Lecture 3- Nose And Tongue

Question 1

Olfactory epithelium

Answer 1

organ of smell located in the roof of the nasal cavity.

Question 2

Olfactory sensory neurons

Answer 2

bipolar neurons with a thin apical dendrite that terminates in a knob with several olfactory cilia

Question 3

Olfactory cilia

Answer 3

are long, largely non-motile cilia covered in mucous, which is the solvent for odorants (chemicals we smell).

Question 4

Anosmia

Answer 4

temporary or permanent loss of the sense of smell, often caused by head injuries, localized inflammation or neurological disorders.

Question 5

What is the life span of olfactory neurons?

Answer 5

30-60 days

Replaced by new neurons from olfactory stem cells, the basal cells of the olfactory epithelium.

Question 6

Mitral cells

Answer 6

send impulses down the olfactory tracts to the frontal lobe and to the thalamus, hypothalamus, amygdaloid body, and other members of the limbic system.

Question 7

Olfactory adaptation

Answer 7

prolonged stimulation decreases sensitivity.

People can’t smell a certain odour after being exposed to it for a while.

Question 8

Olfactory transduction

Answer 8

odorant binds to the olfactory receptor, a G protein, and the secondary messenger of cyclic AMP. cAMP opens ion channels to depolarize the cell and cause impulse transmission.

This allows small number of odorant molecules to produce action potential

Question 9

Taste buds

Answer 9

sensory receptor organs for taste

majority located within the papillae of the tongue.

Question 10

Gustatory epithelial cells

Answer 10

taste receptor cells that have microvilli called gustatory hairs that project into taste pores bathed in saliva.

Question 11

Basal epithelial cells

Answer 11

stem cells that divide
every 7-10 days to replace damaged gustatory cells.

Question 12

Difference between chemoreceptors for taste and smell

Answer 12

Gustatory (taste) chemoreceptors are on epithelial cells

Question 13

Five basic taste sensations

Answer 13

Sweet
Sour
Salty
Bitter
Umami

Question 14

What can sourness and bitterness indicate?

Answer 14

Food is spoiled or poisonous

Question 15

Gustatory pathway

Answer 15

Food chemicals (tastants) interact with gustatory epithelial cell membrane.

gustatory cell releases neurotransmitter that causes graded potential depolarization in dendrites of sensory neuron.

The sensory neuron may be stimulated to generate action potential.

Question 16

What gustatory cell is most sensitive?

Answer 16

Bitter receptors

Question 17

What can taste trigger?

Answer 17

Reflexes involved in digestion, such as increased secretion of saliva and increased secretion of gastric juice

Question 18

Why are taste disorders less common than smell disorders?

Answer 18

because taste receptors are served by three different cranial nerves.

Question 19

WhT strongly influences taste?

Answer 19

Smell and stimulation of thermoreceptors, mechanoreceptors, and nociceptors.