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66 Cards in this Set
- Front
- Back
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General Structure of Tubular Organs
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- Muscosa
- Submucosa - Muscularis - Serosa or Adventitia |
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Mucosa
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- innermost layer
- lines all organs that communicate with the exterior surface of the body - all mucosal surface are protected by a surface layer of mucus consisting of mucin secreted by goblet cells - has epithelium, lamina propria and muscularis mucosa |
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Submucosa
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- composed of CT and collagen
- contains glands called Brunner's glands - has Meissner's plexus (part of ANS) |
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Muscularis
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- coat of smooth or skeletal muscle which is important in moving and mixing ingesta
- inner circular, outer longitudinal - myenteric or Auerbach's plexus |
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Serosa or Adventitia
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- serosa= single layer of mesothelial cells
- adventitia=lack a mesothelial covering and have an outer layer composed of CT |
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Esophageal Mucosa
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- epithelium: stratified, squamous type with variable keratinization (non-keratinized in carnivores, heavily keratinized in ruminants)
- lamina propria: dense network of fine, collagen fibers with many elastic fibers and it is more dense than the submucosa - muscularis mucosa: consists of longitudinally oriented smooth muscle |
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Esophageal Submucosa
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- loosely arranged connective tissue
- esophageal glands are found in this layer |
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Esophageal Muscular Layers
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- there are 2 layers
- ruminants and dogs=both skeletal - cats and horses=cranial skeletal, caudal smooth - cardiac sphincter |
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Esophageal Adventitia-Serosa
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- cervical region of the esophagus is surrounded by an adventitia of loose CT, blood vessels and nerves
- thoracic portion is covered by a serosa made of mesothelial cells of the mediastinal pleura |
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Esophagus-Stomach Junction
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- carnivores= abrupt change from stratified squamous to simple columnar epithelium
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General Structure of Tubular Organs
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- Muscosa
- Submucosa - Muscularis - Serosa or Adventitia |
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|
Mucosa
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- innermost layer
- lines all organs that communicate with the exterior surface of the body - all mucosal surface are protected by a surface layer of mucus consisting of mucin secreted by goblet cells - has epithelium, lamina propria and muscularis mucosa |
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Submucosa
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- composed of CT and collagen
- contains glands called Brunner's glands - has Meissner's plexus (part of ANS) |
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Muscularis
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- coat of smooth or skeletal muscle which is important in moving and mixing ingesta
- inner circular, outer longitudinal - myenteric or Auerbach's plexus |
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Serosa or Adventitia
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- serosa= single layer of mesothelial cells
- adventitia=lack a mesothelial covering and have an outer layer composed of CT |
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Esophageal Mucosa
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- epithelium: stratified, squamous type with variable keratinization (non-keratinized in carnivores, heavily keratinized in ruminants)
- lamina propria: dense network of fine, collagen fibers with many elastic fibers and it is more dense than the submucosa - muscularis mucosa: consists of longitudinally oriented smooth muscle |
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Esophageal Submucosa
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- loosely arranged connective tissue
- esophageal glands are found in this layer |
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Esophageal Muscular Layers
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- there are 2 layers
- ruminants and dogs=both skeletal - cats and horses=cranial skeletal, caudal smooth - cardiac sphincter |
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Esophageal Adventitia-Serosa
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- cervical region of the esophagus is surrounded by an adventitia of loose CT, blood vessels and nerves
- thoracic portion is covered by a serosa made of mesothelial cells of the mediastinal pleura |
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Esophagus-Stomach Junction
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- carnivores= abrupt change from stratified squamous to simple columnar epithelium
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Stomach: General
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- epithelial lining initiates the enzymatic and hydrolytic breakdown of food
- muscular tunic aids in mixing ingesta with gastric secretions - lined with glandular epithelium in carnivores and primates and with stratified squamous epithelium in herbivores - muscular layer has 3 layers |
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Stomach: Non-glandular Mucosa
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- stratified squamous portion present in ruminants, horses, pigs and rodents
- may or may not be keratinized - lines the entire forestomach of ruminants (rumen, reticulum, omasum) - terminates at the margo plicatus in horses |
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Stomach: Glandular Mucosa
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- numerous gastric pits
- simple columnar epithelium - each cell has mucinogen granules - surface is covered with a thick, slimy layer of visible mucus that has a high bicarb concentration to protect the mucosa from the acidic gastric secretions - Fundic/gastric glands - isthmus |
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Fundic/gastric glands
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- present in the mucosa or glandular stomach
- simple, branched, tubular glands - Four types of cells: mucus neck cells, chief cells, parietal cells, enteroendocrine cells |
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Isthmus
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- located between the gastric put and the gland below
- site of cell replication |
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Mucus neck cells
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- located in teh neck region of funcic glands and are interspresed between parietal cells
- have less mucinogen than surface mucus cells - bicarb ions maintain a neutral pH and contribute to the gastric mucosa barrier |
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Chief cells
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- lcoated in deeper regions of the fundic glands
- abundant rER - have zymogen granules - they secrete pepsinogen which contacts acidic gastric juice that converts it into pepsin |
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Parietal cells
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- apex of the cell is pointed toward the lumen
- hydrochloric acid maintains gastric pH at 1-2 - HCl initiates the digestive process of protein and activates pepsinogen - produce intrinsic factors that help bind vitamin B12 |
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Enteroendocrine cells
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- over 20 peptide hormones and hormone-like regulating agents are secreted by these cells
- gastrin is one of them and it helps increases the output of parietal cells |
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Cardiac glands
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-found in the caridac region of the stomach
- mostly mucus secreted cells with interspresed enteroendocrine cells - they help to protect the esophageal epithelium from gastric reflux |
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Pyloric glands
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- in pyloric region of the stomach
- same function as cardiac glands |
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Stomach: Submucosa
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- CT, adipose tissue, blood vessels, Meissner's plexus
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Stomach: Muscular Layers
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- inner oblique, middle circular and outer longitudinal layers
- Auerbach's plexus |
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Stomach: Serosa
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- composed of mesothelial cells that are contiguous with the parietal peritoneum of the abdominal cavity
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Ruminant Stomach: General
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- 4 compartemtns: rumen, reticulum, omasum, abomasum
- forestomach has keratinized, stratified squamous mucosal surface - abomasum is similar to the stomach |
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Rumen
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- largest region
- acts as a fermentation vat where microflora produced volatile fatty acids - mucosa has tongue-shaped papillae - protects, metabolizes and absorbs - stratum corneum provides a protective shield against rough, fibrous ingesta and depper layers metabolize short-chain volatile fatty acids |
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Reticulum
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- reduces the ingesta into small particles
- mucosal surface with interconnecting folds-- honeycomb - keratinized stratified squamous epithelium |
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Omasum
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- breaks particles of ingesta down
- has 100 or more interdigitating folds called the laminae - omasal contents are pressed into thin layers in the narrow spaces between teh laminae called teh interlaminar recesses and are reduced to a fine pulp by teh numerous, horny omasal papillaie taht stud the mucosal surface - keratinized stratified squamous epithelium` |
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Abomasum
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- same as the stomach of other species
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Camelid Stomach
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- 3 compartments: C1, C2, C3
- C1-C2 have glandular and non-glandular portions -C3 is similar to abomasum |
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C1
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- occupies most of teh left anterior abdominal quadrant
- cranial and caudal portions separated by a prominent fold or pillar - lined with stratified squamous epithelium - have saccules with mucus secreting cells |
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C2
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- mostly glandular except for a small dorsal patch
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C3
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- middle 3/5 is characterized by longitudinal pleats
- termainl 1/5 has true gastric glands and a red-brown appearance |
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Small Intestine: General
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- digestive enzymes originate fromt eh columnar cells that line the small intestine and the pancreas
- absorptive efficiency is facilitated by: plicae circulares, villi, microvilli |
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Plicae circulares
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- in upper 1/2-2/3 of the small intestine
- circularly arranged mucosal folds - permanent structures in ruminants but disappear in carnivores when small intestine is distended |
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Villi
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- finger like projections
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Microvilli
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- present on the apical surface of columnar cells tha tmake up most of the mucosal surfaces
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Small Intestine: Mucosa
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- villi and crypts (intestinal or mucosal glands)
- 5 cell types in the epithelial surface: enterocytes, goblet cells, paneth cells, enteroendocrine cells, M (microfold) cells |
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Enterocytes
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- have microvilli on teh apical portion to increase surface area
- tall columnar - function to absorb - secrete glycoprotein enzymes needed for terminal digestion in addition to water and electrolytes |
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Paneth cells
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- maintain innate immunity of the mucosal surface
- regulate normal bacterial flora - found in crypt region of teh intestinal glands - contain lysozyme, alpha defensins and other glycoprotesin |
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M (microfold) cells
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- antigen presenting cell
- cover the Peyer's patches or GALT - the epithelial cells have microfolds instead of microvilli on their apical surface |
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Small Intestine: Submucosa
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- dense CT
- submucosal/Brunner's glands which have ducts that open into the crypt region of teh intestinal glands - mucous secretion in dogs and ruminants - serous secretion in pigs and horses - seromucous in cats - Peyer's patches are on teh anti-mesenteric portion |
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Small Intestine: Muscularis
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- inner circular and outer longitudinal smooth muscle
- Myenteric plexus between the two layers |
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Small Intestine: Serosa
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- layer of loose CT covered with mesothelial cells
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Cecum/Colon
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- absorb water, vitamins, and electrolytes
- secretion of mucus - cecum has straight, tubular glands lined with simple columnar epithelium - size of the cecum varies dramatically among species - it is difficult to differentiate section from the colon and the cecum |
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Anal canal
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- terminal segment of the digestive tract
- demarcated by the anorectal line where the simple columnar epithelium changes to nonkeratinized stratified squamous epithelium - mucosa is smooth and lacks glands in ruminants and horses - mucosa in pigs and carnivores has 3 zones: columnar, intermediate and cutaneous zones |
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Columnar zone
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- contains longitudinal folds called anal columns
- nonkeratinized stratified squamous epithelium - modified apocrine sweat glands are present (anal glands) |
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Anal glands
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- modified aporcrine sweat glands
- lipid secretion in carnivores - mucous secretion in pigs |
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Intermediate zone
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- nonkeratinized stratified squamous epithelium
- narrow strip between columnar zone and the cutaneous zone - anal glands are present |
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Cutaneous zone
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- keratinized stratified squamous epithelium
- ducts from teh anal sacs open at the junction of the intermediatea dn cutaneous zones - cdogs have the circumanal glands which are modified sebaceous glands |
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Crop
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- saclike diverticulum of the esophagus
- storage organ where food in moistened and softened by mucus secretions of the esophageal glands - in some birds, crop glands secrete a substance called crop milk which nourishes nestlings until they are mature enough to eat on their own |
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Proventriculus
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- macroscopic papillae
- microscopic folds called plicae which are arranged concentrically around a single duct opening into the apex of each papillus - simple columnar epithelium covers teh plicae and continues into small branches of each duct that enter the proventricular glands - oxynticopeptic cells are found in proventricular glands |
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Oxynticopeptic cells
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- in proventricular glands
- produce pepsinogen and hydrochloric acid |
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Ventricularis (Gizzard)
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- highly muscular
- serves as a grinding organ to macerate ingesta after it is softened in teh proventriculus - lining of the ventriculus is the cuticle of koilin membrane (which is NOT a stratum corneum) - |
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Ceca
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- paired structure
- open in the digestive tract at the junction of the ileum and colon - near the base of each ceca is a nodular mass of lymphoid tissue (cecal tonsil) |
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Cloaca
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- divided by transverse folds into coprodeum, urodeum and proctodeum
- villi are prominent - epithelium is simple columnar - cloacal bursa opens into the proctodeum |
