digestive pt 1 hanggang oropharynx Flashcards
(177 cards)
1
Q
What are the two main components of the digestive system?
A
The alimentary canal and accessory structures (lips, tongue, teeth, and extramural glands).
2
Q
What is the alimentary canal?
A
A tubular and modified tubular structure extending from mouth to anus, generally conforming to a basic tubular organ structure.
3
Q
What organs make up the alimentary canal?
A
Mouth, pharynx, stomach, small intestine, large intestine, rectum, and anus.
4
Q
What reflects the diverse functions of digestive organs?
A
Their histologic modifications from mouth to anus.
5
Q
What is digestion?
A
The process by which food is converted into substances that may be safely absorbed and used by cells.
6
Q
Where does digestion occur?
A
In the lumen of the digestive tube, which is technically outside the body proper.
7
Q
How is digestion accomplished?
A
Through digestive juices secreted by glands in the tube wall and by extramural glands.
8
Q
Why is the epithelial lining of the digestive tract selective?
A
To prevent absorption of undigested substances, which could be fatal.
9
Q
What is the mucous membrane?
A
The wet epithelial lining of the digestive tube and internal passageways that open to the body surface.
10
Q
What are the components of the mucous membrane (tunica mucosa)?
A
Lining epithelium and lamina propria (connective tissue), and sometimes muscularis mucosae.
11
Q
How does the mucous membrane differ from skin?
A
It is not thick and lacks keratin, making it better suited for absorption.
12
Q
What maintains epithelial integrity in mucous membranes?
A
Mucus secretion from individual cells or glands.
13
Q
What is the main substance of the lips?
A
Striated muscle fibers (mainly orbicularis oris) and fibroelastic connective tissue.
14
Q
What covers the outer surface of human lips?
A
Skin with hair follicles, sebaceous glands, and sweat glands.
15
Q
What covers the red free margins of human lips?
A
Modified skin with a layer of dead cells and high levels of eleidin, giving it transparency.
16
Q
Why do human lips appear red?
A
Capillary blood in the connective tissue papillae shows through the transparent epidermis.
17
Q
Why must human lips be frequently wetted?
A
They are not heavily keratinized and lack sebum for protection.
18
Q
How do animal lips differ near the skin-mucous junction?
A
No hairs are present and the epidermis is thicker.
19
Q
What type of epithelium lines the inner surface of lips in animals?
A
Stratified squamous non-keratinizing (carnivores and pigs) or keratinized (ruminants and horses).
20
Q
What are labial glands and where are they located?
A
Small clusters of mucous glands in the lamina propria-submucosa, opening through ducts.
21
Q
What muscle forms the tunica muscularis of the lip?
A
Orbicularis oris (striated muscle fibers).
22
Q
What layers make up the cheek wall?
A
Skin, middle muscular layer, and mucosal lining.
23
Q
What type of epithelium lines the cheeks?
A
Stratified squamous epithelium, may be keratinized or not.
24
Q
What unique feature is present in the cheeks of ruminants?
A
Conical macroscopic papillae for prehension and mastication.
25
What is found in the lamina propria of cheeks?
Dense fibroelastic tissue that merges with submucosa.
26
What structures are found in the submucosa of the cheek?
Elastic fibers, blood vessels, and buccal glands.
27
What types of glands are buccal glands?
Compound tubuloacinar (mucous, serous, or seromucous).
28
What forms the core of the hard palate?
The palatine bone.
29
What type of epithelium covers the hard palate?
Keratinized stratified squamous epithelium.
30
Where is this epithelium especially thick and keratinized?
In the dental pad of ruminants.
31
What glands are found in the caudal region of the hard palate?
Branched tubuloalveolar glands (mucous or mixed).
32
What is the soft palate?
A fibromuscular caudal extension of the hard palate.
33
What muscle makes up most of the soft palate?
The palatinus muscle.
34
What covers the dorsal aspect of the soft palate?
Pseudostratified ciliated columnar epithelium (nasopharyngeal side).
35
What covers the ventral aspect?
Stratified squamous epithelium (keratinized or non-keratinized).
36
What glands and lymphatic tissue are associated with the soft palate?
Glands like those in the hard palate and frequent lymphatic nodules.
37
Where is the palatine tonsil located in pigs?
Entirely within the soft palate.
38
What is the tongue?
A cranial projection from the ventral floor of the buccal cavity.
39
What covers the tongue?
Stratified squamous epithelium.
40
What lies beneath the tongue’s surface?
The lingua propria (connective tissue and skeletal muscle core).
41
How are the muscle fibers arranged in the lingua propria?
Longitudinal, transverse, and oblique (topsy-turvy pattern).
42
What are lingual papillae?
Extensive invaginations of the dermal papillae into the epithelium.
43
What gives the tongue rigidity in horses and ruminants?
Thickened mucosa on the posterodorsal aspect.
44
What is the lyssa and in which animals is it prominent?
A connective tissue structure in carnivores attaching the ventral tongue to the floor.
45
What is the composition of the lyssa?
DWFCT, adipose tissue, skeletal muscle, and connective tissue.
46
Where are lingual papillae usually located?
Dorsal surface of the tongue.
47
What are the five types of lingual papillae?
Filiform, lenticular/conical, fungiform, foliate, and circumvallate (vallate).
48
What is the most numerous lingual papillae type?
Filiform papillae.
49
What is the function of filiform papillae?
Mechanical – prehension and grasping.
50
Where are filiform papillae especially developed?
Cats and ruminants.
51
What is the shape of filiform papillae?
Rose thorn shape with curvature directed caudally.
52
What animals primarily have lenticular/conical papillae?
Ruminants.
53
What do lenticular papillae look like and do?
Double convex lens shape, function in food prehension.
54
Which papillae are mushroom-shaped and may have taste buds?
Fungiform papillae.
55
What is the keratinization status of fungiform papillae?
Less keratinized than other mechanical papillae.
56
What papillae are leaf-shaped and gustatory in function?
Foliate papillae.
57
What glands are found at the base of foliate papillae?
Von Ebner’s glands (serous, gustatory).
58
Where are taste buds located in foliate papillae?
In the lateral epithelial walls.
59
What are circumvallate papillae?
Largest, rarest papillae, surrounded by deep furrows.
60
What function do circumvallate papillae serve?
Gustation – many taste buds in lateral walls.
61
What glands open into the furrow around circumvallate papillae?
Von Ebner’s glands, which cleanse the region.
62
What are taste buds and where are they located?
Taste buds are intraepithelial structures located in the walls of foliate, fungiform, and circumvallate papillae. They are also dispersed in the soft palate, epiglottis, and other areas of the mouth and pharynx.
63
What is the function of taste buds?
They serve as receptors for gustatory (taste) sensations.
64
How do taste buds connect to the surface epithelium?
They open through a small canal called a taste pore.
65
What is the shape and structure of taste buds?
They are ovoid masses of cells that extend from the basement membrane to the taste pore.
66
What are the four types of cells in taste buds?
Type I (Dark cells), Type II (Light cells), Type III (Intermediate cells), Type IV (Basal cells).
67
What are the features of Type I (dark) taste bud cells?
Vacuolated, acidophilic cytoplasm with a dense, elongated nucleus.
68
What are the features of Type II (light) taste bud cells?
Dense, acidophilic cytoplasm and a vesicular, elongated nucleus.
69
What are the functions of Type IV (basal) taste bud cells?
They function as reserve cells that regenerate other taste bud cells. They give rise to dark cells → light cells → intermediate cells → apoptosis.
70
What is the life span of taste bud cells?
Approximately 10 days.
71
Which taste bud cells are believed to be sensory cells?
Types I, II, and III, as they receive nerve fiber synapses.
72
What protrudes from the taste pore in taste buds?
Long, slender microvilli from the sensory cells, called taste hairs.
73
What are the three main parts of a tooth?
Crown, neck, and root.
74
What part of the tooth protrudes above the gingiva?
The crown.
75
What is the mineralized tissue that makes up the bulk of the tooth?
Dentin.
76
What covers dentin in the crown portion of a tooth?
Enamel.
77
What covers dentin in the root portion of a tooth?
Cementum.
78
What is the junction between enamel and cementum called?
The cervical line.
79
What is the space within the tooth that conforms to its general shape?
The pulp cavity.
80
What are the two parts of the pulp cavity?
Pulp chamber (coronal part) and pulp or root canal (narrowed root part).
81
What kind of tissue is the pulp composed of and what is its sensitivity?
Mesenchymal-like connective tissue; it is very sensitive (called the 'nerve of the tooth').
82
How do the nerve and blood supply enter the pulp?
Through the apical foramen at the apex of the root.
83
What structures hold the tooth in place within its alveolus?
Periodontal ligament fibers.
84
What bone structures do tooth roots sit in?
Alveolar processes of the mandible (lower jaw) and maxilla (upper jaw).
85
What is the external mucous membrane covering the alveolar bone called?
Gingiva or gums.
86
What is dentin composed of?
Collagen-rich material deposited in layers by odontoblasts.
87
What are the processes of odontoblasts that become trapped in dentin called?
Odontoblastic processes.
88
What are the tiny canals that house odontoblastic processes called?
Dentinal tubules.
89
What is the junction between the dentin and enamel called?
Dentin-enamel junction.
90
How does dentin sensitivity manifest?
It is sensitive to touch, cold, and acidic foods.
91
What percentage of the dentin matrix is collagen?
About 90%.
92
What proteins make up the rest of the dentin matrix (10%)?
Phosphoprotein, glycoprotein, and proteoglycans.
93
What is predentin?
The uncalcified layer of dentin matrix where proteins are deposited before calcification.
94
What is the hardest tissue in the body that covers the tooth crown?
Enamel.
95
What cell type produces enamel?
Ameloblasts.
96
What are the elongated ends of ameloblasts called?
Tomes processes.
97
What is the structural unit of enamel?
Enamel rod.
98
What are enamel rods made of?
Protein-carbohydrate organic matrix with calcium phosphate in the form of apatite.
99
What is the shape and size of enamel rod subunits?
Tubular, oval in diameter, ~250 Ångstrom units.
100
How does enamel calcify?
It starts discretely near the tubules and increases as the rods lengthen; it reaches 95% mineral content.
101
Can enamel repair itself after damage? Why or why not?
No, because ameloblasts degenerate after enamel formation and tooth eruption.
102
What is the inter-rod substance and how does it differ from rod substance?
It is secreted by ameloblasts and appears identical to rod substance but its subunits run in different directions.
103
What kind of tissue is cementum and who produces it?
Nonvascular calcified connective tissue (modified bone), produced by cementoblasts.
104
What is the origin of cementoblasts?
From mesenchymal cells of the dental sac.
105
What cells reside in the matrix of cementum?
Cementocytes.
106
What structures house cementocytes?
Lacunae and canaliculi.
107
What is the role of cementum regarding the periodontal ligament?
It embeds the ends of the ligament fibers, anchoring the tooth.
108
Which part of the tooth root has acellular cementum vs. cellular cementum?
Upper 1/3 to 1/2 = acellular; the rest = cellular.
109
Where does the periodontal ligament develop from?
From mesenchyme of the dental sac during tooth development.
110
What are Sharpey’s fibers?
The embedded ends of the periodontal ligament fibers in the tooth and alveolar bone.
111
What are the functions of the periodontal ligament?
Tooth suspension, resistance to...
112
What are the functions of the periodontal ligament?
Tooth suspension, resistance to pressure, limited tooth mobility, nutritive supply to cementocytes, tactile sensation, and acting as periosteum.
113
How does the periodontal ligament differ from typical periosteum?
It lacks elastic fibers.
114
What are brachydont teeth?
Simple teeth that stop growing after eruption; have defined crown, neck, and root.
115
What happens to ameloblasts in brachydont teeth after eruption?
They disintegrate.
116
Where is cementum deposited in brachydont teeth?
Only on dentin.
117
What are hypsodont teeth?
Complex teeth that constantly erupt and lack a defined crown, neck, and root.
118
What happens to ameloblasts in hypsodont teeth?
They do not disintegrate and continue enamel secretion beyond eruption.
119
Where is cementum deposited in hypsodont teeth?
On both enamel and dentin.
120
Which animals have hypsodont teeth?
Cheek teeth of ruminants, all horse teeth, incisor teeth of rodents, and canine teeth of pigs.
121
How many major salivary glands are there, and how do they occur?
There are 3 major salivary glands, and they occur in pairs.
122
What are the three largest salivary glands?
Parotid gland, Submandibular (or Submaxillary) gland, Sublingual gland.
123
Which salivary gland is the largest of the three major ones?
The parotid gland.
124
What is the duct of the parotid gland called?
Stensen’s duct.
125
What type of connective tissue capsule surrounds the parotid gland?
A well-defined fibrous connective tissue capsule.
126
What is the structural classification of the parotid gland?
Compound tubulo-alveolar (serous) type.
127
What is characteristic of the duct system in the parotid gland?
It has many prominent intralobular ducts.
128
What shape are the secretory cells of the parotid gland?
Pyramidal.
129
What granules fill the apex of parotid secretory cells and what do they contain?
Zymogen granules; they contain precursors of digestive enzymes.
130
What is found accumulating in the connective tissue septa of the parotid gland?
Fat cells.
131
What is the duct of the submandibular gland called?
Wharton’s duct.
132
Does the submandibular gland have a well-defined capsule?
Yes.
133
What type of duct system does the submandibular gland have?
A fairly prominent duct system.
134
What is the structural classification of the submandibular gland?
Compound alveolar and tubulo-alveolar.
135
What type of secretion is produced by the submandibular gland?
Mixed secretion; majority serous, the rest mucous with serous demilunes.
136
What is the duct of the sublingual gland called?
Rivinus’ duct.
137
What type of capsule does the sublingual gland have?
An ill-defined capsule.
138
What is the structural classification of the sublingual gland?
Compound tubulo-alveolar.
139
What type of secretion is produced by the sublingual gland?
Mixed type; majority mucous, few serous, and mucous units with serous demilunes.
140
Which salivary gland has more prominent connective tissue septa than the others?
The sublingual gland.
141
What are the cellular and bacterial debris present in saliva?
Leukocytes.
142
What are the inorganic and organic components of saliva?
Salt, gases, and organic material.
143
What are the enzymes found in saliva?
Ptyalin (salivary amylase) and maltase.
144
What gives saliva its texture?
Mucus (saliva can be thin and watery or viscous).
145
What affects the composition of saliva?
The type of stimulant that initiates its secretion.
146
How does saliva aid in assimilation?
It lubricates and moistens buccal mucosa and lips.
147
How does saliva contribute to oral hygiene?
It washes away cellular and food debris that could promote bacterial growth.
148
What role does saliva play in swallowing and tasting food?
It moistens food and transforms it into a semisolid or liquid mass.
149
What digestive role does saliva perform?
Salivary amylase (ptyalin) breaks down starch into maltose.
150
What system controls the secretion of saliva?
The autonomic nervous system.
151
How does sympathetic stimulation affect saliva production?
It decreases production.
152
How does parasympathetic stimulation affect saliva production?
It increases production.
153
What is the oropharynx?
An extension of the buccal cavity that connects it with the esophagus.
154
What type of epithelium lines the oropharynx?
Stratified squamous epithelium with varying degrees of keratinization depending on species.
155
What does the lamina propria of the oropharynx contain?
Tonsils, lymph nodules, and scattered leukocytes.
156
What replaces the muscularis mucosae in the oropharynx?
A layer of elastic fibers.
157
What type of glands are in the tunica mucosa of the oropharynx?
Branched tubulo-alveolar mucous glands.
158
What kind of muscle is found in the tunica muscularis of the oropharynx?
Striated (skeletal) muscle.
159
What is the tunica adventitia of the oropharynx made of?
Typical connective tissue that blends with deep fascia.
160
What is the esophagus?
A muscular tube adapted for voluntary and involuntary movement of food to and from the stomach.
161
What type of epithelium lines the esophageal mucosa?
Stratified squamous, either keratinized or nonkeratinized.
162
What does the lamina propria of the esophagus contain in humans and pigs?
Numerous lymph nodules and diffuse lymphatic tissue at the esophageal-gastric junction.
163
How is the muscularis mucosae of the esophagus structured in humans?
It is a thick and complete layer
164
How is the muscularis mucosae structured in horses, ruminants, and cats?
Scattered muscle bundles.
165
Is the muscularis mucosae absent in some species? Where?
Yes; in dogs and pigs, it's absent in the cervical region but becomes complete near the stomach.
166
What kind of glands are in the esophageal submucosa?
Branched tubuloalveolar mucous glands.
167
In which species are esophageal submucosal glands present throughout the esophagus?
Dogs
168
Where are the submucosal glands located in pigs?
In the cervical portion, sparse in the thoracic portion.
169
Where are the submucosal glands located in ruminants, horses, and cats?
In the cervical portion.
170
What allows the esophagus to expand?
Longitudinal folds of the tunica mucosa and submucosa.
171
What type of muscle is found throughout the esophagus in ruminants and dogs?
Entirely striated muscle.
172
What type of muscle makes up the cervical portion of the esophagus in pigs?
Striated muscle.
173
What is the muscle composition of the thoracic portion of the esophagus in pigs?
Mixed muscle.
174
What type of muscle is found in the caudal portion of the pig’s esophagus?
Smooth muscle.
175
How is the muscle type distributed in the esophagus of horses and cats?
Striated muscle up to the middle portion, then smooth muscle caudally.
176
What type of outer layer does the cervical portion of the esophagus have?
Tunica adventitia.
177
What replaces the adventitia in the thoracic portion of the esophagus?
Tunica serosa.
