Histology Prelab - Digestive Glands

Endocrine: Islets of Langerhans (pancreatic islets)

Exocrine: Large interlobular ducts

Pancreatic lobules containing:

-numerous pure serous acinar cells

-Intercalated ducts

-Centroacinar cell

-Intralobular duct

What are the key histological features of the pancreas?

AKA pancreatic islets

Pale clusters of cells interspersed within lobules and surrounded by acinar units

No ducts associated

What are islets of Langerhans?

Large diameter with simple columnar to stratified surrounded by DICT

What are pure serous acinar units?

Smallest duct drains the serous acinar unit

Contains simple squamous/cuboidal epithelium and centroacinar cell

Secretes bicarbnate ion

Drains into intralobular duct

What are intercalated ducts?

Found in center of acinar unit

Light blue/gray stained with central nucleus

Represents the start of the intercalated duct (part of it)

Secretes bicarbonate ion

What are centroacinar cells?

Larger than intercalated duct but still within lobule

Typically cuboidal with thin layer of CT

No striated duct in pancreas, only found in salivary glands

Transport function only

What is an intralobular duct?

the serous acinar cells of the lobule

The ducts that transport digestive enzymes to the duodenum originates within ___________________

Islets of Langerhans (Pancreatic islets)

The endocrine function of the pancreas is associated with _______________________ (histological structure)

This is the location of the rER and the nucleus

Why do serous cells have a basophilic stain at the basal region?

Digestive enzymes

Serous pancreatic acinar cells contain vesicles that contain _____________________

Islets of Langerhans (pancreatic islets)

Centroacinar cells

What are two features that distinguish the pancreas from salivary glands?

Intercalated duct

What is the smallest duct within a pancreatic lobule?

Found in DICT between lobules

DICT often contains BVs and nn.

What are interlobular ducts?

Alpha, beta and delta cells

What cells are found in pancreatic islets?

Secrete glucagon in response to low blood glucose

Works with adrenal gland hormones and responds to sympathetic stimulation

What do alpha cells do in the pancreatic islets?

Secrete insulin in response to high blood glucose

Inhibition of insulin when low blood glucose

What do beta cells do in the pancreas?

Elevated blood glucose by the break down of glycogen, lipids, and proteins as well as release of glucose into blood

What is the outcome of alpha cells secreting glucagon?

Stimulated uptake of glucose into liver cells, neurons, skeletal muscle, and adipose

Glucose stored in cells as glycogen, proteins, or lipids if not used

What is the outcome of beta cells releasing insulin?

Secrete somatostatin in response to ACh, ghrelin, and high glucose

Can inhibit beta cells to prevent hypoglycemia

What do delta cells do in the pancreas?

Hormones released by enteroendocrine cells in duodenum:

CCK - stimulation of bile release

Secretin - simulation of bicarbonate release

When chyme enters the duodenum, how are pancreatic cells stimulated?

Intramural or intrapancreatic ganglia

Parasympathetic ganglia in the pancreas are known as ________________________

Outside the walls of the organs in the celiac and mesenteric ganglia

Where are sympathetic fibers found in the pancreas?

Splanchnic nerve fibers

What are the long, postganglionic sympathetic nerve fibers called in the pancreas?

A CT capsule and serosa (visceral peritoneum)

What covers the outside of the liver?

Hexagonal shape

Centrally placed vein

Several peripherally located portal areas between adjacent lobules

What is do liver lobules look like?

Portal triad:

Portal vein (if small - venule)

Hepatic artery (if small - arteriole)

Bile duct (if small - ductule)

What do portal areas contain in the liver?

From portal area to central vein

What is the direction of the flow of blood within liver lobules?

From center of lobule (near central vein) to portal area

What is the direction of the flow of bile in liver lobules?

Sinusoids between hepatocytes

Portal vessels are drained by what type of capillary?

Sinusoids

What vessels are inter-hepatic?

Portal venule and arteriole

What vessels are interlobular in the liver?

4-6

How many portal areas are there per lobule?

AKA terminal hepatic vein

Located at center of lobule

Receives blood from portal area vessels via sinusoids

What is the central vein of liver lobules?

Epithelial cells in the liver

Represent sinusoids

Responsible for bile and cholesterol synthesis and bilirubin production

What are hepatocytes?

Nothing

What accompanies the central vein in liver lobules?

3, distribution of oxygen and nutrients

Functionally, the liver is said to have __ regions that reflect ______________________________

Zone 1 - periportal area

Zone 2 - mid-lobular area

Zone 3 - centrilobular area

What are the three functional regions within the liver?

Periportal area

What zone in the liver has the most nutrients and oxygen?

Centrilobular area

What zone in the liver has the least nutrients and oxygen?

Centrilobular area

What zone is most susceptible to drug toxicity in the liver?

Periportal area

What zone is best suited for oxidative metabolism?

Bile canaliculi (singular = canaliculus)

Where does bile that is synthesized by hepatocytes first enter?

Canal of Hering

After entering bile canaliculi, where does bile travel?

Bile

"What is the principal exocrine product of the liver?

Closest to central vein

If bile blockage occurs, bile will accumulate in the liver cells closest to the point of blockage. If it is a mild block, where would you see this accumulation?

Closest to portal area

If bile blockage occurs, bile will accumulate in the liver cells closest to the point of blockage. If it is a large block (main hepatic duct), where would you see this accumulation?

Where the blockage occurs

Where is the point of accumulation of bile determined by in a blockage?

Gallstones

What is the most common etiology of bile obstruction?

Pain, nausea/vomiting, jaundice

How is bile obstruction manifested?

Stagnation of bile due to impaired secretion or obstruction of bile flow anywhere along flow path

What is cholestasis?

Intrahepatic, extrahepatic

If the blockage of the bile duct occurs inside the liver, if is considered ________________________. If it occurs outside the liver, it is considered to be ____________________

Bile acids and bilirubin accumulate

Bilirubin accumulates as bile pigment in hepatocytes, bile canaliculi, and in severe cases, bile ductules

Eventually, bilirubin pigments and bile acids spill into blood causing jaundice

What happens if the bile duct is blocked?

Store and concentrate bile synthesized by hepatocytes

What is the function of the gallbladder?

The common bile duct

Bile is delivered to the gallbladder from the liver via ________________________

the 2nd part of the duodenum, hepatopancreatic ampulla, sphincter of hepatopancreatic ampulla (AKA sphincter of Oddi)

To be used, bile is released into ________________________ at the _____________________________ controlled by the ______________________________

Simple columnar epithelium with apical microvilli

Mucosa highly folded - but no true villi and plicae

Crypts are absent

Submucosa and muscularis mucosa absent

muscularis externa present, but no distinct layers

Both adventitia and serosa present

What are the key histological features of the gallbladder?

Absorption of water increases concentration of bile

Why does epithelium in the gallbladder have an absorptive function?

Blood vessel

Identify the structure labeled A

DICT

Identify the type of tissue labeled B

Interlobular duct

Identify the structure labeled C

Pancreatic lobule

Identify the structure labeled D

CT (not specified)

Identify the type of tissue labeled E

Pancreatic islets (islets of Langerhans)

Identify the structures labeled F

Intralobular ducts

Identify the structures labeled G

Interlobular duct

Identify the structure labeled H

ANS ganglia (intramural or intrapancreatic ganglia)

Identify the structure labeled I

Pancreatic serous acinar unit

Identify the structure labeled A

Pancreatic serous cells

Identify the cells labeled B

Intercalated duct

Identify the structure labeled C

Centroacinar cell

Identify the cell labeled D

Centroacinar cell

Identify the cell labeled E

Intercalated duct

What structure is the cell labeled F the beginning of?

Serous cell

Identify the cell labeled G

Intralobular duct

Identify the structure labeled A

Intercalated duct

Identify the structure labeled B

Intercalated duct

Identify the structure labeled A

Centroacinar cells

Identify the cells labeled B

Pancreatic lobule

Identify the structure labeled C

Intralobular duct

Identify the structure labeled D

Centroacinar cell

Identify the cell labeled E

Arteriole

Identify the structure labeled F

Venule

Identify the structure labeled G

Interlobular duct

Identify the structure shown in the image

Arteriole

Identify the structure labeled B

Smooth muscle

Identify the type of tissue labeled B

Interlobular duct

Identify the structure labeled C

Pancreatic lobule

Identify the structure under the label E

Pancreatic islet (islet of Langerhans)

Identify the structure shown in the image

Alpha, beta, and delta cells

Identify the types of cells that would be found in the structure shown in the image

Endocrine

Identify whether the structure shown is exocrine or endocrine

Centroacinar duct cell

Identify the cell labeled A

Centroacinar duct cell

Identify the cell labeled B

Pancreatic islet (islet of Langerhans)

Identify the structure labeled C

Pancreatic serous acinar cells

Identify the cells labeled D

Centroacinar duct cell

Identify the cell labeled E

Intralobular duct

Identify the structure labeled A

Intramural ganglion (intrapancreatic ganglion)

Identify the structure labeled B

Pancreatic islet (Islet of Langerhans)

Identify the structure labeled C

Pacinian corpuscle

Identify A

Large interlobular duct

Identify B