Chapter 7: The Sensory Systems Lesson 7.3 Smell and Taste

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

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.

Olfactory Sense

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

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

Gustatory Sense

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

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