OCB02-2024

Question 1

Which gland(s) has the greatest contribution to whole mouth saliva at rest?

Answer 1

Submandibular and sublingual

Question 2

Which gland(s) has the greatest contribution to whole mouth saliva during stimulation?

Answer 2

Parotid

Question 3

What is the role of saliva in taste perception?

Answer 3

Food components must be dissolved in saliva to reach taste buds

Ductal modification gives low salivary NaCl which allows us to perceive NaCl in food/drink

Resting saliva has a low buffering capacity which allows us to perceive acids

Saliva has a trophic influence on taste buds

Question 4

What are the different stimuli that may cause salivary secretion?

Answer 4

Masticatory/chewing

Gustatory/taste

Olfactory/smell

Psychic influence (animals only)

Movement in the mouth (mainly minor glands)

Thermoreceptive (warmer = increase)

Nociceptive (teething?)

Question 5

How did Carl Ludwig (1850) contribute to the discovery of saliva secretion mechanisms?

Answer 5

Electrically stimulated nerves to salivary glands of recently killed animals which resulted in salivary secretion

Question 6

What did Colin (1854) use horse parotids to show?

Answer 6

Cannulated horse parotid duct to show there was more secretion during chewing

Question 7

What did Hector and Linden use rabbits to show?

Answer 7

Muscle strain resulted in ipsilateral parotid flow

Question 8

What did Lashley (1916) show?

Answer 8

In man, ipsilateral flow was greater than contralateral flow when chewing on one side (Lashley cup and cannula)

Question 9

Describe what is involved in the masticatory-salivary reflex.

Answer 9

Intraoral mechanoreceptors = salivary output is directly proportional to masticatory forces

Edentulous patients still have this reflex so implies a role for gingival mechanoreceptors

Question 10

Which papillae on the tongue have crypts?

Answer 10

Circumvallate and foliate papillae

Question 11

Where do most of our taste buds reside?

Answer 11

In the crypts of the circumvallate and foliate papillae

Question 12

What are the five basic tastes that everyone has?

Answer 12

Sweet

Sour

Salt

Bitter

Umami (sodium glutamate)

Question 13

Does citric acid require a higher or lower concentration than other basic tastes to stimulate parotid secretion? Why might this be?

Answer 13

Lower (10-100 fold less)

Picked up by TRP receptors adapted to respond to acids

Question 14

What tastes do TRP receptors usually pick up?

Answer 14

Chilli/capsaicin

Menthol

Vanilla

Question 15

Why is the concentration of sucrose that produces salivary flow problematic?

Answer 15

Secretion is relatively insensitive to sucrose (low secretion with higher concentrations)

Increased risk of tooth decay as we need more sucrose in order to taste it

Question 16

Does fat have specific receptors? What evidence is there for this?

Answer 16

No difference in flow rate to different levels of fat

Suggests there is no specific receptor to fat

Question 17

Does combining taste and chewing or multiple tastes increase saliva flow?

Answer 17

No (no additive effect)

Question 18

Describe what is involved in the olfactory-salivary reflex.

Answer 18

Initial smell of food (orthonasal) or from back of throat (retronasal)

Submandibular gland has a more prolonged response to smells (not with parotids) which shows glands are differently innervated and differentially stimulated during eating

Should be termed “olfactory-submandibular salivary reflex” instead

Question 19

What does orthonasal mean?

Answer 19

External/environmental smells which enter the nostrils

Question 20

What does retronasal mean?

Answer 20

Internal smells entering the nasal cavity from the back of the throat from the mouth

Question 21

Which stimuli give a greater increase in parotid salivary flow rate compared to resting?

Answer 21

Taste and chewing (> smell and visual)

Question 22

Which glands do smell and taste mostly affect?

Answer 22

Submandibular and sublingual

Question 23

What may the mouthwatering sensation actually be attributed to?

Answer 23

Expulsion of premade saliva due to muscle activity near ducts (not a true reflex) = “gleeking”

Brain influences the muscle rather than the gland

(Saliva has same protein profile as resting saliva)