Chapter 11 - stomach, intestines, rectum, anus

Question 1

What is the esophagus?

Answer 1

a muscular tube that extends from the pharynx (throat) to the stomach

Question 2

What is the esophagus’ function?

Answer 2

transports swallowed material from the pharynx to the stomach

Question 3

Where does the esophagus enter?

Answer 3

enters the stomach at an angle in cardia region - surrounded by the cardiac sphincter muscle

Question 4

As the stomach expands, what happens?

Answer 4

folds of the stomach against esophagus closes the lower end of the esophagus -

• reduces the risk for reflux
• in some species the closure is strong enough to prevent reflux or vomiting (horse, rabbit)

Question 5

What are the 5 different areas in a monogastric stomach?

Answer 5

cardia, fundus, body, pyloric antrum, pyloris

Question 6

What is the cardia?

Answer 6

opening from the esophagus

Question 7

What is the body and what does it do?

Answer 7

distensible middle section

contracts to help mix food

Question 8

What is the fundus?

Answer 8

distensible blind pouch; expands as more food is swallowed

Question 9

Fundus and body contain and do what?

Answer 9

numerous glands

relax with swallowing of food

Question 10

Gastric glands contain…?

Answer 10

parietal cells
chief cells
mucous cells

Question 11

What are parietal cells?

Answer 11

produce hydrochloric acid

Question 12

What are chief cells?

Answer 12

produce the enzyme pepsinogen

Question 13

What are mucous cells?

Answer 13

produce the protective mucus

Question 14

What does the pyloric antrum do?

Answer 14

grinds up swallowed food; regulates hydrocholoric acid
increases contractions in response to swallowing; stimulates mixing, grinding, and propulsive contractions that move food toward the pylorus
has glands that contains G cells - secrete gastrin

Question 15

What is pylorus and what does it do?

Answer 15

muscular sphincter
regulates the movement of chyme from the stomach into the duodenum
prevents backflow of duodenal contents into the stomach

Question 16

What is peristalsis that occurs in stomach and small intestines?

Answer 16

the succession of waves of involuntary muscular contraction of various bodily tubes

Question 17

What layers does the stomach contain?

Answer 17

mucosal layer
submucosa
muscular layer (longitudinal and circular muscle fibers)
outer serosal layer

Question 18

Smooth muscle in stomach wall responds to…?

Answer 18

hormones, peptides, nervous system controls

Question 19

Parasympathetic stimulation causes ______ to relax and ______ contractions in the antrum.

Answer 19

fundus

increases

Question 20

Sympathetic stimulation can cause a _______ in motility - gastric atony,

Answer 20

decrease

Question 21

What is gastric atony?

Answer 21

a large distended stomach lacking in tone as seen in a horse that is a windsucker and continuously swallows air. Predisposes to chronic indigestion.

Question 22

What is gastrin?

Answer 22

produced by the G cells in the antrum of the stomach
increases production of hydrochloric acid
inhibits muscle activity of the fundus

Question 23

What is enterogastric reflex?

Answer 23

distension of the intestines or increased acidity in the duodenum inhibits stomach contraction - delays gastric emptying

Question 24

What is secretin?

Answer 24

released from duodenum in response to excess stomach acid in small intestine

• can cause fundus to relax
• can inhibit peristalsis of the body and antrum of the stomach to slow gastric emptying

Question 25

What is antrum?

Answer 25

The pyloric end of the stomach, partially shut off during digestion from the cardiac end by sphincter muscles in the stomach wall.

Question 26

What is cholecystokinin (CCK)?

Answer 26

released in response to large amounts of fats or proteins in duodenum - decreases contraction of the antrum, body and fundus

Question 27

What is pepsinogen?

Answer 27

secreted by chief cells; precursor for the enzyme pepsin | -breaks proteins into chains of amino acids

Question 28

Intrinsic factor is ?

Answer 28

secreted from glands in submucosa -in some species, intrinsic factor must combine with vitamin B12 in order for B12 to be absorbed from the small intestine

Question 29

What is mucus?

Answer 29

complex of substances; provides protective coating for the stomach against acidic gastric environment -must be secreted continuously

Question 30

What is mucins?

Answer 30

produced by goblet cells in gastric glands; main constituent of the mucous coating

Question 31

What are goblet cells?

Answer 31

a goblet-shaped epithelial cell that secretes mucin

Question 32

What does a bicarbonate ion do?

Answer 32

alkalinizes the mucus

Question 33

What is hydrochloric acid?

Answer 33

- hydrogen H+ and chloride Cl- ions - secreted by parietal cells in the gastric glands then combine in the stomach to produce hydrochloric acid - receptors on parietal cells for gastrin, histamine, and acetycholine involved in regulation of H= and Cl- secretion - selectively blocking one of these receptors decreases the production of stomach acid

Question 34

What is prostaglandins (PGs)?

Answer 34

- inhibit gastrin release -stimulate the gastric glands to produce the bicarbonate ion - enhance blood flow to the stomach - stabalize lysosomes within gastric cells regulate the activity of macrophages and mast cells

Question 35

What are ruminants?

Answer 35

- cattle, sheep, goats - one true stomach and 3 forestomachs - swallow their food, regurgitate it to chew on it some more before swallowing it again (rumination)

Question 36

What is another word for true stomach?

Answer 36

abomasum

Question 37

What is reticulum?

Answer 37

- smallest, most cranial compartment of the forestomach compartments - separated from the rumen by the ruminoreticular fold - lining composed of honeycomb arrangements of folds - reticulum and rumen - coordinated contractions

Question 38

What are the three forestomachs called?

Answer 38

reticulum, rumen and omasum

Question 39

Ruminants _______ their food.

Answer 39

ruminate - swallow food and then bring it back up the esophagus to their mouth (regurgitate) to chew on it some more before swallowing it again (rumination)

Question 40

What's another name for rumination?

Answer 40

chewing the cud

Question 41

What is rumen?

Answer 41

series of muscular sacs partially separated from one another by long muscular folds of rumen wall called pillars

Question 42

Pillars aid in ______ and ______ of ruminal contents.

Answer 42

mixing and stirring

Question 43

What is reticuloruminal contractions?

Answer 43

- allow partially digested plant food to be regurgitated | - allow built-up carbon dioxide or methane gas to be expelled from the rumen