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Organ Histology Final: 7 and 8 > Digestive System: Small intestines > Flashcards

Digestive System: Small intestines Flashcards

1
Q

What are the general functions of the small intestines (SI)?

A

Digestion
Absorb nutrients
Produce intestinal hormones using DNES cells (produce CCK)

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2
Q

What 3 surface adaptations increase surface area by a factor of 400+?

A
  1. Plicae circulares (valves of Kerckring)
  2. Villi
  3. Microvilli
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3
Q

What are the plicae circulares?

A

Permanent folds affecting the mucosa and submucosa; found throughout duodenum, jejunum, and proximal ileum

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4
Q

Where are the microvilli?

A

On the luminal cell surface

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5
Q

What is the surface epithelium of the intestinal mucosa?

A

Simple columnar

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6
Q

What cell types are present in the surface epithelium of the mucosa?

A 
Surface absorptive cells (enterocytes)
Goblet cells
DNES cells (Type I, Type K, Type S)
Regenerative cells
Paneth cells
M (microfold) cells
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7
Q

What are the main functions of the surface absorptive cells/enterocytes?

A

Absorb water and nutrients

Terminal digestion in glycocalyx; cells produce the enzymes and absorb the monosaccharides and peptides created

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8
Q

What do the surface absorptive cells/enterocytes contain?

A

Microvilli

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9
Q

How are the goblet cells distributed in the SI?

A

Few in duodenum, most in ileum

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10
Q

How many DNES cell types are present in the SI?

A

11 types (we only need to know 3)

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11
Q

What do Type I DNES cells produce and do?

A

Produces cholecystokinin (CCK) to stimulate GB contraction and pancreatic secretion of enzymes from serous acini

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12
Q

What do Type K DNES cells produce and do?

A

Produces GIP (gastric inhibitory peptide) which inhibits HCL release

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13
Q

What do Type S DNES cells produce and do?

A

Produces Secretin which stimulates pancreatic secretion of bicarbonate from the pancreatic ducts; secretin also inhibits HCL release and the movement of chyme into SI

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14
Q

How long do the regenerative cells of the SI live? Where are they found?

A

5-7 days

Found in crypts (intestinal gands)

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15
Q

How long do the Paneth cells of the SI live? Where are they found?

A

20 days, they are long lived

Found in base of crypts (intestinal glands)

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16
Q

What is the function of the Paneth cells of the SI?

A

Produce lysozyme

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17
Q

Where are the M (microfold) cells found in the SI?

A

Ileum epithelium over Peyer’s patches

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18
Q

What is the cell structure of the M (microfold) cells?

A

Contain large intracellular pockets that are fairly open to the LP; M cells sample foreign antigens in gut lumen and transfer antigens to lymphocytes and dendritic cells that have entered the M cell pockets

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19
Q

What is the function of the M (microfold) cells?

A

Promote humoral immunity; results in plasma cells producing IgA which is then transferred to epithelial cells and released into gut lumen. M cells are also important in maintaining appropriate gut flora

20
Q

What is the lamina propria of the SI made up of?

A

Loose areolar CT

21
Q

Where is the villus core located?

A

In the lamina propria

22
Q

What is found in the villus core?

A

Lacteals
Vascular components
Some longitudinal smooth muscle

23
Q

What are lacteals and what’s their function?

A

They are lymphocyte capillaries

Function in most lipid absorption

24
Q

Are the vascular components of the villus core larger or smaller blood vessels?

A

Smaller

25
Q

What is the importance of the longitudinal smooth muscle in the villus core?

A

If irritated then muscle contracts and the villi will shorten; this can lead to nutrient deficiencies if irritation is prolonged

26
Q

What does the lamina propria of the SI border?

A

Intestinal glands (crypts of Lieberkuhn)

27
Q

Is muscularis mucosae present in the SI mucosa?

A

Yes, but it’s thin. It connects to smooth muscle in villi

28
Q

What makes up the submucosa of the SI?

A

Dense fibroelastic CT

29
Q

How vascular is the SI submucosa?

A

Very vascular due to larger blood vessels

30
Q

What are the parts of the SI submucosa?

A

Duodenum
Jejunum
Ileum

31
Q

What glands are present in the duodenum?

A

Duodenal (Brunner) glands (seromucous glands)

32
Q

What do the duodenal glands produce?

A

Alkaline mucus

Urogastrone

33
Q

What is the function of alkaline mucus?

A

Neutralizes chyme

34
Q

What is the function of urogastrone?

A

Inhibits HCL secretion and increases mitosis of epithelial cells

35
Q

Where are Peyer’s patches located?

A

Ileum

36
Q

What are Peyer’s patches?

A

Groups of regularly occurring large lymph nodules

37
Q

What plexus is found in the ileum and what type of innervation does it conduct?

A

Submucosal (Meissner’s) plexus- parasympathetic innervation

38
Q

Where is the submucosal found and what is its function?

A

Found close to circular muscles in muscularis externa

Functions to influence mucosa

39
Q

How is the pattern of the muscularis externa of the SI?

A

Normal; inner circular, outer longitudinal

40
Q

What plexus is found in the muscularis externa and what is its function?

A

Myenteric (Auerbach) plexus

Functions to stimulate muscularis externa for peristalsis

41
Q

Where is the myenteric plexus found within the muscularus externa?

A

Between the circular and longitundinal layers of muscle in muscularis externa

42
Q

Where is the serosa found in the SI?

A

In all of the jejunum and ileum, first and last 1-2 cms of duodenum

43
Q

Where is the adventitia found in the SI?

A

In the vertical/descending portion of duodenum

44
Q

Where is the ileocecal valve found?

A

Between ileum and cecum of colon

45
Q

What type of sphincter is the ileocecal valve?

A

Physiological AND anatomical

Organ Histology Final: 7 and 8 (8 decks)

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