Sensory Organs

What are the special senses?

smell (olfaction), pheromone detection, taste (gustation), vision, hearing and balance, touch

What organ is responsible for smell?

nose

What organ is responsible for pheromone detection?

vomeronasal organ

What organ is responsible for vision?

eye

What organ is responsible for taste?

tongue

What organ is responsible for hearing and balance?

ear

How is smell detected?

by special cells located on the mucosa of the nasal cavity

Olfactory Epithelium

mucosa of the nasal cavity that contains sensory receptors

Where are the neurons associated with smell?

pass from the epithelial surface to the olfactory bulb in the cranium after passing through the bony cribriform plate

What is olfactory epithelium held by?

supporting cells that secrete a lipid-rich fluid mucus that entrap chemicals

In olfaction, how do scents reach the nervous system?

odorants dissolve in the fluid and reach the sensory receptors; signal transduction takes place through the neurons

Chemically unrelated compounds (can/cannot) smell similar.

can

How many more olfaction receptors do dogs have than people?

70% more

Where is the vomeronasal/Jacobson's organ found?

on the floor of the nasal cavity

What is the vomeronasal organ?

blind ending caudal sacs (bilateral); duct links nasal and oral cavities caudal to incisor teeth

What is the Flehmen reaction?

animals pump air in and out

The vomeronasal organ is important in _____ behavio.

sexual and social

Where are taste sensory receptors located?

on the tongue mucosa

How do taste signals get to the brain?

sensory neurons

What is another name for taste?

gustation

How is each form of taste detected?

receptor cells have a single receptor type, each receptor can only detect one form of taste

What do gustatory inputs link directly to?

centers controlling ingestion or food avoidance, salivation, insulin release, diuresis when water in pharynx

What is aroma?

the combined effect of neural inputs from the sense of smell and taste

What does the transparent media in the eye do?

conduct light to stimulate photoreceptor cells

What parts of the eye are responsible for transparent media? What do they do?

cornea, aqueous humor, lens, vitreous humor; direct and converge light on the photoreceptor cells on the retina

What parts of the eye are responsible for non-transparent media? What do they do?

choroid, uvea, sclera; support transparent media

What parts of the eye are responsible for the photosensitive layer? What do they do?

retina made up of rod and cone receptor cells; cones for daylight vision and rods for night vision

What parts of the eye are responsible for light splitting chemical compound? What do they do?

rhodopsin in cones and rods; triggers signal reduction through optic nerve, the signals are transmitted to the optic cortex of the brain

Light from images travel through about _____ layers of cells before reaching the cells of the retina.

10

What 3 parts make up the ear?

outer ear, middle ear, inner ear

What parts of the ear are responsible for sound detection?

outer, middle, inner

What part(s) of the ear are responsible for balance and motion?

inner ear

How does the outer ear help with sound detection?

sound collected from external auditory canal to the tympanic canal and tympanic membrane

How does the middle ear help with sound detection?

maleus, incus, and stapes conduct sound to the oval window; also connected by eustachian tube to nasopharynx

How does the inner ear help with sound detection?

oval window transmit waves to the cochlea which contain sensory receptor cells known as Hair Cells from where signals are transmitted to the brain through CN VIII

How does the inner ear contribute to balance and motion?

semicircular canals detect angular movement, while the saccule and utricle (maculae) detect linear acceleration

In the inner ear, what does the cochlea contribute to?

hearing

In the inner ear, what does the semi-circular canal contribute to?

angular movement

In the inner ear, what do the saccule and utricle contribute to?

linear movement

What are the parts of the cochlea?

basilar membrane, organ of corti, hair cells, CN VIII

How does the cochlea contribute to hearing?

fluid movement caused by sound vibration on oval window cause standing wave to travel in cochlea canals, causing hair cells on basilar membrane to bend against tectorial membrane; signals are generated and sent to brain

What do hair cells do in the cochlea?

bend due to fluid movement in the cochlear and discharge electrical signals to the brain

What are the parts of the semi-circular canal in the ear?

cupula, hair cells, CN VIII

How does the semi-circular canal contribute to balance?

hair cells of the cupula bend due to fluid movement and discharge electrical signals to the brain

What are the parts of the Saccule and Utricle?

utricle and saccule, hair cells, CN VII

How do the saccule and utricle contribute to detection of linear acceleration?

hair cells bend due to fluid movement caused by inertia in the saccule and utricle, causing them to discharge electrical signals to the brain

Because the saccule and utricle are in a right angle, what can they do?

can only detect linear movement in one plane; discriminate between forms of linear movements

What is olfaction?

sense of smell

What nerve is responsible for olfaction?

olfactory nerve

What is gustation?

sense of taste

What are the two functions of the ear?

hearing and balance

What is the function of the nose?

smell/olfaction

What is the function of the vomeronasal organ?

pheromone detection

What is the function of the tongue?

taste/gustation

What is the function of the eye?

vision

What allows air to be warmed before entering the lungs?

lots of vascularization and capillary network in the olfactory epithelium

What is the cribiform plate?

bony plate between nasal and cranial cavities

What is the structure of the cribiform plate like?

perforated with small holes

Why are there small holes in the cribiform plate?

so special nerve fibers can pass through to communicate with the olfactory bulb

Why are support cells in the olfactory epithelium important?

to produce mucus that traps chemicals in inhaled air

How are different smells detected?

chemicals dissolve in the mucus to reach sensory receptors, the signal is sent to the brain; different concentrations of odorants determine how it smells

Each smell/taste receptor can detect how many forms of smell/taste?

only one

When something is in the mouth, what is stimulated?

salivary glands

What layers does light go through in the eye?

cornea, aqueous humor, pupil, hole in iris, vitreous humor

What is the texture difference between aqueous and vitreous humor?

aqueous is more water-like; vitreous is gelatinous and semi-solid

What nerve brings info to the brain for processing visual signals?

CN II

What do rods and cones contain? What does this chemical compound cause when it undergoes conformation?

rhodopsin; signal transduction to optic nerve that goes to the brain

How many layers of cells are in the retina?

10

True or false: light hits photoreceptor cells directly.

false, passes through other cell layers

What cells are contained in the fovea?

rods and cones

What is the function of the pinna (outer ear)?

funneling sound

What parts of the ear make up the outer ear?

pinna, concha, ear canal

What parts of the ear are in the middle ear?

tympanic membrane, malleus, incus, stapes

What cranial nerve transmits signals from the ear?

CN VIII

What part of the inner ear detects movement?

semicircular canals

What part of the inner ear detects linear acceleration?

saccule and utricle

How does deafness occur?

hair cells in the cochlea are damaged

What is the structure of the cupula like?

full of hear cells with gelatinous structure on top

What is the function of the cupula?

sends signal of which side of head is moving

How does the cupula detect motion?

when the fluid moves, it pushes the gelatin on the hair cells

How do the utricle and saccule detect movement?

hair cells with crystals on top; when move horizontally, crystals shift, causing the cilia to move