Chapter 11 - Digestive System Flashcards Preview

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Flashcards in Chapter 11 - Digestive System Deck (160):

What are the functions of the digestive system

Prehension, ingestion, mastication, digestive tract , Absorption of nutrients and water, elimination of waste


What is prehension

The grasping of food


What is ingestion

The taking in of food


What is mastication

Chewing of food


What is the digestive tract

Also known as G.I. tract, alimentary canal


List the layers of tissue that compose the wall of the G.I. tract from superficial to deep

1. Serosa.
2. Muscularis composed of longitudinal muscle layer and circular muscle layer
3. Submucosa
4. Mucosa


What is the serosa.

Serosa is a serous membrane which is the outermost layer of the wall of the G.I. tract


What is the serosa composed of

Epithelium, basement membrane, lamina propria


What is the function of the serosa

Protection and secretion, serous fluid reduces friction between layers


What is the muscularis externa composed of

Mainly composed of involuntary smooth muscle. Longitudinal and circular


What is the longitudinal smooth muscle do in the muscularis externa

Shorten tube


What does the circular smooth muscle layer of the muscularis externa do

Constricts the tube


What do the longitudinal and circular smooth muscle in the muscularis externa aid in

The aid in the propulsion of food from the esophagus to the rectum. By means of peristalsis and segmentation


What are sphincters

Thickened rings of circular smooth muscle which act like valves throughout the tract


Where is skeletal muscle found

Mouth, pharynx, cranial portion of the esophagus, and external anal sphincter


What is the skeletal muscle used for

Aids in chewing and swallowing, and defecation


What is peristalsis

Progressive contractions of smooth muscle propelling food down the G.I. tract


What is segmentation

Alternating contractions move food back-and-forth to mix and slow progress down in G.I. tract


What is the submucosa and what does it contain

The submucosa is a layer of loose connective tissue containing blood vessels, lymphatic vessels, follicles, nerves. Elastic fibers allow stretching and restoration of shape


What is the mucosa and what does it contain

The mucosa is a mucous membrane which is the innermost layer. Contains epithelium, basement membrane, lamina propria, muscularis mucosae


What are the functions of the mucosa

Secretion: mucus, digestive enzymes and hormones. Absorption of nutrients and water. Protection against disease


What are the two anal sphincter's

Internal: internal anal sphincter that's involuntarily controlled
External: external anal sphincter voluntarily controlled


What are two serous membranes in the body

Parietal layer which lines the cavities. Visceral layer which covers organs


Where is plural membrane located

Thoracic cavity


Where is the peritoneal membrane located

Abdominal cavity


What is the mesentery

Bands of peritoneal tissue that suspend the digestive tract from the body wall. Contain blood and lymphatic vessels and nerves


What are the digestive organs

Oral cavity, pharynx, esophagus, stomach, small intestine and, large intestine


What is the small intestine composed of

Duodenum, jejunum, ileum


What is the large intestine composed of

Colon, caecum, rectum, anus


What are the secondary organs

Salivary glands, pancreas, gallbladder, liver


What are the functions of the oral cavity

Location of prehension and ingestion. Beginning of mechanical breakdown and chemical digestion. Moistening/lubrication of food which aids in swallowing. Site of evaporative cooling a.k.a. Panting


What is the oral cavity lined with

Mucosa. Gums cover the jawbone


What are the structures of the oral cavity

Lips, tongue, salivary gland, teeth, hard palate, soft palate, oropharynx


What are the salivary glands

Paired exocrine glands with ducts that lead to oral cavity. Produces and releases saliva. Continuous production is increased or decreased by various stimuli


What does the saliva of non-carnivores contain

The enzymes amylase and lipase


What are the functions of the salivary glands

Lubricate and find food together, chemical digestion of carbs and fat, neutralization of bicarbonate stomach acid, evaporative cooling and flush away debris's, reduce overgrowth of microbial populations


What are the functions of teeth

Grasping, tearing, mastication


Where is the upper arcade contained

Contained in the maxilla and incisive bones


Where is the lower arcade contained

Contained in the mandible


What is the occlusial surface

Where the teeth come together


What are the four types of teeth

Incisors, canines, premolars, molars


What is the purpose of the incisors

Grasping and snipping teeth. Most rostral teeth of upper and lower arcade


What are canines for

Tearing teeth located caudal to incisors. Longer than other teeth and pointed at the tip


What are premolars for

Cutting teeth known as the rostral cheek teeth. Has sharp points and surfaces in carnivores


What are the molars for

Grinding teeth known as caudal cheeks teeth. Contain longer, flatter occlusal surfaces


Describe the teeth shape of herbivores

Have flat occlusal surfaces that are good for grinding plant material


Describe the teeth shape of carnivores

More pointed at their occlusal surface, slightly curved caudally. Good for holding pray, tearing, cutting and shredding. They are also have carnassial Teeth


What are carnassial teeth

Found in carnivores, has a scissor like action. In the upper arcade it's the last premolar. In the lower arcade it's the first molar


What is the crown of the tooth

The top of the tooth


What is the apex of the tooth

Bottom of the tooth


What is the pulp of the tooth

Center of tooth


What is the Dentin

Surrounds and protects the tooth pulp


What is the cementum

The calcified layer covering the root of the tooth


What is enamel

Covers the crown of the tooth


What is the gingiva

The gums


What are brachydont

Low crown teeth. Carnivores and omnivores


What is hypsodont

High Crown teeth, continual growth which allows for eating of gritty abrasive material. Herbivores.


What is teeth floating in horses

Occlusal surfaces are smoothed with a file or a rasp


What is the pharynx

Divided into nasal and oral pharynx by soft palate. Tonsils located in the walls between mouth and pharynx. It carries water, food, gas. Muscles in muscularis assistant swallowing. Epiglottis directs food and water down digestive tract by covering larynx


What are the layers of the esophagus wall

Mucosa, submucosa, lumen, muscularis externa(circular/longitudinal) , adventitia.


What is the esophagus

The transport tube from the pharynx to the stomach. It is flaccid/collapsed when not transporting food. Muscularis is composed of upper one third skeletal muscle middle one third mixed and lower one third smooth


Describe the cardiac sphincter

We closure exception is rabbits and horses. Aids in diaphragm and filling of stomach. Mucous glands on both sides of sphincter to reduce damage by gastric acid


What are the predisposing factors of gastroesophageal reflux

Obesity, age, genetics, anesthesia


Describe gastroesophageal reflux

Inflammation which lead to ulcers which leads to perforation


What are the clinical signs of gastroesophageal reflux

Regurgitation, dysphasia, weight loss, evidence of pain


How do you diagnose gastroesophageal reflux



What is the treatment for gastroesophageal reflux

Weight loss, drugs to reduce acid production


What is a hiatal hernia

Upper portion of stomach passes through the diaphragm. Either congenital or acquired. Esophagus does not close off when stomach fills with food


What is megaesophagus

Food accumulates in esophagus and or is regurgitated. Limited peristalsis, either congenital or acquired


What is the treatment for megaesophagus

More liquid diet, feed in the vertical position


What are the concerns with mega esophagus

Reduce nutrient intake, pneumonia due to aspirated food


What are cats and dogs digestive systems considered to be



What are rabbits pigs and horses digestive system is considered to be

Hindgut fermenters


What a goat and cows digestive system considered to be



What is the monogastric stomach and who has it

A stomach that has a single chamber. Carnivores, omnivores, equines


Which regions are the monogastric stomach divided into

Cardia, fungus, body, pyloric antrum, pylorus


What is the monogastric stomach lined with

Folds called rugae


Where is the lesser omentum located

Is anchored caudal to liver by lesser and greater Omenta


What is the Cardia

Opening from the esophagus. Has a cardiac sphincter which reduces reflux


What is the fundus

Distensible blind pouch. Expense as more food is swallowed, then changes shape closing off the esophagus


What is the body

Distensible middle section. Fundus and body contains numerous glands.


What do the gastric glands contain

Parietal cells and chief cells


What do parietal cells produce

Produced hydrochloric acid


What do chief cells produce

Produce the inactive enzyme pepsinogen


What happens when Pepsinogen meets hydrochloric acid

Pepsin is created


What did the mucous cells produce

Produce the protective mucus


What does the pyloric Antrum do

Grinds up swallowed food, regulates hydrochloric acid secretion in fundus and body


What do endocrine tissue in Antrum walls contain

G cells which secretes the hormone gastrin


What is the pylorus

Muscular sphincter which regulates the movement of chime from the stomach into the duodenum. Prevents backflow


What is pyloric stenosis

Hypertrophy of muscle reduces chime passage and causes vomiting


What are the motor functions of the fundus and body

They relax with swallowing of food to allow filling


What is the function of the body of the stomach

Contracts to mix food


What is the function of the pyloric Antrum

Increases contractions in response to swallowing


What is the peristalsis in the stomach and intestine controlled by

Controlled by parasympathetic branch. The Vegas nerve. Trigger is hormones, stretch receptors


What is colic in horses

Abdominal pain which is the leading cause of death


What are some causes of colic and horses

Stress, rapid diet change, stabling, dehydration, ulcers, parasites


The different forms of colic

Gas colic, impaction, spasmodic


What are the symptoms of colic

Discomfort, sweating, rolling, wanting to lay down, kicking flank, absence of got sounds


What is the treatment for colic and horses

Pain relief, nasogastric intubation and surgery


What does the hormone gastrin do

Inhibits muscle activity of the fundus to allow for filling


What is the enterogastric reflex

Distention of the intestine lines or increased acidity in the duodenum inhibit stomach contraction. Delays gastric emptying to allow more time for digestion


What does the hormone secretin do

Hormone released from duodenum in response to excess stomach acid in small intestine. It can cause fundus to relax and inhibit peristalsis of the body and the antrum of the stomach to slow gastric emptying


What does the hormone cholecystokinin do

Hormone released from duodenum in response to large amounts of fats or protein in the duodenum. Decreases gastric contractions to slow emptying


What are the different gastric secretions

Pepcinogen, intrinsic factor, hydrochloric acid, mucus, bicarbonate ions, gastrin


What is Pepcinogen

Secreted by chief cells. Precursor for the enzyme pepsin which hydrolyzes proteins


What is the intrinsic factor

Secreted by parietal cells, required for vitamin B12 absorption by small intestine time in some species. Vitamin B 12 is important to nervous systems development and blood formation


What is mucus

Complexes substances, mucin is a protein produced by goblet cells. Provides a coating for the stomach against acidic gastric environment. Must be secreted continuously. Reduction in mucus coat can lead to gastric ulcers


What is the bicarbonate ion

Alkalinizes the mucus


What is hydrochloric acid

Secreted by parietal cells as separate ions. Low pH inhibits gastrin release. Receptors on parietal cells for gastrin histamine and acetylcholine involved in regard in regulation of H+ and cl- secretion. Selectively blocking one of these receptors decreases the production of stomach acid


What are prostaglandins

Local regulators released by various tissues with a variety of actions. Initiation of inflammation , regulate estrous cycle, vasodilation or bronchial dilation. In initiation of inflammation and vasodilation inhibits gastric release. It stimulates the gastric glands to produce the bicarbonate ion. it enhances blood flow to the stomach and aids in repair of mucosa by regulating the activity of Macrophages and mast cells


What are NSAIDs

Nonsteroidal anti-inflammatory drugs


What do NSAIDs do

Reduces beneficial effects of prostaglandins on gastric mucosa. Can lead to gastritis, gastric ulcers and perforation


Describe the ruminant stomach

For chambers and three fore stomachs, reticulum, rumen, omasum. The true stomach is abomasum


What is rumination

Repeated regurgitation and swallowing of food. Adaptation for herbivorous diet


What is the reticulum

Smallest, most cranial compartment and is separated from the rumen by the ruminoreticular fold. Continuous muscular wall so compartments contract together. The lining is composed of honeycomb folds which increase surface area. Location of hardware disease


What is hardware disease

Sharp objects are consumed and become lodged in the reticulum and can pierced through stomach wall can cause pericarditis


What is the treatment of hardware disease

Oral administration of large magnets, also given product preventatively. Magnets remain in reticulum for life


What is the rumen

Large fermentation vat which is lined with finger like papilla. Series of muscular sacs partially separated by long folds of rumen walls called pillars. Pillars aid in mixing and stirring of rumen contents


What is reticuloruminal contractions

Allow partially digested plant food to be regurgitated. Allow built up carbon dioxide or methane gas to be expelled from the Rumen


What is the rumen

Site of fermentation. Anaerobic cellular respiration


Describe the anaerobic cellular respiration which occurs in the rumen

Microbes Convert cellulose into simple sugars then convert them to VFA. Proteins also digested and converted to VFA or nh3. microbes form proteins and amino acids used by ruminants. Ruminants absorbs VFA in Omasum and metabolizes them back into glucose or fats


What is the omasum or abomasum

Reticulorumen contractions move ingested material into the abomasum Muscular organ with many muscular folds. Mechanically breaks food particles down further. Absorbs VFA and water. Removes B+ carbonate ions


What is the Abomasum

True stomach which is located ventrally. Functions much the same as a monogastric stomach


What is a displaced abomasum

Abomasum is loosely anchored in abdomen. Most common after calving or if it fills with gas.


What is the treatment for a displaced abomasum

Surgery or rolling cow on her back


Describe newborn ruminant digestion

G.I. track functions primarily as a monogastric digestive system. Rumen and reticular are nonfunctional at birth. Bypassed by Reticular groove carrying material from esophagus to Abomasum. Rate of development of the rumen and reticulum are affected by type of diet. Milk versus grain


Describe the small intestine

The site of chemical digestion and nutrient absorption


Describe the duodenum

First short segment that leaves the stomach. Separated from the stomach by the pyloric sphincter


Describe the jejunum

The longest portion of the small intestine


Describe the ileum

Separated from the colon, the large intestine by the ileocecal sphincter


Describe the ileocecal sphincter

It regulates the movement of materials from the small intestine into the colon and cecum. Parasympathetic stimulation increases activity


Describe the small intestine mucosa

Lined with folds called villi. Epithelial cells, Enterocytes have a microvilli brush border that has a few days of life. It's job is to absorb nutrients. The folds contain blood vessels and lymph lacteals which absorb fats


What is an intestinal crypt

Invagination's of mucosa at the base of each villus, containing a variety of cell types


What do stem cells do in the intestinal crypts

They produce new cells to replace villi cells, enterocytes


What do goblet cells do

Produce and secrete mucus


What do Entero endocrine cells do

Produce and secrete hormones such as CCK or secretin


What do paneth cells do

Produce antimicrobial peptides part of innate immune system


What is acute diarrhea or porcine epidemic diarrhea

Highly contagious viral disease causes destruction of mucosal cells, death of microflora of the large intestine. Due to pathogen and sudden diet change, drug therapy. Example parvovirus, panleukopenia virus


What are the two methods of motility in the small intestine

Peristalsis and segmentation.


What are peristalsis and segmentation considered

Coordinated contractions of muscularis externa


What is diarrhea sometimes due to

Decreased segmentation, not increased peristalsis. Some antidiarrheal drugs act to increase segmentation.


What signals the peristalsis and segmentation to start

Reflexes in response to stretching. CCK and PGs may also stimulate intestinal motility


Describe small intestine digestion

Small molecules from stomach or absorbed. Electrolytes, water and vitamins. Larger molecules require chemical digestion such as carbohydrates, proteins and peptides and fats


What does chemical digestion involve

Enzymes in the lumen of the intestine. And enzymes associated with the microvilli membrane


Describe carbohydrate digestion for a polysaccharide

Enzymes released by pancreas. Amylase. Digestion occurs in lumen of duodenum


Describe chemical digestion for disaccharides

Enzymes are in microvilli cell. membrane. Monosaccharides transported into Enterocytes then into capillaries. Enzyme production is influenced by age and diet


Describe protein digestion in general

In the stomach Pepcid digest some proteins and turns them into smaller polypeptides


What are the pancreatic proteases in protein digestion

Polypeptides are turned into smaller polypeptides by five pancreatic proteases, trypsin, chymotrypsin, elastase, aminopeptidase, carboxypeptidase


What is the peptidases in protein digestion

The peptidases and brush border make smaller peptides turn into tripeptides dipeptides And amino acids that are then absorbed by Enterocytes


What is the first step of fat digestion

Mechanical breakdown by agitation in pyloric Antrum, breaks down fat globules, triglycerides, into smaller droplets equals emulsification.


What is the second step in fat digestion

Bile coats the fat droplets in duodenum to preserve emulsification, and allow them to be water-soluble


What is the third step in fat digestion

Pancreatic Lipases turn triglycerides into glycerol, fatty acid, monoglyceride which is glycerol and a fatty acid. Then the small molecules called micelles are absorbed by Enterocytes. Fat soluble vitamins ADEK often incorporated into micelles and absorbed. They then enter lymph lacteals


What is the first step of digestion in the large intestine of herbivores

The caecum is a blind sac at ileocecal Junction which is the site of microbial digestion. The colon has some microbial digestion and all species. the rectum leads to the Anus. No enzymes released, all species have large microbial population, most important to nonruminant herbivores such as hindgut fermenters


Describe the first step of digestion in the large intestine of carnivores

The caecum is underdeveloped and largely nonfunctional. The colon is simple and tubular. It is the site of peristalsis and segmentation to form and move feces. Microbial flora assist in the production of vitamins.


Describe digestion in the large intestine of hindgut fermenters

Nonruminant herbivores such as horses and rabbits and omnivores such as rodents and swine. Large caecum and colon. both are hindgut. Both are the fermentation site similar to fermentation in ruminants.


What are bends in tracts called

Flexures. They're areas of potential obstruction. Impaction colic.


Describe the rectum

Terminal portion of large intestine. Nervous system control of motility and secretions is similar to that of the colon. Numerous mucus secreting glands lubricate and aid the passage of contents. Sensory receptors detect stretching and stimulates the defecation response


Describe the anus

Composed of internal and Extertal muscular sprinters. As was the rectum distends, stretch receptors in the rectum wall cause partial relaxation of the internal sphincter. Perianal trauma can damage muscle and nerves causing fecal incontinence


Describe the digestive system functions of the pancreas

Production of pancreatic enzymes such as amylase, proteases and lipase
Secretes bicarbonate into the duodenum which helps neutralize acidity of gastric chime and maintains the pH of the duodenum needed for enzyme function. Produces insulin and glucagon which helps regulate blood glucose levels


Describe the digestive functions of the liver

Produces bile which is stored in gallbladder. In rodents and horses there's no gallbladder. Removes and neutralizes toxins that enters the body through the G.I. tract. Stores or metabolizes nutrients absorbed by the G.I. tract. Site of glycogenesis, glycogenolysis, gluconeogenesis.