Taste And Smell

Question 1

Describe foliate papillae

Answer 1

Posterolateral surface of tongue. Leaf like vertical folds forming clefts in tongue surface. Taste buds along cleft walls

Question 2

Describe circumvallate papillae

Answer 2

Located just anterior to terminal sulcus. Largest papillae surrounded by deep grooves which von ebners glands open into. Taste buds along lateral wall of papillae

Question 3

Describe fungiform papillae

Answer 3

Scattered across dorsal surface of tongue. Mushroom shaped. Taste buds on superior surface.

Question 4

Describe filiform papillae

Answer 4

Pointed projection on dorsal surface of tongue. Overlapping sheets of epithelial cells, leading to surface roughness. No taste buds

Question 5

What are type 1 taste bud cells

Answer 5

Supporting/sustentacular cells that secrete gel-like substances into taste pore to dissolve chemicals needed by sense by taste buds. Secretory granules and stubby microvilli at apical end

Question 6

What are type 2 cells

Answer 6

Sensory receptors for bitter (back of tongue), umami (centre of tongue), sweet (tip of tongue) compounds. Thick microvilli at apical end

Question 7

What are type 3 cells

Answer 7

Ion channels for recognition of sour (posterolateral tongue) and salty (border of anterior tongue) compounds. No microvilli. Synaptic communication with adjacent nerve fibres.

Question 8

What are type 4 cells

Answer 8

Basal cells. Progenitor cells for other 3 cell types. Found at base of taste bud

Question 9

Innervation of circumvallate and foliate papillae

Answer 9

First order neuron CN9 —> inferior glossopharyngeal ganglion —> synapse at solitary tract nucleus at medulla oblongata —> decussation —> go to thalamus —> gustatory cortex

Question 10

Taste innervation of fungiform and foliate papillae

Answer 10

Chorda tympani CN7 —> geniculate ganglion —> solitary tract nucleus at medulla oblongata —> decussate —> thalamus —> gustatory cortex

Question 11

Innervation of taste buds at soft palate

Answer 11

Cn7 greater petrosal nerve —> geniculate ganglion —> solitary tract nucleus at medulla oblongata —> decussate —> thalamus —> gustatory cortex

Question 12

How does saliva help us taste

Answer 12

Solvent and carrier of compounds present in food. Contain sweet, sour, bitter compounds hence change in salivary composition can affect basal taste.

Question 13

How do we smell

Answer 13

We sniff, speed of air in nostrils increases, more air comes into contact with olfactory epithelium at olfactory cleft

Smell of food in mouth can also be perceived by retronasal route. From the mouth go upwards past epiglottis, enter nasal cavity and come into contact with olfactory epithelium

Odorant molecules diffuse through mucous layer. Chemoreceptors on the surface of olfactory receptor neurons activated, action potential carried through olfactory sensory neuron CN1 at olfactory bulb. Signal carried by olfactory tract to olfactory cortex.

Question 14

What kind of epithelium is olfactory epithelium

Answer 14

Columnar pseudostratified

Question 15

What is aguesia

Answer 15

Inability to detect taste stimulants

Question 16

What is dysosmia

Answer 16

Distorted perception of smell

Question 17

Why might old people be more likely to have sense of taste altered

Answer 17

Taste is resistant to age-related decline!! Denture may block taste receptor cells, leading to transient taste alteration. Polypharmacy, medication can alter sense of taste

Question 18

How might head trauma affect sense of smell

Answer 18

Cribriform plate fracture

Question 19

What is found at basal end of taste bud cell

Answer 19

Gustatory nerve fibres that enter taste bud and synapse with taste bud cells. Type 3 cells!!

Question 20

Which part of mouth more sensitive to bitter taste

Answer 20

Back of tongue

Question 21

Where is olfactory epithelium found

Answer 21

Either side of nasal septum. Superior and middle turbinate

Question 22

Structure of olfactory receptor neurons

Answer 22

Bipolar neuron. Cell body within epithelium. Microvilli at apical end