Comparative Gastrointestinal Anatomy Flashcards
(117 cards)
1
Q
GI tract
A
The organ system, glands, and structures responsible for consuming, digesting, absorbing, and secreting/excreting
2
Q
Another name for the GI tract
A
Alimentary or digestive tract
3
Q
Chyme
A
Semi-fluid mixture of digestive secretions and semi digested food in the stomach
4
Q
Diverticulum
A
Sac/pouch formed in wall of alimentary tracts
5
Q
Sacculated
A
Formed of/divided into sac-like pouches
6
Q
Prehension
A
Getting food in the mouht
7
Q
Rumination
A
Controlled form of vomiting, allowing half-liquid materials to be brought back up the esophagus, swallowing the liquid and deliberate re-mastication of and swallowing of the bolus formed in the process
8
Q
Foregut
A
The stomach + small intestin
9
Q
Hindgut
A
Cecum, colon and rectum
10
Q
Enteroendocrine hormone
A
Peptide that is synthesized primarily in cells of the digestive tract and influences the activity of organ digestives in a hormone manner
11
Q
Hysodont teeth
A
Keep growing
12
Q
Brachydont teeth
A
Are not replaced, do not keep growing
13
Q
Three main functions of the GI tract
A
Digest/absorb Prevent entry of pathogens Eliminate waste (material and toxins)
14
Q
Three classifications of animals based on their GI tracts
A
Simple nonruminants
Nonruminant herbivores
Ruminants
15
Q
GI tract of simple nonruminants
A
Pouch-like, non-compartmentalized stomach, do not depend on microbial digestion in any part of the gut
16
Q
Another name for simple nonruminants
A
Mono-gastric
17
Q
GI tract of non-ruminant herbivores
A
Has modifications to facilitate microbial fermentation, many of the same functions performed as in the rumen
18
Q
Three groups of nonruminant herbivores
A
Foregut fermenters
Colon fermenters
Cecal fermenters
19
Q
Foregut fermenters GI tract
A
Compartmentalized stomach with one or more pouch where microbial fermentation occurs, it is separate from the glandular stomach
20
Q
Colon fermenters GI tract
A
Have an enlarged colon for microbial fermentation
21
Q
What is a disadvantage of colon fermentation
A
It is less efficient than rumen fermentation because of the anatomical location
Since the microbe’s in the hind gut get the stuff the animal cannot digest, it is a less favorable nutrient environment and the products are less available to the host animal
22
Q
Cecal fermenters GI tract
A
Have a large, muscular blind pouch
23
Q
What is cecotrophy
A
Small herbivores consume their soft feces which contain well-fermented material from the cecum rich in protein and vitamins, this results in normal hard pellets
24
Q
What are the four basic layers/tunics of the GI tract
A
Tunica serosa
Tunica muscularis
Tunica submucosa
Tunica mucosa
25
What is the mesentery
The fusion of the tunica serosa in the abd cavity
26
What is the function of the mesentary
Houses vascular and nervous supplies to the digestive tract
27
What is the tunica serosa referred to as in the abdominal cavity vs esophagus and rectum
abd: visceral peritoneum
| esophagus/rectum: tunica adventitia
28
What is the function of the tunica muscularis
Contraction (peristalsis)
29
What is the distinction between in the two layers of the tunica muscularis
The inner layer are circular fibers, the outer layer are longitudinal fibers
30
What is found between the two layers of the tunica muscularis
The myenteric plexus
31
What is the myenteric plexus
Controls the frequency and strength of contraction, part of nervous system
32
What does the tunica submucosa contain
Blood and lymphatic vessels, and the submucosal plexus
33
What is the function of the submucosal plexus
Provides nervous control to affect mucosal glandular secretions, motility and blood flow
34
What/where is the lamina propria
In the mucosa layer, houses blood vessels and lymphatics that supply the epithelium
35
What/where are the GALT
In the mucosa layer, important for immune functions
36
What/where is muscularis mucosae
In the mucosa layer, responsible for movement of villi in the small intestine
37
What are the two types of contractions in the GI tract
Segmental and peristaltic
38
Segmental contractions
Squeezing of the bolus so that it is always being mixed as it moves down the intestine
39
How is segmental contraction acheived
The contraction and relaxation of circular smooth muscles
40
Peristaltic contractions
Propel a bolus down the GI tract away from the oral cavity
41
How is peristaltic contraction achieved?
Contraction of outer longitudinal muscles and inner circular muscles behind the bolus, and relaxation of these muscles ahead of the bolus
42
What are 5 functions of the oral cavity
Prehension, salivation, mastication, taste and formation of a bolus for swallowing
43
Three structures used for prehension
Lips, tongue, teeth
44
What is the chief prehensible organ in cattle
Tongue
45
What are the objectives of mastication
Reduce size, increase surface area, soften, lubricate
46
What has hypsodont teeth
Ruminants and horses
47
What has brachydont teeth
Dogs, cats and humans
48
The rostral two thirds of the tongue is sensitive to...
Temperature, touch, pain
49
The caudal one third of the tongue is...
Innervated by nerves that carry taste sensation from the taste buds
50
What are the 5 tastes
Salty, sour, sweet, bitter and umami
51
What is the composition of saliva
99% water, 1% mucin, salts digestive enzymes and lysozymes
52
Acini
Basic secretory units of salivary glands
53
What are the two types of acinar epithelial cells
Serous cells and mucous cells
54
What are some functions of saliva
Aids in bolus formation, keeps mouth moist, aids in taste, provides enzymes, control bacterial populations
55
What is an additional function of saliva in ruminants
Source of N, P and Na which are used by rumen microorganisms and aid in maintaining the pH of the rumen
56
What are three salivary glands, their locations, and their products
Submandibular (base of tongue) - mix of serous and mucous secretion
Sublingual (under tongue) - mostly mucous
Parotids (below ears) - mostly serous/watery
57
Muscle type in the esophagus
Striated (all in cattle and sheep), smooth muscle in some locations (in cats, horses and humans)
58
What controls salivary secretions
Parasympathic stimulation and secretin
59
Mucins prevent...
Foaming (bloat)
60
What binds the esophagus
Upper and lower esophageal sphincters
61
What keeps the lower esophageal sphincter shut
Gastrin and vagal parasympathetic stimulation
62
What causes the lower esophageal sphincter to relax
Response to the presence of a bolus
63
What is the esophagus lined with
Stratified squamous epithelium
64
4 functions of the stomach
Storage/release, mechanical breakdown, digestion, clotting of milk
65
4 glandular regions in the stomach
Esophageal, cardiac, peptic/fondus, pyloric
66
Esophageal area of the stomach
Extension of esophagus, no glands, alpha-amylase activity
67
Cardiac region of the stomach
Mostly mucus
68
Peptic region/fondus of the stomach
Covered with gastric pits, produce a mix of acid, enzymes, mucus and hormone, largest compartment
69
What are the 3 main cell types of the fondus and what to they produce
Chief/peptic cells (pepsinogen and renin)
Parietal/oxyntic cells (hydrochloric acid)
Mucous surface and neck cells (mucus)
70
Pyloric region of the stomach
Before entry to small intestine, lined by cells that produce mucus and buffer, has enteroendocrine cells that produce hormones
71
Pyloric sphincter
Controls the rate at which the stomach empties
72
What is an example of an entereoendocrine cell
G cells
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3 factors that control acid secretion by parietal cells
Histamine production when pH gets too high - stimulates acid secretion
Gastrin in response to distension and rise in pH - stimulate acid secretion
Parasympathetic afferent vagal nerve
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Stomach motility is increased when...
Gastrin and parasymp. vagus in response to distension
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Stomach motility is decreased by...
Distension of duodenum
Increase in osmolarity in the duodenum
CCK (cholecystokinin) secreted in response to fats and amino acids in the duodenum
Release of secretin in response to reduction in pH in the duodenum
76
What is the crop
A diverticulum of the esophagus, holds food
77
Why is the crop a site of digestion
Continued action of salivary amylase and because of microbial activity
78
Proventriculus
Glandular stomach
79
Gizzard/ventriculus
Muscular stomach, grinds food
80
What is the koilin layer
Coats the muscular stomach, protects from gizzard erosion
81
What stimulates vagal efferent activation of stomach muscle contraction
Distension of the fundus
82
What is the function of the small intestine
Digestion and absorption of nutrients
83
What are the 3 parts of the small intestine
The duodenum, jejunum and the ileum duodenum
84
Villi
Projections of the tunica mucosa in the small intestine into the lumen
85
Crypts
Invaginations of the tunica mucosa of the small intestine (opposite of villi basically)
86
What are found at the tips of mirovilli
Glycocalyx
87
Brush border
Made up of the mircovilli and glycocalyx of each villus
88
Each villus contains...
Arteriole and venules, together with a drainage tube of the lymphatic system a lacteal
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Where do the venules drain
Hepatic portal system
90
Where do lacteals drain
Thoracic lymphatic duct
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What are 3 cell types in crypts
Enterocytes, goblet cells and enteroendocrine cells
92
How many cells slough off the normal villous tip each day
1400
93
The duodenal area is the site of....
Mixing and secretion
94
The jejunal area is the site of...
Absorption
95
What are Brunner's glands and what are they controlled by
Produce alkaline secretion that acts as a lubricant in the duodenum to protect it from the HCl from the stomach
Controlled by secretin when the pH of the fluid falls too low (too acidic)
96
What are some functions of the enterocytes in the crypts
Sodium secretion provides an electrochemical gradient needed to allow absorption
Water secretion reduces osmolarity of digesta
97
What is the primary stimulus of contraction of the small intestine
Distension
98
What are the first contractions of the small intestine to occur
Segmental
99
What moves the bolus through the small intestine
Peristaltic contractions
100
What stimulates small intestine motility
Gastrin and CCK
101
What slows small intestine motility
Secretin
102
What is the function of the liver
Secrete bile to digest fats
103
What is the portal triad
Hepatic artery, portal vein and bile ducts in the liver
104
Where is bile secreted and what is it made up of
Into the duodenum through bile duct
| Made of salts of bile acids, phospholipids, and bile pigments
105
What is bile production stimulated by (and contraction of gall bladder)
CCK
106
What are the small spaces between adjacent hepatocyte membranes
Canaliculus - where bile is secreted into
107
What happens with bile secretion in rats and horses
They do not have a gall bladder so bile flows into the duodenum continuously.
108
What is the exocrine function of the pancreas
Provide enzymes needed for digestion secreted from acinar cells (secreted in inactive form)
109
Function of the large intestine
Absorption of water, secretion of inorganic elements, microbial fermentation, VFAs production, B-complex vitamins, forms feces
110
What are the 3 parts of the large intestine
Cecum, colon and rectum
111
What is a benefit of bacterial action in the large intestine
Synthesis of B vitamins that can be used by the host
112
What species have an ileocolic sphincter and what is its function
Ruminants, cat and dog
| Passage for material from the ileum to the large colon
113
What species have and ileocecal sphincter and what is its function
Horse, pig, rabbit, elephant and rats
| Place where the ileum empties into the cecum
114
What causes the sphincters in the large intestine to relax
Distension of the ileum and gastrin
115
What contractions take place in the ascending colon
Segmental or peristaltic
116
Antegrade contractions
Move material forward
117
Retrograde contractions
Keep material in the cecum longer for more extraction
