Gastrointestinal System

Question 1

What are the 4 functions of the gastrointestinal system?

Answer 1

• Break down food
• Absorb
• Excrete
• Defend

Question 2

What are the four layers of the gastrointestinal system wall?

Answer 2

• Mucosa (deepest)
• Submucosa
• Muscularis externa (shallowest)
• Serosa (or adventitia around the esophagus, rectum and anal canal)

Question 3

What are the six regions of the gastrointestinal system in order from intake to excretion?

Answer 3

• Esophagus
• Stomach
• Small intestine
• Large intestine
• Anal canal
• Rectum

Question 4

What are the three regions of the small intestine, from stomach to large intestine?

Answer 4

• Duodenum
• Jejunum
• Ileum

Question 5

What divides the stomach from the esophagus?

Answer 5

The gastro-esophageal junction

Question 6

What are the three parts (from shallow to deep) of a stomach gland?

Answer 6

• Gastric pit
• Isthmus (neck)
• Gastric gland

Question 7

What do parietal cells secrete?

Answer 7

HCL

Intrinsic factor essential for B12 absorption

Question 8

What type of cells lie at the base of stomach glands?

Answer 8

Chief cells

Question 9

What do chief cells in stomach glands produce?

Answer 9

Zymogen granules, which contain pepsin precurosor

Question 10

What are plicae and where are they found?

Answer 10

Round folds in the wall of the small intestine

Question 11

What are villi and where are they found?

Answer 11

Epithelium folded into projections in the small intestine

Question 12

What two features are found throughout all regions of the small intestine?

Answer 12

• Plicae

- Villi

Question 13

There are glands between villi in the small intestine, what do these do?

Answer 13

Secrete

Question 14

Is the lamina propria of the small intestine vascular or avascular?

Answer 14

Vascular

Question 15

What moves the villi in the small intestine?

Answer 15

The muscular mucosa

Question 16

What is the layer of the small intestine that is responsible for peristalsis?

Answer 16

The muscular externa

Question 17

What are the arrangements of smooth muscle in the inner and outer layers of the muscularis externa in the small intestine?

Answer 17

Inner: circumferential
Outer: longitudinal

Question 18

What regions of the small intestine absorb nutrients?

Answer 18

All of them

Question 19

What is a defining feature of the duodenum?

Answer 19

Brunner’s glands

Question 20

What is characteristic of the jejunum? (2 things)

Answer 20

• HIgh surface area
• Large folds
• No Peyer’s patches or Brunner’s glands

Question 21

What are two things characteristic of the ileum?

Answer 21

• Lymphoid

- Peyer’s patches

Question 22

The small intestine goes from big to small or small to big?

Answer 22

Big to small (in duodenum to ileum direction)

Question 23

What are peyer’s patches?

Answer 23

Only found in the ileum, they are organized lymphoid nodules that facilitate and begin an immune response in the mucosa

Question 24

What is the name of the three longitudinal muscles in the wall of the large intestine? What are there functions?

Answer 24

Tenia coli

Visible just under the serosa, these push waste bolus into the rectum for excretion

Question 25

Where do the tenia coli converge in the large intestine?

Answer 25

The appendix

Question 26

What are the three layers of the mucosa?

Answer 26

- Epithelial lining - Lamina propria (loose connective tissue rich in blood vessels, lymphatics and smooth muscle cells) - Muscularis mucosae (separates mucosa from submucosa)

Question 27

How is the muscularis externa of the GI system wall organized?

Answer 27

- Internal sublayer (closer to lumen) with circular fiber orientation - External sublayer has longitudinal fiber orientation

Question 28

How is food churned and propelled forward in the GI system?

Answer 28

The myenteric plexus and enteric nervous system of the digestive system cause contractions of the muscularis.

Question 29

What is the serosa?

Answer 29

A thin layer of loose connective tissue, rich in blood vessels, lymphatics and adipose tissue with a simple squamous covering epithelium that surrounds the GI system and is continuous to mesenteries (in the abdominal cavity) which are continuous with peritoneum (cavity membrane)

Question 30

What replaces the serosa in the esophagus?

Answer 30

The adventitia, a connective tissue layer that merges with the surrounding tissues and lacks mesothelium (epithelium associated with the serosa)

Question 31

What layer of the GI system is most rich with macrophages and lymphocytes?

Answer 31

The lamina propria in the mucosa

Question 32

The oral cavity is lined with what type of epithelium?

Answer 32

Stratified squamous, may be keratinized or not, depending on location

Question 33

What type of epithelium does the esophagus have?

Answer 33

Nonkeratinized stratified squamous epithelium

Question 34

Where are esophageal glands that secrete mucus in the esophagus found? (ie. what layer of the wall)

Answer 34

The submucosus

Question 35

How is muscle divided down the length of the esophagus?

Answer 35

- upper one third is skeletal muscle - Middle portion is mix of skeletal and smooth - Lower third is exclusively smooth

Question 36

What are the four regions of the stomach?

Answer 36

- Cardia (transitional between esophagus and stomach) - Fundus - Body - Pylorus (to small intestine with pyloric sphincter)

Question 37

What are rugae?

Answer 37

Folds in the mucosa and submucosa of the stomach that flatten when it's filled with food

Question 38

What type of epithelium is in the stomach (past the esophagogastric junction)?

Answer 38

Simple columnar epithelium that invaginates deeply into the lamina propria (each invagination forming gastric pits with openings to the stomach lumen)

Question 39

What cells secrete a thick mucous layer that is rich in bicarbonate ions and protects the mucosa from abrasive effects of food and stomach acid?

Answer 39

Surface mucous cells (goblet cells) Mucous neck cells have less alkaline secretions than surface mucous cells, they are also less columnar.

Question 40

Where are stem cells found in the stomach wall?

Answer 40

In the isthmus of gastric pits

Question 41

What type of cells are found in the gastric pit?

Answer 41

- Surface mucous cells

Question 42

What type of cells are found in the isthmus/neck of gastric pits/glands?

Answer 42

- Mucous neck cells | - Parietal cells

Question 43

What type of cells are found in gastric glands?

Answer 43

- Parietal cells | - Chief cells

Question 44

How many layers of smooth muscle are found in the muscularis of the stomach?

Answer 44

3 - Outer longitudinal layer - Middle circular layer - Inner oblique layer

Question 45

What are the permanent circular or semicircular folds of mucosa/submucosa in the lining of the small intestine called?

Answer 45

Plicase circulares

Question 46

What is the structure of villi in the small intestine?

Answer 46

- Covered in enterocytes (simple columnar) with microvilli covered in glycocalyx - Interspersed goblet cells - Core of lamina propria loose connective tissue (fibroblasts, smooth muscle, lymphocytes and plasma cells) - Fenestrated capillaries - Central lymphatic vessel called the lacteal

Question 47

What is the function of Brunner glands in the duodenum?

Answer 47

Secretes mucus that is alkaline enough to neutralize chyme and protect the duodenum mucus membrane and bring intestinal contents to optimum pH for enzymatic digestion

Question 48

What are Peyer patches in the mucosa and submucosa of the ileum?

Answer 48

Mucosa-associated lymphoid tissue (MALT) consisting of lymphoid nodules underlying epithelial cells

Question 49

The myenteric nerve plexus produces peristalsis. Where is this located in the small intestine?

Answer 49

Between the outer and inner muscularis

Question 50

The mucosa of the large intestine lacks ____ and ____ (except in the rectum).

Answer 50

The mucosa of the large intestine lacks villi and folds (except in the rectum, where there are folds).

Question 51

Where are feces stored prior to evacuation?

Answer 51

The rectum

Question 52

The wall of the colon is puckered into a series of large sacs called ____?

Answer 52

Haustra

Question 53

What type of cells are found in the intestinal glands of the colon?

Answer 53

- Goblet cells - Columnar absorptive cells (colonocytes) - Enteroendocrine cells (small number) - Stem cells (bottom third of gland)

Question 54

What features of colonocytes indicates fluid absorption?

Answer 54

Irregular microvilli dilated intercellular spaces

Question 55

How do the two layers of muscularis differ between the colon and the small intestine?

Answer 55

The outer layer in the colon is split into three longitudinal bands called teniae coli.

Question 56

At the rectoanal junction (rectum - anal canal), the simple columnar mucosal lining of the rectum is replaced by?

Answer 56

Stratified squamous epithelium

Question 57

What are anal columns?

Answer 57

Longitudinal folds in the mucosa and submucosa of the anal canal

Question 58

What layer of the anal wall forms the internal/external anal sphincter? Which sphincter is responsible for defecation?

Answer 58

Internal anal sphincter formed by inner circular layer of muscularis External anal sphincter formed by voluntary skeletal muscle (responsible for defecation)

Question 59

What are the distinguishing feature of the anal canal's submucosa?

Answer 59

venous sinuses

Question 60

What is the distinguishing feature of esophageal submucosa?

Answer 60

Small esophageal glands (mainly mucous)

Question 61

What is the major region in the gut wall providing strength? How?

Answer 61

Submucosa, by many bundles of type I collagen

Question 62

What is the purpose of papillae in the esophagus?

Answer 62

Reinforce epithelium of mucosa into lamina propria

Question 63

How can skeletal muscle be identified in the esophagus? Rather than smooth muscle?

Answer 63

Lots of nuclei

Question 64

Where does lipid digestion begin?

Answer 64

In the stomach with lipase

Question 65

What is chyme?

Answer 65

food and enzymes in the stomach