Digestive System

Question 1

Name the parts of the alimentary canal and their overall function

Answer 1

a. Mouth, pharynx, esophagus, stomach, small intestine, and large intestine
b. Digests and absorbs food

Question 2

Name the accessory digestive organs

Answer 2

a. Teeth, tongue, gallbladder
b. Digestive glands
i. Salivary glands
ii. Liver
iii. Pancreas

Question 3

Describe the layers of the peritoneum and peritoneal cavity

Answer 3

a. Peritoneum: serous membrane of the abdominal cavity
i. Visceral peritoneum on external surface of most digestive organs
ii. Parietal peritoneum lines the body wall
b. Peritoneal cavity between the two layers
i. Fluid lubricates mobile organs
c. Mesentery is a double layer of peritoneum
i. Routes for blood vessels, lymphatics, and nerves
ii. Holds organs in place and stores fat
d. Peritoneal organs are surrounded by the peritoneum
e. Retroperitoneal organs lie posterior to the peritoneum

Question 4

Describe the blood supply of the digestive system

Answer 4

a. Arteries
i. Hepatic, splenic, and left gastric
ii. Inferior and superior mesenteric
b. Hepatic portal (system) circulation
i. Drains nutrient-rich blood from digestive organs
ii. Delivers it to the liver for processing

Question 5

Describe the four basic layers (tunics) of the alimentary canal and cell type

Answer 5

a. Mucosa
b. Submucosa
c. Muscularis externa
d. Serosa

Question 6

Describe mucosa tunica (function and location)

Answer 6

a. Lines the lumen
b. Simple columnar epithelium
c. Functions
d. Secretes mucus, digestive enzymes and hormones
e. Absorbs products of digestion
f. Protects against infectious disease

Question 7

Describe submucosa tunica (tissue, etc)

Answer 7

a. Dense connective tissue
b. Blood and lymphatic vessels and lymphoid follicles
c. Has landmarks that give hints of where you are in the alimentary canal

Question 8

Describe the muscularis externa tunica

Answer 8

a. Smooth muscle
b. Responsible for segmentation and peristalsis
c. Inner circular and outer longitudinal layers
d. Sphincters in some regions

Question 9

Describe the parts of the mouth (oral cavity )

Answer 9

a. Oral (buccal) cavity
b. Bounded by lips, cheeks, palate, and tongue
c. Lined with stratified squamous epithelium

Question 10

Describe the ANS activity in the enteric nervous system

Answer 10

a. Long ANS fibers synapse with enteric plexuses
b. Sympathetic impulses inhibit secretion and motility
c. Parasympathetic impulses stimulate

Question 11

What is the median attachment of each lip to the gum?

Answer 11

Labial frenulum

Question 12

Describe the palate (hard and soft)

Answer 12

a. Hard palate: maxilla and palatine bones
b. Soft palate: fold of skeletal muscle
c. Uvula projects downward from its free edge

Question 13

Describe the tongue (function, muscles, attachment)

Answer 13

a. Functions include
i. Formation of the food bolus
ii. Initiation of swallowing, speech, and taste
b. Intrinsic and extrinsic muscles change the shape and position of the tongue
c. Lingual frenulum: attachment to the floor of the mouth

Question 14

Describe the tongue papillae

Answer 14

a. Surface bears papillae
b. Filiform—whitish, give the tongue roughness and provide friction
c. Fungiform—reddish, scattered over the tongue
d. Circumvallate (vallate) papilla—V-shaped row in back of tongue
i. These three house taste buds
e. Foliate—on the lateral aspects of the posterior tongue (for texture)

Question 15

Which three papillae have taste buds?

Answer 15

a. Filiform
b. Fungiform
c. Circumvallate

Question 16

Describe salivary glands

Answer 16

a. Secretion (saliva)
b. Cleanses the mouth
c. Moistens and dissolves food
d. Aids in bolus formation
e. Contains enzymes (amylases) that begin the breakdown of starch
i. Polysaccharides turned into smaller polysaccharides + disaccharides
ii. Breaks glycosidic bonds between the monosaccharides

Question 17

Describe composition of saliva

Answer 17

a. 98% water, slightly acidic solution containing:
b. Salivary amylase and lingual lipase
i. Breaks triglycerides into glycerol + fatty acids
ii. Breaks ester bonds
c. Mucin traps inhaled particles
d. Lysozyme, defensins, and IgA antibodies protect against microorganisms

Question 18

Describe salivary glands

Answer 18

a. 3 pairs of salivary glands
b. Parotid – near the ear; Stenson’s duct leads to the mouth – inflammation leads to mumps
c. Submandibular – floor of the inner jaw; Wharton’s ducts open under the tongue lateral to the frenulum
d. Sublingual – smallest glands; under tongue

Question 19

Describe pharynx

Answer 19

a. Oropharynx and laryngopharynx
b. Allow passage of food, fluids, and air
c. Peristalsis begins in the pharynx

Question 20

Describe esophagus

Answer 20

a. Flat muscular tube from laryngopharynx to stomach
b. Pierces diaphragm at esophageal hiatus
c. Joins stomach at the cardiac sphincter (LES)
d. No digestive enzymes secreted here

Question 21

Describe digestive processes of the mouth

Answer 21

a. Physical digestion (primarily mastication)
b. Chemical digestion (salivary amylase and lingual lipase)
c. Deglutition (swallowing)

Question 22

Describe the anatomy of the stomach

Answer 22

a. Cardiac region - Surrounds the cardiac sphincter
b. Fundus - Dome-shaped region beneath the diaphragm
c. Body – Larger midportion
d. Pyloric region - Continuous with the duodenum through the pyloric sphincter

Question 23

Describe microscopic anatomy of mucosa of the stomach

Answer 23

a. Simple columnar epithelium

b. Gastric pits lead into gastric glands

Question 24

Describe processes in the stomach

Answer 24

a. Physical, muscular, mechanical digestion
b. HCl and other acids denature proteins
c. Secretion of intrinsic factor required for absorption of vitamin B12 in your stomach
d. Digestion of proteins by pepsin
e. Gastrin is released thru positive feedback and stimulates release of all other gastric secretions
f. Delivery of chyme to the small intestine

Question 25

Name two homeostatic imbalances of the stomach

Answer 25

a. Gastritis: inflammation caused by anything that breaches the mucosal barrier
b. Peptic or gastric ulcers: erosion of the stomach wall - most are caused by Helicobacter pylori (live in acid)

Question 26

Describe nausea

Answer 26

a. Diminished stomach movements from stimulation of vomiting center in medulla oblongata
b. Vomiting Center empties stomach in reverse direction – may purge as far down as cecum! (contains feces)

Question 27

27. Describe gastric contractile activity

Answer 27

a. Basic electrical rhythm (BER) initiated by pacemaker cells (cells of Cajal)
b. Peristaltic waves move toward the pylorus at the rate of 3 per minute
c. Most vigorous contractions near the pylorus
d. Chyme is either:
i. Delivered in 3-ml spurts to the duodenum, or
ii. Forced backward into the stomach

Question 28

Describe regulation of gastric emptying

Answer 28

a. As chyme enters the duodenum receptors respond to stretch and chemical signals
b. Carbohydrate-rich chyme moves quickly through the duodenum
c. Fatty chyme remains in the duodenum 6 hours or more

Question 29

Describe small intestine and its subdivisions

Answer 29

a. Major organ of digestion AND absorption
b. From pyloric sphincter to ileocecal valve
c. Subdivisions
i. Duodenum (retroperitoneal) ~25 cm
ii. Jejunum ~2.3 m
iii. Ileum ~3.5 m

Question 30

Name the ducts/accessories that enter the duodenum and pancreas from the gallbladder

Answer 30

a. Right and left hepatic duct
b. Common hepatic duct
c. Cystic duct
d. Common bile duct
e. Pancreatic duct
f. Hepatopancreatic ampulla and sphincter

Question 31

Describe intestinal folding (structure and function)

Answer 31

a. Increase surface area for nutrient absorption
b. Circular folds (don’t care)
c. Villi
d. Microvilli (aka brushborder)

Question 32

What are villi?

Answer 32

a. Motile fingerlike extensions of the mucosa
b. Simple columnar cells with goblet cells (secrete mucus)
c. Contain lacteal

Question 33

What are microvilli?

Answer 33

Projections (brush-border) of absorptive cells that bear enzymes (enteropeptidases)

Question 34

Describe intestinal crypts (of Lieberkuhn)

Answer 34

a. Intestinal crypt epithelium

i. Secretory cells that produce intestinal juice

Question 35

Describe the submucosal glands

Answer 35

a. Duodenal (Brunner’s) glands of the duodenum secrete alkaline mucus (raspberry shaped)
b. Peyer’s patches of ileum protect distal intestine from against bacteria (triangle or bear paw shaped)

Question 36

Describe liver

Answer 36

a. Largest gland in the body
b. Over 200 known functions
c. Highly regenerative, multinucleate cells
d. Four lobes—right, left, caudate, and quadrate

Question 37

Describe the falciform ligament of the liver

Answer 37

a. Separates the right and left lobes
b. Suspends liver from the diaphragm
c. Round ligament (ligamentum teres) is Remnant of fetal umbilical vein

Question 38

Describe the associated structures of the liver

Answer 38

a. Lesser omentum anchors liver to stomach

b. Common hepatic duct leaves the liver

Question 39

Describe the liver lobules

Answer 39

a. Hexagonal structural and functional units
i. Filter and process nutrient-rich blood
ii. Composed of plates of hepatocytes
iii. Longitudinal central vein
b. Portal triad at corners of lobules
i. Bile duct receives bile
ii. Portal arteriole is a branch of the hepatic artery
iii. Portal venule is a branch of the hepatic portal vein
c. Liver sinusoids are leaky capillaries between hepatic plates
d. Kupffer cells (hepatic macrophages) in liver sinusoids

Question 40

List the hepatocyte functions

Answer 40

a. Blood filtering / reservoir
b. Store fat-soluble vitamins (A, D, B12)
c. Perform detoxification
d. Produce nearly 1L bile per day

Question 41

Describe metabolism of carbohydrates

Answer 41

a. Glycogenesis: glucose to glycogen
b. Glycogenolysis: glycogen to glucose
c. Gluconeogenesis: synthesize glucose from a non-sugar

Question 42

Describe metabolism of lipids

Answer 42

a. Oxidation of fatty acids (not important)
b. Synthesize phospholipids and cholesterol
c. Transport fats to adipose tissue for storage (not important)

Question 43

Describe metabolism of proteins

Answer 43

a. Deamination of amino acids
b. Form urea
c. Synthesize plasma proteins (like fibrinogen and clotting factors)

Question 44

Describe bile

Answer 44

a. Bitter greenish-brown alkaline fluid that aids digestion and is secreted by the liver and stored in the gallbladder
b. Bile salts: cholesterol derivatives that function in fat emulsification

Question 45

45. Describe the gallbladder

Answer 45

a. Muscular sac on the ventral surface of the liver
b. Stores and concentrates bile
c. Releases bile via the cystic duct
d. Gallstones = solid, crystalline cholesterol (not rock)

Question 46

Where is the pancreas located?

Answer 46

a. Mostly retroperitoneal, deep to the greater curvature of the stomach
b. Head is encircled by the duodenum; tail abuts the spleen

Question 47

Describe endocrine and exocrine function of liver

Answer 47

a. Endocrine function
i. Pancreatic islets secrete insulin and glucagon
b. Exocrine function
i. Acini secrete pancreatic juice for a variety of purposes
ii. Granules of secretory cells contain digestive enzymes

Question 48

Describe pancreatic juices

Answer 48

a. Bicarbonate-rich, alkaline solution that neutralizes acidic chyme
b. Enzymes:
c. Amylase and lipases are secreted in active form
d. Proteases are secreted in inactive form to complete protein digestion
e. Maltase, sucrose, lactase, and other brush-border enzymes complete carb digestion

Question 49

Describe digestion of the small intestine (no direct questions on test)

Answer 49

a. Slow movement allows for digestion and absorption throughout the length of the small intestine
b. Chyme from stomach contains unharvested nutrients:
c. Partially digested carbohydrates and proteins
d. Undigested fats and nucleic acids

Question 50

50. Describe protease activation in duodenum (pancreatic juice)

Answer 50

a. Trypsinogen is activated to trypsin by brush border enzyme enteropeptidase
b. Subsequently, procarboxypeptidase and chymotrypsinogen are both activated by trypsin

Question 51

Describe cholecystokinin (CCK)

Answer 51

a. Secreted from duodenal enteroendocrine cells that are exposed to chyme
b. CCK causes gallbladder contraction
c. CCK causes the hepatopancreatic sphincter to relax

Question 52

Describe motility of the small intestines

Answer 52

a. Peristalsis:
b. Initiated in the late intestinal phase
c. Each wave starts distal to the previous
d. Meal remnants, bacteria, and debris are moved to the large intestine

Question 53

Describe large intestine

Answer 53

a. Unique features
i. Teniae coli (like a rubber band shorter than length of colon, causing it to bunch up into haustra)
1. Three bands of longitudinal smooth muscle in the muscularis
b. Haustra
i. Pocketlike sacs caused by the tone of the teniae coli
c. Epiploic appendages (not important)
i. Fat-filled pouches of visceral peritoneum

Question 54

Describe regions of the large intestine

Answer 54

a. Regions
b. Cecum (pouch with attached vermiform appendix)
c. Colon
d. Rectum
e. Anal canal

Question 55

What are the functions of the large intestine?

Answer 55

a. Remember, no digestion is occurring here
b. Vitamins (K), water, and electrolytes are reclaimed
c. Major function is propulsion of feces and defecation
d. Colon is not essential for life

Question 56

Describe motility of the large intestine

Answer 56

a. Gastrocolic reflex
i. Initiated by presence of food in the stomach
ii. Activates three to four slow powerful peristaltic waves per day in the colon (mass movements to rectum)

Question 57

Describe defecation

Answer 57

a. Mass movements force feces into rectum
b. Distension initiates spinal defecation reflex
c. Parasympathetic signals stimulate contraction of the sigmoid colon and rectum
d. Conscious control allows relaxation of external anal sphincter

Question 58

Overview of chemical digestion and absorption of carbohydrates

Answer 58

a. Digestive enzymes
i. Salivary amylase
ii. Pancreatic amylase
iii. Brush border enzymes dextrinase, glucoamylase, lactase, maltase, and sucrase

Question 59

Overview of chemical digestion and absorption of proteins

Answer 59

a. Enzymes
i. Pepsin in stomach
ii. Pancreatic proteases
1. Trypsin
2. Chymotrypsin
3. Carboxypeptidase
b. Other brush border enzymes

Question 60

Overview of digestion and absorption of lipids

Answer 60

a. Pre-treatment- emulsication by bile salts

b. Enzymes- pancreatic lipase

Question 61

Overview of vitamin absorption

Answer 61

a. In large intestine

b. Vitamin K and B- vitamins from bacterial metabolism are absorbed