Intestine Mircoanatomy

Question 1

What are the layers of the digestive tract

Answer 1

Lecture Slide

Mesenteric artery and vein
Mesentary
Serosa
Muscualris
Submucosa
Mucosa
Plica
- Villi
- Mucosa (Mucosal epithelium, lamina porpria)
- Mucosal glands
-submucosal glands
-musclaris mucosae
-lymphatic vessle
-artery and vein
- Submucosal plexus
-cicular muscle layer
myenteric plexus
Longitudal muscle layer

Question 2

Histology slide of ileum

Answer 2

Lecture Slide

Question 3

Celiac disease affects the gut how

Answer 3

autoimmune disease that attacks cells of villi
↳ Villus atrophy - destruction of villi (less SA)
· less absorption
· less digestion
↳ malabsorption

Question 4

Role of lacteals

Answer 4

lacteals :
-blinded-ended capillary at core of villus
-lymphatic vessel
-no smooth muscle in walls
-rely on smooth muscle fibres inside the villus to help propel contents along
-smooth muscle fibres are extensions of the muscularis mucosae into the villus

Question 5

What part is the villus, intestinal gland, mucosa and submucosa

Answer 5

Lecture Slide

Question 6

What transports carbs
What transports lipids

Answer 6

Transport of carbohydrates (monosaccharides), proteins (amino acids), water and electrolytes. Venules in the submucosa are tributaries of the hepatic portal vein.

Transport of absorbed lipids. Lymphatic vessels eventually drain into the venous system.

Question 7

Mucosa of the small intestine:
What cells

Answer 7

Columnar absorptive cells (enterocytes): Absorb the small molecules resulting from digestion

Question 8

Role of micorvilli

Answer 8

microvilli membrane (lipid bilayer) studded with enzymes
- Directly digest items eg glycosidases help to breakdown carbs
- enterokinase activate pancreatic enzymes coming from pancreas

Question 9

Role fo goblet cells
Components

Answer 9

Secrete mucus for lubrication

Mucinogen granules filling apical cytoplasm and Basal nucleus

Question 10

Enteroendocrine cells:
- role
- what is bile made from

Answer 10

enteroendocrine cells to m ake Cholecystokinin (CCK)

Bile:
chyme
HCl
fatty acids
amino acids

Question 11

What does CCK do
What does HCl do

Answer 11

Act on gallbladder to release bile
act on pancreas to release digestive enzymes

HCl:
activates secertin which acts on duodenum (increase bicarb production) and stomach (stop gastrin release)

Question 12

Undifferentiated cells:
role

Answer 12

Stem cells dividing to generate new epithelium
↳ near base of glands
more upwards to replace superficial cells

Question 13

Paneth cells
release what

Answer 13

TNF-a (produces inflammation in response to bacteria and parasites)

Lysozyme (bactericidal; destroys bacterial membranes)

Defensins (increasees ion channels in cell membranes of invading organisms; increases permeability)

Question 14

Compare duodenum, jejnum and ileum

Answer 14

duodenum 25cm
Macroscopically curvy (c shaped), secrete bicarb (brunners glands) , rich in mucus to neutralise acid

jejnum 2.5m
lots of plicae cicurlais and villi for lots of digestion and abs

ileum 3.5m
leads into large intestine and theres lots of bacteria (flora)
lots of defensive mechanisms (lymphatic aggregates aka peyers patches)

Question 15

Label chunk of intestine diagram

Answer 15

Lecture Slide

Question 16

Label small intestine histo

Answer 16

Lecture Slide

Question 17

Label plica histo

Answer 17

Lecture Slide

Question 18

Label villi and crypts histo

Answer 18

Lecture Slide

Question 19

What cells are in epithelium

Answer 19

Simple coloumnar enterocytes
Goblet cells

Question 20

What cells/features are in the lamina propria

Answer 20

BV
Lacteal
SM
Lymphocytes
Fibroblasts (collagen)

Question 21

Label Outer tunics histo

Answer 21

Lecture Slide

Question 22

Label gastric/duodenual junction histo

Answer 22

Lecture Slide

Question 23

Label duodenual brunners glands (submucosa)

Answer 23

Lecture Slide

Question 24

Role of ileocecal valve large intestine

Answer 24

The ileocecal valve regulates the passage of materials into this expanded pouch. Collects and stores the arriving materials and begins the process of compaction

Question 25

Colon - ascending, transverse, descending and sigmoid - mucosa cell types

Answer 25

Smooth, no villi or plicae Mucosal glands (crypts of Lieberkuhn) are numerous. Two cell types predominate: * Columnar absorptive cells (similar to the enterocytes of the small intestine): - absorb water & electrolytes - absorb vitamins produced by bacteria (B & K) * Goblet cells: secrete mucus for lubrication.

Question 26

Label large intestine cell diagram

Answer 26

Lecture Slide

Question 27

Lamina propria Large intestine - cell types -what does it lack

Answer 27

Contains a dense layer of collagen immediately beneath the surface epithelium; also numerous lymphatic nodules (GALT / MALT - gut- or mucosa-associated lymphatic tissue) extending down into the submucosa. No lymphatic vessels drain the lamina propria until the level of the muscularis mucosae is reached; this may explain the relatively slow rate of metastasis from some colon cancers.

Question 28

Muscularis externa Large intestine -layers present and their purpose

Answer 28

Circular and longitudinal layers present. Outer longitudinal layer forms three distinct strips / bands running along the colon (teniae coli) * Allow segments of the colon to contract independently * Contraction pulls the intestinal tube into sac-like pockets (haustra coli)

Question 29

Rectum / Anus -purpose what does each section of it contain

Answer 29

Temporary storage of faecal material; movement of material into this area triggers the urge to defecate. Final portion = anal canal (mucosa contains longitudinal folds called anal columns). Distal margins = transverse folds - marks boundary between columnar epithelium --> stratified squamous. Anal sphincters = internal (smooth muscle) & external (skeletal muscle) End of anal canal = anu

Question 30

Label the large intestine (alimentary canal) anatomy

Answer 30

Lecture Slide

Question 31

Colon histo Label

Answer 31

Lecture Slide

Question 32

Layers of colon histo label

Answer 32

Lecture Slide

Question 33

Colon – mucosa and submucosa Histo label

Answer 33

Lecture Slide

Question 34

Label appendix histo AND specifics of appendix

Answer 34

Lecture Slide

Question 35

Brunners Glands role and located

Answer 35

Secrete bicarb to neutralise acid from stomach in submucosa

Question 36

3 key differences in anus histo

Answer 36

internal (smooth muscle) and external (skeletal muscle) spchniter Anal glands Cells are now straitifoed epithelium instead of coloumnar cells