Chapter 16 Digestive System Flashcards

Question

omentum

Answer 1

A double layer Connects the peritoneum that links the stomach to abdominal wall or to other organs: Lesser omentum Greater omentum

Answer 2

 Lips  Tongue  Teeth  Salivary glands  Hard palate  Soft palate

Answer 3

SALIVARY GLANDS PANCREAS LIVER

Answer 4

Pattern of muscle contraction that propels food through the GI tract As soon as an animal swallows it begins a wave of peristalsis

Answer 5

Transient folds in gastric mucosa Allow stomach to expand when filled with food Increase surface area for absorption "have ridges"

Answer 6

4 chambers First 3 chambers are the forestomachs: reticulum, rumen, and omasum ▪ The forestomachs are lined by stratified squamous epithelium and are non-glandular. Last chamber and “true stomach”: abomasum

Answer 7

 Deposited into oral cavity via ducts  Production varies depending on species  Composition: watery or viscous or mixed

Answer 8

 Secreted by 3 main paired glands * Parotid, mandibular, and sublingual  Lubrication  Antibacterial action  pH regulation  Thermoregulation  Enzymatic digestion

Answer 9

 Adaptations help increase surface area * Organ is long with many loops and coils *Plications (folds) in mucosal lining *Villi in mucosa contain microvilli *Brush border *Intestinal crypts (crypts of Langerhans)

Answer 10

On the left side  Mucosal lining (rugae)  Mechanical digestion  Chemical digestion of protein * HCl * Protease (pepsin)  Pylorus (pyloric valve) - 1 wave valve

Answer 11

 Crown covered by enamel *Enamel * Dentin --Dentin forms bulk of tooth --- Pulp cavity that contains blood and nerves  Gingiva - gums  Root - cemented in gingiva * Dentin * Pulp * Cementum- thin bone that cements * Periodontal ligament

Answer 12

Named by direction the outer surface faces:  Buccal  Labial  Lingual  Palatal

Answer 13

The Teeth Embedded in upper maxilla bone and lower mandible bone Parts of a tooth: Parts of tooth- Crown, Root, Apex, Neck

Answer 14

 Blind diverticulum at beginning of colon *Inconspicuous in carnivores – whipworms in dogs * Large blind tube in ruminants * Huge in equines  3 parts *Base, main body, apex  Ileum opens into cecum, colon, or both (depending on species)

Answer 15

 Muscular tube connecting pharynx to stomach  Lined with folded mucosa  Tunica muscularis * 2 layers (circular and longitudinal) needed to move food

Answer 16

 Enzymes are vital to digestion * lipase, amylase, nuclease, protease  Proenzyme (or zymogen) * All proteolytic enzymes secreted in inactive form * Trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidase A and B * CCK starts the activation process

Answer 17

 Concentrates and stores bile until needed * Bile enters duodenum to emulsify fat - makes fat water soluble  Provides means for liver to excrete waste products even when animal is not eating  Composition of bile * Bile salts * Phospholipids * Cholesterol * Bile pigments

Answer 18

 Components * Cecum – blind sac at ileocecal junction * Colon * Rectum * Anus  Species variation in structure  Primary functions * Recover fluid and electrolytes * Store feces until they can be eliminated

Answer 19

 C-shaped, located just behind diaphragm  Glandular portion with gastric pits: * Cardia * Fundus *Body  Distal portion *Pylorus

Answer 20

= Mouth = Buccal Cavity  Entrance to the GI tract  Contains everything in the mouth  2 parts *Vestibule *Space between lips and cheeks, and outer surface of teeth * Oral cavity *Bordered by inner surface of teeth, and hard and soft palates

Answer 21

= Throat/common passageway  Part of both GI and respiratory tracts  Swallowing sends food from the oral cavity to the esophagus  Structures found here *Eustachian tube * Tonsils

Answer 22

Tube that carries chyme away from stomach and deposits it in the large intestine  Suspended from the body wall by mesentery  Duodenum * Receives chyme through pyloric sphincter * Pancreatic duct opens here * Common bile duct opens here  Jejunum * Longest part * Most chemical digestion and absorption occur here  Ileum * Prominent Peyer’s patches * Empties into large intestine at cecum (horse), at colon (dog and cat), or at cecum and colon (ruminant and pig)

Answer 23

 Functions *Storage of ingested food * Mechanical and chemical breakdown of food *Beginning of protein digestion *Production of intrinsic factor for Vitamin B12 absorption in small intestine  Food leaves stomach in semi-liquid form = chyme

Answer 24

 Functions *Storage of ingested food * Mechanical and chemical breakdown of food *Beginning of protein digestion *Production of intrinsic factor for Vitamin B12 absorption in small intestine  Food leaves stomach in semi-liquid form = chyme

Answer 25

 Muscular structure on ventral surface in oral cavity  3 parts *Apex, body, and root  Papillae on dorsal surface * Mechanical functions * Grooming and moving food into pharynx *Specialized functions * Taste sensations, pain, temperature, touch, and thermoregulation through panting (dogs)  4 types of taste buds -- sweet, sour, salty, bitter

Answer 26

 Only gland in body with both exocrine and endocrine functions!!!  Production of pancreatic amylase, proteases, and lipase (groups of acini) - Exocrine  Secretes bicarbonate into the duodenum * Helps neutralize acidity of contents and maintains the pH in the duodenum needed for proper enzyme function  Produces insulin and glucagon * Help regulate blood glucose levels Adding secretions that enhance digestion

Answer 27

1 - Mouth 2- teeth 3 - tongue 4 - pharynx 5 -esophagus 6 -stomach 7 -duodenum (part of small intestine) 8 - jejunum (part of small intestine) 9- ilium (part of small intestine) (Food doesn't go in Cecum, but it's next. Part of large intestine) 10 - Ascending Colon- 2nd part of large intestine 11 Transverse colon - large intestine 12 - Descending colon - large intestine 13- Rectum - large intestine salivary glands, pancreas, liver contribute to "tube" but aren't part of GI tube 14 Anus

Answer 28

 Herbivores eat plant material * Ruminants: cattle and goats * Non-ruminants: horses  Carnivores eat meat * Cats  Omnivores eat combination of plants and meat * Humans, pigs, dogs

Answer 29

 Adaptations help increase surface area * Organ is long with many loops and coils *Plications (folds) in mucosal lining *Villi in mucosa contain microvilli *Brush border *Intestinal crypts (crypts of Langerhans)

Answer 30

Adding secretions that enhance digestion Parotid- ventral to ear, very large Mandibular- medial to mandible Sublingual- below tongue Zygomatic- cheek bone

Answer 31

Pancreatic acinar cells synthesize and secrete almost all the digestive enzymes active in the lumen of the small intestine which are necessary for nutrient digestion

Answer 32

left medial left lateral quadrate lobe right medial right lateral

Answer 33

 Herbivores * Cattle, sheep, goats, deer, reindeer, moose * Require more food and more complex digestion process than carnivores  Forestomachs are non-glandular * Microorganisms for fermentation in rumen and reticulum * Complex carbohydrates (cellulose) broken down  Abomasum functions same as monogastric stomach

Answer 34

Part of the Forestomachs  Each performs a different digestive function and has different anatomical features  Rumen = “the paunch”  Occupies most of left side of abdominal cavity  Microorganisms ferment carbohydrates, so they can digest fiber  Papillae in mucosa increase surface area for absorption  Pillars divide rumen * Dorsal sac, ventral sac, and 2 caudal sacs

Answer 35

Part of the Forestomachs  Reticulum = “the honeycomb”  Located cranial to the rumen  Contents easily enter and exit to rumen *reticulorumen

Answer 36

Part of the Forestomachs  Links esophagus with omasum in young ruminant  Milk for nursing ruminant bypasses reticulorumen * Goes directly to omasum and abomasum  If groove didn’t close: *Bacteria in reticulorumen would ferment milk * Lactic acid produced would inhibit normal microbial action

Answer 37

Part of the Forestomachs  Omasum = “many plies” or “book stomach”  Connects reticulorumen to abomasum  Folds of mucosa with papillae on surfaces  Absorption of water and salts here

Answer 38

 Elongated “true stomach”  Lined with glandular tissue  Released renin causes milk protein coagulation *Prolongs time for pepsin to break down proteins  Functions like simple monogastric stomach *Exception: abomasum is not a storage compartment  Continuous flow of ingesta into abomasum

Answer 39

Primary contractions = mixing contractions  Ensure content movements between reticulum and rumen  Separate particles based on size

Answer 40

Rumination = “chewing the cud”  Ingesta moves from reticulorumen back into oral cavity for additional saliva and continued chewing  4-step process * Regurgitation * Re-insalivation * Remastication * Re-swallowing

Answer 41

 Eructation = belching = secondary contractions  Responsible for the release of gases * Carbon dioxide and methane produced during fermentation  Without gas release, develop condition of bloat  Area of brainstem controls reticuloruminal activity

Answer 42

 Wide variety of bacteria, protozoa, and fungi in ruminants  Proper balance between types acquired after birth * Controlled by diet and amount of food consumed *Also by interactions between mother and young  Oxygen ingested along with food

Answer 43

 Ruminants’ diet – herbivore * Mostly grasses (roughage): complex carbohydrates * Cellulose, hemicellulose, and pectin *Some grains (concentrates): nonstructural carbohydrates * Starches, fructosans, and simple sugars  Microorganisms use nutrients consumed for their own growth and development  Ruminant can digest microorganisms as source of protein  Complex carbohydrates * Hydrolysis by catalase enzymes to simple sugars  Starches and soluble sugars * Hydrolysis by amylolytic bacteria to monosaccharides and polysaccharides *Saccharides absorbed by microvilli and further metabolized to pyruvate and converted to volatile fatty acids (VFAs) * VFAs are main source of energy for the ruminant

Answer 44

 Lipids found in grasses and plants: * Triglycerides, glycolipids, free fatty acids  Lipids constitute small portion of diet * Too many lipids: decreased appetite, reduced motility of reticulorumen, decreased fermentation of cellulose  Microorganisms in reticulorumen hydrolyze triglycerides *VFAs produced, used to produce energy or stored *Acetic acid (acetate), propionic acid (propionate), and butyric acid (butyrate)

Answer 45

 Fermentation process occurs before enzymatic digestion  Nutrients in food first available to microbes in reticulorumen * Microbial peptidase breaks down proteins to peptide chains * Microbes can synthesize amino acids from ammonium, and by converting non-protein nitrogen (NPN) compounds  Further broken down in small intestine by enzymatic action and transported to liver * Amino acids are metabolized * Urea is produced; goes back to rumen (and then saliva) for reuse in making microbial proteins

Answer 46

 Ruminal microbes process carbohydrates before they are exposed to intestinal enzymes * potential glucose deficiency  Gluconeogenesis * Occurs in liver from non-carbohydrate sources *Propionate, butyric acid, acetate, absorbed amino acids  Conservation of glucose

Answer 47

 Carnivores: simple, tubular colon; poorly developed cecum  Nonruminant herbivores: very large colon and cecum (hindgut) * Fermentation site

Answer 48

Volatile fatty acids are the main energy source for ruminants, providing approximately 70% of the total energy requirements. They are used primarily by the microorganisms for reproduction and growth, with the excess production being used by the ruminant itself.

Answer 49

Equine- Large Colon Bovine- Coiled Colon Porcnie - Spiral Colon

Answer 50

 Food –  Chyme –  Feces – waste product from animal's digestive tract expelled through the anus during defecation * Water (75%) *Bacteria * Fiber * Undigested/unabsorbed nutrients * Waste products

Answer 51

 Prehension  Chewing = mastication  Salivary secretion * Regulated by nervous system *Also triggered by conditioned responses  Swallowing = deglutition *Voluntary *Pharyngeal stage *Esophageal stage – initiates peristalsis

Answer 52

 A proteolytic enzyme  Essential in the digestive process *Begins the chemical digestions of proteins  Activated in the fundus *Pepsinogen secreted by chief cells *Pepsinogen converted to pepsin in presence of HCl

Answer 53

 Last glandular portion of the stomach  Regions: * Pyloric antrum * Pyloric canal * Pylorus  Opens into duodenum through pyloric sphincter  Cells found here * Mucous-secreting cells * G cells secreting gastrin

Answer 54

 3 substances stimulate secretions by glandular cells *Acetylcholine from cholinergic neurons * Gastrin released by G cells * Histamine secreted by enterochromaffin-like cells (ECL-cells) in gastric mucosa  Cephalic phase of secretion – thinking about food! *Anticipation of eating a meal  Gastric phase of secretion *Begins when food enters stomach

Answer 55

 Begins in anticipation of eating *Enteric nervous system is stimulated *Acetylcholine is released and binds to receptors * Parietal cells secrete H+ and Clions * Chief cells secrete pepsinogen into stomach * G cells secrete gastrin into bloodstream

Answer 56

 Begins when food enters stomach * Glandular cells stimulated by stretching of stomach wall *Peptides formed by protein breakdown * Local enteric reflexes, and vagal reflexes to and from brain *Stomach can be as acidic as pH 2.0

Answer 57

Carbs- mouth Protein - stomach Fats- small intestine

Answer 58

 Muscle contractions of stomach wall help break down food particles  Gastric contents released at controlled rate *Specialized smooth muscle pacemaker cells * Fluctuations in resting membrane potential lead to muscle contraction *Acetylcholine elevates resting potential *Entry of Ca++ ions into muscle cell initiates contraction  Each part differs in degree of movement based on its function  Fundus expands to accommodate large volumes of food  Body is a large mixing chamber  Pyloric antrum acts like a pump

Answer 59

 Movements * Fragment food into small particles *Influence rate of gastric emptying  Weak in fundus and body  Progressively stronger as food moves toward pylorus * Larger particles prevented from leaving stomach * Retropulsion

Answer 60

Grinding of food.

Answer 61

Macronutrients-  Carbohydrates  Proteins  Lipids Micronutrients-  Vitamins  Minerals  Water

Answer 62

 Mechanical digestion *Essential to increasing amount of food surface area  Chemical digestion * Digestive enzymes from exocrine pancreas responsible * Carbohydrates – amylase *Proteins – proteases * Lipids (fats) – lipase

Answer 63

 Macronutrients- requires digestion  Micronutrients – nutrient molecules so small that no digestion is required before being absorbed *Vitamins * Minerals * Water

Answer 64

 Starches * Made of repeating glucose monosaccharides  Sugars *Simple monosaccharides (glucose) * Multiple monosaccharides linked together * Disaccharides, sucrose and lactose  Cellulose * Complex carbohydrate

Answer 65

 Proteins  Made of repeating amino acid units  Chain of >50 amino acids = protein  Chain of <50 amino acids = peptide

Answer 66

 Majority of fat found in animal’s diet  Made of a glycerol backbone and 3 fatty acids

Answer 67

 Majority of fat found in animal’s diet  Made of a glycerol backbone and 3 fatty acids

Answer 68

Carbohydrate digestion  Begins with amylase in saliva  Continues in stomach and small intestine  Protein digestion  Begins in the stomach; continues in small intestine  Pepsinogen activated by HCl to pepsin

Answer 69

*Innermost layer of GIT *made of epithelium, lamina propria and muscularis mucosae -epithelium is made of stratified squamous and simple columnar epithelium -mucosa is made of loose areolar connective tissue -muscular mucosae is a thin layer of smooth muscle

Answer 70

*Hormonelike substances that regulate biochemical activities in the tissue they are formed. *Produced from lipids (eicosanoids) *Important role in controlling blood pressure and smooth muscle contraction

Answer 71

--Visceral peritoneum --Parietal peritoneum --Mesentery --Omentum

Answer 72

▪ Monogastric animals, including the dog, cat, and horse ▪ Muscle contractions of the stomach wall contribute to the mechanical breakdown of food particles ▪ Mechanical digestion in the oral cavity and in the stomach is essential to increase the amount of food surface area that can be exposed to the digestive enzymes ▪ Digestive enzymes are responsible for the second phase of digestion, chemical digestion ▪ Luminal chemical digestion breaks down macromolecules being broken down through hydrolysis ▪ Hydrolysis is then repeated in membranous chemical digestion, where the short chain polymers are completely broken down into their most basic component parts ▪ In some animals, such as omnivores, chemical digestion begins with amylase (breaks down starch CHOs) in the saliva. ▪ In animals that do not have amylase in their saliva, the digestion of starch does not begin until the food has reached the small intestine and pancreatic amylase is released. ▪ Protein digestion, on the other hand, begins in the stomach.

Answer 73

▪ Chemical digestion is divided into two phases: ➢ Luminal chemical digestion ▪ Occurs in the lumen of the stomach or intestine ▪ Digestive enzymes mix with food and acid or alkaline fluids to digest free-floating food particles in the lumen ➢ Membranous chemical digestion

Answer 74

▪ Mastication breaks larger food mixing them with saliva to create a rounded mass called a bolus that the ruminant swallows. ▪ Saliva is alkaline and contains both bicarbonate and phosphate which help buffer the rumen during fermentation ▪ As food leaves the forestomachs, it enters the fourth chamber or the “true” stomach, the abomasum ▪ The rumen and the reticulum are where the majority of cellulose is degraded. *contain a large number of microorganisms (bacteria, protozoa, and fungi) that are responsible for a fermentation * During fermentation, complex CHOs such as cellulose and hemicellulose are broken down ▪ The omasum is where the absorption of water and salts take place. ▪ The abomasum (” true stomach”) functions in the same way as the monogastric simple stomach. However, The flow of ingesta into the abomasum is continuous. ▪ CHO digestion – starch end product is volatile fatty acids (main source of energy for the ruminant) ▪ Lipid digestion – triglycerides are hydrolyzed producing VFAs ▪ Protein digestion – the end product are amino acids used to make microbial protein, ammonium to proAnuduce VFAs.

Answer 75

Carboydrates

Answer 76

The opening of the GI tract for elimination of stool ➢ At the junction of the rectum and anus, the mucosa changes from glandular villi to flattened squamous epithelial tissue ➢ Two large muscle sphincters surround the anus to help retain the stool before defecation ➢ The inner anal sphincter is under smooth muscle control while the outer anal sphincter is under skeletal muscle control.

Answer 77

➢ When chyme passes through the large intestine much of the water is absorbed, leaving a semisolid material called feces. ➢ When feces are transported to the rectum, sensory receptors are stimulated. This stimulates the defecation reflex ➢ The animal then perceives the need to defecate

Answer 78

* some microbial digestion ---Ascending ---Transverse --- Descending * most variety between species *reabsorbs fluids and prepare wastes for elimnation

Answer 79

▪ Majority of chemical CHO digestion occurs in small intestine ▪ Starches are one of the few CHOs broken down in the luminal phase ▪ In the membranous phase enzymes in the brush border: --there are specific enzymes for each type of polysaccharide -- Sugars, such as sucrose and lactose, are degraded

Answer 80

*Luminal protein digestion began in the stomach with pepsin and is completed in the small intestine. *The pancreas releases proenzymes that are activated in the lumen of the small intestine. --- the endopeptidases and the exopeptidases ➢ Free amino acids are yielded ➢ Some peptide chains are incompletely hydrolyzed and form dipeptides and tripeptides. ----These are small enough to be absorbed into the intestinal wall

Answer 81

*First phase of chemical digestion *Large macromolecules broken into short polymers through hydrolysis

Answer 82

*Second phase of chemical digestion *Hydrolysis is repeated to completely break down the short chains of polymers formed through luminal digestion

Answer 83

▪ Fats and fat-soluble vitamins are also digested in and absorbed from the small intestine. ▪ Triglycerides are the primary dietary lipids; other lipids include cholesterols, phospholipids, and esters ▪ Lipids are not water soluble and cannot be dissolved in the watery medium of the GI fluids. ▪ In order to digest and absorb fats, a four-step process must occur: ➢ Emulsification ➢ Hydrolysis ➢ Micelle formation ➢ Absorption

Answer 84

Begins in the stomach where lipids are warmed to body temperature and thoroughly mixed. This process helps break lipids into smaller droplets. Emulsification is then completed in the small intestine by the detergent action of bile salts and phospholipids.

Answer 85

▪ Bile salts coat the lipid droplets, causing them to repel one another and remain small individual droplets. Decreasing the size of lipid droplets increases the surface area available for the hydrolytic pancreatic enzymes, lipase and colipase, to break down each triglycerid

Answer 86

▪ The monoglyceride and the two fatty acids are not yet soluble in water, which again would cause a problem if it were not for the bile salts forming micelles ▪ The micelles essentially act like tiny ferries, transporting the fatty acids and monoglycerides to the enterocyte surface. At this point the monoglyceride and fatty acids diffuse into the cell and the bile salts do not. This keeps the bile salts available to transfer other monoglycerides and fatty acids

Answer 87

▪ Inside the enterocyte, the monoglyceride and the two fatty acids are reassembled into a triglyceride and packaged into chylomicrons. ▪ Chylomicrons are spherical structures that are made up of triglycerides, cholesterol, phospholipids, and proteins ▪ The Golgi apparatus packages the chylomicrons into vesicles, which are transported to the cell membrane, from which they are released into the interstitial fluid by exocytosis. ▪ Chylomicrons cannot enter the capillaries because of their large size; instead they are picked up by the lymphatic system and transported to the

Answer 88

The stomach of birds consists of a glandular portion (proventriculus) and a muscular portion (gizzard). The process of chemical digestion begins in the proventriculus. The gizzard is comprised of bands of striated muscles that grind food.