Smell and Taste

1. Smell and Taste AmberScholz, Madeline Trimble, and Jesse Weisman Pitts

2. Essential Questions • How do we smell? • What is the sense of smell used for? • What is responsible for our sense of smell? Where are they located in our brain? • Is it possible to taste something that you smell? • What are the four main qualities of taste? • What are some smell and taste deficiencies?

3. Smell • Olfaction- The sense of smell • Chain of biochemical events- • Odors from the outside interact with receptor proteins that are associated with specialized hairs in the nose. • These hairs relay information about the stimulus to the brain’s olfactory bulb • Olfactory bulbs- Found on the underside of the brain, just below the frontal lobe • Nasal cavities – lie between the floor of the brain and the roof of the mouth and extend from the face to the pharynx; filter inhaled air and sense odors

4. Smell senses are not relayed through the thalamus like most senses • This allows us to assume that smell evolved earlier then other senses • Smell is often associated with memory

5. Why do we smell? • Smell was originally a system in primitive organisms for finding food • Humans use smell with taste to seek and sample food. • In animals smell is used for communication • Pheromones- Chemical signals released by organisms to communicate with other organisms of the same species. • Often used as sexual attractants.

6. Taste • Gustation- Sense of taste • Based on chemistry • The sense of taste and smell work together • The taste of something may actually be the smell • Taste buds – clusters of taste cells found on the surface of the tongue, throat, and roof of mouth representing all taste sensations • Papillae – small, round or cone-shaped protuberances on the top of the tongue that contain taste buds • Taste preference – condition in which animals and humans choose flavors or food over others • Food aversions – occurs after illness; condition in which recently ill person no longer enjoys a certain food even though it did not cause the illness

7. Four Main Qualities • Taste has four main qualities that are found in different regions- • Sweet • Sour • Bitter • Salty

8. Parts of the Tongue • The tip of the tongue is most sensitive to sweet and sour • Bitterness is experienced in the back of the tongue

9. Smell and Taste Deficiencies • Generally difficult to diagnose due to lack of in depth knowledge and understanding • The primary symptom of most is an alteration in taste or smell • Deficiencies in taste and smell may cause anxiety, depression, and nutritional problems because of decreased enjoyment of food • Can be life-threatening due to inability to detect smoke in a fire or identify spoiled food

10. Smell Disorders • Caused by disturbances in the nasal or sinus cavities, allergens, hormonal disturbances, viral infections, dental problems, prolonged exposure to certain chemicals, tobacco smoking, and radiation therapy • Disorders (end in “–osmia”) • Anosmia – inability to detect odors • Hyposmia– decreased ability to detect odors • Dysosmia – distorted identification of smells • Parosmia – altered perception of smell in the presence of an odor, typically unpleasant • Phantosmia – perception of smell without an odor present • Agnosia – inability to classify or contrast odors • Symptoms are closely associated with taste deficiencies

11. Taste Disorders • Caused by oral, middle ear, or respiratory infections, poor oral hygiene, aging (taste bud loss), heredity, endocrine disorders, nerve damage from multiple sclerosis and facial paralysis, and thalamic lesions • Disorders (end in “– geusia”) • Ageusia – inability to detect tastes • Hypogeusia – reduced ability to taste • Dysgeusia – condition in which a strong salty, rancid, or metallic flavor lingers in mouth • Nontaster – a person who has a decreased sense of taste • Supertaster – a person who experiences the sense of taste with far greater intensity than average