Exam 1 Flashcards
Lips
Non-keratinized stratified squamous epithelium (keratinized in ruminants)
Mucosal salivary glands
NO lamina muscularis (means = lamina propria submucosa)
Tunica muscularis = orbicularis oris M.
Tunica adventitia
Cheeks
Nonkeratinized (keratinized in ruminants) stratified squamous epithelium NO lamina muscularis SUBmucosal buccal salivary glands Tunica muscularis = buccinator m. tunica adventitia
Hard Palate
keratinized stratified squamous epithelium
dental pad in ruminants (NO top incisors)
NO lamina muscularis
Submucosa blends with periosteum - salivary glands = palatine except porcine
Soft Palate
oropharyngeal surface is stratified squamous and nasopharyngeal surface is ciliated pseudostratified columnar (respiratory epi.)
NO lamina muscularis
Submucosal salivary glands (palatine)
Tunica muscularis = striated mm.
Tongue
keratinized stratified squamous epithelium
lingual papillae
NO lamina muscularis
tunica submucosa blends with epimysium of skeletal muscle
striated tunica muscularis
Mechanical papillae
always keratinized w/ NO taste buds
- Filiform = most numerous (eq = flat with cornified threads, rum = cone with secondary papilla, feline = caudal spines)
- Conical/Lenticular in ruminants - @ root of tongue
Gustatory Papillae
Non-keratinized stratified squamous epi. w/ TASTE BUDS
- Fungiform (mushroom) - isolated - taste buds on dorsal surface - most abundant in carnivores
- Vallate = LARGEST - taste buds on lateral side of sulcus (looks like lilly), on dorsal-rostral tongue - keratinized dorsally and not laterally? - gustatory glands under
- Foliate = mainly RABBIT - taste buds on lateral surface - papillae on lateral tongue - non-keratinized - gustatory glands - NONE in ruminants
3 cell types in taste buds
- Neuroepithelial cells
- Sustentacular cells - support
- Basal cells - give rise to other types
autonomic control in salivary gland
PSNS - watery saliva (increase capillary permeability)
SNS - thicker saliva
why pre-med with atropine (anti-PSNS) to prevent watery saliva that could be aspirated
Salivary gland Duct arrangement
- intercalate duct - smallest with simple cuboidal epi.
- Intralobular duct = STRIATED - simple columnar epi. acidophilic b/c enzymes/mitos –> only duct to produce: sodium bicarbonate with carbonic anhydrase enzyme
- Interlobular duct = between lobules surrounded by CT
- Lobar ducts
- Main excretory duct
Secretory UNITS
- Acinar - smaller lumen - parotid salivary gland
- Alveolar - little larger lumen - mixed salivary glands -
- Tubular - elongated test tube lumen
- Tubuloacinar/alveolar - comination
Secretory PRODUCT
- Serous = watery - parotid gland
- Mucous = pale staining
- Seromucous = usually mucous acinus with serous demilunes (caps) - in mixed salivary glands (Ex. mandibular)
Parotid salivary gland
serous, compound acinar glands with lobes, intercalated ducts with cuboidal epi, and striated intralobar ducts prominent, interlobular ducts simple columnar and main duct stratified squamous
Mixed/Manidbular salivary gland
Seromucous (serous demilunes), compound tubuloacinar with canaliculi between mucous cells
intercalated ducts & striated intralobular ducts
interlobular ducts 2-layered cuboidal
main duct stratified columnar with goblet cells
Brachydont teeth
all carnivore, incisors of ruminants, porcine
cease to grow after eruption
crown with enamel
roots covered with cementum
Hypsodont teeth
all equine teeth, ruminant cheek, tusks of boar, incisors of rabbit and rodent
continue to grow
no defined crown
cementum covers whole tooth
Enamel
hardest substance, cannot regenerate, produced by ameloblasts (come from inner enamel epithelium)
Dentin
odontoblasts (come from mesenchyme of pulp cavity) beneath cementum and enamel - covers pulp cavity
Cementum
modified bone produced by cementocytes (comes from dental sac)
Formation of brachydont tooth
- invagination of oral ectoderm to form dental lamina
- formation of enamel organ (outer and inner enamel epithelium and stellate reticulum between)
- mesenchyme of pulp cavity differentiates into odontoblasts - make dentin
- inner enamel epithelium into ameloblasts - enamel
- after tooth erupts, dental sac collapses to form cementocytes (-cementum)
Main developmental differences with hypsodont teeth
- dental sac collapses over tooth - cementum = outer layer
2, no defined enamel crown - enamel invaginates into the dentin layer
Microscopic dentin and enamel layers
dentin = dental tubules enamel = enamel prisms
Mammalian Esophagus Tunica Mucosa
non-keratinized stratified squamous in carnivores
keratinized in ruminants, bird, horse and pig
Lamina propria CT
Lamina muscularis - longitudinal smooth muscle layer present caudally in all species but absent cranially in dog and pig
Tunica Submucosa in mammalian esophagus
Loose CT around blood vessels
Seromucous submucosal glands present throughout in canine and cranially in pig ONLY
Tunica Muscularis Mammalian esophagus
Inner circular and outer longitudinal that gets thicker caudally (towards stomach)
100% percent striated in dog and ruminants
porcine = almost all skeletal cranially and mostly smooth caudally
Note: avian crop/esophagus 100% smooth muscle
Tunica adventitia/serosa in esophagus?
Cranially = adventitia - loose CT Caudally = serosa - in abdomen
3 major notes about Porcine esophagus (cat and horse too)
- cranial esophagus contains submucosal glands - fade to none caudally
- Lamina muscularis gets thicker caudally
- Tunica muscularis all skeletal cranially and becomes mainly smooth caudally
Avian Esophagus
- T Mucosa = keratinized stratified squamous epi w/ lymphatic nodules, 100% smooth lamina muscularis and simple branched tubuloalveolar MUCOSAL glands (mucous)
- T. Submucosa = CT
- Tunica Muscularis = 100% smooth muscle
Avian Crop
Diverticulum of esophagus
- very thick keratinized SS epithelium - crop milk = sloughed epithelium (stimulated by prolactin)
- NO mucosal glands or submucosal glands
- Tunica muscularis = 100% smooth muscle
Esophageal-stomach junction
- stratified squamous –> simple columnar
in dog and ruminant: skeletal to smooth muscle - ABSENCE of goblet cells in stomach (distinguish from recto-anal canal junction)
Simple Glandular stomach
- Simple columnar epi w/ mucous glands, Lamina propria gastric glands, 3 layers of smooth muscle in lamina muscularis
- T Submucosa only glands at junction with duodenum
- T muscularis = all smooth muscle - 3 layers (inner oblique, middle circular and outer long.)
- T Serosa
Cardiac gland region
Branched coiled tubular glands
May see in combo with esophagus
SHORT GASTRIC PITS W/ DEEP GASTRIC GLANDS
nuclei of mucous glands round and tend to be centrally located
Fundic Gland region
branched tubular straight glands
Mucous cells
Chief cells - basophilic & Parietal cells (acidophilic-pink)
Endocrine cells
Function of cells in fundic gland region
Chief cells = produce pepsinogen - converted to pepsin in low acidic environment) - also make rennin and gastric lipase - secrete into lumen
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Parietal cells = produce HCl to activate pepsinogen (H+ into lumen and bicarb into vasculature) - secrete into lumen
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Endocrine cells
G cells - produce gastrin - stimulate HCl release & motility
–> trigger: distension in stomach, neuronal, caffeine, pH above 2
D cells = somatostatin (inhibit GH)
secrete into lamina propria then bloodstream
Pyloric gland region
branched coiled tubular glands - short
Mucous cells with smushed nuclei at base
DEEP GASTRIC PITS AND SHORT GASTRIC GLANDS
T muscularis thicker here due to pyloric sphincter
May be followed by small intestine
2 types of Mucous cells
- Surface cells = secrete mucins to lubricate epithelial surface - renew 3 days
- Mucous Neck Cells = in neck of gland - mucins differ
Blood supply to glandular stomach
arterioles and venules in t submucosa
fenestrated capillaries in lamina propria
blood supply to: absorption of nutrients, maintain pH, hormone transport
Avian Stomach
2 parts:
Proventriculus (glandular) - w/ oxynticopeptic cells
Ventriculus (motile) aka gizzard
Avian Proventriculus
- simple columnar epithelium with plicae (folds) to form papillae + lamina propria and lamina muscularis
- Submucosa = submucosal glands b/w layers of lamina muscularis - glandular cells are cuboidal (OXYNTICOPEPTIC cells)
central duct drains to surface of papillae - T muscularis 3 layers & tunica serosa
Oxynticopeptic cells
cells in the glands of avian proventriculus that secrete both HCl and digestive enzymes (function of both chief and parietal cells
Avian Ventriculus
- simple columnar epithelium with branched mucosal glands that secrete cornified product CUTICLE that aides in mashing food
- non-glandular t.submucosa under lamina muscularis
- tunica muscularis smooth muscle with dense CT
- tunica serosa
Stomachs in Ruminant
Forestomach = NO glands (3)
Rumen, Reticulum and Omasum
Glandular simple stomach
Abomasum (mucosal glands, smooth muscle)
Rumen
- stratified squamous keratinized epithelium
- lamina propria extends into papillae
- NO glands
- Lamina muscularis ABSENT
- 2-layered tunica muscularis
- t. serosa
- fermentation end products mostly absorbed in rumen - rich capillary network and large intercellular space facilitates uptake of volatile fatty acids
Reticulum
- stratified squamous keratinized epi
- NO glands
- Lamina muscularis in apex of PRIMARY CRESTS (cross sectional bundle of smooth muscle)
- two layered t muscularis and t serosa
Omasum
- keratinized stratified squamous epithelium forms laminae with horny papillae coming off
- Lamina propria very vascular
- NO glands
- Lamina Muscularis THICK and extends into laminae
- 2 layers of lamina muscularis in cross section and one of t muscularis (1 of 2 layers) in longitudinal in laminae
Omasoabomasal fold
changes from keratinized stratified squamous to simple columnar secretory
Surface area modifications in small intestine
- increased length
- mucosal folds
- villi
- microvilli
- glycocalyx (brush border)
Small intestine structure
- simple columnar epithelium with goblet cells
- lamina propria with mucosal glands in lamina muscularis (one layer of lamina muscularis extends into villi)
- may have acidophilic Paneth cells - submucosal glands = Brunner’s glands & lymphatic nodules
- 2 layered smooth muscle tunica muscularis
Peptides and carbohydrates entrance to small intestine
enzymes in glycocalyx break down and then simple sugars and amino acids enter cell by selective transport
Fats entrance to small intestine
fats are emulsified and packaged as micelles before entering cell - released as chylomicrons into lymphatic system = LACTEALS
Mucosal glands in small intestine
simple branched tubular glands
- progenitor cells = renewal of surface villi cells
- Granular cells of Paneth (horses, ruminants and humans) - produce peptidases (digestive) and lysozyme (anti-bacterial)
- Endocrine cells like in stomach
Submucosal glands in small intestine
intestinal glands = crypts of Lieberkuhn - mainly in duodenum - may be absent
- Mucous (dogs and ruminants), Serous (pig and horse) and Mucoserous (cat) - lamina propria also contains BVs, lymphatics, etc. and smooth muscle of lamina muscularis helps contract and move fluid
Lamina muscularis in small intestine
2 layers of smooth muscle
1. inner circular extends into villi - can shorten villi and helps pump blood in blood vessels and lymph in lymphatics
Innervation of the small intestine
- intrinsic = submucosal plexus (small) & Myenteric plexus (b/w layers of tunica muscularis)
- –> interstitial cells of Cajal - pacemaker cells - mediate input from extrinsic (3/min stomach, 12 duodenum, 10 ileum, 3 colon) - Extrinsic = PSNS - increase motility & SNS = decrease motility
Ileo-cecal junction
aka small intestine –> large intestine
- no plicae circularis - longitudinal folds in LI
- lack of villi
- increase in goblet cells
- well developed t muscularis
Large Intestine strucuture
- simple columnar epithelium with MANY goblet cells - absorb water and nutrients
- NO villi
- inner circular layer of tunica muscularis is typical but outer longitudinal not
- –> thickened bands of smooth muscle (taenia coli) prominent in horse
Recto-anal canal junction
in ruminants: rectal mucosa forms longitudinal folds called rectal columns
in canine: lymphatic nodules present - form drossly visible depressions called rectal pits
- lamina muscularis TERMINATES
- T muscularis - inner circular becomes internal anal sphincter and outer longitudinal ends
- simple columnar with goblet cells to non-keratinized stratified squamous epithelium
- difference from esophageal stomach junction = GOBLET CELLS!!
3 zones of the anal canal
- columnar zone = non-keratinized stratified squamous epithelium
- intermediate zone = mix
- cutaneous zone = keratinized stratified squamous with GLANDS (anal glands = modified sweat glands)
glands in cutaneous zone of anal canal
NOT expressed by vets:
- sebaceous glands (bubbly)
- sweat glands (hollow)
- circumanal glands = hepatoid glands = perianal glands = modified sebaceous glands, lobulated, possible endocrine function, uncastrated dogs can develop tumors here
Anal Sac
- bilateral evaginations of mucosa and located between internal and external anal sphincter muscles
- anal sac glands located in wall of anal sac and consist of sebaceous and apocrine secretory units (feline) and just apocrine in canines
- -> EXPRESSED BY VETS
