your response. Yes, details are good to know, but broad concepts are sometimes more important. Don't blow through this question to quickly!

MIRROR!!

List the bones of the middle ear in order from lateral to medial, giving both the common name and anatomical names.

Malleus (hammer) - secured to the tympanic membrane. Incus (anvil)- connects other bones. Stapes (stirrup) - connects to the inner ear (via the oval window)

k. Meibomian glands

Modified sebaceous glands produce an oily secretion to lubricate the eye

Compare and contrast myopia and hyperopia.

Myopia: (near sided) Sees fine close up. Object focuses too early. Rating of 20/40 means that a person with normal vision can see at 40 feet what a myopic person can only see at 20 feet. Hyperopia: (far sided) Need glasses to see close up. Object focuses too late. Rating of 20/15 means that a person with normal vision can see at 15 feet what a hyperopic person can only see at 20 feet. iv. The hyperopic person will have trouble seeing up close though

What is the clinical significance of the optic disc (blind) spot? What structures are found in this region?

No photoreceptor cells are found in the optic disc

l. Optic disc

No photoreceptor cells are here. Also knowns as optic blind spot.

What is emmetropia?

Normal vision: 20/20

How does the structure, from the previous question number, assist in establishing the pressure in the middle ear?

Normally this is closed, but yawning and swallowing opens this tube briefly to equalize pressure

What is the collective name given to the three bones that make up the middle ear?

Ossicles: smallest bones in the body

Identify the three main regions of the human ear.

Outer Ear, Middle Ear, Outer Ear

Describe the functions of rods and cones.

Rods function: Allows for dim light vision and peripheral vision. Perception is in all grey tones. Cones function: Allows for detailed color vision.

Describe the detailed pathway of a sound wave as it travels through all three main regions of the ear with words AND a picture.

Scala vestibuli aka vestibular canal (terminates at oval window). Scala tympani aka tympanic canal (terminates at round window). Cochlear duct (contains spiral organ of Corti, which is the receptor organ).

Compare and contrast the two types of deafness discussed in class.

Sensorineural Deafness: Involves cochlea of any structures distal to the cochlea! Conduction deafness: Any structure before/in front of the cochlea

What is accommodation in regards to vision?

Shape of lens changes to focus imagine on retina

What is the name given to the thin, fibrous strands that connect the lens of the eye to the ciliary body? While you're at it, what is the function of the ciliary body?

Suspensory ligament Changes the shape of the lens

List the two major muscles of the middle ear? What is their purpose?

Tensor tympani muscle attaches the auditory tube. The stapedius muscle runs from the wall of the middle ear cavity and inserts into the stapes. These two muscles work together to prevent damage to the inner ear under extremely loud conditions.

What causes glaucoma and how does a doctor test for it?

Test: puff of air at the sclera will produce a measurable amount of deformation. Cause: If its drainage is blocked, pressure within the eye may increase and cause compression of the retina and optic nerve.

Which structure in the eye can be transplanted without fear of rejection? Why?

The cornea because it can repair itself easily

Where in the retina would you find a higher concentration of rods?

Towards the edges of the retina.

o. Vitreous humor

Vitreous humor - gel-like substance behind the lens (posterior cavity) keeping the eye from collapsing

Explain how the Weber and Rinne tests can be used to determine the different types of hearing loss.

Weber Test: hearing test using a tuning fork; distinguishes between conductive and sensorineural hearing loss Rinne Test: hearing test using a tuning fork; checks for differences in bone conduction and air conduction

b. Canal of Schlemm

a passageway that extends completely around the eye at the level of corneal limbus. It collects aqueous humor from the anterior chamber and delivers it into the episcleral blood vessels via aqueous veins.

Describe the functions of the following structures of the eye AND be able to label them on a diagram: a. Aqueous humor

a watery fluid produced in the posterior chamber, which circulates through the pupil into the anterior chamber (between the cornea and the lens). If its drainage is blocked, pressure within the eye may increase and cause compression of the retina and optic nerve - glaucoma

Compare and contrast focal point and focal distance.

a. Light Refraction i. Bending of light by cornea AND lens ii. Focal point (sweet side of the retina) 1. Specific point of intersection on retina iii. Focal distance (distance between lens and sweet spot) 1. Distance between center of lens and focal point

Which of these two types of deafness is often the result of prolonged exposure, perhaps over a lifetime, to loud music and is due to the gradual stiffening of the hair cells located in one of the major structures of the inner ear? Explain!

a. Sensorineural deafness: i. results from damage to the delicate neural structures at any point in the hearing pathway ii. This typically result from the gradual loss of the hearing receptor cells: iii. Throughout life iv. Single explosively loud noise v. Prolonged exposure to high-intensity sounds, which cause these cells to stiffen (IPODs) Conduction Deafness:

d. Ciliary body

changes shape of the lens. Smooth muscle attached to lens by suspensory ligament

m. Retina

contains millions of photoreceptors known as rods and cones. From the retina, signals travel towards the brain via the optic nerve.

Which two structures of the eye "bend" light?

cornea and lens

Draw AND label a cross section of the Organ of Corti, showing the relationships of all the membranes, canals, ducts etc

delivers sound

f. Conjunctiva

helps protect inner eye lid, upper and lower, small portion of the eyeball

g. Cornea

i. Cornea is lined with pain fibers (which is why contacts can be so tough to adjust to) ii. When cornea is touched, reflex blinking and increased lacrimal fluid secretion occur iii. Since cornea has no blood supply it is the only tissue that can be transplanted with very little fear of rejection (does not have contact with immune system) iv. transparent, allowing light to pass through 1. Repairs itself easily 2. The only human tissue that can be transplanted without fear of rejection

j. Lens

i. Lens fibers 1. Cells in interior of lens 2. No nuclei or organelles 3. Filled with crystallins, which provide clarity and focusing power to lens ii. Cataract 1. Condition in which lens has lost its transparency

h. Iris

i. Though it seems to appear in many colors (Iris means rainbow), it actually only contains brown pigment ii. When an iris contains a lot of pigment, the eyes appear brown or black iii. If the amount of pigment is small, the short wavelengths of light are scattered from the unpigmented parts of the iris, and eyes appear blue, green, or gray iv. Why, then, do newborn babies often appear to have gray or blue eyes?

i. Lacrimal glands (and the other structures of the lacrimal apparatus)

i. releases fluid that contains mucus, antibodies, and lysozyme (a bacteria-destroying enzyme) ii. Lacrimal gland is located superior and lateral to the eye iii. It releases fluid, which is spread over eye by blinking, and drains via the medial lacrimal canals iv. Consists of the: 1. Lacrimal Gland; tear gland 2. Lacrimal Gland Ducts 3. Lacrimal Puncta Lacrimal Sac

Have a general idea of where an action potential goes from the cochlear branch of the vestbulocochlear nerve into other regions of the brain to be processed.

inner ear

What exactly is color blindness in terms of cone pigments?

is the result of lack of one cone type

What is the name given to the structure within the eye that has a dense concentration of cones? Which region of the eye consists of cones only?

macula fovea centralis

c. Choroid

nourishes retina and prevents light scattering within the eye

Describe the pathway that impulses take after they leave the eye. Make sure to trace the fibers involved in both the left AND right FIELDS OF VISION.

optic nerves in the back of the head cross

Explain, in terms of bleaching, why it takes some time for your eyes to adjust to a dark movie theater when coming from the bright outdoors.

picture

Describe the physiology of the semicircular canals which enable us to detect rotational motion.

tells your brain that where you are in space, keeps equilibrium, and tells brain what motion your head is doing

What's another name for the eardrum?

tympanic membrane or myringa