1. Taste and Smell
Chemoreception

2. Chemoreceptors Receptors for taste and smell
Respond to many of the same stimuli
Chemicals in solution
Receptors for Taste and Smell Compliment each other

3. Page 150 of notes
#1-3
Vagus nerve

4. Circumvallate Papillae

6. Sweet Receptors respond to substances
like Sugar, Saccharine, and some Amino
Acids (Energy-Rich Substances)
*The common factor is the hydroxyl group
(-OH) attached to these substances
Sour Receptors respond to hydrogen
(H+) ions, or the acidity of the solution
Bitter Receptors respond to alkaloids (bases)
*Common factor is the hydroxide (OH-) ions
*Since many natural poisons and spoiled foods are bitter, our dislike for bitterness is protective.
Salty Receptors respond to metal ions (+) in soln (Electrolytes)

8. Spicy foods actually excite the pain receptors in the mouth
Taste Buds
Specific receptors for the
sense of taste
*~10,000 taste buds
*mostly on tongue
*some on soft palate and
inner surface of cheek
Spicy foods actually excite the pain receptors in the mouth

9. *Surround gustatory cells
Supporting Cells
*Surround gustatory cells
Microvilli-
Gustatory Hairs
*Protrude through
taste pore
Cranial Nerve
Fibers
Taste Pore
Connective
Tissue
Gustatory Cells
*Respond to chemicals
in saliva

11. Taste Disorders
Hypogeusia: A reduced ability to taste things (to taste sweet, sour, bitter, or salty substances).
Ageusia: An inability to taste sweet, sour, bitter, or salty substances.
Dysgeusia: A condition in which a foul, salty, rancid, or metallic taste sensation will persist in the mouth

12. Causes of Taste Disorders
Some people are born with taste disorders but most develop after an injury or illness.
Upper respiratory and middle ear infections
Radiation therapy for cancers of the head and neck
Exposure to certain chemicals, such as insecticides and some medications, including some common antibiotics and antihistamines
Head injury
Some surgeries to the ENT (e.g., third molar—wisdom tooth—extraction and middle ear surgery)
Poor oral hygiene and dental problems

13. Sense-Sational Facts
We have almost 10,000 taste buds inside our mouths; even on the roofs of our mouths.
Insects have the most highly developed sense of taste. They have taste organs on their feet, antennae, and mouthparts.
Fish can taste with their fins and tail as well as their mouth.
In general, girls have more taste buds than boys.
Taste is the weakest of the five senses.

14. Olfactory Bulb
*Size of a postage stamp
*Found on roof of nasal cavity

16. Fibers of Olfactory
Tract
Olfactory Bulb
Cribriform Plate of the
Ethmoid Bone
Olfactory
Nerve Fibers
Olfactory Neurons
(Receptor Cells)
Supporting
Cells
*epithelium
Olfactory Hairs
*long cilia
*protrude from nasal epithelium
*continually bathed by mucus to
dissolve chemicals

17. Olfactory Bulb
Fibers of Olfactory
Tract
Cribriform Plate of the Ethmoid
Bone
Olfactory
Nerve Fibers
Olfactory Neurons (Receptor Cells)
Supporting
Cells
*epithelium
Olfactory Hairs
*long cilia
*protrude from nasal epthelium
*continually bathed by mucus to
dissolve chemicals

18. Olfactory Disorders : -osmias
Most result from head injuries
Some result from nasal inflammation
(cold, allergy, smoking)
Aging

19. Anosmia - Inability to detect odors
Hyposmia - Decreased ability to detect odors
Dysosmia - Distorted identification of smell
Parosmia - Altered perception of smell in the presence of an odor, usually unpleasant
Phantosmia – Perception of smell without an odor present
Agnosmia - Inability to classify or contrast odors, although able to detect odors

20. 1/3 of all disorders are caused by a Zn deficiency
Cure is almost instant once the right form of Zn is prescribed.

21. Some brain disorders can destroy the sense of smell – or minimize it.
Olfactory auras (hallucinations) are experienced by epileptics just before a seizure