Histology, Test 1, Quarter 2, Lecture 6

Front 1

Name 6 functions of the intestine

Back 1

Digestion
neutralization of chyme
Absorption
Limit microbial growth
synthesis/secretion
regulation of GI function

Front 2

Name 3 surface features of the intestine

Back 2

Crypts of Lieberkuhn
Villi
Plicae Circulares

Front 3

Describe the cell layers involved in the plicae circulares

Back 3

mucosa and submucosa

Front 4

Location of the plicae circulares

Back 4

small intestine, prominent in the distal duodenum and jejunum, cease to exist distally

Front 5

Describe the cell layers involved in the villi

Back 5

JUST the mucosa

Front 6

Describe the location of the villi

Back 6

small intestine; prominent the in duodenum and jejunum, decrease in size and number distally

Front 7

Describe the shape of villi

Back 7

Wider proximally, tend to get more conical distally

Front 8

What are Crypts of Leiberkuhn?

Back 8

mucous glands

Front 9

Location of Crypts of Lieberkuhn

Back 9

throughout the intestine

Front 10

Describe how to differentiate between a crypt of a villus in a cross section?

Back 10

Crypts will contain lumen on the inside and lamina propria on the outside. Villi will contain lamina propria on the inside and lumen on the outside

Front 11

Describe the mucosal epithelium of the intestine

Back 11

simple columnar

Front 12

Name the 4 types of cells distributed within the intestinal surface epithelium

Back 12

Intestinal absorptive cells, goblet cells, enteroendocrine cells, intraepithelial lymphocytes

Front 13

Name a type of cell that is specifically located in assocation with lymphoid follicles

Back 13

M-cells

Front 14

What is the principal cell of the intestinal surface epithelium?

Back 14

Intestinal absorptive cell

Front 15

Describe the intestinal absorptive cell

Back 15

simple columnar, brush border, centrally located ovoid nucleus

Front 16

What is the primary function of intestinal absorptive cells?

Back 16

absorption

Front 17

Glycocalyx

Back 17

glycoprotein coat covering the microvilli

Front 18

Other than function for absorption, what do the intestinal absorptive cells do?

Back 18

synthesize digestive enzymes

Front 19

What is the function of the glycocalyx?

Back 19

contains enzymes that function in the final stages of digestion

Front 20

Describe how nutrients are absorbed within the intestine

Back 20

Glycocalyx contains enzymes to break down carbohydrates and proteins. These are then transported across the microvilli into the absorptive cell, then transported across the basolateral membrane into the lamina propria

Front 21

Describe the fate of lipids in the intestine

Back 21

broken down in the lumen, diffuse into absorptive cells, resynthesized into triglycerides, get a protein coat and become chylomicra, then released into the extracellular space

Front 22

Other than synthesis of enzymes and absorption, what are absorptive cells capable of?

Back 22

Transcytosis of IgA from the lamina propria to the intestinal lumen

Front 23

Where is IgA synthesized and secreted?

Back 23

in the plasma cells of the lamina propria

Front 24

How is IgA transported from the lamina propria to the lumen of the intestine?

Back 24

Binds to basolateral surface of intestinal absorptive cells, endocytosed via clathrin-coated vesicles, travels through endosomal reactions, released at the cell surface

Front 25

What is the function of IgA in the intestinal lumen?

Back 25

regulate microbial growth

Front 26

What are goblet cells?

Back 26

goblet-shaped mucous secreting cells

Front 27

Describe the organelle structure of the goblet cell

Back 27

Triangular nucleus, apical secretory vesicles, RER at the base

Front 28

Describe the pattern of goblet cell frequency in the intestine

Back 28

Increase in number proximally to distally

Front 29

Describe the location of enteroendocrine cells in the intestine

Back 29

Located within the surface of the intestine as well as in the crypts of lieberkuhn

Front 30

Describe the derivation of intraepithelial lymphocytes

Back 30

blood-derived

Front 31

Function of intraepithelial lymphocytes in the intestine

Back 31

Provide mucosal immunity

Front 32

Describe the frequency of intraepithelial lymphocytes

Back 32

present during infection, also increased in some disease states such as Celiac disease

Front 33

Where are M-cells located?

Back 33

in the epithelium overlying the lymphoid follicle

Front 34

What is the function of the M-cell?

Back 34

to facilitate an immune response by transporting antigens across the epithelium

Front 35

Describe the structure of the M-cell

Back 35

Contains a deep invagination at the basal membrane that contains macrophages, dendritic cells, and lymphocytes. Apical surface is covered by lamellae

Front 36

How do M-cells function in the antigen-presenting process?

Back 36

M-cells take up antigens from the intestinal lumen via endosomes at the surface, transfer to the basolateral pocket, then to antigen-presenting cells beneath M-cells

Front 37

How do antigen-presenting cells act once they receive an antigen from the M-cell?

Back 37

The endocytose the antigen and present it to lymphocytes

Front 38

What are M-cells derived from?

Back 38

progenitor cells in the crypts of lieberkuhn

Front 39

Characterize the Crypts of Lieberkuhn

Back 39

simple straight mucosal glands

Front 40

What is the function of the crypts of lieberkuhn?

Back 40

production of epithelial cells (the invagination forms a protective niche from the harsh lumen)

Front 41

Name the 3 types of cells located within the crypts of lieberkuhn

Back 41

Undifferentiated progenitor cells
Paneth cells
Typical intestinal cells

Front 42

How can progenitor cells be differentiated from intestinal absorptive cells?

Back 42

cells undergoing mitosis are progenitor cells

Front 43

Why would typical intestinal cells be located within the crypts of lieberkuhn?

Back 43

Because the crypts create all surface epithelial cells, so they would naturally have immature cells of all surface epithelial cells

Front 44

Where are Paneth cells located?

Back 44

at the base of the crypt of lieberkuhn

Front 45

Describe the structure of Paneth cells

Back 45

columnar, large aprical highly refractile granules

Front 46

What do Paneth cell granules contain?

Back 46

antibacterial proteins

Front 47

What is the function of the Paneth cell?

Back 47

regulate microbial growth

Front 48

Where in the intestine are Paneth cells located

Back 48

in the small intestine (NOT in the large intestine)

Front 49

Describe the lamina propria of the intestine

Back 49

loose connective tissue, highly cellular

Front 50

What is the function of the lamina propria in the intestine?

Back 50

immunological defense (contains plasma cells and lymphocytes and macrophages)

Front 51

What layer of the intestine are lymphoid follicles typically found?

Back 51

mainly in the lamina propria, but also can be located in the submucosa

Front 52

Describe the pattern of frequency of lymphoid follicles within the intestine

Back 52

increase proximally to distally with large masses of them located within the appendix

Front 53

What are Peyer's Patches?

Back 53

visible as white spots, aggregates of lymphoid follicles within the intestine on the antimesenteric side of the ileum

Front 54

Describe the mucosa covering the lymphoid follicles

Back 54

bulges into the lumen, lacks villi, contain M cells