GIT Flashcards
1
Q
GI system
A
- lips to anus (external)
- multiple associated structures (teeth, salivary glands, liver, LN)
- ingestion, digestion, absorption, elimination
- immune surveillance/barrier
- great species variation*
2
Q
Gross layout
A
- mouth (oropharynx)
- esophagus
- stomach
- intestine
- rectum
- anus (cloaca)
3
Q
Microscopic layout
A
- mucosa: epithelium, lamina propria, muscularis mucosa
- submucosa
- muscularis
- adventitia (serosa)
4
Q
What is found in the muscularis mucosa?
A
Small band of smooth muscle
5
Q
What is found in the submucosa?
A
Loose areolar CT where blood vessels travel
6
Q
Mucosa
A
Stratified squamous lines the mouth and esophagus (rumen, reticulum, and omasum)
- changes to simple columnar deeper in the GIT
- lamina propria: accumulation of lymphocytes below the epithelial layer and BM
7
Q
Submucosa
A
Varies in thickness
- thin up high and thicker in the lower intestine
8
Q
Muscularis
A
Varies, have skeletal muscle in the esophagus and smooth muscle lower in the GIT
9
Q
Serosa
A
Present as peritoneum in the abdomen
- adhered to other connective tissue in the cervical and mediastinum
10
Q
Oral cavity
A
- lips (mucocutaneous junction)
- tongue: stratified squamous epithelium, skeletal muscle
- teeth
- tonsils: caudal portion of oropharynx
- salivary glands
11
Q
Tongue
A
- stratified squamous epithelium (papillae and taste buds)
- voluntary striated muscle
- sublingual glands: produce saliva
12
Q
Teeth
A
Crown: visible portion - enamel: outermost surface, only on the crown - dentin: dense CT - pulp: extends from crown to root Root - cementum - dentin - pulp - central canal/nerve
13
Q
Tonsils
A
- location: palantine (swine), sublingual
- epithelium: crypts
- lymphoid nodules: vary with degree of antigen stimulation
14
Q
Salivary glands
A
- add moisture/ emulsify
- begin digestion (CH2O)
- buffer, minerals
- antimicrobial
- major glands: parotid, mandibular, sublingual, zygomatic
15
Q
Salivary gland components
A
- paired
- epithelial lined: lobules, acinus (-i), myoepithelium (characteristics of muscle, but is epithelium)
- ducts
- secretions: serous (water/protein), mucous, mixed (water and mucous based secretions)
16
Q
Acini
A
Clusters of glands, separated by fine connective tissue
17
Q
Mucous is ______
A
Proteinaceous, stains pink
18
Q
Are salivary glands exocrine or endocrine?
A
Exocrine!
- secrete product into a duct before it reaches the target area
19
Q
Esophagus
A
Muscular conduit - oropharynx to stomach - cervical - thoracic (extends to stomach) Stratified squamous epithelium - some submucosal glands Smooth and voluntary muscle
20
Q
Adventitia of the esophagus
A
Does not have a discrete adventitia in the cervical region –> is attached to CT of trachea and cervical muscles
Does have an adventitia in the thoracic cavity and out into the abdomen
21
Q
What are the 3 organs that cross the diaphragm
A
- aorta
- vena cava
- esophagus
22
Q
Avian anatomy
A
Crop: esophagus
- stratified squamous, place for food storage, prone to infection
Proventriculus: chemical stomach
Gizzard: chew/grind food after it is treated with HCl
23
Q
Monogastric stomach
A
- cardiac
- fundic
- pyloric
24
Q
Ruminants
A
- rumen (paunch)
- reticulum (honeycomb)
- omasum (plies) - toward the right side of the animal
- abomasum (true/chemical stomach) - toward the right side
25
Rumen, reticulum, omasum
```
Stratified sqamous epithelium
- many commensals
- mostly fermentation
- reducing environmnet
- some absorption
Omasum
- water absorption
```
26
If you sterilize the rumen, then the cow cannot digest _____
Cellulose
27
Abomasum/stomach
- longitudinal folds (rugae)
- columnar epithelium with numerous goblet cells producing mucus and gastric pits
- regions: cardiac, fundus, pyloric
28
What are the mucus secreting regions of the stomach?
Pyloric and fundus
29
Cardiac and pyloric region
Mostly mucus
30
Torus pyloricus
Structure found only in pigs
| - tumor like area near the pylorus
31
Fundic region
Majority of stomach
| Glandular secretions
32
Gastric glands
- simple branched tubular glands
- mucus (goblets)
- pepsin from chief cells (deeper in gland) and zymogen granules
- HCl from parietal cells
- intrinsic factor (glycoprotein) from parietal cells
- enteroendocrine secretions into the LP
33
Small intestine
- principal site digestion/absorption (species variation)
- 3 major portions: duodenum (medium), jejunum (long), and ileum (short)
- mesentary: support and contains vessels (incl. lymph nodes)
34
Small intestinal mucosa
```
Villus
- finger-like projections
- crypts
- shorter/lower
Columnar epithelium
- microvilli
Lacteal (most prominent in the jejunum)
Lamina propria
```
35
SI microscopic anatomy
- mucosa: columnar epithelium with brush border (microvilli on top of villi)
- submucosa: glands, loose areolar CT
- muscularis
- serosa: simple squamous on CT base
36
Muscularis
Inner circular layer
Outer longitudinal layer
- contracts, allows for peristalsis
37
SI cell types
- enterocytes: enzymes, H2O, absorption, tight junctions, brush border
- goblet cells
- paneth cells
- enteroendocrine cells
- M cells
38
Microscopic features
Lamina propria/submucosa
- submucosal glands in the duodenum
- submucosal plexus
- myenteric plexus
- GALT: dome sites and M cells
39
Villous length
Duodenum: tall villi, deep crypts
Jejeunum: middle, middle, middle
Ileum: short villi, shallow crypts, MALT
40
Ileum has ________ attachment
Antimesenteric
41
Large intestine/cecum
- species variation (hind gut fermenter)
- mostly straight tubular crypts
- no villi
- many goblets
- no paneth cells
- lymphoid tissue
42
If there is no villi, then you are in the _____ or _____
Stomach; large intestine
43
Large intestine/cecum functions
- more lymphoid tissue (GALT)
- absorption (water, nutrients)
- elimination
- mucocutaneous junction
44
Pancreas
Exocrine (duct)
- digestive enzymes: acini, proteases, lipases
Endocrine (ductless)
- metabolic hormones: islets, insulin, glucagon, somatostatin
45
Exocrine portion of the pancreas
```
Serous gland
Zymogen granules
- trypsinogen
- chymotrypsinogen
- proteases, peptidases
- lipases
- amylolytic enzymes
- nucleolytic enzymes
Bicarbonate (ductules)
Neural and hormonal control
```
46
Acinus
"clusters of grapes"
- lined by simple cuboidal that dump contents into duct that ends up in the small intestine
- serous gland: product is water and mostly proteinaceous
47
Endocrine portion of pancreas
- islets
| - mostly blood glucose control: glucagon, insulin, somatostatin
48
Liver
Largest gland in the body
Metabolism
Bile production: gall bladder for storage (digestion)
49
Liver metabolism
- carbohydrates
- lipids
- protein production (serum)
- protein catabolism (NH3)
- vitamins, minerals
- toxins, pharmaceuticals
50
Liver gross
- anterior abdomen
- lobes
- dual blood supply
- -> hepatic artery (25%)
- -> portal vein: GI, pancreas, spleen drainage (75%)
51
Liver histologic
```
Constituents
- parenchyma
- CT stroma
- vessels
- perisinusoidal spaces
Lobules
- classic (functional)
- portal (exocrine)
- acinar
```
52
Portal triads
Surround central veins
53
What are the 3 structures within a portal triad
- hepatic artery
- portal vein
- bile duct
54
Hepatocytes
```
Cuboidal
Anastomosing plates/cords
High metabolic activity
- mitochondria
- ER (rough, smooth)
- golgi
- lipid droplets
- glycogen
```
55
Other cells of the liver
- discontinuous endothelium
- kupffer cells
- stellate cells
56
Bile ducts are lined by ____
Cuboidal epithelium
57
Bile canaliculi
Tiny white spots between adjacent hepatocytes
58
Liver blood flow
Portal triad
- hepatic artery, portal vein, and bile duct
Sinusoids: incomplete endothelium
Central vein
59
Biliary tree
- bile canaliculus
- bile flow opposite blood flow
- ductules --> bile ducts
60
Gall Bladder
- species variation
- stores/concentrates bile
- high cuboidal epithelium --> tight junctions, irregular microvilli
- no muscularis mucosa/submucosa
- smooth muscle
- serosa (visceral peritoneum
61
What animals do not have a gall bladder?
Killer whales, white tailed deer, rats, and horses
