8- Histology of Small & Large Intestines Flashcards

1
Q

The small intestine is the principal site for digestion of food and absorption of digestion products. What are the components of the small intestine?

A

Duodenum
Jejunum
Ileum

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2
Q

These are transverse folds with a submucosal core that lie within the small intestine. They cannot lay flat if distended, and are visible in the jejunum but less so in the ileum.

A

Plicae Circulares

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3
Q

These are mucosal folds that project into the lumen and cover the surface of small intestine. They are covered with a simple columnar epithelium of enterocytes and goblet cells.

A

Intestinal Villi

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4
Q

Intestinal Villi have a core of loose CT with microvasculature and a ________.

A

Lacteal

***This is lymphatic vessel of small intestine that absorbs digested fats!

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5
Q

In Intestinal Villi, _________ produce enzymes for digestion and absorption.

A

Enterocytes

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6
Q

In Intestinal Villi, ________ ________ provide mucus coating to shield from abrasion and bacterial invasion.

A

Goblet Cells

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7
Q

Intestinal Villi are covered with _________ to increase absorptive surface area.

A

Microvilli

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8
Q

This layer of the small intestine is composed of simple columnar epithelium with tubular intestinal glands. It contains the lamina propria and muscularis mucosae.

A

Mucosa

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9
Q

This layer of the small intestine is composed of dense irregular CT. It contains neurovasculature, lymphatics, and glands may be present.

A

Submucosa

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10
Q

This layer of the small intestine has inner circular and outer longitudinal layers of muscle.

A

Muscularis

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11
Q

This layer of the small intestine has loose CT covered by visceral peritoneum.

A

Serosa

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12
Q

Motility of the SI and LI is innervated by the…

A

ANS

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13
Q

The ENS (intrinsic) consists of the…

A

Submucosal (Meissner) Plexus

Myenteric (Auberbach) Plexus

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14
Q

Extrinsic innervation for the SI and LI are preganglionic parasympathetics via _______ and _______ nerves, and postganglionic sympathetics.

A

Vagus

Pelvic

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15
Q

Intestinal Glands are simple tubular glands lined by simple columnar epithelium. What cells do they contain?

A

Enteroendocrine Cells
Paneth Cells
M (Microfold) Cells
Intestinal Stem Cells

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16
Q

Intestinal Glands are continuous with the simple columnar epithelium that covers the…

A

Intestinal Villi

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17
Q

Intestinal Glands open onto the luminal surface of the intestine at the base of the _______.

A

Villi

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18
Q

These cells are found throughout the intestinal glands. They secrete peptide hormones to control gut motility, regulate secretion of enzymes, HCl, bile, and other components for digestion.

A

Enteroendocrine Cells

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19
Q

What do Enteroendocrine Cells secrete?

A
Gastrin
Secretin 
GIP (Gastric Inhibitory Polypeptide) 
Motilin 
CCK (Cholecystokinin)
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20
Q

These are pyramidal-shaped cells at the base of intestinal glands. There are large, eosinophilic secretory granules in their apical cytoplasm.

A

Paneth Cells

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21
Q

These cells function in innate immunity by secreting antimicrobial substances (lysozyme, alpha-defensins). They regulate normal bacterial flora via antibacterial action and phagocytosis.

A

Paneth Cells

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22
Q

These cells reside in a niche at the crypt base near Paneth Cells. They repopulate the epithelial lining by daughter cells moving out of the crypts. They differentiate into Goblet Cells, Enterocytes, and Enteroendocrine Cells.

A

Intestinal Stem Cells (ISCs)

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23
Q

These are epithelial cells specialized for transepithelial transport of particles and microorganisms. They are located in the ileal mucosa, overlying Peyer patches.

A

M (Microfold) Cells

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24
Q

M (Microfold) Cells have a pocket formed by deeply invaginated membrane and containing…

A

Lymphocytes

Macrophages

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25
Q

The apical surface of the M Cells express receptors that bind specific macromolecules and Gram-negative bacteria (i.e., E. Coli). These are then internalized and transferred to immune cells. M Cells function as highly specialized…

A

Antigen-Transporting Cells

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26
Q

This is the junction between the pylorus (stomach) and the duodenum.

A

Gastroduodenal Junction

27
Q

At the Gastroduodenal Junction, the ________ has a thick wall due to the pyloric sphincter and there are pyloric glands at the base of each gastric pit.

A

Pylorus

28
Q

At the Gastroduodenal Junction, the ________ has abundant Brunner’s glands in the submucosa that are deep to the muscularis mucosae. There are secretory mucosa with villi.

A

Duodenum

29
Q

The duodenum is the initial segment of the small intestine. It contains _______ _______ in the submucosa, which are tubuloacinar mucous glands that produce an alkaline secretion to neutralize acidic chyme.

A

Brunner’s Glands

30
Q

The duodenum collects bile and pancreatic secretions via the…

A

Hepatopancreatic Ampulla

31
Q

This portion of the small intestine has long finger-like villi with tubular intestinal glands. The villus core contains a well-developed lacteal.

A

Jejunum

32
Q

The jejunum has lymphoid nodules/follicles in the lamina propria and NO _______ _______.

A

Submucosal Glands

33
Q

This portion of the small intestine has shorter finger-like villi and Paneth Cells found at the base of the intestinal glands.

A

Ileum

34
Q

The Ileum has _______ _______, which are mucosal lymphoid nodules specific to the Ileum only.

A

Peyer’s Patches

35
Q

Food is propelled from the Ileum into the Cecum through the…

A

Ileocecal Valve

***Occurs at Ileocecal Junction

36
Q

At the Ileocecal Junction, there is an abrupt transition from villi of SI to the glandular epithelium of the LI. The Ileocecal Valve is a thickened extension of the _______ _______ which has a critical function to limit reflux of colonic content into the Ileum.

A

Muscularis Mucosae

37
Q

This is what absorbs water, sodium, vitamins, and minerals. It also uptakes sedatives, anesthetics, and steroids.

A

Large Intestine

38
Q

In the large intestine, the openings of tubular intestinal glands (called _______ _______ _______) are hallmark of the mucosa.

A

Crypts of Lieberkuhn

39
Q

The hallmarks of this are intestinal glands, goblet cells, but NO intestinal villi.

A

Large Intestine

40
Q

This layer of the large intestine has glandular, simple columnar epithelium that contains colonocytes, goblet cells, stem cells, and enteroendocrine cells.

A

Mucosa

41
Q

This layer of the large intestine has lamina propria and muscularis mucosae. GALT is extensive and may penetrate the submucosa.

A

Mucosa

42
Q

This layer of the large intestine is composed of dense irregular CT and is vascularized.

A

Submucosa

43
Q

This layer of the large intestine has a typical inner layer and an outer longitudinal layer organized into taeniae coli that will form haustra.

A

Muscularis

44
Q

Intraperitoneal portions of the colon are covered by…

A

Serosa

45
Q

The large intestine has glands consisting of simple columnar epithelium with NUMEROUS ______ _____. This is a hallmark of the colon.

A

Goblet Cells

46
Q

This disease is aganglionosis in the distal colon. It occurs in 1:5000 neonates and presents as constipation, poor feeding, and progressive abdominal distention.

A

Hirschsprung’s Disease

47
Q

In Hirschsprung’s Disease, there are mutations of the ______ gene required for migration and differentiation of NCC. Results in failure of NCC development in both plexuses of a bowel segment.

A

RET

48
Q

In (SHORT/LONG) segment Hirschsprung’s disease occur in 85% of cases and are confined to the rectosigmoid region.

A

Short

49
Q

In (SHORT/LONG) segment Hirschsprung’s disease occur in 10% of cases and extends past the rectosigmoid colon to the splenic flexure.

A

Long

50
Q

This form of Hirschsprung’s disease affects the entire colon. Occurs in 5% of cases.

A

Total Colonic Aganglionosis

51
Q

How can we diagnose Hirschsprung’s disease?

A
    • Delayed BM < 48 hrs after birth
    • Rectal biopsy
    • Barium enema
52
Q

How can we treat Hirschsprung’s disease?

A

Surgical removal of the affected colon segment

53
Q

This is the upper part of the rectum, and has typical mucosa with tubular intestinal glands and transverse rectal folds.

A

Rectum Proper (Upper Part)

54
Q

This is the lower part of the rectum.

A

Anal Canal

55
Q

In the anal canal, there are ______ ______ with mucosal folds.

A

Anal Columns

56
Q

In the anal canal, there are _______ ______ with depressions between the columns.

A

Anal Sinuses

57
Q

In the anal canal, there are _______ _______ that extend into the submucosa and muscularis externa.

A

Anal Glands

58
Q

In the rectum, there are _______ _______ which are large apocrine glands surrounding the anal orifice.

A

Circumanal Glands

59
Q

What are the 3 zones of the anal canal?

A
Colorectal Zone (Upper 1/3)
Anal Transitional Zone (Middle 1/3)
Squamous Zone (Lower 1/3)
60
Q

This zone of the anal canal consists of simple columnar epithelium identical to the rectum.

A

Colorectal Zone (Upper 1/3)

61
Q

This zone of the anal canal consists of simple columnar epithelium and transitions to stratified squamous epithelium of perianal skin.

A

Anal Transitional Zone (ATZ – Middle 1/3)

62
Q

This zone of the anal canal consists of stratified squamous epithelium continuous with the perineal skin.

A

Squamous Zone (Lower 1/3)

63
Q

At the level of the anus, the inner circular layer thickens to form the…

A

Internal Anal Sphincter