The Chemical Senses Gustatory

All have Chemoreceptors In order for a sensation to be registered by the individual … the chemical (aroma or taste sensation) must be dissolved in solution. Mucus Saliva

Gustatory Pathway Most all taste receptors are located on the tongue in raised structures called Papillae

Gustatory Pathway There are a few receptors in the lining of the cheek and soft pallet

Gustatory Pathway Epithelial supporting cells forming the taste bud have microvilli called Gustatory Hairs connected directly to dendrites Gustatory cells are shed and replaced every 7 to 10 days

Gustatory Pathway The act of tasting evokes reflexes in the digestive system. Increase of saliva production Increase of gastric juices release

Gustatory Pathway The digestive process begins in the mouth ?

Gustatory Pathway Taste is approximately 80% Olfactory

Gustatory Pathway The Hot sensation of peppers excite pain receptors

Gustatory Pathway Thermo receptors, mechanoreceptors, and nociceptors stimulation of these receptor cites may enhance or detract from the quality of the sensation

Gustatory Pathway There are three major types of papillae: 1. Filiform: no taste buds found

Gustatory Pathway 2. Fungiform: Mushroom shaped All over the tongue Highest concentration found at the tip and sides Taste buds are found on the top of the the papillae

Gustatory Pathway 3. Circumvallates: Largest and least numerous (7-12) form a V at the back of the tongue The taste buds are located on the sides of these papillae

Taste Many substances produce several sensations, thus exciting many different taste buds. Many of the taste buds will respond to each of the following qualities.

Taste Bitter: Produced by alkaloids (hydroxide ions) generally found on the back of the tongue

Taste Salt: Metal ions Appears to be evenly distributed

Taste Sour Produced by hydrogen ions Generally found on the sides of the tongue

Taste Sweet: Sugars and some amino acids Generally found on the tip of the tongue

Gustatory Pathway Damage to: Glossopharyngeal nerve – bitter taste diminished (Cranial Nerve Number?) Facial nerve – sweet, sour, salty taste diminished (Cranial Nerve Number?)

The Chemical Senses Olfactory

Olfactory Pathway Receptors are found on the roof of the nasal cavity - bilaterally There are approximately 5 million olfactory receptor cells

Olfactory Pathway Collectively, these receptors are referred to as : Olfactory epithelium

Olfactory Pathway Regulation of air flow: To reduce the stimulation of receptors: Inhale slowly through your nose Or inhale through your mouth What bone structures allow for the air being channeled?

Olfactory Pathway Regulation of air flow: To heighten the stimulation of receptors: Inhale quickly through your nose with your mouth closed

Olfactory Pathway The sensation of an Aroma is stimulated by the excitation of olfactory hairs protruding from the olfactory epithelium in a field of mucosa manufactured by glands in the lamina propria

Olfactory Pathway In order for an aroma to be detected, it must be volatile 1. the aroma must be in a gaseous state 2. the aroma must be water soluble Why can we not smell natural gas?

Olfactory Pathway Acclamation A process where the sense of olfaction adapts quickly CNS response is not a diminished response from the receptor group

Olfactory Pathway Olfactory neurons are quite different from other neurons: basal cell differentiation they are replaced approximately every 60 days by a process called basal cell differentiation in the olfactory epithelium

Compare: Gustatory paths separates four distinct chemical sensations Olfactory paths distinguish tens of thousands of different sensations with only 15 to 30 different types of receptors

Compare: The sensation of smell requires the stimulation of ALL receptors in the nasal concha prior to detection The sense of taste? Each taste is independent of the other and does not require the other receptors to be stimulated

Compare: The irritating response of strong aromas such as ammonia stimulates pain receptors What is the response and why is it important? Pain receptor stimulation in the mouth provides us with the sensation of hot (spicy). How do you deal with food that is too spicy?