L24 Digestive System II

Question 1

Small salivary glads are found where?

Answer 1

Small salivary glands are situated in submucosa of oral cavity and tongue.

Question 2

How are the small salivary glands grouped?

Answer 2

• Lingual
• Labial
• Buccal
• Molar
• Palatine

Question 3

There are three large salivary glands the __1__ (beneath the tongue), the __2__ (floor of the mouth), and the __3__.

Answer 3

1) sublingual
2) submandibular
3) parotid

Question 4

The sublingual gland is the tongue and has [many or few?] ducts.

Answer 4

many

Question 5

The ducts of the submandibular gland are behind the __?__

Answer 5

teeth

Question 6

The parotid gland is the largest salivary gland, and it empties into the mouth at __?__

Answer 6

the second molar

Question 7

All salivary glands are __?__ glands

regarding the shape

Answer 7

tubulo-acinar

Question 8

The large salivary glands secrete different things. The glands proximal to the oral cavity (i.e. sublingual) secrete __1__. The distal glands (i.e. parotid) secrete __2__. While the submandibular (in the middle) secretes __3__.

Answer 8

1) mucous acini
2) serous acini
3) serous and mucousj acini

Question 9

What is the largest gland in the body?

Answer 9

The liver

Question 10

Is the liver an endocrine or exocrine gland?

Answer 10

Exocrine

Secretes onto an epithelium via a duct

Question 11

Comment on the blood flow to the liver.

Answer 11

Highly vascularised.

Receives blood from 2 vessels: hepatic artery and hepatic portal vein.

25% arterial blood, 75% venous blood.

Blood is discharged into small sinusoids (sinusoidal capillaries). From here it flows through a central vein to the hepatic vein and then back to the heart via IVC.

There are no ‘normal’ capillaries in the liver.

Question 12

The liver has __1__ lobes. There and __2__ major lobes and __3__ minor lobes.

Answer 12

1) four
2) two
3) two

2 major = left and right
2 minor = caudate and quadrate

Question 13

The liver is surrounded by what type of tissue?

Answer 13

Connective tissue

Question 14

What are kupffer cells?

Answer 14

Sinusoidal macrophages found in the liver. They destroy bacteria and degrade worn out blood cells.

Question 15

The __1__ is the basic functional unit of the liver. It is made up of specialised epithelial cells called __2__.

Answer 15

1) liver lobule

2) hepatocytes

Question 16

Hepatocytes are arranged in __?__

Answer 16

lobules

Question 17

Within a liver lobule there are three zones that show the amount of nutrients, oxygen and toxins found within the hepatocytes there. What are the three zones called?

Answer 17

1) Periportal
2) Midzone
3) Centriolobular

Question 18

Which hepatic lobule zone is least oxygenated and has the lowest nutrient content?

Answer 18

Zone 3 - centriolobular

• Lowest nutrient content but larger glycogen and fat deposits
• Least oxygenated

Question 19

True or false: The periportal zone has the lowest toxin concentration?

Answer 19

False.

Zone 1: Periportal

• Highest nutrient content
• Most oxygenated
• Highest toxin concentration

Question 20

Where is bile produced and what is it made of?

Answer 20

Produced by hepatocytes, passed into bile canaliculi for transport to bile duct (counter-current to blood flow).

Composed of:

• Organic: bilirubin
• Inorganic: bile salts

Question 21

What are cholangiocytes?

Answer 21

Cells lining the bile duct.

• short microvilli
• one cilium per cell: senses change in flow

Question 22

What vessels join to form the left and right hepatic ducts?

Answer 22

Intrahepatic bile ducts

Question 23

How do terminal and intrahepatic bile ducts differ histologically?

Answer 23

Terminal are lined by cuboidal epithelium.

Intrahepatic are lined by columnar epithelium.

Question 24

The cystic bile duct leads where?

Answer 24

To/from gallbladder

Question 25

The common bile duct leads where?

Answer 25

To duodenum

Question 26

What is the function of the gallbladder?

Answer 26

Stores and concentrates bile.

Watery bile received from hepatic duct. Water and ions are absorbed out by mucosa - empties thick, concentrated bile into common bile duct.

Question 27

True or false: The mucosa of the gallbladder contains no mucus-producing cells

Answer 27

True.

Question 28

True or false: There bottom layer of the mucosa of the gallbladder is the muscularis mucosae

Answer 28

False. The gallbladder has no muscularis mucosae or submucosa.

Question 29

Describe the histology of the gallbladder.

Answer 29

Columnar epithelium with microvilli. No goblet cells, no muscularis mucosae and no submucosa. Beneath mucosa is smooth muscle (muscularis externa), and then adventitia.

Question 30

What is cholecystokinin (CCK)?

Answer 30

A peptide hormone released from inclusion cells in duodenum.

Triggers dilation of the hepatopancreatic sphincter and contraction of the gallbladder. This ejects bile into duodenum through the duodenal ampulla.

Question 31

True or false: The pancreas is both an exocrine and endocrine organ.

Answer 31

True.

Endocrine function accounts for approx 1% of pancreas (islets of Langerhans)

Question 32

Describe the shape of the exocrine glands in the pancreas.

Answer 32

Tubulo-acinar

Question 33

What is the path taken by pancreatic juice from secretion to the duodenum?

Answer 33

1) Secretory acini
2) Acini ducts
3) Intercalated ducts
4) interlobular collecting ducts
5) Pancreatic duct
6) Bile duct
7) Duodenum

Question 34

What structure forms the endocrine unit of the pancreas?

Answer 34

Islets of Langerhans

Question 35

What are the main cell types found in Islets of Langerhans?

Answer 35

• Alpha cells: glucagon
• Beta cells: insulin and amylin (stimulates glycogen, protein, and FA synthesis)
• Delta cells: somatostatin (inhibits endocrine cells, acts locally)

Question 36

What are the pancreatic endocrine minor cell types?

Answer 36

• PP-cells (stimulate gastric chief cells, inhibit bile secretion)
• Epsilon cells (secrete ghrelin to stimulate appetite)
• Enterochromaffin cells (secretin, motilin, substance-P)
• D1 cells (secrete vasoactive intestinal peptide, relaxes stomach and gallbladder, reduces arterial BP)