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Human Organs and Tissues > Gastrointestinal > Flashcards

Flashcards in Gastrointestinal Deck (72):
1

4 layers of the GI tract

Mucosa: epithelium, lamina propria, muscularis mucosae
Submucosa: glands, blood vessels, nerves
Muscularis propria/externa: inner circular and outer longitudinal muscle layer
Adventitia/Serosa

2

Circumvallate papillae

Dome-shaped
Sunken structures
8-12 of them
Taste buds

3

Filiform papillae

Small conical prominences on lingual surface
No taste buds

4

Fungiform papillae

Mushroom shaped projections on the surface among the filiform but mainly at the tip and lateral margins
Have taste buds on the upper surface

5

Foliate papillae

Short vertical folds on the lateral margins
Taste buds scattered over the surface
Serous glands drain into the fold and clean the taste buds

6

How many teeth do children vs adults have?

Children: 20
Adults: 32

7

3 major salivary glands

Parotid
Sublingual
Submandibular

8

Function in the salivary glands
1. Serous cells
2. Intercalated duct cell
3. Striated duct cell

1. Secrete amylase - digests starch into maltose
2. Secretes bicarbonate, absorbs Cl-
3. Modifies saliva to be hypotonic with plasma

9

Upper 1/3 of esophagus is...

Striated muscle! Voluntary

10

GERD

Gastrointestinal reflux disease
Lower esophageal sphincter fails to close properly
Stomach contents leak back, reflux
Can taste stomach fluid in the back of the mouth
Frequent heartburn

11

Eosinophilic Esophagitis

Inflammation or swelling of the esophagus
Diagnose with endoscopy and biopsy
Large number of eosinophils cause inflammation
Stiffening or narrowing of the esophagus
Can lead to difficulty swallowing (dysphagia)

12

3 types of stomach glands

Cardiac glands
Pyloric glands
Gastric/fundic glands

13

4 types of cells in the stomach glands

Mucous cells
Parietal cells or oxyntic cells
Chief cells
Enteroendocrine cells

14

What do
1. Mucous cells
2. Parietal cells or oxyntic cells
3. Chief cells
4. Enteroendocrine cells
secrete?

1. Secretes mucus into the lumen
2. Secretes HCl, intrinsic factor into lumen and bicarbonate into blood
3. Pepsinogen (zymogen, gets converted to pepsin) into lumen
4. hormones - G cells secrete gastrin into blood

15

How is the stomach unique?

Has 3 layers of muscle (oblique muscle is extra)

16

Barrett's esophagus

Stratified squamous epithelium of the esophagus is replaced by simple columnar epithelium with goblet cells
Strong association with esophageal adenocarcinoma

17

Brunner's glands

Only in the small intestine (submucosa)
Secrete alkaline fluid containing neutral and alkaline glycoproteins and bicarbonate ions

18

Crypts of Liberkuhn

Secrete carbohydrases, proteases, and lipases
In the mucosa

19

4 principle cell types in the small intestine

Enterocytes
Paneth cells
Goblet cells
Enteroendocrine cells

20

What do
1. Enterocytes
2. Paneth cells
3. Goblet cells
4. Enteroendocrine cells
secrete?

1. Digest and absorb things
2. Secrete lysozyme and defensins into lumen
3. Mucus into lumen
4. Secretin, CCK, GIP, others into blood

21

Period acid-Schiff stain

Used to detect polysaccharides such as glycogen, and glycoproteins, glycolipids, and mucins

22

Endopeptidases

Cleave the polypeptide at interior bonds

23

Exopeptidases

Cleave the terminal amino acid

24

2 subclasses of exopeptidases and where they cut

Aminopeptidases: cleave off the terminal amino acid at the amine end of the chain
Carboxypeptidases: cleave off the terminal amino acid at the carboxyl end of the chain

25

Colipase

Binds to the lipidase and enhances its activity by anchoring to the lipid-water interface
Free fatty acids and monglyceride are generated, which combine with other lipids and bile salts to form water-soluble micelles

26

Zonula occludens

Tight junctions
Proteins are occludins and claudins
Most important barrier in making it tight
Most apical

27

Zonula adherens

Adherens/intermediate junctions, belle desmosome
Cadherins (homophilic) - bind to each other
Catenins are linked to cellular actin

28

Desmosomes

Macula adherens
Cadherins and desmoplakin linked to intermediate filaments
Junction communicates with the skeleton of the cell

29

Plicae circulares

In the small intestine
Folds of the mucosa into the lumen (has crypts and villi)
Even more surface area

30

Glycocalyx

Acidic mucopolysaccharides and glycoprotein matrix on the apical surface, on the microvilli

31

Gastrin
(secreted by, source and stimulus, target organ, response)

S: stomach mucosa
SS: stomach in response to food
TO: stomach, small intestine
R: release of HCl, increase of intestine movement, release of pepsinogen

32

Secretin
(secreted by, source and stimulus, target organ, response)

S: Small intestine
SS: duodenum in response to acidic chyme
TO: pancreas
R: secretion of alkaline digestive proenzyme, inhibits intestine motility

33

Cholecystokinin
(secreted by, source and stimulus, target organ, response)
More details

S: Small intestine
SS: intestinal cells in response to food
TO: pancreas, gallbladder
R: secretion of proenzymes and bile
Secreted by I cells in the epithelium
Inhibits gastric emptying and gastric acid secretion, stimulates acinar cells of the pancreas to release digestive enzymes, increased production of bile, contraction of the gall bladder, relaxation of the sphincter so bile can enter duodenum

34

Gastric Inhibitory Peptide
(secreted by, source and stimulus, target organ, response)

S: Small intestine (K cells)
SS: Intestinal cells in response to fat
TO: stomach, pancreas
R: insulin secretion, inhibits gastric secretion and motility
Actions on fat cells and bone remodelling

35

Haustr

Pouches formed by the taenia coli

36

Taenia coli

3 independent long ribbons of smooth muscle just below the serosa, along the colon length
Condensations of the longitudinal muscle layer

37

Cecum functions

Salt recovery (uptake)
Lubricates sold waste
Bacterial digestion of cellulose

38

Appendix

Same histology as the rest of the intestine
Small blind ending pouch from the cecum
Thickened walls (due to lymphoid tissue)
Longitudinal smooth muscle layer does not aggregate into taenia coli

39

4 different kinds of epithelium and their location in the large intestin

Simple columnar epithelium in the upper zone
Stratified squamous epithelium in the middle and lower zones
Simple columnar epithelium of the anal glands
Stratified columnar epithelium of the anal sinuses, crypts, and ducts of the anal glands

40

Myenteric Plexus

Aka Auerbach's plexus
Major role in motility and passing food through the digestive tract

41

Submucosal Plexus

Aka Meissner's plexus
A secondary plexus
Derived and formed by branches that have perforated the circular muscle
Innervates the epithelial layer and muscularis mucosae

42

Celiac disease

Genetic predisposition to an autoimmune, crossreactive reaction to gluten (modified by transglutaminase)
Pale, loose and greasy stool affecting absorption
Range from almost asymptomatic to very bad malnutrition

43

Lactose intolerance

Lack of lactase (cleaves lactose into glucose and galactose)
Results in high concentrations of lactose reaching the colon and affecting the osmotic state, passively drawing water into the lumen
Normally the amount of lactase declines with age

44

Colitis

Inflammation of the colon
Multiple causes
Abdominal pain and diarrhea

45

Chron's vs ulcerative colitis

C: inflammation affects the alimentary tract
UC: inflammation affects colon and rectum

46

Irritable bowel syndrome

Non-inflammatory symptom based diagnosis
Chronic abdominal pain, discomfort, bloating, and diarrhea/consitpation

47

Diverticulosis

Small weak areas in the colon wall allowing the mucosa to protrude through, forming tiny pouches called diverticuli
Usually no problem but can bleed, become inflamed or infected to become diverticulitis

48

Colon polyps

Familial adenomatous polyposis
Small growths
Some develop into cancer over a long time

49

Occult vs frank blood

O: high GI bleed
F: low GI bleed

50

Triad in portal area

Hepatic artery
Bile duct
Portal vein

51

Sinusoids

Low pressure channels that receive blood from terminal branches of hepatic artery and portal vein and deliver it to central canal
Lined with fenestrated endothelial cells and flanked by hepatocytes

52

Space of Disse

Between endothelium and hepatocytes
Plasma accumulates and retrogradely flows back into the lymphatics

53

Kupffer cells

Type of macrophage that engages bacteria coming from the intestine
In the sinusoids
Deal with foreign particles (gut endotoxins)

54

Stellate cell

Between sinusoid and hepatocytes (in space of Disse)
Make collagen fibrils and ECM materials

55

Hepatocyte function

Bile production, uptake and transport
Lipid uptake and metabolism
Glycogen synthesis
Detoxification by p450 enzymes
Protein synthesis (ex: albumin, complement, fibrinogen, lipoproteins)

56

2 functions of bile

Emulsification of lipid aggregates
Solubilization and transport of lipids

57

Hering's canal

Vessels collecting bile from the canaliculli

58

Bile ducts

Collect bile from Hering's canals
Parallel to hepatic arteries and portal veins

59

Common hepatic duct

Collects bile from hepatic ducts and branches into the cystic duct and then the common bile duct which then empties into the duodenum

60

Jaundice

Increased bilirubin in the blood

61

Cirrhosis

Normal liver cells are replaced by scar tissue due to chronic liver disease
Alcohol abuse most common

62

Steatosis

Fatty liver disease
Cholesterol or TAGs accumulate

63

Types of exocrine cells in pancreas

Acinar: secretes digestive enzymes
Ductal: secrete bicarb

64

Types of endocrine cells in pancreas

Alpha cells: glucagon
Beta: insulin
Delta: somatostatin

65

Action, precursor and activator for:
1. Trypsin
2. Chymotrypsin
3. Elastase
4. Carboxy'dase A/B

1. Endopeptidase, trypsinogen, enteropeptidase/enterokinase and trypsin
2. Endopeptidase, chymotrypsinogen, trypsin
3. Endopeptidase, proelastase, trypsin
4. Exopeptidase, procarboxy'dase A/B, trypsin

66

What activates enteropeptidase?

Duodenase

67

Somatostatin

Produced by delta cells in the pancreas
Reduces smooth muscle contractions in tract and gall bladder

68

Pancreatic insufficiency

Lose about 90% ability to secrete digestive enzymes
Patients unable to digest food, resulting in malabsorption of nutrients (including vitamins)
Impaired absorption of fats causes diarrhea, weight loss, malnutrition

69

Cystic fibrosis

Loss of the CFTR
Decreased production of sodium bicarbonate makes secretions dehydrated, thickened, blocking ducts
Pancreas continues to make enzymes that damage it, leading to fibrosis

70

Peyer's patches

Mucosal inductive site
Where the cells become stimulated
Have M cells

71

Intraepithelial lymphocyte

Function is not entirely clear
Likely play a role in detecting pathogens or react to infected or damaged (and cancerous) epithelial cells
Have cytotoxic properties so are able to kill abnormal cells

72

Histatins

Antifungal properties
Made in salivary glands