Chapter 10: Digestive System Flashcards
1
Q
What system consists of a long hollow tube or tract (alimentary canal) that extends through the body from the oral cavity to the anus?
A
digestive system
2
Q
salivary glands, liver, and pancreas produce numerous secretions that are delivered to the digestive tract through the?
A
excretory ducts
3
Q
The wet epithelial lining of the digestive tube and of other internal passageways that open to the surface constitutes a barrier between the body proper and the outside environment. The characteristics of this membranes are their absorptive capacity and its ability to secrete mucous.
A
Tunica mucosa (mucous membranes)
4
Q
What is derived from the endoderm, is a stratified squamous in the oral cavity, oral pharynx, esophagus and anal canal; it is simple columnar in the stomach, intestines and rectum.
A
epithelium (mucous membrane)
5
Q
What is a layer of loose connective tissue beneath the endothelium; it contains small blood and lymphatic cells. In some organs, it contains glands that are referred to as mucosal glands because they are confined to the mucosa.
A
lamina propria
6
Q
What is a thin layer of smooth muscle bordering the submucosa?
A
lamina muscularis (muscularis mucosae)
7
Q
What is a dense, irregular connective tissue layer of digestive tube that contains blood and lymphatic vessels and the submucosal (Meissner’s) plexus of nerves. Some organs are characterized by glands (submucosal glands) and lymphoid nodules in this layer.
A
Tela submucosa
8
Q
What is a layer of muscle responsible for the movement of ingesta through the digestive tract. This consists of two layers of smooth muscle - an inner circular and an outer longitudinal - through most of the tract.
A
Tunica muscularis
9
Q
Tunica muscularis is a layer of muscle responsible for the movement of ingesta through the tract. This consists of two layers of smooth muscle - an inner circular and an outer longitudinal - through most of the tract. Between them lies the?
A
myenteric (Auerbach’s) plexus.
10
Q
The muscle around the oral cavity is?
A
skeletal
11
Q
In the upper esophagus, the muscle layer contains mainly?
A
skeletal muscle
12
Q
In the upper esophagus, the muscle layer contains mainly skeletal muscle, which is replaced by what muscle in the lower portion?
A
smooth muscle
13
Q
The colons outer longitudinal layer is gathered into three bands, called the?
A
taeniae coli.
14
Q
The digestive tract’s outer covering differs by location. The esophagus and rectum are surrounded and held in place by a connective tissue and adventitia like that around blood vessels. Intraperitoneal organs (jejunum, ileum, and colon) are suspended by mesenteries and covered by a serosa composed of a thin layer of loose connective tissue covered by a simple squamous epithelium (mesothelium). Retroperitoneal organs (duodenum, ascending and descending colon) are bound to the posterior abdominal wall by adventitia and covered on their free (anterior) surfaces by serosa.
A
Tunica serosa (serous membrane) and adventitia
15
Q
What is the initial portion of the digestive system. Here, food is ingested, masticated (chewed), and lubricated for swallowing. The major structures of this cavity are the lips, tongue, oral lining, and the salivary glands. Since food is broken down physically in the oral cavity, this cavity is lined by a protective, non-keratinized stratified squamous type of epithelium. The same type of epithelium extends over and covers the inner surface of the lips.
A
oral cavity
16
Q
The junction between the integument and the digestive system occurs on the ? They are covered outside by skin containing hair follicles, sebaceous glands and sweat glands; and inside by a mucous membrane.
A
lips
17
Q
like the lips, are composed of an external covering - the skin, a middle muscular layer, and a mucous membrane lining.
A
cheeks
18
Q
- The mucosa has keratinized stratified squamos epithelium.
- Thick in ruminants and forms the dental pads (pulvinus dentalis).
- Branched tubuloacinar mucous and seromucous glands are located in the caudal part of this palate in all domestic animals except the pig.
A
Hard Palate
19
Q
What is formed by a fold of mucous membranes of the oral and nasal cavities, with a core of striated muscle fibers.
- The oral surface is covered by a stratified squamos epithelium, whereas the nasal mucosa has a ciliated, pseudostratified columnar epithelium.
- The propria and submucosa contain branched tubuloacinar mucous and seromucous glands
A
soft palate
20
Q
What is a muscular organ covered by a mucous membrane. It is important in prehension, mastication and swallowing of food?
A
tongue
21
Q
dorsal surface of the tongue is irregular and with numerous epithelial elevations called?
A
macroscopic papillae
22
Q
What are the most numerous among the types of papilla. They are slender, sharp-pointed structures that have a mechanical function in the movement of food into and within the oral cavity. The shape is like a rose thorn with its thorn directed caudad. They project above the surface of the tongue and are covered by a keratinized stratified squamos epithelium with a thick stratum corneum.
A
Filiform papillae
23
Q
What papillae occur on the root of the tongue in dog, cat and pig as well as on the cheek and floor of the oral cavity of other species. They are larger than the filiform type and usually are not highly keratinized.
A
Conical papillae
24
Q
What papillae are flattened lenticular-shaped (like a double convex lens) projections of the tongue surface and occur mainly in the ruminants especially prominent on the dorsum of the caudal one-third of the tongue. They are covered by stratified squamos epithelium and have a core of dense irregular connective tissue.
A
Lenticular papillae
25
What papillae are scattered among the filiform papillae and have dome-shaped upper surface in the horse and pig. The shape is suggestive of mushroom, a type of fungus, and thus the name fungiform. They are covered by a nonkeratinized stratified squamos epithelium containing one or more taste buds on the upper surface.
Fungiform papillae
26
What papillae located on the dorsum and rostral to the root of the tongue, are large, flattened structures completely surrounded by an epithelium-lined cleft or moat. The lingual surface is covered by a stratified squamos epithelium with taste buds on the papillary side of the moat.
Vallate papillae
27
What papillae are parallel folds of the lingual mucosa located at the lateral border just rostral to the palatoglossal arch. They are leaf-shaped separated from each other or the associated mucous membrane by an invagination of the mucous membrane. The folds are covered with stratified squamos epithelium, with taste buds on the sides of the folds.
Foliate papillae
28
What are ellipsoidal clusters of sensory cells embedded in the stratified squamos epithelium of the fungiform, vallate and foliate papilla.
taste buds
29
What of the tongue is most sensitive to sweet and salt?
tip
30
What portion of the tongue is sensitive to bitter?
posterior
31
What portion of the tongue is sensitive to sour taste?
lateral edges
32
What are small openings of the tastes buds that extend from the basement membrane.
Taste pores
33
What cell type in the taste buds are spindle-shaped, studded with microvilli (taste hairs) that project into the taste pore, and located in the center of the bud?
Neuroepithelial cells Neuroepithelial cells
34
What cell type in the taste buds are spindle-shaped, located toward the periphery and between the taste cells?
Supporting or sustentacular cells
35
What cell type in the taste buds are located near the basement membrane?
Basal cells
36
What special structures of the tongue in dogs, that is filled with adipose tissue, striated muscle, blood vessels and nerves.
lyssa
37
What are highly mineralized structures in the oral cavity that serve the domestic mammals in procuring, cutting, and crushing food and as weapons of offense and defense.
teeth
38
The roots of the teeth are set into bony ridges called ? In these processes are sockets (alveoli) - one for the root of each tooth.
alveolar process
39
The teeth are suspended and held firmly in their alveoli by bundles of connective tissue fibers known collectively as?
peridontal membrane or preferably as peridontal
ligament
40
What fibers are embedded collagenous fibers that hold the tooth in place. They are arranged so that when pressure is exerted on the biting surface of the tooth, the tooth being suspended by them will not be pressed further into the narrowing socket, and at the same time the tooth is permitted some slight movement within its alveolus.
Sharpey’s fibers
41
- Also called simple teeth
- Short and cease to grow after eruption is completed
- Divisible into a definitive crown, neck and root
- Enamel organ is intact until the time of eruption
- Ameloblasts disintegrate after eruption of the crown
- Cementum is deposited only on the dentine
Brachydont teeth
42
- Also called complex teeth
- Much longer than the brachydont teeth and continue their growth throughout a portion of the adult life of the animal.
- They do not have crown and neck but an elongated body with the roots and neck forming in some species only after a delayed period. The tusks of the boar continue to grow throughout its life and never develop roots.
- Enamel organ is ruptured prior to eruption
- Ameloblasts do not disintegrate; they continue to secrete enamel for an extended period beyond eruption
- Cementum is deposited on both the dentin and the enamel
- Include the cheek teeth of ruminants, all the teeth of horse, incisor teeth of rodents and the canine teeth of the pig.
Hypsodont teeth
43
What is the hardest substance in the body composed of 99% mineral (hydroxyapatite) and 1% organic matrix by weight. It covers the crown of the brachydont teeth but lies beneath a layer of cementum in the hypsodont teeth.
Enamel
44
What constitutes the major part of the tooth composed of 70% mineral (crystallites and hydroxyapatite) and 30% organic matter?
Dentin
45
The dentin that surrounds the pulp cavity is lined with a layer of special cells called ? whose function is related to the production of dentin.
odontoblasts
46
What structure of teeth that is a yellowish, mineralized layer of slightly modified bone.
Cementum
47
Bundles of collagen fibers, called ?, are embedded in the cementum of the tooth and extend into the bony socket.
perforating cementum fibers
48
perforating cementum fibers form what membrane?, which anchors the tooth in the socket. They are produced by cementoblasts.
peridontal membrane
49
What structure of teeth that is composed of connective tissue cells and fibers, matrix, numerous blood vessels, and nerves.
Dental pulp
50
What glamds include parotid, mandibular, and sublingual glands of all domestic animals, the zygomatic gland of carnivores, and the molar gland of cat. These glands, located outside of the mouth, produce a watery secretion called saliva.
major salivary glands
51
What are small clusters of seromucous secretory units in the submucosa of the oral cavity and are named according to their location
minor salivary glands
52
What in domestic animals is the largest of the major salivary glands, predominantly serous, although occasional isolated mucous secretory units may occur in the dog and cat
parotid salivary gland
53
The apex of each cell in parotid salivary gland is filled with secretory granules containing digestive enzymes. The granules are referred to as ? because they initiate the digestion of carbohydrates.
zymogen granules
54
Parotid Salivary Gland duct is called?
Stensen’s duct
55
Mandibular Salivary Gland main duct is called the?
Wharton’s duct
56
What gland is a compound branched tubuloacinar gland. It is a mixed type, majority of secretory units are composed of serous, and the rest are mucous with serous demilunes. It has a well-defined capsule and fairly prominent duct system. The columnar epithelium of the interlobular ducts gradually changes to two-layered cuboidal epithelium and finally becomes stratified squamos epithelium before it enters the oral cavity. Goblet cells may occur in the epithelium of the main duct.
mandibular salivary gland
57
Sublingual Salivary Gland main duct is called?
Rivinus duct
58
What gland is a compound tubuloacinar gland. The main duct is called Rivinus duct. It has an ill-defined capsule. Mixed type: majority of secretory units are mucous; a few serous; and mucous with serous demilunes. In cow, sheep and pigs, they are almost entirely mucous, with relatively few serous demilunes. In dogs and cats, in addition to the typical mucous acini and demilunes, these glands contain clusters of serous acini with well-developed intercellular canaliculi.
sublingual salivary gland
59
What glands is present only in carnivores named from its location between the zygomatic arch of the temporal bone. The parenchyma is composed of long branched tubuloacinar secretory units that are predominantly mucous secreting. Intercalated and striated ducts are almost non-existent, but isolated patches of tall, striated cells are present within the low cuboidal epithelium of the interlobular ducts.
Zygomatic salivary gland
60
What glands of cat, located in the fascia beneath the mucosa of the lower lip near the commissure is histologically similar to zygomatic salivary gland. It is a compound tubuloacinar gland that is predominately mucous secreting.
molar salivary gland
61
Clusters of serous, mucous or seromucous of what gland? occurring throughout the oral cavity are generally named according to their location. Mucous tubular and acinar units frequently have serous demilunes associated with them.
minor salivary glands
62
What glands are located in the submucosa and between the intrinsic muscle bundles of the tongue?
Lingual glands
63
What glands associated with the vallate and foliate papillas are entirely serous and their ducts open into the furrow at the base of the papillae.
Gustatory glands
64
What is a mixture of some cellular and bacterial debris and leukocytes; salt, gases, mucus, organic material, two enzymes (ptyalin or salivary amylases and maltase), immunoglobulins, and ionic secretions are produced by cells in different salivary glands, although the major composition of this is water.
saliva
65
What is an extension of the buccal cavity and connects it with the esophagus?
oropharynx
66
What is a long, soft tube that extends from the pharynx to the stomach?
esophagus
67
What is a dilated, hollow organ of the digestive tube that is situated between the esophagus and the small intestine?
stomach
68
stomach functions are performed by mechanical and chemical actions, which reduce the ingested food material to a semi-liquid mass called?
chyme
69
What is the most superior region in the stomach, surrounds the entrance of esophagus in the stomach?
Cardia
70
What form the major portion of the stomach; their mucosa contains deep gastric glands that produce most of the gastric secretions or juices for digestion of food?
Fundus (body or corpus)
71
What is the most inferior organ of the stomach, ends at the border of the duodenum of the small intestine?
Pylorus
72
What region is absent in carnivores and small in pigs. In horse, it extends a considerable distance and ends abruptly at the margo plicatus. In ruminants, it reaches the greatest development and is subdivided into rumen, reticulum and omasum.
non-glandular region
73
The glandular mucosa has extensive folds called ?, which flattens as the stomach fills.
rugae
74
The glandular mucosa has extensive folds called rugae, which flattens as the stomach fills. Permanent elevations, called ?, subdivide the mucosa and bulge into the lumen.
gastric areas
75
The glandular mucosa has extensive folds called rugae, which flattens as the stomach fills. Permanent elevations, called gastric areas, subdivide the mucosa and bulge into the lumen. The surface is studded with small depressions or invaginations called ?, continuous with gastric glands and receive their secretory products.
gastric pits
76
What region of the stomach is the non-glandular portion of the stomach
- Lined by stratified squamos epithelium, keratinized or non-keratinized.
- Limited in carnivores, man and swine; in ruminants, it is extensive and is subdivided into rumen, reticulum and omasum.
Esophageal region
77
What region of the stomach are branched, coiled tubular glands that opens into the gastric pits.
- The beginning is marked by a transition called the margo plicatus in the horse.
- It occupies a narrow strip at the junction of the glandular and non-glandular mucosae in all domestic mammals except the pig, where it covers nearly half of the stomach including the diverticulum ventriculi.
- The neck and upper body are lined by cuboidal cells, which are mucus secreting. The remaining cells of the gland are columnar, mucus secreting cells. Some parietal cells may be present in the canine cardiac gland while some chief cells may be present in porcine cardiac glands. Argentaffin cells (enteroendocrine cells) are located between the lining cells of the glands. The argentaffin cells secrete hormones, which control the secretory and muscular activities of the gastrointestinal organs.
Cardiac gland region
78
What region of the stomach are branched, coiled and relatively short compared to other gastric glands
- The gastric pits are deeper than in other regions of the stomach
- Predominant cell type is mucus secreting cell similar to that in the cardiac gland
- Has a well-developed inner circular layer of the tunica muscularis that forms the pyloric sphincter at the gastroduodenal junction. This encircles the caudal portion of the stomach and causes the submucosa and mucosa to bulge into the lumen. In ruminants and pigs, this protuberance called the pyloric tortus is especially prominent. At the pyloric-duodenal junction, the submucosal glands are found in the submucosa of the pyloric region.
- Occupies approximately half of the stomach in carnivores but only one-third in the horse stomach and in the ruminant abomasum. In the pig, the pyloric region is small, representing about one-fourth of the stomach.
Pyloric gland region
79
What region of the stomach are straight, branched tubular glands that extends to the lamina muscularis.
- Well-developed in all species
- Composed of four regions: base, body, neck and isthmus. The isthmus or opening of the gland into the gastric pit is continuous with a constricted part of the gland, the neck. The body continuous from the neck and terminates as a slightly dilated and bend adenomere, the base.
Fundic gland region
80
What zone has thinner mucosa with thinner gastric pits and has short tortuous glands that appear in groups and do not reach the muscularis mucosae?
Light zone
81
What zone is adjacent to the pyloric region and has thicker mucosae, shallow gastric pits, and the fundic glands that resemble those of other species?
Dark zone
82
Cell type in the stomach that are pyramidal-shaped cells with a basally positioned nucleus and apically positioned secretory granules. They are the predominant cells of the fundic glands.
Chief cells (or zymogen cells)
83
Cell type in the stomach that are large, polygonal, distinctive eosinophilic cells located primarily in the upper half of the gastric glands between other gland cells
Parietal cells (or oxyntic cells)
84
Parietal cells (or oxyntic cells) secrete what acid ? a major component of gastric juice
hydrochloric acid
85
Cell type in the stomach that are located in the upper region of the gastric gland near the gastric pits.
- The product of this cells along with that of the cells in the surface epithelium, is mucus; it covers the stomach lining with its protective layer.
- Mucus secretion is less viscous than that secreted by the surface lining cells. It may be capable of differentiating into surface lining and/or glandular lining cells.
- The secretion may protect the fundic gland from the proteolytic and hydrolytic activities of the proteases and HCl, respectively.
Mucous neck cells
86
Cell type in the stomach is described at times in the isthmus and may be responsible for the replacement of the lining and glandular cells?
Transitional cell
87
Cell type in the stomach that secrete a variety of polypeptides and proteins with hormonal activity that influences various functions of the digestive tract. These cells are not confined to the gastrointestinal tract but are also found in the respiratory organs and other organs of the bod
Enteroendocrine (APUD-amine precursor uptake decarboxylation) cells
88
The stomach of ruminants has four structurally distinct parts. The first three parts (rumen, reticulum and omasum) are collectively called the ?, lined with non-glandular mucous membrane having a stratified squamos epithelium.
forestomach
89
What is the glandular portion in stomach of ruminants similar to the simple stomach of other species?
abomasum
90
What part in stomach of ruminants is characterized by the presence of small tongue-shaped conical papillae that project into the lumen from the tunica mucosa?
Rumen or paunch
91
What part in stomach of ruminants has a mucosa with permanent anastomosing folds, giving it the appearance of a honeycomb?
Reticulum or honeycomb
92
What begins at the cardia and passes ventrally on the medial wall of the reticulum to end at the reticulo-omasal orifice?
reticular or esophageal sulcus
93
What part in stomach of ruminants is characterized by the presence of numerous rounded, horny papillae as well as smaller papillae that stud the surface of the mucosa?
Omasum or book
94
junction of the omasum with the abomasum is marked by a mucosal fold, called the ?, where the epithelium changes abruptly from stratified squamos to simple columnar epithelium.
omaso-abomasal fold
95
It is a long tube that extends from the junction with the stomach to the junction with the large intestine. This region is highly modified for the secretion and absorption facilitated by several specialized structures.
Small intestine
96
The tunica mucosa is thrown into circularly or spirally disposed folds called? These folds also contain portions of the tunica submucosa and disappear in the lower and/or middle of the ileum. These folds are permanent, spiral folds of mucosa (with submucosal core) that extend into the intestinal lumen; they are most prominent in the proximal portion of the small intestine, where most of the absorption takes place, and decrease in prominence closer to the ileum.
plicae ciculares (valves of Kerking)
97
The surface of the tunica mucosa over the folds is studded with tiny finger-like projections called? The villi cover the surface of the intestine, extend into the lumen and are also prominent in the proximal portion of the small intestine. They are broader in the duodenum and have no muscularis mucosa and tunica submucosa. In the upper jejunum, they are tongue-like and lower down they are finger-shaped.
villi
98
Presence of ? on the free or luminal surfaces of the absorptive columnar cells. They are cytoplasmic extensions that cover the apices of the intestinal absorptive cells. They are visible under a light microscope as a striated (brush) border.
Microvilli
99
What region is the fixed portion of the small intestine. It presents regularly shaped, blunt and wide villi. Their mucosa forms the highly corrosive action of the gastric secretions.
Duodenum
100
When acidic chyme enters the duodenum from the stomach, the glands secrete an ? rich in bicarbonate ions. This fluid then neutralizes the acidic chyme from the stomach and protects the duodenal surfaces from digestion.
alkaline fluid
101
What is the mesenteric region of the small intestine. They are essentially similar to the duodenum. The villi are slender, smaller and fewer than in the duodenum. The remaining mural elements are typical.
Jejunum
102
What is similar to jejunum except for the following:
a) More goblet cells
b) Presence of Peyer’s patches which are very prominent especially in pigs
c) Villi are club-shaped
d) Plica circulares are no longer present.
Ileum
103
Most cells in the intestinal epithelium are tall, columnar absorptive cell with a prominent striated (brush) border (microvilli) covered by a thick glycocalyx coat. The outer glycocalyx coat not only protects the intestinal surface from digestion, but also contains the enzyme required for the terminal digestion of carbohydrates and proteins and the carriers for transporting the products of digestion into the cell. Intestinal cells absorb amino acids, glucose, and fatty acids - the end products of protein, carbohydrates, and fat digestion, respectively. Amino acids and glucose are transported through intestinal cells to the blood capillaries.
Columnar cells
104
Interspersed among the columnar absorptive cells are what cells ? that increase in number toward the distal region of the small intestine (ileum). These cells secrete mucus that lubricates, coats, and protects the intestinal surface from the corrosive action of digestive chemicals and enzymes.
goblet cells
105
What cells are also found in the epithelium of the villi and intestinal glands. These cells secrete numerous regulatory hormones of the intestine, including gastric inhibitory peptide, secretin, and cholecystokinin (pancreozymin). These intestinal hormones control the release of gastric and pancreatic secretions, intestinal motility, and contractions of the gall bladder
Enteroendocrine or APUD (amine precursor uptake decarboxylation) cells
106
What cells are specialized pyramidal cells that contain deep-staining eosinophilic granules and have basally displaced nucleus, located at the base of the intestinal glands. Their exact function is not completely known however, these cells produce lysozyme, an antibacterial enzyme that digest the cell walls of some bacteria and appears to control the microbial flora of the small intestine.
Paneth cells
107
What is generally areolar or loose connective tissue that forms the core of the villi and surrounds the intestinal glands?
Lamina propria
108
Numerous aggregations of lymphoid nodules, called ?, are found in the ileum
Peyer’s patches
109
What cells continually sample the antigens of the intestinal lumen, ingest the antigens, and transport them to the underlying lymphocyte, where the specific antibody to the foreign antigen is developed.
M cells
110
What are located in the intestinal mucosa and open into the intestinal lumen at the base of the villi?
crypts of Lieberkuhn
111
What is single lymphatic capillary located in the center of the lamina propria of the villus?
Lacteal
112
What is a connective tissue layer of collagen and elastic bundles located between the lamina muscularis and tunica muscularis?
Tela submucosa
113
What mural element in all species consists of inner circular and outer longitudinal smooth muscle layers. It is thickest in horse, in which the two layers are nearly equal in thickness. The connective tissue between the two layers contains myenteric plexus (Auerbach’s plexus).
Tunica muscularis
114
What is the caudal continuation of the alimentary canal, which begins from the ileo-caecal junction and ends in the anus. The principal functions of the this intestine are to absorb water and minerals from the residual contents and form feces.
large intestine
115
- presents taeniae ceci, the thickened, longitudinally oriented bands of smooth muscle and elastic fibers from the outer longitudinal layer of the tunica muscularis.
- In herbivores with simple stomach (e.g. horse) the relatively large caecum is an important bacterial fermentation reservoir, but in carnivores, it is small.
- It has a substantial number of lymphatic nodules scattered throughout its length. In dog, pig and ruminants, it is located around the ileocaecal opening; while in horse and cat, they are concentrated near the blind end of the caecal sac.
Caecum
116
- Presents taenia coli. The tunica mucosa is substantially thicker, owing to the increased length of the intestinal glands as compared to the small intestine. In pig and horse, the outer longitudinal layer of the tunica muscularis of the colon (similar to caecum) forms a large, flat muscle bands containing numerous elastic fibers, the taenia coli.
- Diameter is generally greater than that of the small intestine
- Lamina muscularis is interrupted such that intestinal glands may extend into thesubmucosa
- Submucosa often becomes distended by the lymphatic tissue.
Colon
117
- Visible grossly because of pitlike depressions, rectal pits, in the mucosa overlying these lymphatic nodules.
- In ruminants, the rectal mucosa is thrown into longitudinal folds, the rectal columns (columnae rectales) near the junction with the anus
- In dogs, about 100 solitary lymphatic nodules are prominent feature of the rectum
- It has similar structure to other regions of the large intestine except:
- Taenia coli are absent
- Tunica muscularis is thicker
- More goblet cells
- Tunica adventitia replaces the tunica serosa
- Lamina propria may present erectile tissue
Rectum
118
- A mucocutaneous junction marked by a transition of the lining epithelium from simple columnar to nonkeratinized stratified squamos at the anorectal line.
- At the level of the recto-anal junction, the lamina muscularis mucosa and the outer layer of the tunica muscularis end. The inner layer of the tunica muscularis continues and terminates as the internal anal sphincter.
- Tunica adventitia is present and blends with the surrounding connective tissue may be associated with the anal glands and the circumanal glands in certain species.
Anus
119
What distinct zone of the anal canal contains longitudinal columns or anal columns, between which are anal sinuses.
Columnar zone (zona columnaris ani)
120
What distinct zone of the anal canal is relatively narrow. The mucosa is lined with stratified squamos epithelium and anal glands occupy the submucosa.
Intermediate zone (zona intermedia)
121
What distinct zone of the anal canal is lined by keratinized stratified squamos epithelium?
Cutaneous zone (zona cutanea)
122
In the outermost part of the cutaneous zone, near the junction with the skin, the mucosa of the dog contains large modified sebaceous glands, the?
circumanal glands
123
What is a single, largest gland in the body and accounts for 2-5% of the total body weight. It opens into the duodenum via the common bile duct. It has a highly strategic location and is characterized by a multiplicity of complex functions.
liver
124
What function of liver where the main exocrine function of the hepatocytes is the secretion of the bile, which enters tiny bile canaliculi located between adjacent hepatocytes. In the liver the bile flows toward the bile duct located at the periphery of the liver lobule and exactly in the opposite direction from the flow of blood.
Excretion Secretion (bile)
125
What function of liver where it also stores glucose (as glycogen), fats and various vitamins. When the cells of the body need glucose, glycogen stored in the liver is converted back into glucose and released into the blood stream.
Storage (lipids, vitamins A and B, glycogen)
126
What function of liver where the endocrine functions of the liver are related to the synthesis of the numerous plasma proteins, including albumin and blood clotting factor prothrombin and fibrinogen?
Synthesis (fibrinogen, globulins, albumin, prothrombin)
127
What function of liver where the kupffer cells, specialized phagocytic cells derived from blood monocytes and located in the hepatic sinusoids, phagocytize particulate material and cellular debris and remove it from the blood?
Phagocytosis (foreign particulate matter)
128
What function of liver where the liver cells detoxify various drugs and harmful chemicals?
Detoxification
129
What function of liver where the bile salts that are present in the bile are necessary to emulsify the fats that enter the small intestine (duodenum) from the stomach. This action of the bile promotes easier digestion of the fats by the fat-digesting enzymes, the pancreatic lipase produce by the pancreas. The cells inthe small intestine subsequently absorb the digested fats.
Esterification (free fatty acids to triglycerides).
130
In fetus, the liver cells perform ? an important function in the blood cell production. Thus, the liver is an essential organ for life.
hemopoiesis
131
These are the primary structural and functional subunits of the liver. These are highly versatile cells that perform numerous vital functions.
hepatocytes
132
the hepatocytes synthesize and release a secretory product called ? into a system of ducts, they are exocrine cells.
(bile)
133
What liver cells are interspersed among the sinusoidal endothelial cells and on their luminal surfaces?
Kupffer’s cells
134
What liver cells are stellate cells that are associated with sinusoids but lie in the space of Disse. They accumulate fat and store vitamin A in the form of retinyl esters.
Fat-storing cells
135
This large vein is formed by the junction of mesenteric and splenic veins. Mesenteric veins deliver oxygen-poor, nutrient-rich blood from capillaries in the intestinal walls. The splenic vein delivers by-products of RBC destruction from the splenic sinusoids.
Hepatic portal vein
136
The hepatic portal vein, which supplies about 75% of the liver’s total blood volume, enters through the?
hilum on the liver’s inferior surface
137
Hepatic portal vein branches repeatedly to form the ? that penetrate the liver parenchyma and empty their blood into the hepatic sinusoid.
portal venules
138
What is a smaller vessel, a branch of the celiac artery and enters the liver alongside the portal vein. It follows the latter’s branching pattern and empties oxygen-rich blood into the same sinusoids. It supplies about 25% of the liver’s blood volume.
Hepatic artery
139
Serving as the liver’s capillaries, these lies between the radially oriented hepatocyte plates and receive blood from branches of both the portal vein and the hepatic artery. The mixing of venous and arterial blood occurs only in the ? of the liver.
Hepatic sinusoids
140
The mixing of venous and arterial blood occurs only in
the hepatic sinusoids of the liver. The blood then flows towards what blood vessel? that is found in the liver lobules.
central vein
141
The liver sinusoids are dilated blood channels lined by a discontinuous layer of the fenestrated endothelial cells and Kupffer’s cells, which are separated from the underlying liver cells, the hepatocytes, by a perisinusoidal space called the?
space of Disse
142
What blood vessel lies at the center of the classic liver lobule that receive blood from the sinusoids and deliver it to larger sublobular veins, which merge to form even larger hepatic veins.
Central veins
143
What blood vessel collect oxygen- and nutrient-poor blood from the sublobular veins. They converge to form large veins that exit the liver’s upper surface and empty into the posterior vena cava.
Hepatic veins
144
What liver lobule is based on the direction of blood flow. The liver substructure exhibits a pattern of interlocking hexagons.
Classic liver lobule
145
One triad occupies a potential portal space at each of the six corners of the lobule. Each triad contains three main elements surrounded by a connective tissue: a portal venule (branch of portal vein), a hepatic arteriole (branch of hepatic artery) and a bile ductule (tributary of the larger bile ducts).
Portal triad
146
What is a single vein that marks the center of each lobule. It can be distinguished from the portal triad by its larger opening and lack of a connective tissue investment.
Central vein
147
What liver lobule is based mainly on the direction of bile flow, which is opposite to that of blood. The liver parenchyma is divided into interlocking triangles, each of which has a portal triad at the corner and a central vein at each of its three corners. Bile produced by the hepatocytes, enters the membrane-bound canaliculi between them and flows within the hepatocyte plates toward the bile duct in the portal triad. Liver lymph in the spaces of Disse flow in the same direction as bile., toward the lymphatic vessels in the triad.
Portal lobule
148
What liver lobule is based on changes in oxygen, nutrient, and toxin content as blood flowing through the sinusoids is acted on by hepatocytes.
Hepatic acinus (acinus of Rappaport)
149
What zone of hepatic acinus is closer to the vessels, has the best blood supply?
Zone I - (peripheral zone
150
What zone of hepatic acinus is closer to the central vein, has the poorest blood supply?
Zone III - (centrolobular zone)
151
What is consists of bile acids, phospholipids, cholesterol, bilirubin, water and electrolytes?
Bile
152
Cholic acid is synthesized from cholesterol and conjugated with glycine or taurine to form glucocholic and taurocholic acid, respectively.
Bile acids
153
What is water-insoluble byproduct of the hemoglobin catabolism that accompanies the disposal of worn erythrocytes by the cells of the mononuclear phagocytic system in the spleen, liver and bone marrow.
Bilirubin
154
Bilirubin is carried by the blood to the hepatocytes, which conjugate it with glucoronic acid to form ? This water-soluble substance is secreted with other bile components, into the bile canaliculi.
bilirubin gluconide
155
Bile in the canaliculi flows towards the portal triads (opposite to the blood which flows in the sinusoids). At the lobule periphery, the canaliculi empty into short, narrow bile ductules (also called cholangioles or Hering’s canal), which are lined by the cuboidal cells with clear cytoplasm. The ductules deliver the bile to the bile ducts in the portal triads. The bile duct empty into successively larger ducts, ending in a single hepatic duct that joins the cystic duct from the gall bladder to form the common bile duct (ductus choledochus). This empties the bile into the duodenum. Where the common bile duct penetrates the duodenal wall, it is encircled by a thick layer of smooth muscle, the sphincter of Oddi. Although the liver produces bile continuously, the sphincter opens fully only when a particular fatty meal enters the duodenum. When the sphincter is closed, bile backs up the common duct, through the cystic duct, and into the gallbladder.
Biliary tract
156
Bile in the canaliculi flows towards the portal triads (opposite to the blood which flows in the sinusoids). At the lobule periphery, the canaliculi empty into short, narrow bile ductules (also called cholangioles or Hering’s canal), which are lined by the cuboidal cells with clear cytoplasm. The ductules deliver the bile to the ? in the portal triads.
bile ducts
157
The bile duct empty into successively larger ducts, ending in a single hepatic duct that joins the cystic duct from the gall bladder to form the?
common bile duct (ductus choledochus)
158
Where the common bile duct (ductus choledochus) penetrates the duodenal wall, it is encircled by a thick layer of smooth muscle, the?
sphincter of Oddi
159
What is a small, hollow organ attached to the inferior surface of the liver. It receives, stores, and concentrates bile by absorbing its water.
gallbladder
160
In response to the entrance of dietary fats into the small intestine, a hormone called?, is released into the blood stream by the enteroendocrine cells located in the intestinal mucosa. It is carried in the blood to the gallbladder and causes rhythmic contractions of the smooth muscle in the wall of the gallbladder. This action forces the bile to enter the duodenum by way of the common bile duct.
cholecystokinin
161
What is the the main accessory digestive organ, is an encapsulated, lobulated, compound tuboloacinar gland containing both exocrine and endocrine secretory units. It produces an alkaline fluid with numerous digestive enzymes that breakdown proteins, fats, and carbohydrates into smaller molecules for absorption in the small intestine. The stroma consists of a thin capsule that gives rise to delicate connective tissue septa separating the parenchyma into distinct lobules.
pancreas
162
pancreas secretory unit is called?
pancreatic acinus
163
Most of the pancreas consists of the exocrine secretory units or acinar cells, which secrete?
pancreatic enzymes
164
Pancreatic secretions are regulated both by hormones and vagal stimulation. Two intestinal hormones called ?, secreted by the enteroendocrine cells of the duodenal mucosa into the blood stream, regulate the pancreatic secretions.
secretin and cholecystokinin
165
In response to the presence of acidic chyme in the small intestine, what release stimulates the pancreatic cells to secrete large amount of watery fluid rich in sodium bicarbonate ions? This fluid, which has little or no enzymatic activity, is produced primarily by the epithelial cells that line the smaller pancreatic ducts. The function of this fluid is to neutralize the acidic chyme and create optimal environment for the activity of the pancreatic enzymes.
secretin
166
In response to the presence of fats and proteins in the small intestine, what release stimulates the acinar cells in the pancreas to secrete large amounts of different digestive enzymes? The pancreatic enzymes that are produced in the acinar cells enter the duodenum in an inactive form and are then activated by a hormone secreted by the intestinal mucosa.
cholecystokinin
167
Scattered throughout the secretory acini in the pancreas are the pale-staining, spherical units of the cells called? these group of cells constitute the endocrine portion of the pancreas.
pancreatic islets (islets of Langerhan’s)
168
Pancreatic islet cells produce important hormones such as?
insulin and glucagons
169
What cells produce the hormone glucagons, whose main physiological function is to increase the levels of glucose in the blood. This function is primarily accomplished by accelerating the conversion of glycogen, amino acids, and fatty acids in the liver into glucose; this conversion elevates the sugar levels in the blood.
alpha cells
170
What cells on the pancreatic islets produce the hormone insulin, whose release is stimulated by the elevation of the glucose after meal. The main physiological function of insulin is to lower the glucose level of the blood by accelerating membrane transport of glucose into cells, especially into the cells of liver, muscle, and fat. Insulin also accelerates the conversion of glucose into glycogen in the liver. The effects on insulin in the levels of blood glucose are just the opposite to that of the glucagons.
beta cells
171
What cells secrete the hormone somastostatin, which decreases and inhibits the secretion of both insulin and glucagons through local action within the pancreatic islets.
delta cells
172
The delta cells secrete the hormone called ?, which decreases and inhibits the secretion of both insulin and glucagons through local action within the pancreatic islets
somastostatin
173
Whqt cavity differs from that of mammals in the following:
- Lips and cheeks are absent
- Presence of cornified beak appended to the upper and lower jaws
- Tongue is narrow, pointed, devoid of taste buds and contains a bone, the entoglossal bone
- Teeth are absent although rudimentary tooth buds are present in some birds
- Definitive salivary glands are absent, instead simple branched tubulo mucous glands are present
- Lining epithelium is keratinized stratified squamos.
Buccal Cavity
174
Tongue is narrow, pointed, devoid of taste buds and contains a bone, the?
entoglossal bone
175
What region of the Avian Digestive System presents the following features:
- Lining epithelium is keratinized stratified squamos
- Lamina propria is loose connective tissue with diffuse lymphatic tissue and lymphatic nodules
- Tunica mucosa and submucosa are arranged in longitudinal folds
- Muscularis mucosa is undulating
- Lamina propria presents simple branched tubuloalveolar mucous glands
Esophagus and Crop
176
What is an esophageal diverticulum. The lining epithelium is thicker than that of the esophagus of Avians.
crop or ingluvies
177
In columbiform birds, the superficial cells of the lining epithelium undergo a fatty change to a substance called? This moistens the food through its mucoid secretions as well as macerates the materials through the muscular contractions of the tunica muscularis.
crop milk
178
What is the glandular stomach of birds?
Proventriculus
179
What is connected to the proventriculus by a narrow isthmus, which is devoid of submucosal glands.
Ventriculus or gizzard or muscular stomach
180
What intestate is not divisible histologically into different regions. It is similar to the intestine of mammals except for the following:
- No muscularis mucosa
- Lamina propria - tunica submucosa contain large quantities of diffuse and nodular lymphatic nodules
- Tunica muscularis may contain a third layer of circular muscle in the inner portion.
Small intestine
181
What are two blind sacs appended to the junction of the small and large intestines in avian digestive system?
Ceca
182
The accumulation of nodules at the caecal orifice is called?
caecal tonsil
183
This has short and thick villi and an increased number of goblet cells. Other than this feature, the region is similar to the small intestine
Rectum
184
a common orifice for digestive, excretory and reproductive systems. It is divisible into three regions: coprodeum, urodeum and proctodeum.
Cloaca
185
What part of lower digestive tract presents the following features:
- Lining epithelium is keratinized stratified squamos
- Tunica mucosa is highly folded
- Muscularis mucosa is absent
- Striated muscle of the tunica muscularis forms the anal sphincter
Anus
