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The Chemical Senses

The Chemical Senses. Gustatory. All have Chemoreceptors. In order for a sensation to be registered by the individual … the chemical (aroma or taste sensation) must be dissolved in solution. Mucus Saliva. Gustatory Pathway.

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The Chemical Senses

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  1. The Chemical Senses Gustatory

  2. All have Chemoreceptors • In order for a sensation to be registered by the individual … the chemical (aroma or taste sensation) must be dissolved in solution. • Mucus • Saliva

  3. Gustatory Pathway • Most all taste receptors are located on the tongue in raised structures called Papillae

  4. Gustatory Pathway • There are a few receptors in the lining of the cheek and soft pallet

  5. Gustatory Pathway • Epithelial supporting cells forming the taste bud have microvilli called Gustatory Hairs connected directly to dendrites • Gustatory cells are shed and replaced every 7 to 10 days

  6. Gustatory Pathway • The act of tasting evokes reflexes in the digestive system. • Increase of saliva production • Increase of gastric juices release

  7. Gustatory Pathway • The digestive process begins in the mouth ?

  8. Gustatory Pathway • Taste is approximately 80% Olfactory

  9. Gustatory Pathway • The Hot sensation of peppers excite pain receptors

  10. Gustatory Pathway • Thermo receptors, mechanoreceptors, and nociceptors stimulation of these receptor cites may enhance or detract from the quality of the sensation

  11. Gustatory Pathway • There are three major types of papillae: 1. Filiform: no taste buds found

  12. Gustatory Pathway 2. Fungiform: Mushroom shaped All over the tongue Highest concentration found at the tip and sides Taste buds are found on the top of the the papillae

  13. Gustatory Pathway 3. Circumvallates: Largest and least numerous (7-12) form a “V” at the back of the tongue The taste buds are located on the sides of these papillae

  14. Taste • Many substances produce several sensations, thus exciting many different taste buds. Many of the taste buds will respond to each of the following qualities.

  15. Taste • Bitter: • Produced by alkaloids (hydroxide ions) generally found on the back of the tongue

  16. Taste • Salt: • Metal ions • Appears to be evenly distributed

  17. Taste • Sour • Produced by hydrogen ions • Generally found on the sides of the tongue

  18. Taste • Sweet: • Sugars and some amino acids • Generally found on the tip of the tongue

  19. Gustatory Pathway • Damage to: • Glossopharyngeal nerve – bitter taste diminished (Cranial Nerve Number?) • Facial nerve – sweet, sour, salty taste diminished (Cranial Nerve Number?)

  20. The Chemical Senses Olfactory

  21. Olfactory Pathway • Receptors are found on the roof of the nasal cavity - bilaterally • There are approximately 5 million olfactory receptor cells

  22. Olfactory Pathway • Collectively, these receptors are referred to as : Olfactory epithelium

  23. Olfactory Pathway • Regulation of air flow: • To reduce the stimulation of receptors: • Inhale slowly through your nose • Or inhale through your mouth • What bone structures allow for the air being channeled?

  24. Olfactory Pathway • Regulation of air flow: • To heighten the stimulation of receptors: • Inhale quickly through your nose with your mouth closed

  25. Olfactory Pathway • The sensation of an Aroma is stimulated by the excitation of olfactory hairs protruding from the olfactory epithelium in a field of mucosa manufactured by glands in the lamina propria

  26. Olfactory Pathway • In order for an aroma to be detected, it must be volatile • 1. the aroma must be in a gaseous state • 2. the aroma must be water soluble • Why can we not smell natural gas?

  27. Olfactory Pathway • Acclamation • A process where the sense of olfaction adapts quickly • CNS response is not a diminished response from the receptor group

  28. Olfactory Pathway Olfactory neurons are quite different from other neurons: they are replaced approximately every 60 days by a process called basal cell differentiation in the olfactory epithelium

  29. Compare: • Gustatory paths separates four distinct chemical sensations • Olfactory paths distinguish tens of thousands of different sensations with only 15 to 30 different types of receptors

  30. Compare: • The sensation of smell requires the stimulation of ALL receptors in the nasal concha prior to detection • The sense of taste? • Each taste is independent of the other and does not require the other receptors to be stimulated

  31. Compare: • The irritating response of strong aromas such as ammonia stimulates pain receptors What is the response and why is it important? • Pain receptor stimulation in the mouth provides us with the sensation of “hot” (spicy). How do you deal with food that is too spicy?

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