Digestive system

Ingestion and fragmentation of food

Lips

Fragmentation of food

Teeth

Fragmentation and swallowing

Tongue

Fragmentation and moistening of food: swallowing

Salivary glands

Passage of food from oral cavity to te stomach

Esophagus

Completion of fragmentation and begining of digestion

Stomach

Digestion; emulsification of fats by enzymes from pancreas and bile from the liver

Small intestine duodenum

Completion of digestion and absorption

Small intestine jejunum and ileum

Apsorption of water from liquid residue

Large intestine cecum and colon

Storage of feces prior to defecation

Rectum

Route for defacation of feces outside the body

Anus

THE DIGESTIVE SYSTEM is subdivided into

GIT I, GIT II

covers the oral cavity ( lips,tongue, major salivary glands) and gastrointestinal tube/tract (esophagus, stomach,small and large intestine).

GIT I

includes the organs associted to digestion like liver, gall bladder and pancreas.

GIT II

folds of fibroelastic tissues and core of skeletal muscles.

Lips

Surface of lips

External, inner or labial muscle, Intermediate surface

Surface of lips which contains of hair

External surface

Other term for inner surface in lips

Labial muscle or labial glands

Intermediate surface consist of

Stratified squamous epithelium, either kera or nk

highly muscular organ (prehensile) used to get food into the mouth and for the sense of taste

Tongue

highly muscular organ

Prehensile

has a core of skeletal muscles that runs in three different direction allowing a wide range of movement to manipulate foodstuff

Tongue

ventral surface is muco- cutaneous and the dorsal surface is covered with stratified squamous epithelium

type and number vary greatly among species

Tongue

ventral surface is muco- cutaneous and the dorsal surface is covered with stratified squamous epithelium that forms the so-called

Lingual papillae

in domestic animals there are usually

five lingual papillae

highly keratinized, sharply pointed,mechanically break food material.

Filiform

Numerous in ruminants and cats used in lapping milk.

Filiform

smooth with a rounded surface or described as mushroom-like ; mechanical and gustatory in function

Fungiform

are like fungiform but larger in size,tends to project above other papillae;functions mechanically but not gustatory

Conical

Leaf shaped defined by an invagination of mucous membrane on their sides,usually occur in cluster, many taste buds are present on its lateral surface

Follate

the largest, indented by a very deep moat, do not rise above surface of the tongue

Circumvallate

absent in ruminants but well developed in horses and dogs

Follate

are intraepithelial structures located in the walls of foliate, fungiform and circumvallate papillae.

Taste buds

appear as ovoid or barrel-shaped cell masses which extend from basement membrane and open through a small canal(taste pore) at the epithelial surface.

Taste buds

The microvilli extend into the taste pore are

Taste hair

Three cell types are visible in the taste bud:

Gustatory cells, supportive cells, basal cells

have a dense cytoplasm and vesicular nucleus.

Gustatory cells

have vacuolated cytoplasm and dense nucleus.

Supportive cells

are small and located along the lateral and basal taste bud borders.

Basal cells

are exocrine glands emptying their secretions into the buccal cavity.

Salivary glands

vary as to their location, size and nature of secretion.

Salivary glands

from their distance to the buccal cavity, they are classified into

major and minor salivary glands.

glands are near the oral cavity

minor salivary

are distant from the mouth ,include the parotid, submandibular and sublingual

major glands

Type of secretory cells in Parotid

Serous

Type of secretory cells Sublingual

Mucous

Type of secretory cells Submandibular

Mixed

part of the tooth visible, composed of dentine and enamel

Crown

Parts of crown

Dentin and enamel

the part embedded in the alveolus made of the dentine, enamel and cementum

Root

region between the crown and root of the tooth

Neck

tissue inside the root containing blood vessels and nerves

Dental pulp

thus is the most sensitive part of the tooth

Dental pulp

Organization of tubular Organ

Tunica mucosa consist of:

\*Clue this is Lamina

epithelialis mucosae, propria mucosae, muscularis mucosae

Organization of tubular Organ

Tunica mucosa, Tunica submucosa. Tunica muscularis, Tunica serosa/adventitia

Organization of tubular Organ

Tunica submucosa consist of:

loose c.t. glands, lymph nodules, adipose tissue

Organization of tubular Organ

Tunica muscularis (smooth muscle) consist of

Oblique layer, Inner circular, Outer longitudinal

Organization of tubular Organ

Consist of:

thin DWFCT

Organization of tubular Organ

In tunica muscularis what layer is not always be present

Oblique layer

Organization of tubular Organ

Tunica serosa/adventitia - thin DWFCT is reinvested by a

Mesothelium

The Simple Stomach

➢Tunica mucosa ▪i%%n empty stomach%%, this layer is %%thrown into deep longitudinal fold%%s called ______that extend from the lamina muscularis mucosae to the lumen

Rugae

the rugae are much reduced in size as a result of distension of the tunica mucosa ▪to accomodate the presence of a large amount of food material

In full stomach

consists of simple columnar epithelium that forms branched, tubular glands; organized into gastric pits that open onto the lumen and gastric glands and empty into the base of the gastric pits

Lamina epithelialis

loose areolar connective tissue that in the glandular stomach is minimal between gastric glands and difficult to see in sections; highly vascular containing many blood and lymphatic capillaries

Lamina propria

dense connective tissue containing thick collagen fibers; located between the lamina propria and the lamina muscularis mucosae

Stratum compactum

prominent in carnivores where it probably helps prevent the perforation of the wall of the stomach by sharp objects such as bones that might be present in the lumen

Stratum compactum

consists of several layers of smooth muscle oriented both longitudinally and circularly; usually not very thick

Lamina muscularis mucosae

typical loose connective tissue contains parasympathetic ganglia located in submucosal plexuses

Tunica submucosa

submucosal plexuses also known as

Meissner's plexuses

Tunica muscularis: typical smooth muscle consisting of at least two layers, an inner circular layer and an outer longitudinal layer; parasympathetic ganglia located between the two muscle layers is the

myenteric or Auerbach's plexus

typical small amount of loose connective tissue with overlying simple squamous epithelium or mesothelium

Tunica serosa

Cell types in the gastric gland

line the gastric pit and secrete mucous and bicarbonate ions to protect the epithelium from digestion by gastric juice (contains HCl and pepsin) present in the stomach lumen

Mucous neck cells

Mucous neck cells contains

HCL and pepsin

Cell types in the gastric gland

dispersed between the parietal cells; secrete pepsin(ogen) and gastric lipase

Chief cells

Cell types in the gastric gland

round cells that contain distinct eosinophilic (pink) cytoplasm and round, prominent nucleus; secrete HCl and intrinsic factor, needed for absorption of vitamin B12.

Parietal (oxyntic) cells

secrete histamine (stimulates acid)

Enterochromaffin like cell

squamous like which appear to cuff other cells of the crypt; produce somatostatin ( inhibits acid)

D cells

usual occur at the base of the crypt;secrete gastrin (stimulates acid)

G cells

Epithelium invaginates into lamina propria forming

gastric pits (foveolae)

are present at the gastric pits

Tubular glands

Variation per stomach region:

– mucus neck cells with occasional parietal cells

Cardiac region

– parietal cells (secrete HCl) and chief cells (secrete pepsinogen)

Fundic region

– mucus neck cells, G cells, occasional parietal cells

Pyloric region

### 3 types of stomach region

Cardiac, fundic, pyloric

The Complex Stomach

In rumen

characterized by the presence of long (1.0-1.5 cm long) conical

Tunica mucosa

The Complex Stomach

In rumen

projections called papillae that extend in to the lumen

Tunica mucosa

The Complex Stomach

In rumen

keratinized stratified squamous.

Lamina epithelialis mucosae

The Complex Stomach

In rumen

typical; no glands

Lamina propria

The Complex Stomach

In rumen

absent; instead a thickened layer of connective tissue that extends into the papilla; the connective tissue looks like a smooth

Lamina muscularis mucosae

The Complex Stomach

In rumen

merges with lamina propria; no glands or lymphoid aggregates.

Tunica submucosa

The Complex Stomach

In rumen

typical

Tunica muscularis, Tunica serosa

The Complex Stomach

In omasum

is thrown into folds called laminae (leaf- like)covered with a highly keratinized strat squam epith

tunica mucosa

The Complex Stomach

In omasum

has sparse loose connective tissue

lamina propria

The Complex Stomach

In omasum

extends into the primary laminae %%usually in two layers.%%

laminae muscularis mucosa

The Complex Stomach

In omasum

•In between these two layers of the laminae muscularis mucosae there is a

layer of smooth muscle belonging to the tunica muscularis.

The Complex Stomach

In omasum

These %%three layers of smooth muscle intertwine%% as they extend toward the tip of the laminae and eventually fuse to form

one large mass of muscle at the tip.

The Complex Stomach

In reticulum

Tunica mucosa: when viewed from the lumen, the mucosa looks like a

honeycomb or reticulum

Similar to rumen

Reticulum

\-series of connected vertical primary folds give rise to secondary and tertiary papillae which project into the lumen

Reticulum

The Complex Stomach

In reticulum

a layer of smooth muscle extends from the tips of the papillae down to the position of the lamina muscularis mucosa in esophagus

Lamina muscularis mucosa