Transcript Slide 8.39a
Special Senses: Taste and
Smell
Ch. 8c
Chemical Senses – Taste and
Smell
Both senses use chemoreceptors
Stimulated by chemicals in solution
Taste has four types of receptors
Smell can differentiate a large range of
chemicals
Both senses complement each other
and respond to many of the same
stimuli
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 8.34
Olfaction – The Sense of Smell
Olfactory receptors are in the roof of the
nasal cavity
Neurons with long cilia
Chemicals must be dissolved in mucus for
detection
Impulses are transmitted via the
olfactory nerve
Interpretation of smells is made in the
cortex
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 8.35
Olfactory Epithelium
Figure 8.17
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 8.36
Quick Quiz 1 of 2
• What are the receptors for smell called?
• What nerve carries smell impulses to
the brain?
The Sense of Taste
Taste buds
house the
receptor
organs
Location of
taste buds
Most are on
the tongue
Soft palate
Cheeks
Figure 8.18a, b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 8.37
The Tongue and Taste
The tongue is covered with projections
called papillae
Filiform papillae – sharp with no taste buds
Fungifiorm papillae – rounded with taste
buds
Circumvallate papillae – large papillae with
taste buds
Taste buds are found on the sides of
papillae
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 8.38
Structure of Taste Buds
Gustatory cells are the receptors
Have gustatory hairs (long microvilli)
Hairs are stimulated by chemicals
dissolved in saliva
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
8.39a
Structure of Taste Buds
Impulses are carried to the gustatory
complex by several cranial nerves
because taste buds are found in
different areas
Facial nerve
Glossopharyngeal nerve
Vagus nerve
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
8.39b
Anatomy of Taste Buds
Figure 8.18
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Slide 8.40
Taste Sensations
Sweet receptors: tip of tongue
Sugars
Saccharine
Some amino acids
Sour receptors: back sides of tongue
Acids
Bitter receptors: Back of tongue
Alkaloids
Salty receptors: Frong sides of tongue
Metal ions
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 8.41
Quick Quiz 2 of 2
• What are the receptor cells called that
carry taste sensations to the brain?
• On what part of your tongue to you
sense sweet?