Histology Of The Small And Large Intestine

Question 1

Endocrine secretion happens in the small intestine. True or false? Thank

Answer 1

True

Question 2

Viewed with the naked eye, the lining of the small intestine shows…

Answer 2

…a series of permanent circular or semilunar folds called plicae circulares

Question 3

Plicae circulares are composed of…

Answer 3

mucosa and submucosa

Question 4

Plicae circulares are best developed in the

Answer 4

Jejunum

Question 5

The entire mucosa of the small intestine is covered by…

Answer 5

…short outgrowths called villi

Question 6

What are intestinal villi?

Answer 6

Mucosal(epithelium plus lamina propria) outgrowths that project into the lumen

Question 7

Which parts of the mucosa form the villi?

Answer 7

epithelium plus lamina propria

Question 8

Each villus has a core of loose connective tissue that extends from the lamina propria. True or false?

Answer 8

True

Question 9

Each villus contains

Answer 9

Fibroblasts
Lymphocytes and plasma cells
Smooth muscle fibers
Fenestrated capillaries
A lacteal (a central lymphatic)

Question 10

Shapes of intestinal villi

Answer 10

In the duodenum, they are leaf-shaped but gradually assume finger-like shapes moving towards the ileum

Question 11

Intestinal villi are covered by…

Answer 11

…a simple columnar epithelium of absorptive cells (enterocytes) and goblet cells

Question 12

What are intestinal crypts or crypts of Lieberkükn?

Answer 12

They are small openings of short tubular glands between the villi

Question 13

The epithelium of each villus is continuous with…

Answer 13

…that of the intervening glands

Question 14

The epithelium of the intestinal glands contain:

Answer 14

• Absorptive/enterocytes
• Goblet cells,
• Paneth cells,
• Enteroendocrine cells
• Stem cells that give rise to all these cell types

Question 15

What will you find in the basal half of absorptive cells?

Answer 15

An oval nucleus

Question 16

At the apex of each absorptive cell is…

Answer 16

…a homogeneous layer called the striated /brush border

Question 17

When viewed with the electron microscope, the striated border of absorptive cells is seen as…

Answer 17

…a layer of densely packed microvilli covered by glycocalyx

Question 18

How many microvilli is each absorptive cell estimated to have?

Answer 18

An average of 3000 microvilli

Question 19

Microvilli greatly increase the area of contact between the intestinal surface and the nutrients. True or false?

Answer 19

True

Question 20

Total absorptive area of the intestines

Answer 20

200m.square

Question 21

What absorb the nutrient molecules produced by digestion?

Answer 21

Enterocytes

Question 22

Which cells are interspersed between the absorptive cells?

Answer 22

Goblet cells

Question 23

Goblet cells are less abundant in the ___ but are abundant in the ____?

Answer 23

They are less abundant in the duodenum and more numerous in the ileum

Question 24

Which cells produce glycoprotein mucins that are hydrated to form mucus to protect and lubricate the lining of the small intestine?

Answer 24

Goblet cells

Question 25

Paneth cells are exocrine cells with large eosinophilic secretory granules. True or false?

Answer 25

True

Question 26

Paneth cells are located in...

Answer 26

...the basal portion of the intestinal crypts below the stem cells (arrow heads)

Question 27

Paneth cells undergo exocytosis to release...

Answer 27

...lysozymes, phospholipase A2, and defensins

Question 28

Products of exocytosis of Paneth cells do what?

Answer 28

They bind and breakdown membranes of microorganisms and bacterial cell walls

Question 29

Paneth cells functions

Answer 29

–Innate immunity | –Regulation of the microenvironment of the intestinal crypts

Question 30

Enteroendocrine cells represent...

Answer 30

...part of the widely distributed diffuse neuroendocrine system

Question 31

Upon stimulation, enteroendocrine cells secrete...

Answer 31

...various peptide hormones by exocytosis

Question 32

Effects of hormones secreted by enteroendocrine cells

Answer 32

Paracrine (local) or endocrine effects which include: - Control of peristalsis - Regulation of secretions necessary for food digestion - Sense of being satiated after eating

Question 33

What are M cells?

Answer 33

They are specialized epithelial cells for transport of particles and microorganisms

Question 34

M cells are located in...

Answer 34

the ileum, overlying the lymphoid follicles of Peyer patches

Question 35

M cells contain

Answer 35

macrophages and lymphocytes

Question 36

Functions of M cells

Answer 36

They are important in the defense provided by mucosal immunity and transport of particles and microorganisms

Question 37

The lamina propria move round the core of each intestinal villus, bringing with it microvasculature, lymphatics, and nerves. True or false?

Answer 37

False. It penetrates.

Question 38

What are responsible for the rhythmic movements of villi which are important for efficient absorption?

Answer 38

Smooth muscle fibers inside the villi

Question 39

What facilitates local movements of the plicae circulares that help propel lymph from the lacteals into submucosal and mesenteric lymphatics?

Answer 39

Contractions of the muscularis mucosae

Question 40

What are the duodenal Brunner glands?

Answer 40

Large clusters of branched tubular mucous glands present in the proximal part of the duodenum with small excretory ducts opening among the intestinal crypts

Question 41

The mucus produced by the Brunner glands is acidic with pH from 2 to 4.8. True or false?

Answer 41

False. It is alkaline with pH 8.1-9.3

Question 42

Where are Peyer’s patches present in the ileum?

Answer 42

In both the lamina propria and submucosa

Question 43

Peyer’s patches are...

Answer 43

...lymphoid nodule aggregates and an important component of the mucosa-associated lymphoid tissue (MALT)

Question 44

The muscularis of the small intestine is composed of...

Answer 44

- an internal circular layer - an external longitudinal layer between which is the myenteric (Auerbach) nerve plexus • The serosa- Covered by a thin serosa

Question 45

Function of the myenteric (Auerbach) nerve plexus

Answer 45

It produces peristalsis

Question 46

What kind of serosa covers the small intestine?

Answer 46

Thin serosa

Question 47

Lacteals are especially important for...

Answer 47

...lipid absorption

Question 48

The mucosa of which organ in the GIT lacks villi?

Answer 48

Large intestine

Question 49

Which part of the intestine lacks folds?

Answer 49

Everywhere except the rectum

Question 50

The whole length of the large intestine is penetrated by...

Answer 50

...tubular intestinal glands

Question 51

The glands and the intestinal lumen of the large intestine are lined by...

Answer 51

...absorptive, goblet and a few population of the enteroendocrine cells

Question 52

Absorptive cells of the large intestine are called...

Answer 52

Colonocytes

Question 53

Properties of colonocytes

Answer 53

They have irregular microvilli and dilated intercellular spaces indicative of active fluid absorption

Question 54

In which part of the large intestine are Goblet cells most abundant?

Answer 54

Towards the distal part of the colon and the rectum

Question 55

Functions of goblet cells in the large intestine

Answer 55

Production of mucus for lubrication

Question 56

The lymphoid cells and lymphoid nodules of the lamina propria oftentimes extend into the submucosa of the large intestine. True or false?

Answer 56

True

Question 57

The richness in MALT in the large intestine is orchestrated by...

Answer 57

...the large bacterial population in this segment of the digestive tract

Question 58

The appendix with little or no absorptive function, plays important role in MALT. True or false?

Answer 58

True

Question 59

Omental appendages stem from...

Answer 59

...the serosa

Question 60

The muscularis of the large intestine is made up of...

Answer 60

...longitudinal and circular layers

Question 61

Type of epithelium at the anorectal junction

Answer 61

Stratified squamous epithelium of the skin at the anus

Question 62

The mucosa and submucosa of the anal canal form...

Answer 62

...several longitudinal folds called the anal columns

Question 63

Fate of the circular layer of the rectum

Answer 63

Near the anus, the circular layer is thickened to form the internal anal sphincter

Question 64

What is Crohn disease?

Answer 64

A chronic inflammatory bowel disease that occurs most commonly in the ileum or colon. It causes excessive lymphocytic activity and inflammation in any or all the tract producing pain, localized bleeding, malabsorption and diarrhea