Chemical Senses (Taste and Smell)

• Smell and Taste receptors both respond to the presence of chemical substances.

Smell (Olfaction)

Stimulus: airborne molecules or vapors

 

Anatomy:

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• olfactory receptors respond to a variety of odors, and the overall pattern of responding results in the perception of a particular scent

 

 

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• receptors are linked directly to brain (don't go through spinal cord and brain stem) linked to olfactory cortex & limbic system (amygdala).

• memory:

 

 

 

 

• emotion:

 

 

 

 

Taste (Gustation) -

Stimulus: any substance/chemical that dissolves in saliva.

• 5 basic taste categories: sweet, sour, salty, bitter, and "umami" (Japanese word for meaty or savory produced by MSG)

 

Anatomy:

• tongue is a muscle covered with mucous membrane containing little bumps (papillae).

 

 

 

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• most taste buds respond to multiple substances such as both acids and salts, but respond maximally well to only one type.

 

 

 

• Perception of Smell and Taste senses are intertwined

 

 

 

Taste Thresholds and Tongue Regions: all areas on tongue respond to all flavors (except middle which is like the "blind spot")--but certain flavors are more noticeable on certain areas.

• sides of tongue

 

• front of tongue

 

 

• soft palate (roof of mouth in back)

 

 

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Cutaneous Perception

Touch:

 

 

 

Density of Nerve Fibers:

 

 

 

 

Two-point thresholds: the smallest distance of two separate points of stimulation on skin that just produces the perception of 2 distinct points.

 

Touch linked with kinesthesis and proprioception.

Kinesthesis:

 

 

 

Proprioception: