Gastrointestinal Flashcards

Question

4 layers of the esophagus and what they look like

Answer 1

Mucosa: the epithelium, lines the organ wall Submucosa: connective tissue supporting the mucosa Muscularis: the smooth muscle layer, allow distensibility and propulsion of lumen contents Serosa: the serous membrane layer on the outside of the organ

Answer 2

Starts as a voluntary action (not present if anesthetized) – food is pushed by the tongue back into the pharynx Continues as an involuntary action Reflex contraction of pharynx, movement of epiglottis to cover glottis, relaxation of esophagus to allow entry of food bolus. Followed by peristalsis – a wave of muscular contraction along a tubular organ Contraction of longitudinal and relaxation of circular muscles to open the lumen on the aboral (away from the mouth) side of the bolus Contraction of the circular muscles on the oral side Once in the stomach, there is a natural fold and tone in the cardiac sphincter of the stomach to help prevent reflux In horses – this sphincter prevents vomiting as well

Answer 3

Relaxation of pyloric sphincter (found at distal end of stomach) Reverse peristalsis to move ingesta from the SI into the stomach Relaxation of cardiac sphincter Inspiratory movement against a closed glottis + forceful contraction of abdominal muscles = vomiting Closed glottis prevents aspiration The soft palate directs food out of the mouth

Answer 4

Area surrounding the opening of the esophagus into the stomach

Answer 5

A distensible, blind pouch, which can expand as more food is swallowed

Answer 6

Distensible end in the middle stomach

Answer 7

Distal portion of stomach Grinds up food Regulates acid production Produces mucus

Answer 8

Muscular sphincter that regulates the movement of chyme (semi-digested stomach contents) into the small intestine Prevents backflow from small intestine into stomach

Answer 9

The stomach is shaped like a C Inside curve of the C is called the lesser curvature of the stomach Outside curve is called greater curvature of the stomach The mucosal lining of the stomach occurs as longitudinal folds called rugae

Answer 10

they masticate, swallow, mix and ferment food in the rumen, regurgitate and chew again (also called chewing the cud), then swallow again. Usually graze, then lie down and ruminate One rumination cycle lasting about 1 minute between regurgitation and reswallowing Rumination allows relatively rapid food gathering (while watching out for predators), then later mastication (while safe and resting) Very efficient fiber digestion: food is repeatedly mixed with saliva and ground to increase the surface area exposed to microbial activity in the rumen

Answer 11

Reticulum Rumen Omasum Abomasum

Answer 12

Small Most cranial compartment Separated from rumen by rumenoreticular fold Has honeycomb appearance to mucosa (increases surface area) Coordinated contraction with rumen (reticulorumen contractions)

Answer 13

Largest forestomach compartment Occupies most of the left half of the abdominal cavity Mucosa has a ‘pile rug’ appearance Fermentation chamber (along the reticulum) Separated into different compartments by rumenal pillars – essentially muscular sacs

Answer 14

This assists mixing of rumen contents during contractions Contractions occur in a synchronized manner Controlled primarily by a vagus nerve of parasympathetic system Also affected by rumen pH, presence of VFA in the rumen, consistency of the rumen contents, degree of rumen distension, and feedback degree from other areas in the GIT

Answer 15

is the expulsion of carbon dioxide and methane gas from fermentation that accumulates in the top of the rumen (gas cap). Coordinated contraction of rumen and relaxation of esophagus

Answer 16

During fermentative digestion, plant material is broken down by enzymes from microbes (bacteria, fungi and protozoa) in the rumen. Cellulose convert cellulose to monosaccharides (simple sugars) and polysaccharides Starch is also broken down into monosacchardies

Answer 17

Microbes convert these saccharides to volatile fatty acids, methane and CO2 Protein is broken down by microbial proteases to amino acids Amino acids are then used by microbes to make proteins, or are converted to VFA’s and ammonia (NH3) Ammonia can be picked up by other microbes to synthesize new amino acids Travels to liver, converted to urea, which is then used as a nitrogen source for rumen microbes Can feed urea as another nitrogen source to boost protein made by microbes.

Answer 18

VFA’s = propionic acid, butyric acid, and acetic acid VFA’s are absorbed across rumen wall and go to liver for conversion to glucose (mostly propionic acid) , to make adipose tissue and milk fats (dairy cattle) or are burnt for energy.

Answer 19

Microbes eventually move with ingesta through the GIT and end up being digested in SI These microbes provide an important protein source for the ruminant animal (microbial proteins!) B vitamins and Vitamin K are also made in the rumen

Answer 20

**It is extremely critical to maintain the correct balance of microbes, feed, pH, and gas production in the rumen Any alteration can cause bloat, acidosis, and death Includes sudden diet change, particularly more starch

Answer 21

The third chamber of the ruminant stomach Has lots of surface area due to presence of large mucosal folds – looks like leaves or pages in a book(often called the ‘butcher’s bible’) Strong muscles in omasal wall – important for further mechanical breakdown Also has absorptive function – VFA’s, water, and bicarbonate Prevents neutralization of abomasal acid

Answer 22

The true stomach – similar to monogastric in structure and function

Answer 23

A milk diet does not require or lend itself to fermentation. The rumen and reticulum of nursing calves are undeveloped and lack the microbial population necessary for efficient fermentation Young ruminants have a reticular grooce or esophageal groove, which directs milk into the omasum when swallowed, bypassing the rumen and reticulum Seems to work better if calf is suckling vs drinking from a bucket How long the reticular groove functions depends on how soon the calf is introduced to grain and hay

Answer 24

Stomach submucosa contains gastric pits, glands which produce Mucus HCl Enzymes Hormones (gastrin)

Answer 25

Mix of mucin (produced by goblet cells in the gastric glands), water, and bicarbonate ions (secreted on the surface to neutralize stomach acid) Necessary to protect stomach wall autodigestion due to pH of 2-3 in stomach Is broken down by HCl so must be continuously secreted to prevent gastritis and ulcers

Answer 26

Secreted by parietal (oxyntic) cells as separate ions– H+ and Cl-. This acts to sterilize the food, protects against GI infections and starts the denaturation of proteins Secretion is controlled by receptors on parietal cells for: Gastrin (a gastric hormone, see later) Acetylcholine Histamine

Answer 27

Secreted by chief cells Stimulated by gastrin Precursor for pepsin (made by cleaving pepsinogen with HCl) Pepsin catabolizes (breaks down) proteins to smaller amino acid chains- peptides

Answer 28

Produced by G cells in antrum in response to filling and presence of peptides Increases hydrochloric acid (HCl) production in parietal (oxyntic) cells and pepsinogen release from the chief cells of the fundus and body Causes muscular relaxation in fundus- allows greater filling

Answer 29

Both stomach and intestine contain circular and longitudinal muscles responsible for food propulsion, hunger contractions and to assist grinding Motility varies depending on the stage of ingestion/digestion and the area of the stomach

Answer 30

Initiated by pace maker nervous cells that rhythmically depolarize using calcium channels Stimulate smooth muscle to contract Contraction is modified by autonomic nervous system: Increased by parasympathetic stimulation Except fundus which relaxes So prepares a space in stomach for food Inhibited by sympathetic stimulation Can cause atony (lack of motility) in stressful situations

Answer 31

Produced by the duodenum in response to excess stomach acid in SI Causes relaxation of the fundus Inhibits peristaltic movements in the antrum and body to delay further movement of ingesta into the duodenum

Answer 32

Produced in response to fats and proteins in the duodenum Inhibits gastric contractions and slows gastric emptying Stimulates gallbladder contractions

Answer 33

Fundus and body tend to relax with ingestion – allows distention and storage of food. Also relaxes when antrum is distended with food Antrum tends to contract with ingestion – this is inhibited by acid, fats and proteins in the SI. Propels food towards polyrus Liquid enter SI Solids hold back for more mixing and grinding Stomach of a carnivore empties relatively quickly – within a few hours. Horse and pig take about 24 hours to empty a full stomach

Answer 34

Digestion Proteins Fats Charbohydrates: storage (starch) and saccharides Most of the absorption of nutrients Sugars, amino acids, fats Water Minerals

Answer 35

extends from pylorus to jejunum Receives: Ingesta from stomach Bile from the liver Pancreatic secretions

Answer 36

Longest part of small intestine

Answer 37

Shortest segment of small intestine Indistinguishable from the jejunum Connects to colon of large intestine by the ileocecal sphincter

Answer 38

The small intestine is long and forms many loops and coils The mucosa is folded into pilcations Intestinal crypts sink beneath the surface The site of cell proliferation Secrete fluid into the intestine to dilute the chyme (partially digested food) Absorption is accomplished by extremely high surface area exposed to the lumen

Answer 39

finger-like projections which arise between crypts

Answer 40

tiny projections off the apical surface of the epithelial cells of the villi Form a brush border Cells have enzymes for digestion and carrier molecules for absorption in/on the cell membrane As in stomach, intestinal wall produce mucus

Answer 41

A luminal mucosa (simple columnar epithelium with goblet cells) A submucosa (connective tissue) A muscular later (smooth muscle) An outer serosa (the visceral peritoneum)

Answer 42

Progressive, propulsive contractions Move ingesta through GIT

Answer 43

mixing, churning contractions Increase exposure of chyme to intestinal wall, its digestive enzymes and for absorption Slow the movement of ingesta through GI tract

Answer 44

Carbohydrates, fats, and proteins need to be broken down by enzymes in the GI tract There are two sources of enzymes: The pancreas, the major source Enzymes on the microvilli of the SI villi

Answer 45

Simple sugars (glucose and other monosaccharides) absorbed through epithelium by secondary active transport Glucose leaves cells for blood by diffusion through basement membrane

Answer 46

may be present in saliva, always secreted by pancreas into duodenum Converts starch to disaccharides (sucrose, maltose, lactose)

Answer 47

enzymes in the microvilli cell membrane Convert disaccharides to monosaccharides (glucose, fructose, galactose) The proportion of enzymes depends on diet

Answer 48

Protein digestion begins in the stomach and continues in the intestines. Pepsin breaks proteins into polypeptides in the stomach In small intestine pancreatic proteases further break down proteins in the intestine. Major examples are Trypsin Chymotrypsin Elastase Carboxypeptidase Proteases are originally secreted as inactive substances and are activated in the lumen of the GI tract Protects against auto digestion Luminal digestion yields free amino acids and small peptides The final stage of breakdown is by peptidases in the microvilli of cell membrane Produces amino acids Amino acids are then absorbed on carrier proteins in the microvilli by secondary active transport similar to glucose Leave for blood by diffusion through basement membrane

Answer 49

More complicated than carbs and proteins We absorb fats as triglycerides Fat tends to clump into droplets Digestive system uses emulsification to break up droplets Warmed and mixed in the stomach

Answer 50

Emulsification makes fat into small droplets with a large surface area. This allows Fat soluble vitamins to attach (Vitamin A, D, E, and K) Pancreatic lipases to digest fat Dietary triglycerides are hydrolysed into free fatty acids and monoglycerides are produced

Answer 51

bile acids (salts) are added: Secreted by liver through bile duct into duodenum are bipolar: bond to the fat with hydrophobic end and water with hydrophilic end Forms a micelle Monoglycerides, fatty acids and bile salts Micelles than transport the lipid to the villi Bile salts remain in the lumen Only absorbed in ileum Monoglycerides and fatty acids diffuse into cell Reassembled into triglycerides Packaged with protein and excreted from the cell as chylomicrons Too big to enter capillaries Travel in lymph directly to the vena cava The exception is medium chain triglycerides Chain length is shorter and directly enter blood

Answer 52

A wide tube Functions to recover water and electrolytes, to store feces for elimination and to ferment fiber. Four sections Cecum Colon-3 segments Ascending Transverse Descending

Answer 53

Blind diverticulum (or sac) at beginning of colon (at the ileocecal junction) Poorly developed in carnivores, Moderate size in ruminants Large and highly developed in horses, rats, guinea pigs and rabbits THIS is our appendix!

Answer 54

divided into three segments in the most monogastric species Ascending- proximal portion which courses cranially Transverse- courses from right to left Descending- connects transverse colon to rectum The colon has numerous mucus secreting glands and uses peristaltic and segmental contractions to control movement through it.

Answer 55

Is very large and is located on the right side of the peritoneal cavity

Answer 56

usually called the large colon Consists of four large banks that travel in pairs, one dorsal one ventral, on both sides of the abdomen

Answer 57

divided into sacculations called haustra. The longitudinal muscle forms prominent bands called tenia.

Answer 58

A short transverse colon connects to the small colon Small colon Equivalent to descending colon Longer than in carnivores

Answer 59

The ascending colon is long. Doubled into a spiral that runs in the mesentery supporting the small intestine. Hence often called the spiral colon. Short transverse colon Descending colon

Answer 60

In all species water and electrolytes are absorbed in the large intestine. This is the principal function of the entire LI of cats and dogs and the small colon of horses Fermentation occurs in the cecum and colon, but it varies depending on species. Horses, rabbits and guinea pigs are examples of hind gut fermenters Fiber cannot be digested by mammalian enzymes in the SI

Answer 61

Cecum and large colon function as fermentation chambers for fiber Microbes and end products identical to those found in ruminants VFA’s absorbed across cecal and large colon wall

Answer 62

Much of starch and protein digested and absorbed in the SI of hind gut fermenter Microbial protein cannot be absorbed Bicarbonate secreted directly into the cecum and colon Microbes that perform fermentation are sensitive to some antibiotics Caution with horses/rabbits with antibiotics

Answer 63

stores feces prior to defecation Terminal portion of the colon which continues into the pelvic cavity Has many mucus-secreting glands for lubrication Sensory receptors for stretch – stimulates defecation response

Answer 64

Composed of an internal and external muscular sphincter to allow controlled passage of feces

Answer 65

autonomic NS control Parasympathetic NS – causes relaxation Usually occurs with increased colonic motility Sympathetic NS – causes constriction

Answer 66

voluntary control When the internal sphincter relaxes and allows fecal contents to contact the anal mucosa – stimulates conscious need to defecate Defecation occurs with voluntary relaxation of external sphincter

Answer 67

Exocrine gland function important for digestion Secretes Proteases, amylase, and lipase from pancreatic acinar cells Bicarbonate to help neutralize stomach acid Travel through pancreatic duct to duodenum

Answer 68

Second largest organ of the body (skin is first) Lies caudal to diaphragm Divided into lobes and further subdivided into microscopic lobules Hepatic portal system: system of veins that drain the intestine and deliver blood to the liver. This assists the phagocytic and nutrient process functions of the liver.

Answer 69

Filter and detoxify substances absorbed from the GI tract into the blood Phagocytic cells in the hepatic sinusoids Absorb and store vitamins, minerals and glucose from GI tract Make bile: which contains bile acids (salts), cholesterol, and bilirubin (yellow)

Answer 70

Bile is collected in canaliculi Drain into bile ducts Merge to form hepatic duct Connects to the gallbladder (storage compartment for bile acids). (Not present in horses) The common bile duct drains the gallbladder and liver Merges with the pancreatic duct just before opening into the duodenum Makes some blood proteins Albumin: important for maintaining blood oncotic pressure Diseased liver = low albumin = low oncotic pressure = ascites The liver is important in glucose metabolism:

Answer 71

Gallbladder contracts in response to cholecystokinin Released in response to the presence of fats and proteins in the intestine, thereby providing the bile for fat emulsification when it is needed! Bile acids are reabsorbed with fats through the hepatic portal system, removed from the blood, and recycled by the liver to make more

Answer 72

makes glycogen From sugars absorbed from gut

Answer 73

breaks down glycogen Between meals to maintain blood glucose

Answer 74

makes glucose During starvation From amino acids (especially in cats) Propionate in herbivores

Answer 75

Most common congenital abnormality involving the lips of small animals Genetic or teratogens (substances that cause defects during development) Cleft lip- due to a disturbance of the process making the jaws and face during embryonic development Cleft palate- found in newborn of all species Defect may involve the soft palate alone, or may extend rostrally through the maxillary bones to the lips Initial sign is milk dropping from the nostrils when newborn attempts to nurse

Answer 76

(sialocele or cyst) An excessive accumulation if saliva in and/or around the gland Trauma or inflammation occludes the duct or ruptures the duct or gland Shows up as a fluctuant swelling without and associated fever Can affect any of the salivary glands

Answer 77

Congenital: constrictive bands of tissue from a persistent aortic arch Acquired: paralysis of muscle due to problem with muscle or nerves

Answer 78

Protrusion of abdominal contents into the subcutis through a natural or abnormal opening in the body wall Three types Umbilical Inguinal Scrotal (males)

Answer 79

(gastric dilatation and volvulus) AKA gastric torsion/bloat Seen in large, deep-chested and giant breed dogs most commonly The classic presentation history involves exercise after a heavy meal or heavy water consumption

Answer 80

Distended abdomen Retching with no vomit production Drooling Pacing Distress

Answer 81

These animals quickly go into shock and unless treated, die Treatment is IMMEDIATE surgery Stabilize patient and relieve pressure Correct the twist Resect any areas of dead stomach wall May require any splenectomy Tack stomach to body wall to prevent reoccurance GASTROPEXY

Answer 82

Chronic or acute inflammation of the gastric mucosa Can be caused by disease, diet, bacteria, irritants etc.

Answer 83

An increased water content of feces Large volume of fluid pass through the GI tract daily Secretions of GI glands (saliva, stomach, pancreas) Direct secretion by surface epithelial cells Total volume of fluid passing through the gut daily is greater than total body water Imbalances b/w secretion and absorption result in diarrhea Can be profuse and cause rapid dehydration Diarrhea can be from small intestinal or large intestinal diseases

Answer 84

Colic ia abdominal pain The GI tract is mainly sensitive to dissension Obstruction is the common cause of distention Twists/displacement of GI tract Kink lumen and block outflow Fluid accumulates in the GI tract Colic Dehydration Electrolyte and acid base imbalances

Answer 85

Can involve one or more of previously described conditions: intussusception, torsion, volvulus, impaction or obstruction, foreign bodies, enteritis Is a serious problems in horses as 20% are surgical and can be fatal

Answer 86

Infrequent or hard to pass fecal movements Feces usually accumulate in the descending colon or rectum Dry out and harden as water is absorbed by mucosa

Answer 87

Decreased peristalsis Inadequate dietary fiber: GI tract contracts in response to distension Electrolyte imbalances Calcium: important for muscular contraction Potassium: important for nerve stimulation Stress: sympathetic nervous stimulation Drugs: beware of atropine especially in horse

Answer 88

Acute or chronic inflammation of the mucous membranes of the small intestine and large intestine There are many causes- infectious disease, diet, foreign bodies, irritant drugs or chemicals, parasitism

Answer 89

Protrusion of all or part of the rectum through the anus Seen in all species, but most common in young animals, or postpartum

Answer 90

Usually the result of trauma In small animals - the result of passing a foreign body In large animals - often the result of rough rectal palpation

Answer 91

Examined at necropsy: a full gall bladder means that the animal was not eating prior to death Gallbladder can have mucous accumulation that can cause rupture Gallbladder mucocele

Answer 92

A general term used to describe an inflammation of the liver Sings include: weight loss, nervous signs due to low blood glucose or high blood ammonia, jaundice (bilirubin accumulation) and edema

Answer 93

seen most commonly in dogs The patient is typically middle-aged, inactive and obese Acute pancreatitis is very painful Chronic pancreatitis results in loss of functional pancreas More common in cats Exocrine pancreatic insufficiency Decreased production of digestive enzymes Animal unable to break down food See weight loss and abnormal stool which is often profuse, voluminous and fatty, may be diarrhea.

Answer 94

Insufficient production of, or sensitivity to, insulin Can be secondary to pancreatitis in dogs Type 1 Insulin deficiency Dogs and some cats Type 2 Insulin resistance Most cats

Answer 95

Signs Polyuria Polydipsia Weight loss Cataracts in DOGS Neuropathy in CATS Treatment Insulin and diet changes

Answer 96

Bloat=abdominal distension Ruminal bloat is th distention due to ruminal gas accumulation Large daily gas production Is a serious problem is cannot be eructated Frothy bubbles Some microbes produce slime Ruminal atony (milk fever) Bloat causes pressure on the diaphragm, inhibiting heart and lung function

Answer 97

perforation of the reticulum by a foreign body (usually metallic) and an associated localized peritonitis Magnets have been placed in the reticulum (orally) to collect metal objects and keep them from penetrating the wall

Answer 98

The most common is the "LDA" Or left-side displacement of the abomasum which normally lies on the floor ( midline or slightly to the right) of the abdominal cavity Displaces to the left between the rumen and the abdominal wall (RDA’s develop on the right) Generally, a condition seen in large, richly fed, high- producing dairy cows immediately after parturition Correction is surgical

Gastrointestinal Flashcards

(123 cards)