1. Chapter 7: The Sensory Systems
Lesson 7.3
Smell and Taste

2. Smell and Taste olfactory sense (sense of smell)
injuries and disease of the nose
gustatory sense (sense of taste)
disorders of the tongue

3. Olfactory Sense olfactory region – dime size area in nasal cavity
olfactory receptor cells – can get covered in mucus when you have a cold
olfactory hairs – neurons covered in thin layer of mucus
Odor molecules land on hairs and dissolve in the mucus
Once dissolved they stimulate receptors cells
olfactory filaments send the impulses through the olfactory nerve which then collect in the olfactory bulb (thickened area of the nerve) and finally to he olfactory center in the cortex
Since olfactory nerve passes through the limbic system (emotions), a smell my trigger a positive or negative emotion.

4. Olfactory Sense

5. Injuries and Disorders of the Nose
rhinitis
inflammation of nasal membrane (common cold)
Irritation (infection, allergy) causes the release of histamines which cause congestion and drainage
Treatment needs to remove the irritation and use antihistamines to counter act the effect of the histamines
septum problems (slightly off center is normal)
deviated septum (large shift of the cartilage to one side)
Perforated septum is a hole due to damage
Damage from toxic fumes
Damage from drug abuse

6. Gustatory Sense Taste buds – about 10,000 sensory receptors Tasting
Located on lips, top and back of mouth, most on tongue
Papillae on the tongue (bumps) = gustatory cells
Gustatory cells send tiny hairs (gustatory hairs) up through taste pores in the tongue
Tasting
When eating food, it mixes with saliva and dissolves into compounds called tastants
The tastants stimulate the hairs which send impulses to the brain
Three cranial nerves are responsible for taste:
Facial nerve
Glossopharyngeal nerve
Vagus nerve

7. Gustatory Sense

8. Gustatory Sense Individual taste buds have 50 – 100 gustatory cells
Each gustatory cell responds to only one of the 5 basic tastes:
Sweet
Salty
Sour
Bitter
Umami – taste of beef and monosodium glutamate, a seasoning in food for taste
Flavors detected are also influenced (75-90%) by smell, texture, and temperature. Humans can detect approximately 10,000 flavors.
Spicy foods stimulate pain receptors – some like it, some do not

9. Disorders of the Tongue
Infection – treated with antibiotics
severely bitten tongue during a traumatic accident
tongue piercing
Injury – tongue heals more quickly than any other part of the body.
hairy tongue - abnormal growth of gustatory hairs
Bad hygiene, medications, coffee or tea drinking, tobacco use, radiation treatments
brush the tongue as well as the teeth
burning mouth syndrome – burning sensation, metallic taste, chronic pain
Many causes, treatments are tailored to the underlying disorder
Over time it can cause depression and anxiety