(06) Digestive System I - Oral Cavity

Question 1

1. Digestive system is a tubular tract the contents of which are technically where?
2. The contents are what?

Answer 1

1. outside the body
2. foreign materials

Question 2

1. Oral cavity is lined by which type of epithelium?
2. keratinized in what?

Answer 2

1. stratified squamous
2. herbivores (due to course diet)

Question 3

1. Oral cavity is lined by a mucous membrane (moist surface) that includes what?
2. What keeps the mucous membrane moist?

Answer 3

1. epithelium and underlying CT (l. propria/submucosa)

(note that mucous membranes are commonly found in tubular organs (eg gastrointestinal tract, respiratory tract, urogenital tracts)

2. Secretions of glands and/or epithelial cells

Question 4

1. What represent a mucocutaneous junction and form the entrance to the oral cavity?
2. covered by what?
3. The underlying l. propria/submucosa forms long papillae which extend into what?
4. The core of the lip contains what?

Answer 4

1. the lips
2. thick stratified squamous epithelium
3. the thick epithelial layer
4. fibroelastic CT and skeletal muscle

Question 5

(Palate)

(dorsal wall of oral cavity)

(divided into hard and soft palate)

(Hard palate)

1. Hard palate consists of what over bone?
2. Rostrally it has what?
3. The submucosa is continous or dicontinuous with periosteum of these bones?
4. What in ruminants is located in the rostral part of the hard palate? Replaces what?
5. It has a thick what to withstand stress from lower incisors?

Answer 5

1. mucous membrane
2. transverse ridges
3. continuous
4. dental pad; upper incisors
5. stratum corneum

Question 6

(Soft Palate)

1. Located where relative to the hard palate?
2. consists of mucous membrane covering what?
3. May contain what two things?
4. The transition to respiratory epithelium occurs on what surface of the soft palate?

Answer 6

1. caudal
2. skeletal muscles
3. lymphatic nodules and glands
4. dorsal surface

Question 7

(Buccal Wall - the wall of the cheek)

1. located where relative to facial muscles?
2. contains what two things?

Answer 7

1. deep to the facial muscles
2. minor salivary glands and openings of ducts from major salivary glands

Question 8

(Tongue)

1. A mucous membrane sack filled with skeletal muscles oriented in what planes?
2. intrinsic or extrinsic lingual muscles?
3. Epithelium thicker on dorsal or ventral surface?

Answer 8

1. all planes
2. both
3. dorsal

Question 9

1. A midventral what is prominent rostrally in the tongue of the dog?
2. It is a collagenous tube filled with fat and connective tissue

Answer 9

1. lyssa

Question 10

1. Epithelial Papillae of tongue and oral cavity have what two functions?

Answer 10

1. mechanical (keratinized) or gustatory (contain taste buds)

Question 11

(Filiform Papillae)

1. mechanical or gustatory?
2. how common?
3. found where?
4. apical surfaces are keratinized and point where?

(the size of filiform papillae varies with species)

1. delicate and thread like
2. coarse each with large rostral supporting papilla

Answer 11

1. mechanical
2. most numerous
3. dorsal surface of rostral 2/3 of tongue
4. caudally
5. horse
6. cat (important for grasping food and grooming)

Question 12

(Conical Papillae)

1. mechanical or gustatory?
2. located where?
3. are large (grossly observable) with keratinized epithelium and large CT core

Answer 12

1. mechanical
2. root of tongue and cheek inner-surface

Question 13

(Fungiform Papillae)

1. gustatory or mechnical?
2. scattered where?
3. may be keratinized in what?
4. taste buds founds where in carnivores and where in herbivores?

Answer 13

1. gustatory (and possibly mechanical)
2. rostral dorsal surface of tongue (distribution is species specifc)
3. herbivores
4. dorsal surface in carnivores; lateral surface in herbivores

Question 14

(Lenticular papillae)

1. gustatory or mechanical?
2. grossly visible?
3. lentil shaped (ie half of a biconvex lens)
4. keratinized?
5. Found where in ruminants?

Answer 14

1. mechanical
2. yes
3. yes
4. dorsal prominence of the tongue

Question 15

((Circum) Vallate papillae)

1. mechanical or gustatory?
2. arranged in a V at what border of the root of the tongue?
3. Each papilla is surrounded by a depression called a what?
4. Taste buds are located on what surface, and open into what?
5. The number of papillae varies with species

Answer 15

1. gustatory
2. rostral border
3. moat
4. lateral, the moat

Question 16

(Foliate papillae)

1. mechanical or gustatory?
2. Found in a row at what margin of the tongue? rostral to what?
3. They are leaf like and separated by furrows
4. Numerous taste buds are located on what surfaces of the foliate papillae?

Answer 16

1. gustatory
2. the lateral margin; the palatoglossal arch
3. the lateral surfaces

Question 17

(Gustatory Glands)

1. serous secreting with ducts opening into what or what?
2. Secretions function as a medium through which chemicals diffuse to what?

Answer 17

1. the “moat” around vallate papillae or into the furrows between foliate papillae
2. the taste buds

Question 18

(Taste BUDS)

1. Located on what papillae?
2. What other two places?

(comprised of oval clusters of columnar cells located within the epithelium and extending through its thickness)

3. An apical what opens into the oral cavity?

Answer 18

1. fungiform, vallate, foliate
2. epiglottis and soft palate
3. taste pore

Question 19

(An apical taste pore opens into the oral cavity. The columnar cells are of two types and their properties are being actively researched)

1-2. What are the two types?

3. What divide to replace the columnar cells every few days?

Answer 19

1. sensory (neuroepithelial) cells with taste receptors on apical processes, basal synaptic vesicles and apparent nerve contacts
2. supportive (sustentacular) cells with apical microvilli an higher levels of L-type Ca channels, needed for nerve impulse generation

(Interactions between sensory and support cells may influence tastant sensitivity. Paracrine between sensory and support cells by neuromodulators such as CCK or serotonin)

3. Basal cells

Question 20

(Taste sensation)

1. sensory cells express specialized receptors that are responsible for the various modalities of taste.

2-3. Receptors are of what two types?

4. Can a single cell respond to mutliple taste modalities?

Answer 20

2. metabotropic (G-protein coupled - gusducin)
3. ionotropic (direct ion channels)
4. yes

Question 21

learn this - but not receptors/2nd messengers!!!

1. What are the metabotropic receptors?
2. What are the iontropic receptors?

Answer 21

1. sweet, bitter, umami
2. salt and sour