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Olfaction

Gustation

The Special Senses

Olfaction

Figure 15.21a

Olfactory tract

Olfactory bulb

(a)

Nasal

conchae

Route of

inhaled air

Olfactory

epithelium Olfaction

Cilia

Olfactory epithelium of

nasal cavity

Olfactory bulb

Neurons in olfactory tract

Temporal lobe

Cribriform plate

Olfactory neuron

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)

Gustation

• Taste buds are receptors

– Chemical stimulation nerve impulse to parietal lobe

– Salty, sweet, bitter, sour and umami

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Gustation

• Most of our sense of taste comes from smell

• Let’s do an experiment…

Figure 15.23a

(a) Taste buds are associated with fungiform,

foliate, and circumvallate (vallate) papillae.

Fungiform papillae

Epiglottis

Palatine tonsil

Foliate papillae

Lingual tonsil

Circumvallate papillae

Figure 15.23b

(b) Enlarged section of a

circumvallate papilla.

Taste bud

Circumvallate papilla

Figure 15.23c

Taste fibers

of cranial

nerve

Connective

tissue

Gustatory

(taste) cells

Taste

pore

Gustatory

hair

Stratified

squamous

epithelium

of tongue

(c) Enlarged view of a taste bud.

Basal

cells

1) Encapsulated nerve endings

a) Tactile (Meissner’s) corpuscles

- Mechanoreceptor that senses fine touch

- Concentrated in fingertips, tongue, lips

b) Lamellated (Pacinian) corpuscles

- Respond to heavier degrees of pressure

- Deep within skin, some visceral organs

c) Ruffini’s corpuscles

- Stretch in connective tissue

d) Muscle spindles and Golgi tendon organs

- Tension and position of muscles and joints

More Special Senses:

Cutaneous ReceptorsReceptors

Lamellated/Pacinian

Ruffini’s

Golgi Tendon

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2) Free nerve endings

- Neurons that branch between other cells

throughout the body

- Pain and temperature

Cutaneous Receptors

• Visceral and somatic pain

– Visceral pain is difficult to localize referred pain

• Somatosensory cortex doesn’t know where the heart is,

so it produces shoulder pain

– Phantom pain

• Intact sensory neurons

produce pain in amputated

limbs

Pain