OB P4- Tongue and taste buds

Question 1

What are the 3 main functions of the tongue?

Answer 1

• Ingestion
• Sensory
• Integrated action

Question 2

Describe the ingestion function of the tongue?

Answer 2

•  Mastication
•  Suckling
•  Swallowing
•  Cleansing mouth

Question 3

Describe the sensory function of the tongue.

Answer 3

-Taste/ gustation
> Quality control prior to ingestion : protection, food selection, food avoidance , reflex effects

-Touch/ mechanoreception

Question 4

Describe the integrated action function of the tongue.

Answer 4

speech

Question 5

What Is gustation?

Answer 5

gustation is activation of nerual pathways from tthe periphery to the centre

Question 6

What is the common chemical sense?

Answer 6

Nociception-pain
- activated sensation vie free nevre endings in the epithelium in the mouth and pahrynx - SPICY FOOD - capsacin - burn in hot food -

Question 7

Where are the extrinsic muscles of the tongue found?

Answer 7

Originate from structures outside the tongue and insert into the tongue

Question 8

Name the 4 extrinsic muscles of the tongue.

Answer 8

– Genioglossus (XII)
– Hyoglossus (XII)
– Styloglossus (XII)
– Palatoglossus (X)

Question 9

What role do the extrinsic muscles have?

Answer 9

•  Change shape of tongue

-  Move tongue bodily (protrude, retract, depress, and elevate the tongue)

Question 10

Where are the intrinsic muscles of the tongue found?

Answer 10

originate and insert within the substance of the tongue

Question 11

Name the 4 intrinsic muscles of the tongue.

Answer 11

– superior longitudinal
– inferior longitudinal
– transverse
– Vertical

Question 12

What role do the intrinsic muscles of the tongue have?

Answer 12

Change shape of tongue:
– lengthening and shortening
– curling and uncurling its apex and edges
– flattening and rounding its surface

Question 13

what are the receptors in the tongue?

Answer 13

taste buds

Question 14

How many taste buds are found throughout the mouth and pharynx?

Answer 14

2000-5000

Question 15

Where are the taste buds found?

Answer 15

hard/soft palate junction

Question 16

where are the majority of the taste buds?

Answer 16

tongue:
– dorsal and lateral aspects
– most in papillae

Question 17

What are the 4 types of papillae?

Answer 17

• Circumvallate
• foliate
• fungiform
• filiform

Question 18

What papillae have no taste buds?

Answer 18

filiform

Question 19

Where the location of filiform papillae?

Answer 19

anterior part of tongue

Question 20

What is the structure of the filiform papillae?

Answer 20

– Cone shaped
– Connective tissue core
– Keratinised epithelial cover 
• tough abrasive surface
– Non-keratinised epithelium inbetween 
• flexibility

Question 21

where is the location of fungiform papillae?

Answer 21

anterior part of the tongue

Question 22

What is the innervation off the fungiform papillae?

Answer 22

VII Facial (carried by lingual via chorda tympani)

Question 23

what do fungiform papillae look like clinically?

Answer 23

red spots

Question 24

How many fungiform papillae are there?

Answer 24

200

Question 25

How many taste buds are there per fungiform papillae?

Answer 25

– Anterior: 1-18 – Mid tongue: 1-9 – ~ 1120 fungiform taste buds per tongue

Question 26

Where is the location of the foliate papillae?

Answer 26

Lateral margin of posterior aspect in 4-11 parallel ridges

Question 27

What is the innervation of the foliate papillae?

Answer 27

– VII (anterior) | – IX (Posterior)

Question 28

What glands hang down from foliate papillae?

Answer 28

serous glands of von ebner

Question 29

How many taste buds are there per foliate papillae?

Answer 29

– 117 | – ~1280 foliate taste buds per tongue.

Question 30

where is the location of the circumvallate papillae?

Answer 30

Anterior to sulcus terminalis

Question 31

What is the innervation of the circumvallate papillae?

Answer 31

IX glossopharyngeal

Question 32

How many circumvallate papillae are there in the mouth?

Answer 32

– 3-13 circumvallate papillae per tongue – 252 taste buds per papillae – ~2200 circumvallate taste buds per tongue

Question 33

What is the importance of salvia?

Answer 33

-Essential for normal taste - solvent and transport - Taste pores bathed in: > pooled saliva >fluid from serous glands of von Ebner - Taste adapted to salivary environment - Serous glands of von Ebner: > diffusion pathway > remove stimuli by active secretion > secrete binding proteins

Question 34

What happens at a taste pore?

Answer 34

- containing pore substance - travels through pore - stimulus transferred to nerves

Question 35

what are the 4 types of cells types in taste buds?

Answer 35

- Type I -dark cells - Type II - light cells - Type III- receptors - Type IV

Question 36

Describe Type I - dark cells.

Answer 36

– support cells | – producers taste pore substance

Question 37

Describe type II - light cells .

Answer 37

– ? immature type III cells – ? support cells – ? Receptors

Question 38

Describe type III- receptors cells.

Answer 38

synaptically coupled to gustatory nerves

Question 39

Describe Type IV cells.

Answer 39

precursors of types I - III

Question 40

Describe the taste bud cell turnover.

Answer 40

-  Autoradiography -  10 life span -  Sequence: type IV, I, II, III

Question 41

What is the most mature cell type?

Answer 41

Type III

Question 42

what is the nerve supply to the posterior 1/3 tongue?

Answer 42

IX

Question 43

what is the nerve supply to the anterior 2/3 tongue?

Answer 43

VII (via chorda tympani and V3)

Question 44

What is the nerve supply to the epiglottis?

Answer 44

X

Question 45

What afferents and efferents affect taste buds?

Answer 45

-  Ad afferents, non-myelinated in taste bud  | - Also efferent effects

Question 46

where are non-lingual taste buds found?

Answer 46

-  Found on soft palate and/or epiglottis  - Sparse -  Not on papillae but possibly on slightly elevated areas

Question 47

what are the receptor mechanisms at taste buds?

Answer 47

- Transduction : - chemical stimulus ( salt, sweet, sour) to electrical energy (action potentials) - probably type III (and II) cells

Question 48

Describe the receptor mechanisms of salt.

Answer 48

direct entry of Na+ ion -> depolarisation

Question 49

Describe the receptor mechanism of sour.

Answer 49

– e.g. citric acid in lemons – free H+ ions blocks K+ channels – decreased K+ movement out of the cell  -> depolarisation

Question 50

Describe the receptor mechanism of sweet and bitter.

Answer 50

– 2nd messenger pathway | – blocks of K+ channel  depolarisation

Question 51

What is the steps of receptor mechanisms?

Answer 51

- Depolarising receptor cell potential - open voltage gated Ca2+ channels - increaed intracellular free Ca2+ - release of neurotransmitter - depolarisation of afferent nerve ending