Special Senses ppt

April 23, 2012 | By | Reply More

Special Senses ppt

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Special  Senses
Taste

Smell

Vision

Hearing

Balance

The  Special Senses

respond to chemicals in  an aqueous solution

food dissolved in saliva

airborne chemicals dissolved  in mucous membrane

Taste and smell are  involved with specific receptor cells called chemoreceptors

Taste

The  Tongue

Taste  Buds

Circumvallate Papilla

Filiform

papilla

Fungiform

papilla

Connective  tissue

Tongue  epithelium

Taste Buds

Taste Buds

Salty-  metallic ions

Sweet- sugar

Sour- H+

Bitter- alkaloid

Why are they  important?

Five Basic  Tastes

Umami- savory/meaty

Experiment

Dry tongue  with a paper towel and place a little  sugar on surface.

What do you  taste?

Gustatory  pathway

Facial  nerve (afferent) 2/3 anterior portion of tongue

Glossophyngeal posterior 1/3 of tongue

Vagus nerve- few taste buds on epiglottis an pharynx

These afferent fibers synapse in medullathalamus gustatory cortex in parietal lobes and fibers to hypothalamus in limbic system

Taste triggers reflex involved in digestion; causes an increase of saliva in mouth (amylase) and gastric juice in stomach

acids cause strong salivary  reflex

bad tasting food causes  gagging  or reflexive vomiting

taste can change over  time

taste is 80% smell

Mouth also  contains:

Thermoreceptors

Mechanoreceptors

Nociceptors- sensitive nerve  fibers that are aware of painful stimuli

Smell  not as good as  animals; however, some  people are wine tasters,  perfumers

If  you smell a particular  odor all day, you  won’t recognize its  presence, you become  accustomed, ex. garbage  men

Old  people lose sense of  smell- lots of perfume

Humans  can distinguish 10,000  or so chemicals

What  we really smell is  pain: ex. chili, ammonia,  menthol (cold)

Specific  chemicals cause specific  patterns of neurons  to fire
Olfaction

Figure  15.21a

Olfactory  tract

Olfactory  bulb

(a)

Nasal

conchae

Route  of

inhaled  air

Olfactory

epithelium

Olfaction

Figure  15.21a

Mitral  cell (output cell)

Olfactory

gland

Olfactory

tract

Olfactory

epithelium

Filaments  of olfactory nerve

Cribriform  plate of ethmoid bone

Lamina  propria connective tissue

Basal  cell

Supporting  cell

Dendrite

Olfactory  cilia

Olfactory  bulb

Glomeruli

Axon

Olfactory  receptor cell

Mucus

Route  of inhaled air

containing  odor molecules

(b)

Olfaction

Cortical Regions Associated  with Olfactory Information

Olfactory  auras- prior to epileptic  attack

May  be genetic or a  cold (mucus), allergy,  zinc deficiency

loss  of sense of smell

Lose  sense of smelllose taste

Uncinate- olfactory hallucinations; may be psychological ex. rotting meat smell

Anosmias

sclera

iris

pupil

tear

drainage canal

The Eye

cornea

Medial commisure

lateral commisure

palpabre

palpabre

Lacrimal caruncle

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