Histology of GI Glands Flashcards Preview

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Flashcards in Histology of GI Glands Deck (56):
1

Digestive glands have lubricating, protective, digestive, and absorptive functions mediated by their secretory products. What are the 3 main digestive glands?

Major salivary glands: associated with oral cavity through independent excretory ducts

Exocrine pancreas: secretes alkaline aqueous and enzymatic product into the duodenum

Liver: endocrine and exocrine gland with extensive access to blood circulation

2

______ glands may exist as simple invaginations of the epithelium or may have no contact with epithelial surface. They secrete mucus, hormones, enzymes, and wastes.

Exocrine

3

_________ = part of exocrine glands that acts as passageway for glandular secretions to be released

________ = cellular part of exocrine glands that synthesize and release secretory product

Excretory duct

Secretory units

4

Secretory cells of exocrine glands are organized in an _______

Acinus

5

______ acini = cloudier looking cytoplasm, produce thick, glycoprotein rich product

______ acini = clear-staining cytoplasm, produce a water-based product

_______ = contain a core of mucous cells surrounded by serous demilune

Mucous

Serous

Mucoserous

6

The secretory component of exocrine glands may be _____ or ________, both of which may be coiled or branched

The duct system may be a _____ gland or _____gland

Tubular; alveolar

Simple (unbranched); compound (branched)

7

3 possible mechanisms of secretion from exocrine glands. What is the most common for the GI system?

Merocrine = exocytosis of apical end of secretory cells (sweat glands)

Holocrine = disintigration of the secretory cell (sebaceous glands)

Apocrine = release of membrane-enclosed vesicles (sweat glands)



**most GI glands are merocrine**

8

Describe general histology of a salivary gland

Secretory (epithelial) cells line the ducts and produce saliva (release controlled by ANS)

CT capsule with septa divides gland into lobes (interlobar septa), and smaller lobules (interlobular), providing rout for neurovasculature

9

What are the 3 types of salivary glands? Which one is largest?

Parotid (largest)
Sublingual
Submandibular

10

Which salivary gland is often confused histologically with the pancreas? How can the 2 be differentiated?

Parotid

Differentiated based on presence of adipocytes in parotid gland tissue, as well as presence of islets of langerhans in pancreas

11

The parotid gland is formed by acini containing exclusively ______ cells with a basal nucleus and an apical cytoplasm with secretory granules.

Granules are rich in proteins, including _____-rich proteins, enzymes, and proteins with ______ activity like cystatins and hystatins.

The parotid gland has the longest _____ ducts. ______ cells can be visualized at the periphery of each acinus

Serous

Proline; antimicrobial

Intercalated; myoepithelial

12

Which of the salivary glands is considered mixed, but it is predominantly mucous?

Sublingual gland

13

Describe histological characteristics of the sublingual gland

Lacks defined capsule but is divided by CT into small lobes

Intercalated and striated ducts are poorly developed

14

Which of the salivary glands has both serous and mucous cells but serous cells predominate?

Submandibular gland

15

Describe histological features of submandibular gland

Mucous cell-containing acini are capped by serous demilunes (surrounding myoepithelial cells control serous secretions)

Intercalated ducts are shorter and striated ducts are longer than those in parotid gland

16

Hepatic _____ = polygonal structures that comprise functional unit of the liver

_______ = liver cells that function in metabolism, storage, and bile production (similar to acinar cells in that they secrete an exocrine product but they are organized in columns)

Lobules

Hepatocytes

17

Components of hepatic lobules

Central venule in core of hepatic lobule - collects blood in hepatic sinusoids

Hepatocytes

Sinusoids

Portal triad = branches of hepatic a. and portal v. and bile duct

18

While looking at a liver slide you note the following things:

_____ ____ delineated on all sides by CT

_____ ______ = brown staining stick-like structures located in between hepatocytes

_____ ____ including portal vein branches, hepatic a. branches, and bile ductules

Hepatic lobule

Bile canaliculi

Portal triad

19

There are 3 ways to reference the functional organization of the liver:

______ = based on structural units of the liver

_____ = based on bile drainage pathway from adjacent lobules toward the same bile duct

______ = based on [O2] gradient along sinusoids of adjacent lobules

Hepatic lobule

Portal lobule

Liver acinus

20

Describe the hepatic lobule functional organization of the liver

Hexagonal in shape and centered on central venule

Portal triads are positioned at angles of hexagon

[this is classic organization]

21

Describe portal lobule functional organization of the liver

Portal triad is the central axis, draining bile from the surrounding hepatic parenchyma

22

Describe the liver acinus functional organization of the liver

Boundaries are determined by a terminal branch of the hepatic a.

Flow of arterial blood creates gradient of O2/nutrients

Establishes zones 1, 2, and 3; cells within each zone have different metabolic functions

23

Describe the 3 zones delineated in the liver acinus functional organization of the liver

Zone 1 = closest to portal triad; hepatocytes actively synthesize glycogen and plasma proteins, O2 concentration is high

Zone 2 = intermediate

Zone 3 = furthest from portal triad; poor O2 concentration, this zone important for detoxification. Hepatocytes here are susceptible to hypoxic damage

24

The hepatocyte is the exocrine and endocrine cell of the liver. They form anastomosing ____-cell thick plates which limit sinusoidal spaces

The _________ is what separates the hepatocyte plates from the blood sinusoidal space. Blood from the portal vein and hepatic a. flows into the sinusoids and is drained by the _____ _____. Excess fluid in this space is collected in the ________ (periphery of hepatic lobule), drained by lymphatic vessels.

One

Perisinusoidal space of Disse; central venule; Space of Mall

25

The apical domain of hepatocytes borders the ______ ______, a trench-like depression lined by microvilli that is sealed at the sides by occluding junctions to prevent leakage of ____, the exocrine product of the hepatocyte

Bile canaliculus; bile

26

The basolateral domain of the hepatocyte has abundant microvilli facing the space of _____. It is important for absorption of ________-borne substances and secretion of plasma proteins

Disse; blood

27

Specialized macrophages found along the endothelial lining of hepatic sinusoids (larger than the endothelial cells). these cells detect and phagocytose aging erythrocytes

Kupffer cells

28

The pancreas has both endocrine and exocrine gland functions but is primarily exocrine. The exocrine pancreas is what type of gland?

Branched tubuloacinar gland

[organized into head, neck, body, and tail]

29

Arterial supply to pancreas

Vessels derived from celiac trunk/artery, SMA, and splenic a.

30

Venous drainage of pancreas

Venous drainage flows into portal venous system and splenic v.

31

Efferent innervation of pancreas

Through vagus and splanchnic nn

32

Does the pancreas have a capsule? How are its lobules separated?

Pancreas is surrounded by CT but does not have a capsule proper

Lobules are separated by CT septa carrying blood and lymphatics, nerves, and excretory ducts

33

What is the functional unit of the exocrine pancreas?

Serous acinus

34

The functional unit of the pancreas is the serous acinus. The lumen of the acinus begins the secretory-excretory duct system, and is lined with what cell type unique to the pancreas?

Centroacinar cells - continuous with low cuboidal epithelium and secrete bicarb, sodium, and water to alkalinze secretions

35

What are the 3 identifying characteristics of a pancreatic acinar cell?

Well developed RER

Prominent golgi apparatus

Apical domain of zymogen granules

36

How does the content of the zymogen granules of pancreatic acinar cells change with a protein-rich diet vs. a carb-rich diet?

Protein rich diet —> increased synthesis of proteases

Carb-rich diet —> increased synthesis of amylases, decreased synthesis of proteases

37

Zymogen granules contain inactive proenzymes normally activated in the duodenum. Premature activation of these enzymes may result in what condition?

Acute Pancreatitis

38

Premature activation of pancreatic enzymes results in autodigestion of pancreatic gland following their release, particularly with _______ —> _________, and inactivation of _____ inhibitor

Trypsinogen; trypsin; trypsin

39

What are some triggers for acute pancreatitis attacks? What are the symptoms?

Usually follows trauma, heavy meals or excessive alcohol ingestion, or biliary tract disease

Symptoms: severe abdominal pain, nausea, and vomiting

40

Condition characterized by fibrosis and partial or total destruction of pancreatic tissue, of which alcohol is a major cause

Chronic pancreatitis

41

______ from the duodenum binds to receptors of pancreatic acinar cells and stimulates granule release

Cholecystokinin

42

What is the pathway of secretion from the pancreas, starting at the intercalated ducts?

Intercalated ducts —> interlobular ducts** —> main pancreatic duct directly into hepatopancreatic ampulla

**note that exocrine pancreas lacks striated ducts

43

Which of the following glands specific to the GI system is characterized by a straight tubular lumen, simple columnar secretory cells, and is found in the large intestine?

A. Simple tubular glands
B. Simple coiled tubular glands
C. Simple branched tubular glands
D. Compound branched tubular glands
E. Compound alveolar/acinar glands
F. Compound tubulo-alveolar/acinar glands

A. Simple tubular glands

44

Which of the following glands specific to the GI system is characterized by multiple tubular portions connecting to single unbranched duct, simple columnar secretory cells without goblet cells, and are found in the stomach?

A. Simple tubular glands
B. Simple coiled tubular glands
C. Simple branched tubular glands
D. Compound branched tubular glands
E. Compound alveolar/acinar glands
F. Compound tubulo-alveolar/acinar glands

C. Simple branched tubular glands

45

Which of the following glands specific to the GI system is characterized by branched duct system, acinar secretory portion, and are found in the pancreas?

A. Simple tubular glands
B. Simple coiled tubular glands
C. Simple branched tubular glands
D. Compound branched tubular glands
E. Compound alveolar/acinar glands
F. Compound tubulo-alveolar/acinar glands

E. Compound alveolar/acinar glands

46

Which of the following glands specific to the GI system is characterized by single tube coiled in 3D, simple cuboidal secretory cells, and are typical integumentary sweat glands?

A. Simple tubular glands
B. Simple coiled tubular glands
C. Simple branched tubular glands
D. Compound branched tubular glands
E. Compound alveolar/acinar glands
F. Compound tubulo-alveolar/acinar glands

B. Simple coiled tubular glands

47

Which of the following glands specific to the GI system is characterized by branched ducts with tubular, acinar, and tubular with acinar demilunes, secrete a mucoserous product, and are characteristic of submandibular salivary gland?

A. Simple tubular glands
B. Simple coiled tubular glands
C. Simple branched tubular glands
D. Compound branched tubular glands
E. Compound alveolar/acinar glands
F. Compound tubulo-alveolar/acinar glands

F. Compound tubulo-alveolar/acinar glands

48

Which of the following glands specific to the GI system is characterized by branched duct system, tubular secretory portion, and are characteristic of Brunner’s glands in the duodenum?

A. Simple tubular glands
B. Simple coiled tubular glands
C. Simple branched tubular glands
D. Compound branched tubular glands
E. Compound alveolar/acinar glands
F. Compound tubulo-alveolar/acinar glands

D. Compound branched tubular glands

49

Trace saliva flow from acinus to main duct; include changes in epithelium along the way

Acinus —> intercalated duct (squamous to low cuboidal epithelium) —> striated duct (cuboidal to columnar epithelium) —> interlobular duct (pseudostratified columnar) —> lobar duct (stratified columnar) —> main duct

50

Organelles in hepatocytes

RER = synthesis of plasma proteins

SER = synthesis of glycogen, lipids, and detox mechanisms

Golgi = glycosylation of secretory proteins and sorting of lysosomal enzymes

Lysosomes = degradation of aged plasma glycoproteins, iron storage

Peroxisomes = contain oxidases and catalases for beta-ox of FA’s and production/breakdown of hydrogen peroxide, also contain peroxins which are proteins involved in peroxisome biogenesis

51

Pathology of liver characterized by increased iron absorption and accumulation in lysosomal hepatocytes. complications include cirrhosis and cancer of liver

Hereditary hemochromatosis

52

Hereditary disorder of copper metabolism in which excessive deposits of copper in liver and brain lysosomes produce chronic hepatitis and chronic liver disease

Wilson’s disease

53

In chronic liver disease, perisinusoidal cells remain in quiescent, nonproliferative state but can proliferate when activated by ____ cells and _______

This leads to ______ and inflammatory cells in distorted portal space

Kupffer; hepatocytes

Fibrosis

54

What 3 conditions may result from long-term consumption of ethanol?

Fatty liver - reversible if EtOH consumption discontinued

Steatohepatitis - fatty liver + inflammatory reaction

Cirrhosis - collagen proliferation or fibrosis

55

Acute vs. chronic hepatitis

Acute = characterized by loss of appetite, nausea, vomiting, jaundice

Chronic = defined by presence of fibrosis, together with hepatocyte necrosis and inflammatory lymphocytic activity

56

Different types of viral hepatitis

HAV = caused by spread through ingestion of contaminated food/water; causes acute hepatitis that rarely becomes chronic

HBV = via sexual contact, blood/serum transfer thru shared needle in drug abuse; 10% develop chronic hepatitis

HCV = largely caused by blood transfusion; 50-70% develop chronic hepatitis. Therapy available via antiviral agents