Digestive System

Question 1

Mesentery

Answer 1

Peritoneal layers that support most of the abdominal organs (keeps them in place).

Question 2

Omentum

Answer 2

Multi-layered folds of the peritoneum
that drapes over intestines like an
apron. Used for adipose deposits
(for insulation)

Question 3

Peristalsis

Answer 3

Bands of smooth muscle contract alternatingly to propel substances through

Question 4

Deglutition

Answer 4

To swallow (delivering the bolus from the pharynx to the stomach)

Question 5

Oral Cavity: Gross Anatomy

Answer 5

• Includes teeth (dentition),
  tongue, and salivary glands
• Receives and mechanically
  digests food through mastication, performs some chemical digestion through saliva (creating bolus)

Question 6

Oral Cavity: Microscopic Anatomy

Answer 6

• Stratified squamous, non-keratinized lined mucosa
• Skeletal muscle muscularis
• Digestive Process:

oSalivary amylase breaks down polysaccharides (carbohydrates) into
disaccharides

oLingual lipase initiates triglyceride breakdown into glycerol & fatty
acids

Question 7

Pharynx

Answer 7

• Passageway for food, fluids & air
• Stratified squamous, non-keratinized lined mucosa
• Muscularis layer contains pharyngeal constrictors for deglutition (swallowing)

Question 8

Esophagus

Answer 8

• Straight, collapsible tube. Passageway for food & fluids.
• Mucosa transitions from non-keratinized stratified squamous epithelium to simple columnar
• Muscularis layer transitions from skeletal to smooth muscle

Question 9

Stomach: Gross Anatomy

Answer 9

• J-shaped pouch that receives bolus and
  mixes it with gastric juice in response to
  the hormone gastrin.
• Contains impermanent gastric folds called rugae for distention (stretch)
• Gastroesophageal and pyloric sphincters
  are its gatekeepers/ valves

Question 10

Stomach: Functions

Answer 10

• Initiates protein digestion
• Carries on limited absorption (very small amounts of water & some small molecules)
• Produces chyme

Question 11

Stomach: Microscopic Anatomy

Answer 11

• Simple squamous mucosa with goblet cells (mucus prevents ulceration)
• Contains gastric pits that lead to gastric glands
• Muscularis has 3 layers (oblique, circular, and longitudinal)

Question 12

Parietal Cells:

Answer 12

Secrete HCl and intrinsic factor (for vitamin B12 absorption)

Question 13

Chief Cells:

Answer 13

Secrete inactive pepsinogen (enzyme). When pepsinogen contacts HCl, it is
activated and becomes pepsin.
Pepsin breaks polypeptides (proteins) down into smaller peptide fragments

Question 14

Enteroendocrine cells:

Answer 14

Releases hormones such as gastrin to
regulate stomach secretions & motility

Question 15

Duodenum

Answer 15

• Initial C-shaped curvature of the small intestine
• Receives acidic chyme and mixes it with bile and pancreatic juice to neutralize the chyme and continue chemical digestion

Question 16

Pancreas: Gross Anatomy

Answer 16

• Located retroperitoneally
• Lies horizontally in the abdomen,
  emptying into the duodenum
• Responds to the duodenal hormones cholecystokinin (CCK) and secretin

Question 17

Pancreas: Microscopic Anatomy

Answer 17

• Composed of simple cuboidal cells that form acini
• Acini secrete pancreatic enzymes

Question 18

Pancreatic Amylase:

Answer 18

Breaks down polysaccharides into disaccharides

Question 19

Pancreatic Lipase:

Answer 19

reaks down triglycerides into glycerol & fatty acids

Question 20

Trypsin, Chymotrypsin, and Carboxypeptidase:

Answer 20

Proteolytic enzymes, break down polypeptides into smaller peptides

Question 21

Nuclease:

Answer 21

Breaks nucleic acids into nucleotides

Question 22

Liver & Gallbladder

Answer 22

• Liver is the largest internal organ in the body, composed of lobes that metabolize carbohydrates, lipids, and proteins.
• The liver also stores glycogen, filters & detoxifies blood, and secretes bile.
• Gallbladder is a small sac that concentrates and stores the bile that the liver produces.
• Both respond to the duodenal hormone cholecystokinin (CCK).

Question 23

Liver & Gallbladder

Answer 23

• Liver is composed of lobules containing hepatocytes and macrophages.
• Bile salts emulsify fats and aid in the absorption of fatty acids, cholesterol, and
  certain vitamins

Question 24

Jejunum =

Answer 24

middle segment of small intestine

Question 25

Ileum =

Answer 25

final segment, leads chyme to the cecum (beginning of colon) via the ileocecal sphincter.

Question 26

Jejunum & Ileum: Gross Anatomy

Answer 26

* Lined with permanent circular folds that maximizes digestion of chyme & nutrient absorption.

Question 27

Jejunum & Ileum: Microscopic Anatomy

Answer 27

* Mucosa has villi that are composed of simple columnar cells with microvilli (brush border), and goblet cells. * Intestine’s enteroendocrine cells secrete CCK and secretin. * Muscularis has 2 layers (circular and longitudinal layers)

Question 28

Peptidase:

Answer 28

Breaks peptides into amino acids

Question 29

Sucrase, Maltase, and Lactase:

Answer 29

Breaks disaccharides into monosaccharides

Question 30

Phosphatase:

Answer 30

Breaks nucleotides into nucleosides and phosphates

Question 31

Nucleosidase:

Answer 31

Breaks nucleosides into nitrogenous bases and ribose/ deoxyribose

Question 32

Large Intestine

Answer 32

* Includes the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, & anal canal * Absorbs majority of water and electrolytes from chyme to form feces * Pockets of haustra are created by bands of teniae coli * The appendix projects from the cecum (part of MALT)

Question 33

Large Intestine: Microscopic Anatomy

Answer 33

* Majority of the mucosa is composed of simple columnar epithelium with goblet cells. Anal canal mucosa requires stratified squamous epithelium. * Majority of the muscularis layer has 2 layers of smooth muscle (circular and longitudinal layers). * Anal canal has 2 anal sphincter layers: o Internal = smooth muscle o External = skeletal muscle

Question 34

Review: Hepatic Portal System

Answer 34

* Splenic vein, inferior mesenteric vein, and superior mesenteric vein merge to form the hepatic portal vein * Blood enters the liver to be filtered by the hepatic portal system * Filtered blood is sent through hepatic veins that return blood to the IVC * Special Features: * Liver lobules contain central veins with hepatocytes radiating from them * Phagocytic macrophages reside in the live

Question 35

GERD

Answer 35

Gastroesophageal Reflux Disease, requires PPIs (proton pump inhibitors to raise stomach pH), antacids, and dietary modifications

Question 36

Emesis

Answer 36

* Vomiting

Question 37

Impaction

Answer 37

Severe obstruction of bowels (hardened, rock-like stools)