Chapter 23; The Digestive System

Absorption

process by which the products of digestion pass through the alimentary tube mucosa into the blood or lymph

Accessory Digestive Organs

organs that contribute to the digestive process but are not part of the alimentary canal; include the tongue, teeth, salivary glands, pancreas, liver

Adventitia

outermost layer or covering of some organs

Alimentary Canal

the continuous hollow tube extending from the mouth to the anus; its walls are constructed by the oral cavity, pharynx, esophagus, stomach, and small and large intestines

Amylase

digestive system enzyme that breaks down starchy foods

Anus

distal end of digestive tract; outlet of rectum

Appendicitis

inflammation of the appendix (worm-like sac attached to the cecum of the large intestine)

Bile

greenish-yellow or brownish fluid produced in and secreted by the liver, stored in the gallbladder, and released into the small intestine

Bilirubin

yellow pigment of bile

Bolus

a rounded mass of food prepared by the mouth for swallowing; any soft round mass

Calculus

a stone formed within various body parts

Cecum

the blind-ended pouch at the beginning of the large intestine

Cholecystokinin (CCK)

an intestinal hormone that stimulates gallbladder contraction and pancreatic juice release

Chyme

semifluid, creamy mass consisting of partially digested food and gastric juice

Cirrhosis

chronic disease of the liver, characterized by an overgrowth of connective tissue or fibrosis

Colon

regions of the large intestine; includes ascending, transverse, descending, and sigmoid portions

Defecation

elimination of the contents of the bowels (feces)

Deglutition

swallowing

Digestion

a series of catabolic steps in which complex food molecules are broken down to their building blocks by enzymes

Digestive System

system that processes food into absorbable units and eliminates indigestible wastes

Diverticulum

a pouch or sac in the walls of a hollow organ or structure

Duodenum

first part of the small intestine

Emesis

reflexive emptying of the stomach through the esophagus and pharynx; also known as vomiting

Esophagus

muscular tube extending from the laryngopharynx through the diaphragm to join the stomach; collapses when not involved in food propulsion

Feces

material discharged from the bowel; composed of food residue, secretions, bacteria

Gallbladder

sac beneath the right lobe of the liver used for bile storage

Gallstones (Biliary Calculi)

crystallized cholesterol that obstructs the flow of bile from the gallbladder

Gastrin

hormone secreted in the stomach; regulates gastric juice secretion by stimulating HCl production

Gastroenteritis

inflammation of the gastrointestinal tract

Hepatitis

inflammation of the liver

Histamine

a chemical messenger (neurotransmitter or paracrine); causes vasodilation and increased capillary permeability; in stomach causes acid secretion

Hydrochloric Acid (HCl)

acid that aids protein digestion in the stomach; produced by parietal cells

Hydrolysis

process in which water is used to split a substance into smaller particles

Ileocecal Valve

site where the small intestine joins the large intestine

Ileum

terminal part of the small intestine; between the jejunum and the cecum of the large intestine

Interstitial Endocrine Cells

cells located in the loose connective tissue surrounding the seminiferous tubules; they produce androgens (most importantly testosterone), which are secreted into the surrounding interstitial fluid

Intrinsic Factor

substance produced by the stomach that is required for vitamin B12 absorption

Jejunum

the part of the small intestine between the duodenum and the ileum

Labia

lips; singular: labium

Large Intestine

portion of the digestive tract extending from the ileocecal valve to the anus; includes the cecum, appendix, colon, rectum, and anal canal

Liver

lobed accessory organ that overlies the stomach; produces bile to help digest fat, and serves other metabolic and regulatory functions

Mastication

chewing

Mesenteries

double-layered extensions of the peritoneum that support most organs in the abdominal cavity

Molar

(1) a solution concentration determined by mass of solute1 liter of solution contains an amount of solute equal to its molecular weight in grams. (2) Broad back teeth that grind and crush

Monosaccharide

literally, one sugar; building block of carbohydrates; e.g., glucose

Occlusion

closure or obstruction

Palate

roof of the mouth

Pancreas

gland located behind the stomach, between the spleen and the duodenum; produces both endocrine and exocrine secretions

Pancreatic Juice

bicarbonate-rich secretion of the pancreas containing enzymes for digestion of all food categories

Pepsin

enzyme capable of digesting proteins in an acid pH

Peritoneum

serous membrane lining the interior of the abdominal cavity and covering the surfaces of abdominal organs

Peritonitis

inflammation of the peritoneum

Pharynx

muscular tube extending from the region posterior to the nasal cavities to the esophagus

Pyloric Sphincter

valve of the distal end of the stomach that controls food entry into the duodenum

Rennin

stomach-secreted enzyme that acts on milk protein; not produced in adults

Rugae

elevations or ridges, as in stomach mucosa

Saliva

secretion of the salivary glands; cleanses and moistens the mouth and begins chemical digestion of starchy foods

Small Intestine

convoluted tube extending from the pyloric sphincter to the ileocecal valve where it joins the large intestine; the site where digestion is completed and virtually all absorption occurs

Sphincter

a circular muscle surrounding an opening; acts as a valve

Splanchnic Circulation

the blood vessels serving the digestive system

Stomach

temporary reservoir in the gastrointestinal tract where chemical breakdown of proteins begins and food is converted into chyme

Trypsin

proteolytic enzyme secreted by the pancreas

Ulcer

lesion or erosion of the mucous membrane, such as gastric ulcer of stomach

Uvula

tissue tag hanging from soft palate

Villus

one of the finger-like projections of the small intestinal mucosa that tremendously increase its surface area for absorption

Describe the function of the digestive system, and differentiate between organs of the alimentary canal and accessory digestive organs.

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List and define the major processes occuring during digestive system activity.

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Name one organ of the alimentary canal found in the thorax. Name three organs located in the abdominal cavity.

1

What is the usual site of ingestion?

2

Which digestive system activity actually moves nutrients from the outside to the inside of the body?

3

Describe stimuli and controls of digestive activity.

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When sensors in the GI tract are stimulated, they respond via reflexes. What types of digestive activity may be put into motion via those reflexes?

4

The term "gut brain" does not really mean that there is a brain in the digestive system. What does it refer to?

5

Describe the location and function of the peritoneum.

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Define retroperitoneal and name the retroperitoneal organs of the digestive system.

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Define splanchnic circulation.

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Indicate the importance of the hepatic portal system.

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How does the location of the visceral peritoneum differ from that of the parietal peritoneum?

6

Of the following organs, which is/are retroperitoneal?

7

What name is given to the venous portion of the splanchnic circulation?

8

Describe the tissue composition and general function of each of the four layers of the alimentary canal.

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Name the layers of the alimentary canal from the inside out.

9

Jerry has been given a drug that inhibits parasympathetic stimulation of his digestive tract. Should he "eat hearty" or temporarily refrain from eating, and why?

10

Describe the gross and microscopic anatomy and the basic functions of the mouth, pharynx, and esophagus.

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Describe the composition and functions of saliva, and explain how salivation is regulated.

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Explain the dental formula and differentiate clearly between deciduous and permanent teeth.

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How does the oral vestibule differ from the oral cavity proper?

11

Which structure forms the roof of the mouth?

12

Besides preparing food for swallowing, the tongue has another role. What is it?

13

What is the importance of the serous portion of saliva?

14

Name three antimicrobial substances found in saliva.

15

Seven -year-old Tina ran to her daddy to show him her lower central incisor which she had wiggled until it "fell out." Is this a primary or permanent tooth? What name is given to teeth that (according to Tina) fall out??

16

Which tooth substance is harder than bone? Which tooth region includes nervous tissue and blood vessels??

17

Which teeth are the "grinders"?

18

To which two organ systems does the pharynx belong?

19

How is the muscularis externa of the esophagus unique in the body?

20

What is the functional significance of the epithelial change seen at the esophagus-stomach junction?

21

Describe the mechanisms of chewing and swallowing.

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What role does the tongue play in swallowing?

22

How are the respiratory passages blocked during swallowing?

23

Identify structural modifications of the wall of the stomach that enhances the digestive process.

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Name the cell types responsible for secreting the various components of gastric juice and indicate the importance of each component in stomach activity.

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Describe stomach structure and indicate changes in the basic alimentary canal structure that aid in digestive function.

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What structural modification of the stomach wall underlies the stomach's ability to mechanically break down food?

24

Two substances secreted by cells of the gastric glands are needed to produce the active protein-digesting enzyme pepsin. What are these substances and which cells secrete them?

25

Which protective substances or activities make up the so-called mucosal barrier?

26

Explain how gastric secretions and stomach motility are regulated.

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Define and account for the alkaline tide.

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Name the three phases of gastric secretion.

27

How does the presence of food in the small intestine inhibit gastric secretion and motility?

28

How does the pH of venous blood leaving the stomach change during a meal?

29

Identify and describe structural modifications of the wall of the small intestine that enhances the digestive process.

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Differentiate between the role of the various cell types of the intestinal mucosa.

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Describe the function of intestinal hormones and paracrines.

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What common advantage do circular folds, villi, and microvilli provide to the digestive process? Which of these modifications cause chyme to spiral through the lumen and slows its passage??

30

What are brush border enzymes?

31

What is a lacteal and what is its function?

32

Name three secretory products that help protect the intestinal mucosa from bacterial damage.

33

Describe the histologic anatomy of the liver.

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State the role of bile in digestion.

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Describe the role of the gallbladder.

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What is a portal triad?

34

What is the importance of the enterohepatic circulation?

35

What is the role of the stellate macrophages of the liver?

36

State the role of pancreatic juice in digestion.

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What do zygomen granules contain?

37

What is the functional difference between pancreatic acini and islets?

38

Describe how bile and pancreatic juice secretion into the small intestine are regulated.

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What is the make up of the fluid in the pancreatic duct? In the cystic duct?? In the bile duct???

39

What stimulates CCK release and what are its effects on the digestive process?

40

Distension of the stomach and duodenal walls have different effects on stomach secretory activity. What are these effects?

41

Which is more important in moving food along the small intestine - peristalsis or segmentation?

42

What is the MMC and why is it important?

43

List the major functions of the large intestine.

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Describe the regulation of defecation.

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What propulsive movements are unique to the large intestine?

44

What is the result of stimulation of stretch receptors in the rectal walls?

45

In what ways are enteric bacteria important to our nutrition?

46

List the enzymes involved in digestion; name the foodstuffs on which they act.

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List the end products of protein, fat, carbohydrate, and nucleic acid digestion.

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Describe the process by which breakdown products of foodstuff are absorbed in the small intestine.

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What type of chemical reaction is the basis of all enzymatic food breakdown?

47

Fill in the blank: Amylase is to starch as _____ is to fats.

48

What is the role of bile salts in the digestive process? In absorption??

49

Describe embryonic development of the digestive system.

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Describe abnormalities of the gastrointestinal tract at different stages of life.

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From which germ layer does the digestive system mucosa develop?

50

How does cystic fibrosis interfere with the digestive process?

51

Why are colon and stomach cancers so dangerous?

52