Self Evaluation | Digestive System

Question 1

A rabbit is brought to your office. It has wet matted hair and slimy drool around its mouth and on its chest. Its hair coat is in general matted and the rabbit is in a thin condition. It has been eating a high
legume/corn mix diet. What are you likely to see on examining the rabbit carefully?

Answer 1

Malocclusion of the molars or incisors

Question 2

During the swallowing reflex, the dorsal soft palate is elevated. Why?

Answer 2

To prevent ingesta from entering the nasopharynx and coming out the nose

Question 3

The premolars of a horse are classified as (A) __________ teeth. Enamel ridges wear more slowly than the ridges composed of (B) __________ and (C) __________ that keep the occlusal surface sharp.

Answer 3

(A) Hypsodont, (B) dentin and (C) cementum

Question 4

What kind of receptors does the neurotransmitter released by post ganglionic fibers of the vagus nerve stimulate?

Answer 4

Muscarinic receptors on target cells

Question 5

A horse consuming red clover hay is drooling several liters of foamy drool per hour.
(A) What is in the clover?
(B) And what is it doing/acting on? Be specific

Answer 5

(A) Slaframine. (B) Salivary muscarinic receptors

Question 6

__________ exist between muscle cells that form a syncytium. These structures allow ion fluxes to pass freely from one cell to another within the syncytium.

Answer 6

Gap junctions

Question 7

How does vasoactive intestinal peptide affect the lower esophageal sphincter?

Answer 7

Relaxes it to allow entry of bolus

Question 8

How does gastrin affect the lower esophageal sphincter?

Answer 8

Tightens it close

Question 9

Arrange the following possible sites of impaction in a horse in order, with 1 being first (most orad) and 6 being last.
(A) Pelvic flexure of colon
(B) Pylorus of stomach
(C) Sternal flexure
(D) Entrance to transverse colon
(E) Cecocolic orifice
(F) Diaphragmatic flexure

Answer 9

1, B; 2, E; 3, C; 4, A; 5, F; 6, D
Pylorus of stomach
Cecocolic orifice
Sternal flexure
Pelvic flexure of colon
Diaphragmatic flexure
Entrance of transverse colon

Question 10

Arrange the steps (A–G) involved in defecation in order from first (1) to last (7).

a. Conscious decision is made to defecate and signals are sent back down spinal column to somatic motor nerves which reach the external anal sphincter via the pudendal nerve

b. Peristalsis in descending colon sends fecal material to rectum

c. Stretch receptors in vicinity of internal anal sphincter sense presence of matter and send afferent impulses to sacral spinal cord via sacral spinal nerves

d. Sacral spinal parasympathetic efferent fibers to internal anal sphincter are activated and the sphincter relaxes

e. Pressure on external anal sphincter is sensed by receptors in vicinity of external anal sphincter sending afferent impulses to the higher centers of the brain

f. External and sphincter relaxes and with abdominal muscle contraction raising intra-abdominal pressure the fecal matter is passed out

g. Rectum is normally devoid of feces

Answer 10

1, G; 2, B; 3, C; 4, D; 5, E; 6, A; 7, F

Question 11

What kind of cells produce histamine within the gastrointestinal tract?

Answer 11

Enteroendocrine cells of the fundic stomach

Question 12

Giving nonsteroidal anti‐inflammatory drugs for long periods can cause ulcers to develop because many NSAIDs block (A) __________, resulting in failure of damaged cells to produce (B) __________. This leads to failure to increase (C) __________ needed for cell repair.

Answer 12

(A) Cyclooxygenase 1, (B) PGE and PGI, (C) blood flow

Question 13

The alkalinity of pancreatic fluid is achieved by pancreatic duct cells that resorb (A) __________ ions from the pancreatic acinar secre tions and add (B) __________ ions to those secretions.

Answer 13

(A) Chloride, (B) sodium and potassium

Question 14

Many enzymes produced by pancreatic acinar cells are secreted in an inactive form. What happens if they accidentally become activated within the acinar cells or the interlobular pancreatic ducts?

Answer 14

Digestion of body tissues leading to pancreatitis

Question 15

Within a single functional unit of the liver the hepatocytes that are closest to the portal vein are receiving (A) the least or (B) the most oxygenated blood. Choose one option.

Answer 15

(B) the most oxygenated blood.

Question 16

Bilirubin and many drugs are excreted via the biliary system. Generally, the process involves hepatocytes removing water‐insoluble compounds bound to plasma albumin and increasing their water solubility by __________ and then releasing them into the bile canaliculus.

Answer 16

Hydroxylating them at various sites and conjugating them to a water-soluble compound like glucuronic acid

Question 17

What is the function of M or dome cells in the intestine?

Answer 17

Present antigens from the lumen to lymphocytes and dendritic cells residing in the lamina propria

Question 18

Chloride is actively secreted into the lumen of the small intestine by __________ cells.

Answer 18

Crypt enterocyte

Question 19

A clostridial bacterial toxin is ingested by a dog who got loose and obtained dinner from the neighbor’s garbage can. The toxin activates receptors on (A) __________ cells located at the base of the crypts, which secrete serotonin in response to the toxin. The sero tonin acts on neighboring cells and causes (B) __________ chan nels in the basolateral membrane of (C) __________ cells to open.

Answer 19

(A) Enteroendocrine, (B) calcium, (C) crypt

Question 20

Between meals, crypt cells are largely inactive. Crypt secretion of chloride increases shortly after a meal causes distension of the stomach. The crypt secretory process in this case is controlled by the (A) __________ which releases (B) __________ onto (C) __________ receptors of the crypt cells.

Answer 20

(A) Vagal parasympathetic, (B) acetylcholine, (C) muscarinic

Question 21

With regard to digestion and absorption of dietary proteins:
A. Trypsinogen first becomes converted to trypsin by what?
B. Which cells produce this substance?
C. What stimulates these cells to produce the trypsin activating factor?

Answer 21

(A) Enteropeptidase, (B) villous enterocytes, (C) cholecystokinin

Question 22

With regard to the gallbladder:
A. Contraction of the gallbladder is stimulated by which hormone?
B. Made by which cells?
C. Located where?
D. Made in response to what stimulus?

Answer 22

(A) Cholecystokinin, (B) enteroendocrine cells, (C) duodenum, (D) fats and peptides entering the duodenum

Question 23

A micelle consists of fatty acids, monoglycerides, and cholesterol surrounded by what?

Answer 23

Bile salts

Question 24

Two proteolytic enzymes are produced by (A) __________ cells of the fundic gastric glands. One is secreted as an inactive enzyme called (B)________. It is activated to its proteolytic form by (C) ________. The other proteolytic enzyme is especially important to the neonatal mammal trying to digest its milk meals and is called (D)__________.

Answer 24

(A) Chief, (B) pepsinogen, (C) acid of stomach, (D) rennin

Question 25

Facilitated diffusion of tryptophan across the apical membrane of a villous cell in the jejunum requires which of the following. List all correct answers. A. Amino acid carrier protein B. Sodium C. Calcium D. GLUT‐2 transporter E. ATP (directly) F. Tryptophan cannot be transported across jejunum

Answer 25

A and B

Question 26

Name three brush border membrane‐bound enzymes involved in the final stages of carbohydrate digestion in the villi of the jejunum.

Answer 26

Lactase, sucrase, maltase, trehalase, dextrinase, enterocyte amylase

Question 27

Number, in the order in which they occur (1, first to 9, last), the steps in fat digestion in a dog. A. CCK stimulates gallbladder contraction and secretion of pancreatic enzymes including pro‐colipase B. Micelles are formed, allowing the lipophilic contents to cross the unstirred water layer and glycocalyx of the villous enterocyte C. Chylomicrons exocytose through basolateral membrane and enter the lacteals D. Stomach contractions emulsify ingested fat E. Fat entering duodenum stimulates CCK release by enteroendocrine cells F. Pro‐colipase is activated to colipase by trypsin in the lumen of the intestine G. Colipase, lipase and bile salts act together on emulsified fat to begin triglyceride breakdown H. Triglycerides are reformed and packaged in cholesterol– apolipoprotein B48 structures known as chylomicrons I. Micelles contact brush border membrane and fatty acids, monoglycerides, cholesterol and fat‐soluble vitamins cross cell membrane lipid bilayer into cytosol

Answer 27

1, D; 2, E; 3, A; 4, F; 5, G; 6, B; 7, I; 8, H; 9,C

Question 28

Magnesium citrate ingestion relieves constipation since Mg is not readily absorbed across the intestinal epithelium. This causes an increase in __________ of the chyme, causing water to remain in the intestinal lumen and exit with the feces.

Answer 28

Osmolarity

Question 29

Chloride is actively secreted into the lumen of the jejunum by which cells?

Answer 29

Crypt cells

Question 30

Secreted by the cells of question 9, chloride enters the cell from the blood/extracellular fluid: A. With its concentration gradient and with its electrical gradient B. With its concentration gradient and against its electrical gradient C. Against its concentration gradient and with its electrical gradient D. Against its concentration gradient and against its electrical gradient

Answer 30

B. With its concentration gradient and against its electrical gradient

Question 31

Glucose molecules are unable to cross the apical membrane by simple diffusion because they are (A) __________. Fortunately, glucose can be cotransported across the apical membrane because of several forces that aid its movement. These include the force generated by high glucose concentrations above the apical membrane during the final phases of brush border digestion. The rest of the force needed to permit facilitated diffusion of glucose into the cell is provided by (B) __________ moving (C) with or against (choose one) its concentration gradient and (D) with or against (choose one) its electrical gradient.

Answer 31

(A) Too large, (B) Na+, (C) with its concentration gradient and (D) with its electrical gradient

Question 32

Volatile fatty acids are the end product of anaerobic bacterial fermentation within the rumen and colon of herbivores and are absorbed across the epithelium to serve as major energy sources for these species. Many of the drugs you will utilize are also weak acids or weak bases. These compounds are absorbed by a process known as (A) _________. The weak acid or weak base only crosses the lipid bilayer membrane of absorptive cells when it is in the (B) __________ state. For a weak base with a pKa of 10.8, absorption across the epithelium would be expected to occur most readily in the (C) stomach or jejunum (choose one).

Answer 32

(A) Nonionic diffusion, (B) nondissociated (uncharged) state, (C) jejunum

Question 33

What is the fate of glucose in the dog?

Answer 33

The glucose will reach the small intestine and be absorbed by Na+/ glucose cotransporters. Glucose provides about 4 kcal metabolizable energy per gram.

Question 34

What is the fate of glucose in the ruminant?

Answer 34

The rumen bacteria will anaerobically utilize the energy in glucose by glycolysis. The end products of anaerobic glycolysis will be a mix ture of VFAs and lactic acid, depending on the type of bacteria that takes up each glucose molecule. The ruminant will derive about 2.2 kcal metabolizable energy per gram glucose.

Question 35

What is the fate of glucose in the horse?

Answer 35

The rumen bacteria will anaerobically utilize the energy in glucose by glycolysis. The end products of anaerobic glycolysis will be a mix ture of VFAs and lactic acid, depending on the type of bacteria that takes up each glucose molecule. The ruminant will derive about 2.2 kcal metabolizable energy per gram glucose.

Question 36

What is the fate of glucose in the horse?

Answer 36

The glucose will reach the small intestine and be absorbed by Na+/ glucose cotransporters. Glucose will provide about 4 kcal metabolizable energy per gram

Question 37

What is the fate of glucose in the horse?

Answer 37

The urea will likely be absorbed from the small intestine and some will be immediately excreted in the urine. The rest may be converted to ammonia in the liver. If a large amount is fed, the dog will eventually exhibit ammonia toxicity.