stratified squamous epithelium

nonkeratinized in carnivores

keratinized in herbivores

Growth Period of Brachydont Teeth?

Hypsodont?

-Brachydont: short growth perior (stop shortly after eruption)

-Hypsodont: long period of time, sometimes forever

-crown above the gingiva (covered by enamel)

-one or more roots that extend into the alveolus (covered by cementum)

-most of the tooth is composed of dentin

-in center is dental pulp

Where is the periodontal membrane located?

Function?

Composition?

-Location: between the cementum and the alveolar bone

-Function: holds the tooth in the socket

-Composition: mostly collagen fibers

Definition: Free Gingiva

What does it compose?

-the superficial gingiva adjacent to the tooth that is not attached to the tooth

-it composes the gngival margin (surrounding the crown of the tooth)

-cylindrical shape

-no crown and some lack roots

-entire superficial layer is cementum

-medial layer is enamel

-deepest layer is dentin

What causes the uneven surface characteristic of hypsodont teeth?

Why is this beneficial?

-the cementum and dentin are abraded faster than enamal in between them, thus it extends upward as ridges on the suface of the tooth

-increases the grinding efficiency of the tooth

5 Types of Papillae on the Anterior of the Tongue

1. Filiform: aid in manipulating material (cats/ ruminants)

2. Conical: aid in manipulating ingested material

3. Fungiform: smooth rounded surface, HAVE TASTE BUDS

4. Circumvallate: large, surrounded by a depression, HAVE TASTE BUDS

5. Foliate: absent in ruminants but prominant in horse and dogs, HAVE TASTE BUDS

-glands on the sides of circumvallate papillae

-release serous secretion into the depression to help clear material from the taste buds

1. Parotid glands: mostly serous (watery soln rich in enzymes)

2. Sublingual glands: mostly mucous

3. Submandibular glands: mixed glands, the serous cells often form demilunes

-secretion leaves the acinus and enters a thin intralobular duct that merge to form larger ducts

-called interlobular and primary ducts after emerging from lobules

Outermost to innermost

1. Tunica mucosa:

a) Lamina muscularis mucosae

b) Lamina propria

c) Lamina epithelialis mucosae

2. Tunica submucosa

3. Tunica muscularis

4. Tunica serosa

-Herbivores: keratinized stratifies squamous epi

-Carnivores: nonkeratinized stratified squamous

Describe the Tunica Mucosa of the Esophagus

(include the breakdown into subdivisions)

Lamina epithelialis: stratified squamous epi (ker= herbivore and nonker= carnivore)

Lamina propria: collagen fibers, capillaries, lymphatics

Lamina muscularis: longitudinal smooth m.

-loose CT that allows formation of mucosal folds so tha esophagus may distend

-contains mucous glands (lot in dogs, absent in horses and cats)

-contains lymphoid nodules

-skeletal m. on the anterior but smooth m. on posterior end

**completely skeletal m. in dogs and ruminants

Lamina epithelialis: surface epi is simple columnar, surface mucous cells, has gastric pits

Lamina propria: filled with tubular glands, contains parietal+chief+nuck mucous+endocrine cells

Defintion: Gastric Pits

Location?

-Function: secrete HCl

-Location: lamina propria of the tunica mucosa of the glandular stomach (sides of glands)

-Histology: large, spherical, eosinphilic

-Function: secrete pepsinogen (conv to pepsin)

-Location: base of glands in lamina propria of tunica mucosa of glandular stomach

-Histology: basophilic, may appear vacuolated

-Function: contain mucus precursor granules

-Location: neck of glands in lamina propria of tunica mucosa of glandular stomach

-Location: lamina propria of tunica mucosa of glandular stomach

-Function: secrete hormones (Gastrin) that help control the activity of the stomach

-M: Tunica Submucosa of the Stomach

-A: Tunica Muscularis of the Stomach

-M: muscles of lamina muscularis mucosae

-A: muscles of the tunica muscularis and blood vessels

-Rumen, Reticulum, Omasum: no glands in the lamina propria

-Abomasum: has typical glands in the lamina propria

-Rumen: tongue-shaped

-Reticulum: short projection on ridges that form a honeybomc structure

-Omasum: short projection on folds of tissue

What are the 3 main types of folds in the SI?

What is their purpose?

-Their purpose is to increase surface area to maximize the rate of absorption

-Plicae circulares (valves of Kerckring): permanent crescent-shaped folds that involve mucosa and submucosa

-Villi: folds of lamina epithelialis and lamina propria project about 1 mm

-Microvilli: microscopic rojections of apical plasma mem of epithelial absorptive cells

-Villi

-Crypts

-Epi is simple columnar with brush border

-consists of enterocytes, goblet cells, and a few enteroendocrine cells

-Core is composed of the lamina propria: CT that contains blood vessels and lacteals (lymphatic vessels)

Definition: Crypts of Lieberkuhn

Function?

What cells do they contain?

-simple tubular invaginations extending to the muscularis mucosae

-Function: generative area for renewal of the lining epi and secretory

-Cells:

      -Upper: absorptive cells and goblet cells

      -Lower: stem cells and Paneth Cells

-Location: in crypts in the Tunica Mucosa of SI

-Function: help fight infection (like neutrophils)

-Histology: have prominent eosinphilic granules  

Describe the Tunica Submucosa of the SI

(Does it contain anything unique?)

-typical

-but it contains Meissner's plexi

Describe the Tunica Muscularis of the SI

(Does it have any unique features?)

-typical

-contains Auerbach's plexi

-Function: bundles of unmyelinated axons connecting them to form a continuous network to innervate muscularis and blood vessels

-Location: tunica Muscularis of the SI

-Definition: large pale-staining pathces of lymphocytes (called lymphoid nodules)

-Location: in the ILEUM of the SI

-SI: villi and crypts

-LI: relatively smooth due to lack of plicae or villi

Describe the epi of the LI

What is its primary function?

-absorptive columnar cells and goblet cells

-main function of the epi is absorption of water and the production of mucus

-Above the Anal Canals: simple columnar epi

-At Anal Valves: nonkeratinized stratified squamous epi

-75%

-25%

-SI

-to bring in nutrients, water, vitamins, ions, etc that were absorbed during digestion

-Lipids

-They travel through lymphatic vessels to the thoracic duct

-metabolize absorbed molecules or return them to the bloodstream

-degradation of toxic substances

-production of bile

-synthesis of many plasma proteins

-stores carbohydrats as glycogem

-removes foreign particles from the bloodstream

-arranged in hexagons (lobules)

-margins delineated by CT but spaces filled with sinusoids

-in the Lobules, hepatocytes are radially arranges around a branch of the hepatic artery (central vein)

-portal canal at each corner of the lobule

-contains a branch of the portal vein, lyphatic vessels, a brach of heptaic artery, and a bile ductule

-located at the corners of lobules

-lined by endothelial cells

-also home to Kupffer Cells

-Function: phagocytic cells that remove old RBCs from circulation

-Location: walls of sinusoids in the Liver

Describe the endothelium of liver sinusoids

Function?

-extremely fenestrated and lack a basal lamina

-permits the surface of the parenchymal cells to be bathes in blood plasms but doesn't lose RBCs

-bile ductules lead to the hepatic duct

-eventually end up in gall bladder

-80

-5

-Definition: cosist of 40-50 pyramidal cells around a single lumen

-Location: in the pancreas

-Function: produce large amounts of digestive enzymes

-ducts carry secreted products and secrete Bicarbonate and water

-secreted material exits the acinar lumen=> intercalated duct/intralobular duct=> interlobular ducts=> pancreatic ducts

-Intralobular Duct/Intercalated Duct: cuboidal or low columnar cells

-Interlobular ducts: (wie within septa) low columnar epi with some goblet cells

1) Alpha Cells: 15% of cells, secretory granules contain glucagon

2) Beta cells: 75%, contain insulin

3) Delta cells: 5%, contain somatostatin \

 -cannot use LM, must use immunocytochemistry