Ch 21 Special Senses

• Olfaction=


  Sense of smell
• 3 types of cells in olfactory epithelium (located in nasal cavity)

  •receptor cells

  •supporting cells

  •basal cells
• Olfactory Receptor Cells (1st order)


  •interact w/ odorants

  •nonmotile cilia w/receptors

  •axons thru cribriform plate
• Supporting cells


  •Columnar epithelial crlls

  •Physical support, nourishment electrical insulation, provide proteins, detoxification
• Basal cells

  •stem cells producing new receptor cells

  •only last~1 month
• Olfactory glands produce 


  Mucus
• Mucus 


  -moistens epithelial surface

  -dissolves odorants
• Cilia are covered by 


  Plasma membrane & contain olfactory receptors
• Which type of the following types of cell in olfactory epithelium contains the axon that is in CN I which penetrates the cribriform plate?

  Olfactory receptor cells
• Taste=


  Gustation
• 5 types of receptors for taste

  Salty

  Sour

  Sweet

  Bitter

  Unami
• Salty=


  Na+
• Sour=


  H+
• Unami-

  meat/savory
• We have 10k taste buds


  •tongue

  •soft palate

  •pharynx

  •epiglottis

  •lungs
• All taste buds have have each type of

  Taste receptor
• Chemicals in food can stimulate olfactory receptor, which increase


  Sensation
• 3 types of epithelial cells making a taste bud

  1.Supporting cell

  2.Gustatory receptor cell

  3.Basal cells
• Supporting cell 


  •surrounds 50 receptor cells

  •contain microvilli
• Gustatory receptor cell


  •microvilli (gustatory hairs)

  •receptors define taste

  •signal sensory neurons

  •~10 day life span
• Basal Cells


  •produce supporting cells

  •supporting cells develop into receptor cells
• Papillae=


  Raised elevations housing taste buds
• 3 types of papillae

  Vallate papillae

  Fungiform papillae

  Foliate papillae
• Vallate papillae


  •”raised edge surrounding a depression”

  •posterior tongue, inverted ’V’

  •12, each holding 300-500 taste bud
• Fungiform papillae


  •mushroom shaped

  •cover entire tongue

  •each hold 5 taste buds
• Foliate papillae


  •lateral tongue

  •degenerate in early childhood
• Filiform papillae are structural only-


  No taste
• Filiform papillae 


  •cover entire tongue

  •tactile receptors

  •increase friction b/w food & tongue
• Basal cells turn into supporting cells which then turn into

  Gustatory receptor cells
• How is CN V involved w the tongue?

  Anterior 2/3 of tongue-pain, temp, & touch
• Palpebrae=


  Eyelids
• Tarsal plate/glands:


  Oily fluids
• Conjuctiva:


  NKSSE (non-keratinized stratified squamous epithelium)
• Eyelashes/eyebrows:


  Sebaceous ciliary glands at base
• 6 Extrinsic eye ms’s

  •CN III-sup/inf/med rectus

  -inf oblique

  •CN IV-superior oblique

  •CN VI-lateral rectus
• Lacrimal gland 


  •lateral superior to eye

  •interacted by CN VII (facial) parasympathetic
• Lacrimal fluid=


  Watery solution+salts+mucus+lysozyme
• Lysozyme destroys 


  Bacteria to keep eye clean
• Lacrimal fluid has 


  Dif types of oily fluid from tarsal gland
• Each gland produces~


  1 mL per day