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Flashcards in Digestive System Deck (79):
1

Mucosa

Layer of the digestive tract facing the lumen
Absorptive, secretory (mucus), protective (microbes)

Made up of three layers
Epithelium
Lamina propria
Muscularis mucosae

2

What type of epithelium makes up the mucosa of the esophagus?

Stratified squamous

3

What type of epithelium makes up the mucosa of the stomach?

Simple columnar

4

What type of epithelium makes up the mucosa of the analrecto junction?

Stratified squamous

5

Lamina propria

Layer of the mucosa made up of loose fibrous CT
Contains blood and lymph vessels, sometimes lymph nodules, and sometimes glands

6

Muscularis mucosae

Thin layer of the mucosa made up of smooth muscle
Helps with movement

7

Submucosa

Layer of the digestive tract
Dense fibrous CT with many blood and lymph vessels, sometimes lymphoid nodules, and the submucosal or Meissner's plexus

8

Meissner's plexus

Aka submucosal plexus
Plexus of nerve fibers that control motility of the digestive tube and glandular secretion

9

Muscularis externa

Layer of the digestive tract made up of two layers of smooth muscle
Inner layer of muscle is circular
Outer layer of muscle is longitudinal
Responsible for peristalsis

10

Serosa

Layer of the digestive tract
Thin layer of loose CT covered by simple squamous epithelium (mesothelium)
Found in parts of the digestive tract that are free (not connected to other organs)

11

Adventitia

Layer of the digestive tract
Fibrous CT without cells that fuse with the surrounding tissue
Found in parts of the digestive tract that connects to other organs

12

Esophagus

Part of the digestive tract
No digestive function or glands
Connects the mouth to the stomach
Transports material from the mouth to the stomach

13

What two things move material through the esophagus?

Contractions of the esophagus and gravity

14

Mucosa of the esophagus

S squamous epithelium
Lamina propria contains lymphoid nodules
Muscularis mucosae thinnest near stomach

15

Submucosa of the esophagus

Contains Meissner's plexus
Presence of GALT/MALT
Secretory glands that secrete mucus to keep the lining moist called esophageal and cardiac glands

16

Muscularis externa of the esophagus

Upper 1/3 skeletal muscle
Middle 1/3 mix of skeletal and smooth muscle
Lower 1/3 smooth muscle

17

Adventitia of the esophagus

Contained in the part of the esophagus in the neck

18

Serosa of the esophagus

Seen after the esophagus penetrates the diaphragm

19

Stomach

Organ of the digestive system
Contains gastric glands in the fundus and body
Contains pyloric glands in the pylorus

20

Gastric glands

Function in protein digestion
Found in the fundus and body of the stomach

21

Pyloric glands

Function to secrete mucus to protect the mucosal stomach lining from the very low pH
Found in the pylorus of the stomach

22

Mucosa of the fundus and body of the stomach

Contains gastric glands
Consists of mucous neck cells, parietal (oxyntic) cells, chief (zymogenic) cells, enteroendocrine cells, and stem cells

23

Mucous neck cells

Cells found in the gastric glands of the stomach
Secrete mucus

24

Parietal (oxyntic) cells

Cells found in the gastric glands of the stomach
Secrete HCl and intrinsic factor (vitamin B12 absorption)

25

Intrinsic factor

Secreted by parietal (oxyntic) cells of the gastric glands of the stomach
Important for vitamin B12 absorption
Vitamin B12 is important for hemapoiesis

26

Chief (zymogenic) cells

Cells found in the gastric glands of the stomach

Secrete granules containing the inactive enzyme pepsinogen that becomes active pepsins upon exposure to low pH
Pepsins then function for digestion

Produce gastric lipase that digests lipids

27

Enteroendocrine cells of the stomach

Cells found in the gastric glands of the stomach

28

Stem cells of the gastric glands

Cells that differentiate into all cells of the gastric glands

29

Chloride shift

Bicarbonate leaves the cell and chloride enters

30

Layers of the digestive system

Mucosa
Submucosa
Muscularis externa
Adventitia or serosa

31

Pepsinogen

Zymogen of pepsin released by chief cells

32

Pepsinogen is activated by _______.

low pH

33

Pepsin

Enzyme for digestion of proteins into peptides

34

Zymogen

Inactive form of an enzyme

35

Mucosa of the pylorus of the stomach

Contains pyloric glands that produce lysozyme, gastrin, and somatostatin

36

Lysozyme

Digests bacterial cell walls

37

Gastrin

Peptide hormone secreted by G cells of the mucosa of the pylorus that promotes secretion of gastric acid (HCl) by parietal cells

38

G cells

Enteroendocrine cells of the pylorus that secrete gastrin

39

Somatostatin

Hormone produced by D cells that inhibits secretion of other enteroendocrine cells

40

D cells

Enteroendocrine cells in the pylorus that produce somatostatin

41

Muscular external of the stomach

Three layers of smooth muscle
Inner oblique
Middle circular
Outer longitudinal

42

The stomach is covered by a thin _______.

serosa

43

Small intestine

Site of digestive tube where the digestive processes are completed and nutrients are absorbed
Consists of three segments, the duodenum, ileum, and jejunum

44

Leiomyomas

Benign tumors of smooth muscle cells
Most common type of tumor in the stomach and small intestine
May become large

45

Epithelium of the mucosa of the small intestine

Contains intestinal folds (plicae circulares) covered with villi that project into the lumen
Villi are covered by enterocytes containing microvilli
Folds, villi, and microvilli all increase surface area
Goblet cells are interspersed with enterocytes

46

Plicae circulares

A series of folds consisting of mucosa and submucosa
Increases surface area
Covered by villi that also increase surface area

47

Enterocytes

Simple columnar absorptive cells with microvilli that cover the villi of the small intestine
Microvilli are covered by glycocalyx that take nutrients into the cells after being hydrolyzed by brush border enzymes

48

Villus structure

Each villus has a core of loose CT that extends from the lamina propria and contains fibroblasts, smooth muscle fibers, lymphocytes and blood cells, fenestrated capillaries, and a central lymphatic lacteal

49

Brush border enzymes

Enzymes proceeded by enterocytes and released by the glycocalyx of the brush border of enterocytes of the small intestine
Consists of disaccharidases and peptidases

50

Disaccharidases

Brush border enzyme that hydrolyzes disaccharides to monosaccharides

51

Peptidases

Brush border enzyme that hydrolyzes peptides to amino acids

52

Gland of Lieberkühn

Aka crypts of Lieberkühn
Short, tubular glands between the villi of the small intestine
Epithelium of each villus is continuous with that of the gland
The epithelium contains pluripotent stem cells at the bottom that differentiate into all the cell types of the small intestine

53

Pluripotent stem cells at the bottom of glands of Lieberkühn differentiate into these 5 cell types.

Enterocytes, goblet cells, paneth cells, enteroendocrine cells, and M (microfold) cells

54

Goblet cells

Cells that secrete glycoprotein mucins that form mucus when hydrated and function to protect the lining of the small intestine
Interspersed among enterocytes

55

Paneth cells

Exocrine cells with large, eosinophilic secretory granules in their apical cytoplasm
Found in the basal portion of intestinal crypts below stem cells
Function for innate immunity and regularing the crypt environment

56

Enteroendocrine cells of the small intestine

Cells that secrete various peptide hormones

57

M (microfold) cells

Specialized epithelial cells in the mucosa of the ileum overlying the lymphoid follicles of Peyer's patches
Characterized by basal membrane invaginations containing many lymphocytes and APCs
Selectively endocytose antigens and deliver them lymphocytes and dendritic cells that deliver them to the lymph nodes

58

Paneth cell granules release what three enzymes? What is their function?

Lysozyme, phospholipase A2, and defensins
To digest cell walls of bacteria and membranes of microorganisms

59

Defensins

Hydrophobic peptides that digest cell walls of bacteria and membranes of microorganisms

60

Lamina propria of the mucosa of the small intestine

Loose CT containing extensive blood and lymph vessels, nerve fibers, smooth muscle cells, and diffuse lymphoid tissue
Penetrates the core of each villus

61

Muscularis mucosa of the mucosa of the small intestine

Helps to produce movements of the plicae circulares and to propel lymph from lacteals
Contain Peyer's patches in the ileum

62

Submucosa of the small intestine

Contains larger blood and lymph vessels and the diffuse, interconnected neurons of the submucosal or Meissner nerve plexus
The duodenum contains duodenal or Brunner glands
Contain Peyer's patches in the ileum

63

Peyer's patches

Aggregated lymphoid nodules found in the lamina propria and submucosa of the ileum of the small intestine
Distinguishing feature of the ileum
Functions in immunity

64

Brunners glands

Aka duodenal glands
Glands of the duodenum that contain small excretory ducts opening into the intestinal crypts
Distinguishing feature of the duodenum

65

How can you distinguish the duodenum, ileum, and jejunum from one another?

The duodenum contains duodenal or Brunner glands, the ileum contains Peyer's patches, and the jejunum contains neither

66

Muscular externa of the small intestine

Well developed in the small intestine
Composed of an inner circular layer and an outer longitudinal layer
Between the two layers is the myenteric or Auerbach nerve plexus that produces peristalsis

67

Enteric nervous system

Autonomic
Consists of the submucosal (Meissner) and myenteric (Auerbach) nerve plexuses

68

The small intestine is covered by a thin _______.

serosa

69

Large intestine

Aka bowl or colon
Large tube of the digestive tract that function for water and electrolyte absorption and forms indigestible material into feces

Consists of several parts:
Cecum
Ileocecal valve and the appendix
Ascending, transverse, descending, and sigmoid colon
Rectum

70

Rectum

Part of the colon where feces is stored prior to evacuation

71

Epithelium of the mucosa of the colon

Does not contain villi
No major folds, except in the rectum
Penetrated by tubular intestinal glands
Glands and lumen are lined with goblet and colonocytes cells and a small number of enteroendocrine cells

72

Colonocytes

Columnar absorptive cells of the colon mucosa
Have irregular microvilli and dilated intercellular spaces for absorption of fluids

73

Lamina propria of the mucosa of the colon

Rich in lymphoid cells and nodules that extend into the submucosa
MALT dude to large bacterial population in the colon

74

Muscularis externa of the colon

Longitudinal and circular layers of smooth muscle
Fibers of the outer layer are gathered into three separate longitudinal bands called teniae coli (distinguishing feature of the colon)
Forms the haustra

75

What parts of the colon are covered by serosa?

Intraperitoneal portions

76

Haustra

A series of large sacs of the wall of the colon
Formed by the muscularis externa

77

How does the muscularis externa form the haustra?

The muscularis externa is smaller than the tube (colon) so the tube condenses

78

Diverticula

Bulges in the muscularis externa that form when the wall of the muscularis externa is weak
Fecal matter can get trapped

79

Which cells of the glands of Lierburkuhn secrete lysozyme?

Paneth cells