Lecture 20: Digestive System 1 Flashcards
(105 cards)
1
Q
Prehension
A
Ingestion followed by fragmentation
2
Q
5 functions of the GI system
A
1. Prehension 2, Mechanical and enzymatic breakdown (fermentation) of nutrients 3. Absorption 4. Synthesis/secretion 5. Excretion of waste materials
3
Q
Lining epithelium from lips to non-glandular stomach
A
Stratified squamous epithelium
4
Q
Lining epithelium in glandular stomach and intestine
A
Simple columnar
5
Q
Oral cavity is formed by
A
Lips and cheeks, palate, pharynx, tongue
6
Q
Mucosa of the oral cavity is lined by
A
Stratified squamous epithelium
7
Q
In ruminants, the oral cavity has
A
Dental pad
8
Q
Tongue epithelium
A
Covered by mucosa, a stratified squamous epithelium, keratinized on dorsal side
9
Q
Dorsal/upper surface of tongue is irregular due to
A
Presence of papillae (mechanical and gustatory)
10
Q
Tongue’s main component
A
Skeletal muscle arranged in three directions (longitudinal, transversal, and vertical)
11
Q
Does the tongue have a tunica submucosa?
A
Nope
12
Q
Hard structures of teeth
A
Enamel
Dentin
Cementum
13
Q
Soft tissues of teeth
A
Pulp
Peridontal ligament
14
Q
Enamel is produced by
A
ameloblasts that cover the external surface
15
Q
Dentin location and production
A
Beneath enamel
By odontoblasts
16
Q
Cementum is formed by
A
cementoblast
17
Q
Tooth pulp
A
Loose connective tissue and nerves
18
Q
Root mesenchyme of tooth pulp is derived from
A
Neural crest cells
19
Q
Peridontal ligament is made by
A
fibroblasts
20
Q
General organization of digestive organs
A
Muscular tube with 4 coats/tunics
- Muscosa
- Inner epithelium
- Middle lamina propria
- Thin outer muscularis mucosa - Submucosa
- Muscularis
- Serosa
21
Q
Tunica submucosa structure
A
- Loose CT, looser than in lamina propria mucosae
- May contain glands, vessels, a nerve plexus, and lymphatic nodules.
22
Q
Purpose of submucosa
A
facilitates motility of mucosa
23
Q
If lamina muscularis is absent, the combined area is called
A
lamina propria/submucosa
24
Q
Tunica muscularis may be what muscle?
A
Smooth or skeletal
25
Usually ___ layers of smooth muscle:
2
- Inner circular
- Outer longitudinal
26
Tunica muscularis controls
Lumen size and motility of tube
27
Tunica muscularis contains
myenteric plexus (Auberbach), vessels, nerves, nerve cell bodies in ganglia on the plexus
28
A plexus
- Two autonomic nervous system divisions in the same location in the enteric wall
- Neuron cell bodies of parasympathetic ns and enteric ns, their axons and the axons of the sympathetic neurons
29
Enteric plexus controls
Glands and smooth muscle of organs
30
Tunica serosa is composed of
mesothelium and loose CT +/- adipose tissue
31
Tunica adventitia is composed of
loose/dense CT only
32
What is the most external tunic
T. serosa
33
Tunica serosa is continuous with
mesentery, omentum, and pleura
34
Adventia covers portions of
the esophagus, rectum, vagina, bronchi, trachea where passing through the mediastinum, body wall, and neck
35
Esophagus epithelium
- Stratified squamous epithelium
- Mucus glands in submucosa
- May have a lamina muscularis mucosae
36
Esophagus healing
poorly
37
Tunica muscularis of esophagus may be composed of
Skeletal muscle only or a combo of skeletal and smooth
38
Innervation of esophagus
Cr N X
39
Tunica adventitia of esophagus
Loose CT without mesothelium, covers most of the esophagus
40
Stomach description
Distention of digestive tube with sphincters at entry (cardia) and at exit (pylorus)
41
Tunica mucosa of stomach
May be non-glandular (cutaneous), glandular (with simple columnar epithelium)
42
Mucus membrane of the stomach can be
- Cutaneous, non-glandular
| - Glandular with simple columnar epithelium
43
Margo plicatus in the equine stomach
Junction between glandular and non-glandular stomach
44
Simple stomach
Carnivores and humans with glandular mucosa only
45
Composite stomach
Pig and horse with both glandular and cutaneous mucous membrane
46
Compound multichambered stomach
Ruminants, non-glandular mucosa in forestomachs
47
Forestomach - who has it and structure/function
- Ox, sheep, goats
- 3 compartments, lined with stratified squamous epithelium
- Fermentation vat
- Papillated mucosa
- Volatile fatty acid absorption
48
Three compartments of the forestomach in a compound multichambered stomach
- Rumen: largest of the three, low papillae
- Reticulum: honeycomb mucosa
- Omasum: "many piles," butcher's bible
49
Rumen and reticulum functions
Mixing, absorption, eructation, regurg, movement of ingesta , and VFA absorption
50
Omasum functions
Squeezing ingesta, liquifies and moves it to the abomasum for further digestion
51
Ruminal papillae in the epithelium allows for
Increased SA with stratified squamous epithelium with desmosomes to enhance passive absorption of volatile fatty acids in rumen
52
Proventricles are lined with
stratified squamous keratinized epithelium
53
Glandular stomach in ruminants
- Abomasum
| - True stomach for these species
54
The three glandular regions in all domestic species
- Cardiac
- Fundic
- Pyloric
55
What allows distention of the stomach?
Longitudinal rugae
56
Gastric pits
invaginations of the lining epithelium in the stomach
57
Cardiac region of the stomach is mostly composed of
mucous glands
58
Fundic region of stomach is composed mainly of
proper gastric glands (parietal and chief cells)
59
Gastric glands are lined by
Simple columnar epithelium, which dips down and creates gastric pits
60
Three types of gastric glands
1. Cardiac glands - mainly mucus
2. Proper gastric glands (fundic)
3. Pyloric glands - mucus glands
61
Cardiac gland region
Near esophageal stomach junction composed mainly of mucus glands and a few parietal cells
62
Fundic region with proper gastric glands is composed of
- Parietal
- Chief cells/peptic
- Stem cells
- Enteroendocrine cells
63
Pyloric region
- Mucus glands
- G cells produce GI hormone gastrin
- All gastric (exocrine) glands empty into gastric pits
64
Chief cells in fundic region of glandular stomach
- Basophilic
- Secrete pepsinogen in adult
- Secrete chymosin in infants to curdle milk, allowing further digestion along intestine
65
Chymosin can be called what in ruminants
Rennin
66
Parietal cells in fundic region of glandular stomach
- Acidophilic
| - Secrete HCl and intrinsic factor needed for vitamin B12 absorption vitamin
67
Enteroendocrine cells require what to see them?
- Special stains
| - Ex. Silver "argentaffin" cells and/or salts of chromium to see enterochromaffin cells
68
Intestines are lined by
simple columnar epithelium with goblet cells
69
Small intestine structure
- Plicae, villi, microvilli to increase SA
- Submucosal glands located in duodenum
- Lymphatic nodules in distal small intestine
- Myenteric plexus and submucosal plexus
70
Total absorbing area in human small intestine is
200 m2
71
Plicea increases absorbing area of small intestines by how much
3 fold
72
Intestinal villi increase absorbing area of small intestines by how much
10 fold
73
Microvilli of enterocytes in the small intestine increase absorbing surface by
20 fold
74
Ability to absorb antibodies from colostrum is...
short and temporary (1-2 days) in ruminants, horses, and pigs
75
Villi are confined to what intestine?
small
76
As the base of the villi in the small intestine are
Crypts of lieberkuhn, corresponding to the invaginations of the lining epithelium
77
Lacteals in the small intestine begin
in the center of the villi
78
The duodenum has what kind of glands
Brunner's glands
79
Three regions of the small intestines
Duodenum
Jejunum
Ileum
80
Three regions of the large intestines
Caecum
Colon
Rectum
81
Lacteals
- Blind-ended lymphatic vessels in intestinal villi
| - Chyle found in lacteals is filtered through intestinal lymph nodes before re-entering blood at jugular vein
82
Peyers patches
Aggregations of lymphoid nodules present in lamina propria and submucosa of the small intestine
83
Where are peyers patches found
Distal jejunum and ileum, but varies according to species
84
Paneth cells location
Located near the crypt base in some species (primates, horses, and rodents)
85
Paneth cells function
- Considered to have both secretory and phagocytic functions; produce cryptdin and lysins (substances toxic to bacteria)
- Act in a paracrine manner by opening anion channels in enterocytes causing chloride secretion from crypt enterocytes
86
Enteroendocrine cell location
Primarily localized in crypts
87
Enteroendocrine cell function
-Produce serotonin, glucoinsulotropic peptide, catecholamines, gastrin, somatostatin, serotonin, cholecystokinin, secretin, bombesin, enteroglucagon, and likely others in response to chemical and mechanical stimuli
88
Does the large intestine have villi?
Nope
89
Purpose of large intestine
Absorbs H2O and mucus
90
Are there intestinal crypts in the large intestine?
Yup, but relatively long
91
Taenia coli
Flat bands composed of smooth muscle and elastic fibers in the large intestines of pigs and horses
92
Large intestine is innervated by
Vagus nerve, celiacomesenteric ganglia, caudal mesenteric ganglia, hypogastric nerves, pelvic nerves
93
ID structure in duodenum
Brunner's glands in tunica submucosa
94
ID structure in Jejunum
none
95
ID structure in ileum
Peyer's patches in tela submucosa
96
Rectum purpose
Stores feces, secretes lots of mucus
97
Three different glandular regions in the anus
1. Anal glands - empty into lumen of anus
2. Anal sac glands - empty into anal sacs
3. Circumanal glands - nonpatent ducts, no function known - may form benign tumors
98
Innervation of sphincter muscles
ANS - internal
| Somatic - external
99
Rectum ends in
Anal canal lined by squamous epithelium, with it being keratinized near the muco-cutaneous junction
100
Tubuloacinar anal glands
- Present in pigs and dogs
| - Located in submmucosa and muscularis of the anal canal
101
Location of anal sacs in carnivores
- Paired anal sacs are located lateral and below anal sacs in carnivores
- Between inner smooth muscle of internal anal sphincter and outer skeletal muscle of external anal sphincter
102
Anal sacs are lined by
keratinized, stratified squamous epithelium
103
Glands of anal sacs
Apocrine tubular in dog
| Apocrine tubular and sebaceous in the cat
104
Circumanal gland location
Subcutis around anus in the dog
105
Circumanal gland compostion
- Sebaceous glands in upper portion, non-sebaceous glands in lower portion
- Non-sebaceous glands resemble hepatocytes so are named hepatoid glands
