Njds Histology - Digestive Glands

Front 1

Question: What organ functions as both an exocrine and an endocrine gland?

Back 1

Answer: Pancreas

Front 2

Question: The exocrine portion of pancreas is responsible for..

Back 2

Answer: The production and release of digestive enzymes

Front 3

Question: Where do digestive hormones produced from?

Back 3

Answer: In aggregates of cells called ISLETS OF LANGERHANS (Digestive hormones are eventually released into the bloodstream)

Front 4

Question: Which digestive enzymes do exocrine component of pancreas produce?

Back 4

Answer: 1.Lipase - breaks down fats 2.Carboxypeptidase - breaks down certain peptide bonds 3.Trypsin - hydrolyzes peptide bonds 4.Chymotrypsin - cleaves carboxyl links of certain amino acids 5.Amylase - breaks down starch and glycogen 6.Elastase - hydrolyzes elastin

Front 5

Question: What are the 2 hormones that control pancreatic secretion?

Back 5

Answer: 1.Secretin - produced by enteroendocrine cells of the small intestine. Causes buffer to be released by ductal cells, and insulin release 2.Cholecystokinin - produced by APUD cells of small intestine. Causes gall bladder contraction, slows gastric emptying time, stimulates pancreas enzyme secretion

Front 6

Question: Describe the structure of exocrine portion of the pancreas

Back 6

Answer: The exocrine portion of the pancreas is compound acinar gland, similar to the parotid gland. The acini are made up of acinar and centroacinar cells (intra-acinar extension of the intercalated ducts).

Front 7

Question: When digestive enzymes are produced from acini, which pathway do they follow?

Back 7

Answer: Acinar cell -> Centroacinar cell -> Intercalated ducts -> columnar interlobular ducts (there are no striated ducts in the pancreas) -> Two main ducts - Duct of Santorini (accessory) and Duct of Wirsung (main)

Front 8

Question: The duct cells in pancreas produce..

Back 8

Answer: Bicarbonate-rich buffer solution, which neutralizes the acidic gastric contents passing into the duodenum

Front 9

Question: Endocrine component consists of..

Back 9

Answer: The islets of Langerhans, which are distributed throughout the pancreas, but are more numerous in the tail of the gland.

Front 10

Question: Describe the structure of the cells of the islets of Langerhans

Back 10

Answer: The cells are round to polygonal in shape, and surrounded by a rich capillary network. A thin capsule of reticulin fibers separate each islet from the exocrine pancreatic parenchyma.

Front 11

Question: How many types of cells comprise the islets of Langerhans and what are they?

Back 11

Answer: Five types of cells.
1. Alpha(A)-cells
2. Beta(B)-cells
3. Delta(D)-cells
4. F(PP) cells
5. G cells

Front 12

Question: What is the morphology and function of Alpha(A)-cells?

Back 12

Answer: Large cells with dark cytoplasm that are mainly found on the periphery of the islet (20% of islet cells).
Secrete glucagon, which increases blood sugar.

Front 13

Question: What are the mechanism and functions of glucagon?

Back 13

Answer: Glucagon is released when blood glucose levels are low - acts on hepatocytes, which break down glycogen into glucose and release it into bloodstream. It also activates gluconeogenesis.

Front 14

Question: What is the morphology and function of Beta(B)-cells?

Back 14

Answer: (70% of islet cells) Smaller in cell and granule size than A-cells.
Secrete insulin, which decreases blood sugar.

Front 15

Question: What are the mechanism and functions of insulin?

Back 15

Answer: Insulin binds to insulin receptors on cells (especially skeletal muscle, liver, and adipose), which allows glucose to be taken into cell. It also encourages glucose utilization by cells, increases protein synthesis and formation and storage of neutral lipids.

Front 16

Question: What is the function of Delta(D)-cells?

Back 16

Answer: (5% of islet cells)
Secrete somatostatin

Front 17

Question: What are the functions of somatostatin?

Back 17

Answer: Serves both a paracrine and endocrine function (inhibits hormone release in adjacent A and B cells of pancreas, and reduces smooth muscle contractions of the alimentary tract and gall bladder.

Front 18

Question: What is the function of F(PP)cells?

Back 18

Answer: (1% of islet cells)
Secrete pancreatic polypeptide (inhibits exocrine pancreatic secretions)

Front 19

Question: What is the function of G cells?

Back 19

Answer: (1% of islet cells)
Secrete gastrin, which stimulates production of HCL by parietal cells in stomach.

Front 20

Question: What is the second largest organ of the body?

Back 20

Answer: Liver

Front 21

Question: What are the main functions of liver?

Back 21

Answer: It serves to process and store the nutrients absorbed by the digestive tract, in addition to many other functions.

Front 22

Question: The liver is surrounded by..

Back 22

Answer: a thin capsule called Glisson's capsule, which extends into the organ subdividing it into lobes and lobules.

Front 23

Question: How many kinds of lobules do liver contain and what are they?

Back 23

Answer: 3 kinds
1. The liver (classic) lobule
2. The portal lobule
3. Hepatic acinus (lobule)

Front 24

Question: The liver lobule consists of..

Back 24

Answer: a poorly-demarcated collection of hepatocytes that form a hexagonal structure.

Front 25

Question: What is the name of an area (point) where three liver lobules contact each other

Back 25

Answer: Portal Area (TRIAD)

Front 26

Question: Portal area is comprised of..

Back 26

Answer: connective tissue, hepatic artery, portal vein, bile duct and (sometimes)lymphatics

Front 27

Question: How many triads per one liver lobule?

Back 27

Answer: 3-6 triads

Front 28

Question: What is located at the center of the liver lobule?

Back 28

Answer: Central vein (toward which there are converging plates of anastomosing hepatocytes, enclosing liver sinusoids)

Front 29

Question: Describe portal lobule.

Back 29

Answer: Another method of visulaizing liver function (in terms of bile drainage).

Front 30

Question: The portal lobule is a 1.______ structure with the 2._______ at the center and the 3._______ at the tip of each angle.

Back 30

Answer:
1.triangular
2.portal triad
3.central vein

Front 31

Question: Describe hepatic acinus.

Back 31

Answer: a diamond-shaped area that is supplied by a terminal branch of the distributing veins encompassing portions of two adjacent liver lobules.

Front 32

Question: How many zones are in hepatic acinus?

Back 32

Answer: 3 zones
Zone I - closest to the distributing vein and the first to affect or be affected by the passing blood; these hepatocytes are actively synthesizing proteins
Zone II - middle zone (transition zone)
Zone III - encounters blood on its way to the central vein that has been heavily altered by zones I and II. Largely deoxygenated blood; the hepatocytes here play a role in detoxification.

Front 33

Question: Liver receives blood from two sources. What are they?

Back 33

Answer: Portal vein (80%) and hepatic artery (20%)

Front 34

Question: What are the properties of blood that passes portal vein?

Back 34

Answer: Oxygen-poor, nutrient-rich blood from pancreas, spleen and intestines.

Front 35

Question: In the triads, the branches of the portal vein are called..

Back 35

Answer: the portal venules

Front 36

Question: Branches of portal vein that surround the periphery of the lobules are called..

Back 36

Answer: the distributing veins

Front 37

Question: What is the pathway of deoxygenated-blood exiting the liver starting from distributing veins?

Back 37

Answer: Distributing veins -> inlet venules -> sinusoids -> central vein -> sublobular vein -> hepatic veins -> out of liver

Front 38

Question: Hepatic arter branches to form the 1.______, some of which occupy the 2._______, and some of which empty directly into the 3.________.

Back 38

Answer:
1.interlobular arteries
2.portal area
3.sinusoids

Front 39

Question: The sinusoids contain both..

Back 39

Answer: arterial and venous blood

Front 40

Question: Hepatocyte morphology and location.

Back 40

Answer: Polyhedral cells with 1-2 nuclei that form anastomosing plates that converge towards the central vein. They are exposed at several points to the walls of the sinusoids or to adjacent hepatocytes.

Front 41

Question: What is the space between adjacent hepatocytes called?

Back 41

Answer: Bile canaliculus

Front 42

Question: What are the functions of hepatocytes?

Back 42

Answer:
1.Storage - vitamins (A,D,B12)
2.Transformation and detoxification - inactivation of drugs and toxins
3.Protein synthesis - mainly blood proteins (for coagulation, immune system, transport)
4.Metabolism - lipids, carbohydrates, proteins
5.Excretion - bilirubin (breakdown product of hemoglobin)
6.Bile production

Front 43

Question: What are the functions of bile?

Back 43

Answer: absorbs fats, eliminates most of the cholesterol produced by the liver, excretes the breakdown products of blood.

Front 44

Question: What is space of Disse?

Back 44

Answer: Space of Disse separates the endothelial cells of the sinusoids from the hepatocytes.

Front 45

Question: Which components comprise space of Disse?

Back 45

Answer: Hepatocyte microvilli, nonmyelinated nerve fibers, Ito cells(fat storage), and pit cells(type of NK cell).

Front 46

Question: What phagocytic cell reside within the sinusoids?

Back 46

Answer: Kupffer cells

Front 47

Question: Bile is composed of..

Back 47

Answer: cholesterol, lecithin, fatty acids, bilirubin glucuronide, bile salts, and water. Most of these components are absorbed in the intestine and transported via the blood to the bile canaliculi.

Front 48

Question: What is bile canaliculi?

Back 48

Answer: the initial part of the bile duct system. It consists of narrow channels between adjacent hepatocytes, into which protrude microvilli. The canaliculi reach their endpoint near the portal areas - bile therefore flows in the opposite direction of blood

Front 49

Question: What are the cell types of the bile duct?

Back 49

Answer: clear cuboidal or columnar cells.

Front 50

Question: Numerous bile ducts eventually converge to form..

Back 50

Answer: the right and left hepatic ducts (which lead bile to gall bladder)

Front 51

Question: Gall bladder is a 1.______ organ that rests along the underside of the 2._______.

Back 51

Answer:
1.hollow
2.liver

Front 52

Question: What are the functions of gall bladder?

Back 52

Answer: Functions in bile storage, concentration, and release. Also, communicates with the hepatic duct by way of the cystic duct, to form the common bile duct.

Front 53

Question: What are the layers of gall bladder

Back 53

Answer: Mucosa (highly folded, simple columnar epithelium), lamina propria (areolar connective tissue), muscularis externa, and serosa. No muscularis mucosa.

Front 54

Question: What hormone causes gall bladder contraction?

Back 54

Answer: cholecystokinin, which is released by the enteroendocrine cells of the small intestine from the stimulus of dietary fat present within its lumen.

Front 55

Question: Bile empties into duodenum through..

Back 55

Answer: ampulla of Vater (junction of common bile duct and pancreatic duct surrounded by sphincter of Oddi)