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Testing123 > GI tract histo > Flashcards

GI tract histo Flashcards

1
Q

GIT

A

Hollow organs of GIT have identical fundamental structure

–> 4 layers + diff. nr of sublayers

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2
Q

Tounge

A
  • Ant. region has lingual papillae
  • Dorsal surf (behind sulcus terminalis) er w.out papillae
  • Root has lingual tonsils
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3
Q

Tongue, basic structure

A
  • It is a mass of striated muscle, cov by mucous membrane
  • Mucous membr, smooth on lower surf
  • Muscle fibers arranged í three interweaving planes (longitudinal, vertical og transversal)
  • Submucosa on lower surface
  • Dorsal surface has no submucosa
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4
Q

Tongue, basic structure

A
  • It is a mass of striated muscle, cov by mucous membrane
  • Mucous membr, smooth on lower surf
  • Muscle fibers arranged í three interweaving planes (longitudinal, vertical og transversal)
  • Submucosa on lower surface
  • Dorsal surface has no submucosa
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5
Q

Lingual papillae

A

-Dorsal surf on anterior body has papillae (formed by lamina propria/muc.membrane)

  1. Filiform papillae;
    - most numerous (tall, narrowed)
    - cov w stratified sq keratinized epith
    - engir taste buds
  2. Fungiform papillae
    - narrow stalk
    - scattered taste buds
    - stratified sq nonkeratinized
  3. Circumvallate papillae
    - largest ones
    - in front of sulcus terminalis
    - each papilla surr. by circular furrow, lined w stratified sq epithelium
    - with taste buds
  4. Foliate papillae
    - rudimentary in humans
    - along posterolateral sides
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6
Q

Taste buds

A

Intraepithelial taste receptors
-at their base; sensory - neuroepith.cells, synapse w fibers of afferent neurons

  • supporting cells: elongated, apical surf w microvilli
  • basal stem cells; small cells, near basal lamina
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7
Q

General structure of GIT

A

1) Tunica mucosa:
- Lamina epithelialis
- Lamina propria mucosa
- Lamina muscularis mucosa

2)Tunica submucosa

3) Tunica muscularis externa
- stratum circulares
- stratum longitudinalis

4)Tunica adventitia/serosa

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8
Q

Tunica mucosa: Lamina epithelialis

A
  • absorption, secretion, protection og barrier against pathogens
  • stratified sq. non-keratinized epithelium vs simple columnar epith.
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9
Q

Tunica mucosa: Lamina propria

A

Loose CT beneath the epithelium

  • rich blood + lymph. circulation
  • immune cells: plasma cells, macrophages and lymphoid cells
  • *MALT hér
  • isolated lymphocytes
  • aggregates of l.cytes in terminal ileum-PREYERS PATCHES(GALT)
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10
Q

Tunica mucosa: Lamina muscularis mucosa

A

Few layers of smooth muscle cells beneath Lamina propria

-Natural frontier milli mucosa og submucosa

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11
Q

Enteric nervous system

A

Gut innervated w its own intrinsic nerve supply;

  • nerve fibers
  • clusters of nerve cells-peripheral ganglion cells
  • glial cells
  • ->located across all layers of GIT tube, en mest í MUSCULARIS EXTERNA OG SUBMUCOSA
  • Muscularis externa:
  • larger myenteric auerbach plx (regulates smooth m contraction, peristalsis, GIT motility)
  • Submucosa;
  • smaller submucosal meissner plx (regulates mostly glandular secretions, local blood flow)
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12
Q

Tunica submucosa

A

Loose CT
*Blood + lymph. vessels

  • might contain glands:
    a) muc.glands í esophagus. b)Brunner glands í duodenum

*Meissner submucosal autonomic nervous plx

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13
Q

Tunica muscularis externa

A

*skeletal muscle; esophagus og external anal sphincter

  • smooth muscle;
    a) stratum circular(internal) b)stratum longitud.(external)

*Ventriculus(stomach): 3 muscle layers, fibrae oblique innermost layer

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14
Q

Tunica muscularis externa frh

A

myenteric auerbach plx:
*Cajal interstitial cells (pacemakers), fyrir complex motility, peristalsis, secretions, transcellular transport, regeneration

–> Together w submucosal meissner plx = autonomic enteric nervous system (neurotransmitters)

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15
Q

Tunica adventitia/Serosa

A

1)Serosa: Thin layer of CT, cov w mesothelium

2) Adventitia; Thick layer of CT, carrying blood vessels, lymphatic innervation, without outer cover
- Fibers anchor the organ into its outer surroundings

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16
Q

Esophagus

A
  • Tunica mucosa:
  • Lamina epithelialis, stratified sq. non-keratinized
  • Lamina propria, loose CT. near stomach eru esoph.mucinus glands
  • Lamina muscularis: one layer, longitudinal muscle cells
  • Tunica muscularis externa:
  • stratum circulare (inner)
  • stratum longitudinale (outer)
  • Upper third esophagus=skeletal muscle
  • Middle esophagus=both skel/smooth m
  • Lower third=only smooth muscle
  • Tunica adventita/serosa:
  • loose CT. Only intraperitoneal p. of esophagus has serosa w mesothelium.
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17
Q

Stomach

A
  • Digestion proteins, triglicerides
  • forms chyme
  • prod. HCL, intrinsic factor and gastric lipase
  • prod. hormones (td gastrin, ghrelin)
-Wall consists of:
Tunica mucosa
Tunica submucosa
Tunica muscularis externa
Tunica serosa
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18
Q

Layers stomach

A

1) Tunica mucosa:
* Lamina epithelialis: simple columnar epithelium: secretes alkaline mucous
- epithelium of stomach invaginates into lamina propria=Gastric pits

  • Lamina propria: loose CT w fibroblasts, plasma cells, mast cells, lymphocytes and blood vessels
  • occupied by tubular glands (ext from base of gastric pits and reach lamina muscularis mucosa

*Lamina muscularis mucosa: one layer smooth muscle

2) Tunica muscularis externa:
- Innermost oblique layer: in cardiac region
- Middle circular layer: in pyloric region (forms pyloric spchinter)
- Outer longitudinal: smá evident hjá pylorus

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19
Q

Glands of stomach

A

1)cardiac glands 2)gastric glands proper 3)pyloric glands

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20
Q

Glands of stomach

A

1)Chief cells: columnar or pyramidal cells. Basophilic cytoplasm, nuclei near base, apical part w secretory granules w inactive pepsinogen enzyme and gastric lipase.

2) Parietal cells: Largest. Rounded or pyramidal cells. Spherical nucleus centrally, eosinophilic cytoplasm.
* Apical plasma membrane w invagination–>Intracellular canaliculi
* They produce Gastric Intrinsic factor og HCL

3)Mucous neck cells: Irregular/cuboidal/columnar. Nucleus near base. *prod mucous

4) Stem-Regenerative cells: Low columnar cells, oval nuclei.
* High rate of mitosis

5) Enteroendocrine DNES cells:
* Diffuse neuroendocrine system cells/D-cells: Somatostatin
* G-cells: Gastrin
* Enterochromaffin cells/EC-cells: Serotonin, Histamin

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21
Q

Small intestine: absorption surface

A

1) Plicae Circulares: Transverse folds of mucosa + submucosa
* Most developed in Jejunum

2) Vili: 0.5-1.5 mm. Long finger-like proj. of Lamina Propria into lumen
3) Microvilli: Modified apical plasmalemma of enterocytes covering intestinal villi

4)Crypts of Lieberkuhn:
*Simple tubular intestinal glands: Invagination of Lamina Epithelia into Lamina Propria
-cov by simple columnar epithelium, Goblet cells, Paneth cells(granulated epith. cells that secrete antimicrobial peptides/proteins t.d lysozyme, alpha-defensins and phospholipase A2),
Regenerative cells and enteroendocrine cells

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22
Q

Small intestine

A

Tunica mucosa:

  • Lamina epithelialis: Simple columnar epith
  • Absorptive cells(enterocytes), Goblet cells, Stem cells, Paneth cells, Enteroendocrine DNES cells, M-cells(take up intestinal microbial antigens->deliver them to GALT for immune rspns.)
  • Lamina Propria: forming core of vilus. Here are also intestinal glands (crypts of lieberkuhn)
  • Lamina propria and submucosa in ileum PEYERS PATCHES(L.nodules)
  • Tunica Submucosa: dense irregular CT
  • In duodenum, duodenal glands (Brunners glands)
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23
Q

Large intestine

A

Tunica Mucosa:

  • LIberkuhn crypts: Long and lined w very abundant goblet cells, færri absorptive cells og færri enteroendocrine cells.
  • No villi, no paneth cells
  • Lamina Propria: rich in lymphoid cells+nodules.

Tunica muscularis externa:

  • Inner circular, Outer longitudinal
  • Outer longitudinal is not continuous along surface–>forming taeniae coli (bands)
24
Q

Appendix

A
  • Is a diverticulum of the cecum
  • General structure similar to large intestine
  • fewer og shorter crypts of lieberkuhn
  • small, narrow og irregular lumen
  • lamina propria og submucosa m l.nodules
  • no taeniae coli
  • infrequent paneth cells
25
Q

Digestive glands (or glands associated w dig.system)

A

1) Liver (hepar)
2) Gallbladder (vesica fellea)
3) pancreas
4) major salivary glands

26
Q

Prenatal development of dig.glands

A 
1)Liver dev: from endoderm. 
The base(primordium) ---> hepatic diverticulum

2)Pancreas dev: from endoderm of the duodenum.
From dorsal wall–> dorsal bud
From ventral wall–> ventral bud
(Liver + pancreas dev: weeks 3-5)

3)Parotid gland: From ectoderm.
Epith. of primitive oral cav (stomodeum)

4)Submandibular gland: From endoderm
Epith. of floor of oral cav

5)Sublingual gland: From endoderm
Laterally to primordium of submandibular gland

(Major salivary glands dev: weeks 6-7)

27
Q

Liver (hepar)

A
  • largest organ um 1.5kg -Triangle shape -Intraperitoneal
  • In right upper fjórðung f neðan þind
  • 2main lobes, Right lobus dexter og Left lobus sinister.
  • On the right are caudate and quadrate lobes
  • Peritoneum on surface, except hjá fossa for gallbladder
  • Gilsson capsule(capsula fibrosa): on liver surf. Dense irregular CT grows into the hepatic parenchyma along the vessels and bile ducts (esp. in the portal spaces)
  • Porta hepatis: On visceral surf. Reinforced gilsson capsule.
  • Entry site for proper hepatic A, portal V
  • Exit for hepatic veins, common hepatic duct and l.vessels
28
Q

Liver function

A

Central metabolic organ:

a) exocrine: bile prod.
b) endocrine: hormone (td angiotensinogen)
- Performs um 500 funct.

  • C.hydrate, lipid + prot. metabolism:
  • C.hydrate: synth+storage glycogen (glycogenesis or glycogenolysis). Gluconeogenesis from AA, glycerol osfr

-Protein: N-AA synth, E-AA degradation, albumin synth
*coagulation factors:
I) fibrinogen II)prothrombin and V, VII, XIII
*Protein C, Protein S, antithrombin

-Lipid: synth of fatty acids, synth/degradation of cholesterol, triglycerides, phospholipids, lipoproteins(VLDL, HDL), ketone bodies.

28
Q

Liver function

A

Central metabolic organ:

a) exocrine: bile prod.
b) endocrine: hormone (td angiotensinogen)
- Performs um 500 funct.

  • C.hydrate, lipid + prot. metabolism:
  • C.hydrate: synth+storage glycogen (glycogenesis or glycogenolysis). Gluconeogenesis from AA, glycerol osfr

-Protein: N-AA synth, E-AA degradation, albumin synth
*coagulation factors:
I) fibrinogen II)prothrombin and V, VII, XIII
*Protein C, Protein S, antithrombin

-Lipid: synth of fatty acids, synth/degradation of cholesterol, triglycerides, phospholipids, lipoproteins(VLDL, HDL), ketone bodies.

29
Q

Liver function frh

A
  • erythrocyte forming in first trimester
  • blood reservoir (10% of total blood volume)
  • bile synth
  • detoxification: t.d ammonia, foreign subst..
  • hormone synth/degradation: angiotensinogen, thrombopoietin, IGF-1(insulin like growth factor), insulin degradation
  • Vitamin/mineral store: vít A, D, B12, E, K. minerals Fe(ferritin), Cu, Zn
  • lymph formation
  • p. of mononuclear phagocytic system
30
Q

Liver parenchyma organization

A
  • Hepatic lobule (lobule of central vein): building block of liver
  • formed by hepatocytes, arranged in cords, converge radially into central vein
  • Hepatic sinusoids: milli cords of hepatocytes (arterial+venous blood)
  • Cords of hepatocytes SURR. by reticular fibers
31
Q

Portal space

A

Along each hepatic lobules corners eru 3-6 portal spaces, filled w CT.

3 structures (portal-Gilssons Triad)

1) interlobular A (br of proper hepatic A)
2) interlobular V (br of portal V)
3) interlobular bile duct (simple cuboidal epith)

32
Q

Vascular supply of liver: Dual blood supply

A

1) Portal vein (deoxynated blood); brings 75% of blood from stomach, intestines and spleen rich in nutrients, low in O2.
2) Proper hepatic A (oxygenated blood): supplies 25% of blood. Low nutrients, High O2.

3)Arterial supply:
Abd.aorta --> Celiac A -->
common hepatic A -->proper hepatic A
--> segmented arteries --> interlobular aa
--> circumlobular aa --> sinusoids
  • Portal vein –> interlobular vein –> sinusoids
  • -> central vein –> (after leaving liver) Hepatic vein
  • -> IVC –> right atrium
33
Q

Bile ducts

A

1) Intrahepatic:
*bile canaliculi –>
Herrings ducts (simple cuboidal-Cholangiocytes) –>
Interlobular bile duct (Cholangiocytes) –>
Right + left hepatic ducts

3) Extrahepatic:
* Common hepatic duct + cystic duct = common bile duct (ductus choledochus)
* Common bile duct + pancreatic duct =hepatopancreatic ampulla (open on major duodenal papilla)

34
Q

Liver regeneration

A
  • Regenerative capacity is low under normal cond.
  • It regenerates after partial surgical resection (hepatectomy), and after toxic or infectious damage
  • loss of parenchyma –> mitosis of hepatocytes (Compensatory hyperplasia)
  • Oval cells: regenerative cells, located milli cholangiocytes
35
Q

Liver parenchyma organization

A

A classic hepatic lobule (lobule of the central vein)

  • portal lobule; central veins of three hepatic lobules, in the middle is one portal space (Triad)
  • Hepatic acinus; central veins of two hepatic lobules + two portal spaces. (area supplied by one circumlobular artery + one circumlobular vein)
  • distribution of hepatocytes in hepatic acinus acc. to O2 gradient and nutrient content;
    1) Zone 1 (periportal): high O2 + nutrients. Td prot synth
    2) Zone 2 (transient): average O2 + nutrients
    3) Zone 3 (periacinar): low O2 + nutrients. T.d lipid synth og storage, detoxification
36
Q

Liver parenchyma organization

A

A classic hepatic lobule (lobule of the central vein)

  • portal lobule; central veins of three hepatic lobules, in the middle is one portal space (Triad)
  • Hepatic acinus; central veins of two hepatic lobules + two portal spaces. (area supplied by one circumlobular artery + one circumlobular vein)
  • distribution of hepatocytes in hepatic acinus acc. to O2 gradient and nutrient content;
    1) Zone 1 (periportal): high O2 + nutrients. Td prot synth
    2) Zone 2 (transient): average O2 + nutrients
    3) Zone 3 (periacinar): low O2 + nutrients. T.d lipid synth og storage, detoxification
37
Q

Hepatocyte

A
  • Polygonal shape
  • forming anastomosing cords
  • 70-80% af liver volume
  • round nucleus, 1-2 nucleoli (sometimes two nuclei)
  • eosinophilic c.plasm (MANY m.chondrias)
  • basal surf (vascular pole): facing sinusoids. Has microvilli
  • Lateral surf (biliary pole): creates bile ducts. Has microvilli

*Lateral surf: tight junct (occludens), adherent junct(adherens og desmosomes) og gap junct

38
Q

Hepatocyte frh

A

RER; synth of albumin, coagulation factors, enzymes

SER: enzymes for biotransformation and detoxification of subst. Synth of bile acids, cholesterol and degredation of heme.

Lysosomes: degredation of damaged plasma proteins, storage of Fe and Cu

Inactive lysosomes: yellow-brown pigment lipofuschin

39
Q

Nonparenchymal liver cells

A

1) endothelial cells: simple sq. epith in sinusoids walls (have openings–>discontinuous)

  • milli endothelium og hepatocyte surf (blood pole): Perisinusoids space/Space of disse
    function: metabolism place, nutrient intake and foreign subst. + their release

2)Kupffer cells/liver macrophages: p of mononuclear phagocytic system. Remove damaged erythrocytes, foreign subst, bacteria. -Irregular shape -Fe reservoir

3) Hepatic stellate cells/cells of lto: -
- in Perisinusoid space -Star shaped
- not easily þekkjanlegar in preperations
- cytoplasm contains lipid droplets-VÍT A storage(50-80% of total body content)

40
Q

Gallbladder

A

Pear-shaped hollow organ

  • on visceral surf of liver, below right lobe(fossa for vesicae felleae)
  • collect, concentrate og release bile into duodenum (cystic duct joins common hepatic duct = common bile duct)

-svo common bile duct + pancr. duct = hepatopancreatic ampulla

41
Q

Microanatomy gallbladder

A

1) Tunica mucosa;
- forms mucosal folds, lined w simple columnar epithelium w microvilli (resorptive epith)
- Na/K/ATPase pump to concentrate bile.

*In neck (collum) of gallbladder are mucus glands–>protection of mucosa of bile
*The mucosa forms deep invaginations–>
Rokitansky-Aschoff sinuses

  • *Lamina propria; Loose CT
  • **Lamina muscularis mucosa is missing!

2) Tunica muscularis;
- bundles of smooth muscle cells oriented circular, longitudinal and oblique (contraction empties gallbladder)
- Contractions initiated by hormone cholecystokinin CCK og regulated by autonom n.system.

3)Tunica serosa/adventitia: Loose CT sheath

42
Q

Gallbladder-gallstones

A

Bile: yellow-dark green thick liquid.

  • 85% water, bile acids, bile pigments, cholesterol, fatty acids, salts osfr.
  • liver prod um 0.7-1.2 l of bile per day

*gallstones/cholelithiasis: due to disparity milli concentration of cholesterol, bile acids and phospholipids

43
Q

Pancreas

A

exocrine og endocrine funct.

  • Across abd. cav
  • under diaphragm
  • behind stomach
  • milli duodenum og spleen

*retroperitoneal

44
Q

Microanatomy of pancreas

A
  • CT capsule sends septa–>dividing pancreas into lobes and lobules.
  • Septa contain larger ducts, blood, lymphatics and autonom. nerves
45
Q

Exocrine p. of pancreas

A

a) secretory portion (pancreatic acini/alveoli): each composed of several serous, pyramidal cells
- the cells are polarized; basal p. is bsophillic (RER, nucleus) and apical p. is eosinophillic (GA and zymogenic granules-inactive precursors of enzymes)

b)duct system; intralobular;;;
intercalated (simple sq epith) --->
intralobular (simple cuboidal) --->
interlobular (simple columnar) --->
Main pancreatic duct

**Centroacinar cells; cells of the intercalated duct, which ext into the lumen of the acin. (do not contain zymogenic granules)

46
Q

Pancreatic juice of exocrine p. of pancreas

A

Pancr. juice made up of the exocr. component.

  • Enzymes: Trypsin, alpha-amylase, lipases, nucleases osfr.
  • Og alkaline juices (HCO3-)
  • CCK (pancreozymin) stimulates prod. enzymes
  • Secretin prod. alkaline juices to neutralize acidic chyme
47
Q

Pancreas, endocrine part

A
  • endocrine portion makes um 1.5% total volume of pancreas.
  • ->mostly in the cauda (tail)
  • Islet of langerhans (pancreatic islets);
  • round, oval clusters of endocrine cells. Surr by collagen fibers and supp. by fenestrated blood capillaries.

**acute pancreatitis:
sudden life threat. disease due to increased activation of pancr. enzymes. Enzymatic self-digestion and damage to the vessel wall (necrosis) and edema can occur

48
Q

Salivary glands

A
  • Exocrine glands, main ducts open into oral cav
  • prod. saliva og initial digestion of c.hydrates+lipids.
*saliva composition;
98% water
minerals
enzymes; amylase, lipase
leukocytes
epith. cells
lysozyme
IgA
48
Q

Salivary glands

A
  • Exocrine glands, main ducts open into oral cav
  • prod. saliva og initial digestion of c.hydrates+lipids.
*saliva composition;
98% water
minerals
enzymes; amylase, lipase
leukocytes
epith. cells
lysozyme
IgA
48
Q

Salivary glands

A
  • Exocrine glands, main ducts open into oral cav
  • prod. saliva og initial digestion of c.hydrates+lipids.
*saliva composition;
98% water
minerals
enzymes; amylase, lipase
leukocytes
epith. cells
lysozyme
IgA
49
Q

microanatomy salivary glands

A

a) secretory portion, 3 cell types

-Serous cells: pyramidal, round nucleus. Basal p. basophilic (RER). Apical p. m secr. granules (t.d amylase).
They form acinus or alveolus (round w small lumen)

  • Mucus cells: Columnar. Oval nucleus in basal p. Cytoplasm m mucin. They form a tubule (oval shape)
  • Myoepithelial cells: on inner surf. of basement membrane. Squamous cells w long processes. Með myofilaments (actin, myosin) –> contraction empties secretory portion
50
Q

microanatomy salivary glands

A

b) duct system er intralobular;

Intercalated—>Striated—>interlobular—>main duct(stratified columnar, stratified sq. nonkeratinized)

51
Q

Parotid gland

A
  • Paired
  • Alveolar
  • Bara serous gland
  • Many intercalated and striated ducts. Alot of fat cells

*Secretion is sparse, aqeous (alpha-amylase, proteins w antimicrobial effects)

52
Q

Submandibular gland

A
  • paired
  • tubuloalveolar
  • seromucus (mostly serous)
  • more striated ducts in the serous part heldur en í mucus p.
53
Q

Sublingual gland

A
  • paired
  • tubuloalveolar
  • seromucus (mostly mucus)
  • few striated ducts, serous cells
  • not covered by CT capsule
  • main duct joins duct of submandibular gland and form common duct
  • -> enters oral cav (at sublingual papilla)

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