Smell and TasteAmber Scholz, Madeline Trimble, and

Jesse Weisman Pitts

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?

Smell• Olfaction- The sense of smell• Chain of biochemical events-

1. Odors from the outside interact with receptor proteins that are associated with specialized hairs in the nose.

2. 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

• 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

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.

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

Four Main Qualities• Taste has four main qualities that are

found in different regions- 1. Sweet2. Sour3. Bitter4. Salty

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

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

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

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