The Digestive System Structures Identify the basic structures of the digestive system

Oral Cavity lips teeth tongue hard and soft palate salivary glands

Teeth gathers, cuts, grinds food firmly embedded in bone carnivores - sharper herbivores - flatter deciduous teeth - temporary teeth that are replaced by permanent ones

Tooth Anatomy crown - portion of a tooth above the gum line or gingiva covered in enamel root - portion of a tooth below the gum line; anchors tooth to bone twice as long as the crown

Tooth Anatomy incisors - foremost teeth used to bite into food canines - longest teeth used for tearing at food premolars - teeth used for crushing and grinding food molars - caudal most teeth used for crushing and grinding food

Dental Formulas Numbers represent tooth count on ONE side of the mouth Upper # represents maxillary teeth, lower # represents mandibular teeth Letter represents type of tooth. Canines: {I3/3: C1/1: P4/4: M2/3} = 42

Oral Cavity, cont. Saliva - necessary digestive enzyme produced by salivary glands Tongue - skeletal muscle that aids in chewing forms a bolus to be swallowed once food is ground up

Esophagus layered tube that extends from the pharynx into the stomach peristalsis - organized contractions that allow passage of material (food) sphincter - circular muscle at end of esophagus that opens to allow passage of food

Stomach cardia - inlet region of stomach associated with esophagus (sphincter) body - storage region fundus - storage region that allows expansion antrum - region leading into small intestine pyloris - controls flow into small intestine (sphincter)

Liver lies directly in front of the stomach processes nutrients secretes bile (secretion that aids in digestion)

Small Intestine duodenum - first short section; associated with pancreas jejunum - long middle region ileum - terminal region of small intestine

Large Intestine AKA colon main function is absorption of water

Rectum termination of the intestinal tract exits the body at anus (sphincter that controls defecation)

Additional Structures peritoneum - smooth epithelial lining of abdomen mesentery - extension of the peritoneum; carries blood vessels and nerves to small intestine omentum - surrounds abdominal organs; also carries blood vessels

Monogastric Digestion

Oral Cavity where food enters mechanical breakdown begins saliva starts digestion

Esophagus musculome mbranous tube extends from pharynx to stomach peristalsis

Stomach chamber, adds gastric juices to food Hydrochloric Acid break food into smaller particles

Small Intestine complex tube takes food particles not absorbed by stomach duodenum, jejunum, ileum

Cecum blind pouch at beginning of large intestine little function

Large Intestine last major organ of tract main function = absorption of water reservoir for waste

Rectum terminal portion opening = anus undigested food passes as waste

Hind-Gut Fermenters

guinea pigs, horses, rabbits one stomach additional need to digest plant fiber from grass/hay microbial fermentation

Oral Cavity selects pieces of forage with sensitive prehensile lips grinds up food before swallowing

Esophagus carries food to stomach enters stomach at acute angle cannot vomit!!!!

Stomach small stomachs limits amount of food intake continuous foraging, picking at food

Small Intestine major digestive organ 50 - 70% all nutrients absorbed from here

Cecum hind-gut first part of large intestine ferments plant fiber using microbes

Large Intestine similar to monogastric absorption

Rectum terminal portion opening = anus forms fecal balls

Ruminant Digestion

4 chambered stomach regurgitation rumination

Oral Cavity lips are tough long course tongues for grabbing food chew and grind food LESS swallows course bits

Esophagus musculome mbranous tube carries food to stomach peristalsis

Stomach 4 chambers Rumen Reticulum Omasum Abomasum

Rumen first chamber food enters microbes for digestion fermenting vat

Reticulum second chamber collects indigestible particles (metals)

Rumination regurgitation of food for re-chewing “chewing cud”

Omasum third stomach chamber food enters after rumination

Abomasum fourth chamber True stomach gastric juices are secreted

Small Intestine complex tube moves food from stomach to large intestine

Cecum blind pouch at beginning of large intestine little function like monogastric s

Large Intestine last major organ function = absorption reservoir for waste

Rectum terminal portion opening = anus removes waste very runny stool= little wasted