Alimentary Canal of Digestive System

Ileum

"twisted" 12 ft long. Joins the large intestine at the ileocecal valve. TUNICS, PEYER'S PATCHES, GOBLET CELLS.

Mucosa

Inner epithelial tissue lining. Consists of simple columnar epithelium, overlying a lamina propria, and a thin layer of smooth muscle - muscularis mucosa - contains MALT - mucus-secreting goblet cells. Mucus protects epithelium from acid and digestive enzymes.

Anal Canal

Last segment of the lg. intestine. Contains 2 sphincters to open and close anus. Serves to transmit and lubricate stool as it passes externally from the rectum

Rectum

Posterioinferiorly just in front of the sacrum. Postion allows pelvic organs to be examined. Contains three folds that stop feces from being passed along with gas.Is to act as a temporary storage site for fecal matter before it is eliminated from the body through the anal canal.

Gastroesophageal sphincter

Prevents the contents of the of the stomach from regurgitating into the esophagus.

Uvula

Projecting downward from the free edge of the soft palate, fingerlike.

Peritoneum

Outer covering

Ascending Colon

Right side of abdominal cavity.

Right Colic (Hepatic) Flexure

Right turn of the ascending colon to transverse colon.

Intrinsic nerve plexuses

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Submucosa

Deep to the mucosa, layer of connective tissue that houses blood vessels, nerves, hymphatics, and elastic fibers.

Fundus

Dome-shaped part, beneath the diaphram, bulges superolaterally to the cardia.

Greater Omentum

Drapes inferiorly from the greater curvature of the stomach to cover the coils of the small intestine.Contains fat deposits and a large collection of lymph nodes. Mesentary extending from the curvatures that help tether the stomach to other digestive organs and the body wall.

Sigmoid Colon

Inferiorly enters the pelvis, S-shaped. Store fecal wastes until they are ready to leave the body.

Transverse Colon

Across the abdominal cavity.

Mesentery

Fan-shaped, suspends the jejunum and Ileum for the abdomen.

Labial Frenulum

A median fold that joins the internal aspect of each lip to the gum.

ESOPHAGUS

A muscular tube involved in food propulsion. It is posterior to the heart and the trachea, located in the thoracic cavity. It contains smooth and skeletal muscle fibers that contract food and propel it to the stomach. STRATIFIED SQUAMOUS EPITHELIUM.

STOMACH

A temporary "storage tank" where chemical breakdown of proteins begins and food is converted to chyme. It contains 5 regions. SIMPLE COLUMNAR EPITHELIUM.

Lacteals

A dense capillary bed and a wide lymph capillary in the core of each villus.

Lingual Frenulum

A fold of mucosa, secures the tongue to the floor of the mouth and limits posterior movements of the tongue.

Alimentary Canal

Also called gastrointestinal (GI) tract, or gut. A continuous muscular digestive tube that winds through the body. It digests food and breaks it down into smaller fragments, and absorbs the digested fragments through its lining into the blood. Organs are: mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

PHARYNX

Also known as the throat, food enters here after the mouth. Muscles of the pharynx propel swallowed food into the esophagus. Composed of stratified squamous epithelium.

Oropharynx

Common passageway for food, fluid and air that plays a part in the digestive role.

Laryngopharynx

Common passageway for food, fluid, and air.

Chemical Digestion

Complex food molecules are broken down to their chemical building blocks by enzymes secreted into the lumen of the alimentary canal. Begins in the mouth and complete in the small intestine.

Left Colic (Splenic) Flexure

Connects transverse colon to the descending colon.

Muscularis Externa

Consists of 2 layers of smooth muscle - inner circular layer and an outer longitudinal layer. Both contract to produce perstalsis.

Appendix

Contains masses of lymphoid tissue, and as part of MALT. Important role in body immunity.

Defecation

Eliminates indigestible substances from the body via the anus in the form of feces. Only the large intestine defecates.

Microvilli

Exceptinally long, densley packed absorpitive cells of the mucosa give the surface a fuzzy appearance.

Jejunum

Extends from the duodenum to the Ileum. " empty" 8 ft. long. Large folds called plicae circulares. TUNICS.

Villi

Fingerlike projections of the mucosa, "tufts of hair". Digested food is absorbed through the epithelial cells into the capillary blood and the lacteals.

Pyloric Region

Funnel-shaped region, widens to form the pyloric antrum which narrows to form the pyloric canal that terminates at the pylorus.

Filiform Papillae

Gives the tongue surface a roughness that aids in licking semisolid foods and provide friction for manipulating foods in the mouth. Smallest and numerous type, align in parallel rows on the tongue dorsum. They contain keratin, which stiffens them and gives the tongue its whitish appearance.

Gingivae

Gum, surrounds the tooth like a tight collar.

Peyer's patches

Individual and aggregated lymphoid follicles in the submucosa (areolar connective tissue). Increase toward the end of the small intestine indicating huge amounts of bacteria. Found in the ileum of the small intestine.

Cardiac region

Known as cardia or (near the heart) surrounds the cardiac orifice, through which food enters the stomach through the esophagus.

Descending Colon

Left side of posterior abdominal wall.

TUNICS OF ALIMENTARY CANAL ORGANS

MUCOSA, SUBMUCOSA, MUSCULARIS, SEROSA (OR ADVENTICIA), INTRINSIC NERVE PLEXUSES (MYENTERIC NERVE PLEXUS, SUBMUCOSAL NERVE PLEXUS)

Peristalsis

Major means of propulsion, involved alternated waves of contration and relaxation of muscles in the organ walls. Main effect is to squeeze food along the tract, some mixing.

Duodenum

Mostly retroperiteneal, curves around the head of the pancreas. It is the shortest. The pancreas and liver deliver bile and pancreatic juices to the ampulla which opens here. 10 inches long. TUNICS, DUODENAL (BRUNNERS GLANDS)

Propulsion

Moves food through the alimentary canal, includes swallowing, which is initiated voluntarily, and peristalsis, an involuntary process.

ORAL CAVITY OR MOUTH

Mucosa-lined cavity also called the buccal cavity. Lined with a thick stratified squamous epithelium can withstand friction. Produces defensins in response to injury or infection.

Goblet cells

Mucus secreting cells in the epithelium of the villus mucosa (simple columnar epithelium)

Duodenal (Brunner's glands)

Mucus secreting glands, found in the submucosa of the duodenum ONLY. These glands produce an alkaline mucus that helps neutralize acidic chyme moving in from the stomach.

TONGUE

Occupies the floor of the mouth and fills most of the oral cavity. Composed of interlacing bundles of skeletal muscle fibers, and during chewing, grips the food and constantly repositions it between the teeth. Also mixes food with saliva forming it into a compact mass of bolus and pushes into the pharynx. Helps form consonants when we speak.

Tongue

Occupies the floor of the mouth and fills most of the oral cavity. Composed of interlacing bundles of skeletal muscle fibers, and during chewing, grips the food and constantly repositions it between the teeth. Also mixes food with saliva forming it into a compact mass of bolus and pushes into the pharynx. Helps form consonants when we speak.

Serosa

Outer connective tissue layer, composed of visceral peritoneum. Also known as adventitia.

Absorption

Passage of digested end products from the lumen of the GI tract through the mucosal cells by active or passive transport into the blood or lymph. Small intestine is the major absorptive site.

Papillae

Peglike projections of the underlying mucosa.

Mechanical Digestion

Physically prepares food for chemical digestion by enzymes. Mechanical processes include: chewing, mixing of food with saliva by the tongue, churning food in the stomach, and segmentation or rythmic local constrictions of the small intestine.

Foliate Papillae

Pleatlike, located on the lateral aspects of the posterior tongue. House taste buds but function primarily in taste in infancy and early childhood.

Haustra

Pocketlike sacs, to draw up. Cause the colon contents to move to the next haustrum

Lesser Omentum

Runs from the liver to the lesser curvature of the stomach where it becomes continuous with the visceral peritoneum covering the stomach. Mesentary extending from the curvatures that help tether the stomach to other digestive organs and the body wall.

Ingestion

Taking food into the digestive tract, usually via the mouth.

Circumvallate or Vallate Papillae

Ten to twelve, large, located in a V-shaped row at the back of the tongue. Resemble the fungiform papillae, have an additional surrounding furrow.

Plicae Circulares

The circular folds are deep, permanent folds of the mucosa and submucosa.Force chyme to spiral through the lumen, slowing its movement and allowing time for full nutrient absorption.

Hard and soft palate

The hard palate underlain by the palatine bones and palatine processes of the maxillae, forms the rigid surface against which the tongue forces food during chewing. The soft palate is a mobile fold formed mostly of skeletal muscle that rises to close off the nasopharynx when we swallow.

LARGE INTESTINE

The large intestine consists of the cecum and colon. The major function of the large intestine is to absorb water from the remaining indigestible food matter and transmit the useless waste material from the body.

The Body

The midportion of the stomach, continuous inferiorly with the funnel shaped pyloric region.

Fungiform Papillae

The mushroom-shaped that are scattered widely over the tongue surface. Reddish hue.

Pyloric sphincter

The stomach is continuous with the duodenum through this valve which controls stomach emptying.

Lingual Tonsils

These tissue balls help protect the body. These are the seat of production of antibodies that are a part of the natural immune system and combats infections such as Lingual tonsillitis. In other words, these behave like an immunological organ. The term refers to rounded lumps of lymphatic tissue that forms a covering over the posterior area of the human tongue.

SMALL INTESTINE

This is where most chemical digestion and absorption take place. Contains the duodeum, jejunum, ileum.

Teniae Coli

Three separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons. The teniae coli contract lengthwise to produce the haustra, the bulges in the colon.

Anus

To dispose of feces and other waste products out of the body.

Tunics

layers of the alimentary canal.

Cecum

pouch or large tubelike structure in the lower abdominal cavity that receives undigested food material from the small intestine and is considered the first region of the large intestine. The main functions of the cecum are to absorb fluids and salts that remain after completion of intestinal digestion and absorption and to mix its contents with a lubricating substance, mucus.

Myenteric nerve plexus

regulates motility

Submucosal nerve plexus

regulates the activity of glands and smooth muscle