Week 1 - F - Physiology of taste and smell

Question 1

Receptors for taste and smell are chemoreceptors which are stimulated by binding to particular chemicals What is taste perception influenced by?

Answer 1

taste perception is influenced by information from smell receptors

Question 2

What is gustation?

Answer 2

The action of tasting

Question 3

Where are the sensory receptors of taste mainly packaged?

Answer 3

Packaged in taste buds on the tongue

Question 4

Taste buds are arranged like slices of an orange What are the alternating slices of a taste bud? What is the life span of a taste receptor cell? What cells in the taste buds are the taste receptor cells replaced from?

Answer 4

You have receptor cells and support cells A taste receptor cell has a life span of 10 days Taste receptor cells are replaced from basal cells in the taste buds

Question 5

What four regions are taste buds mainly presents?

Answer 5

Mainly present on the tongue, pharynx, epiglottis and pharynx

Question 6

What are the finger-like structures which gives rise to the rough appearance of the dorsum of the tongue ? It is where the majority of taste buds are located

Answer 6

Papillae of the tongue

Question 7

What are the 4 types of papillae on the tongue? Which contain taste buds? Which is most abundant?

Answer 7

Filiform - most abundant papillae but does not contain taste buds Fungiform, Foliate, Vallate all contain taste buds

Question 8

What papillae lie on the lateral wall of the tongue? Which papillae are located in a C shaped-row in front of the foramen caecum?

Answer 8

The foliate papillae The (circum)vallate papillae

Question 9

What groove of the tongue separates the anterior (oral) tongue from the posterior (pharyngeal) tongue? What is formed during the descent of the thyroid diverticulum in embryonic development which was the point of attachemnet of th obilterate thyroglossal duct?

Answer 9

The sulcus terminalis The foramen caecum

Question 10

What does the binding of the taste provoking chemical to the receptor cells of the taste bud cause?

Answer 10

It alters the cells ionic channels and proudces a depolarising receptor potential

Question 11

What does the depolarized receptor potential causes?

Answer 11

It initiates action potentials in the afferent nerve fibres which synapse with the receptor cells The signal is then conveyed to the brain via cranial nerves

Question 12

What povides innervation to the naso,oro and laryngo pharynx? Which nerves are stimulated in coughing and sneezing?

Answer 12

Nasopharynx - upper half is opthalmic nerve, lower half is maxillary nerve Oropharynx - glossopharyngeal nerve Laryngopharynx - vagus nerve innervation

Question 13

Which cranial supplies the anterior two thirds of the tongue with innervation? Which cranial supplies the posterior one third of the tongue with innervation?

Answer 13

Anterior 2/3rds - Chorda tympani - branch of the facial nerve (CN VII) Posterior 1/3rd - Glossopharyngeal nerve (CN IX)

Question 14

What are the five primary tastes? (what is the fifth mainly triggered by)

Answer 14

Salty Sour Sweet Bitter Umami (meaty or savoury) - mainly triggered by glutamate

Question 15

What is loss of taste known as and what are some causes?

Answer 15

Aguesia - can be cossed by glossitis, radiation Some endocrine disorders eg Cushings, Diabetes mellitus

Question 16

What is reduced taste known as and what is distorted taste known as?

Answer 16

Reduced taste - knowna as hypoguesia - can be caused by chemotherapy and medications Dystorted taste - Dysguesia

Question 17

Which mineral is required for the senses of smell and taste?

Answer 17

Zinc

Question 18

What is the patch of mucosa in the roof of the nasal cavity?

Answer 18

Olfactory mucosa

Question 19

What are the three cell types in the olfactory mucosa? (which cell secretes mucus)

Answer 19

Olfactory receptor cells Supporting cells Basal cells - secrete mucus

Question 20

What is the life span of an olfactory receptor cell? What are the precursors of olfactory receptor cells?

Answer 20

Life span - about 2 months Precursors are the basal cells

Question 21

Axons of olfactory receptors collectively form afferent fibres of olfactory nerve What do they pierce to enter the olfactory bulb? Where does the nerve impulses travel once reached the olfactory bulb?

Answer 21

Piece the cribiform plate of the ethmoid bone Travels along the olfactory tract to reach the temporal lobe and olfactory areas

Question 22

During quiet breathing odorants only reach smell receptors by diffusion - olfactory mucosa is above the normal path of airflow The act of Sniffing enhances smelling by drawing air currents upwards within the nasal cavity What two factors must a substance have to be smelled?

Answer 22

To be smelled, a substance must be (1) sufficiently volatile i.e. some of its molecules can enter the nose with inspired air (2) sufficiently water soluble i.e. can dissolve in the mucus coating of olfactory mucosa

Question 23

Anosmia can be due to head injury, nasal polyps and more What is a congenital cause of anosmia?

Answer 23

Kallman syndrome -hypogonadotrophic hypogonadism with ansomia

Question 24

Hyposmia is the reduced ability to smell What may it be an early indicator of?

Answer 24

May e an early indicator of Parkinson’s disease