L24 Digestive System II Flashcards by Sam Quesne

Small salivary glads are found where?

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

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How are the small salivary glands grouped?

Lingual
Labial
Buccal
Molar
Palatine

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

1) sublingual
2) submandibular
3) parotid

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

many

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

teeth

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

the second molar

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All salivary glands are __?__ glands

regarding the shape

tubulo-acinar

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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__.

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

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What is the largest gland in the body?

The liver

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Is the liver an endocrine or exocrine gland?

Exocrine

Secretes onto an epithelium via a duct

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Comment on the blood flow to the liver.

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.

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

1) four
2) two
3) two

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

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The liver is surrounded by what type of tissue?

Connective tissue

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What are kupffer cells?

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

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

1) liver lobule

2) hepatocytes

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Hepatocytes are arranged in __?__

lobules

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?

1) Periportal
2) Midzone
3) Centriolobular

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

Zone 3 - centriolobular

Lowest nutrient content but larger glycogen and fat deposits
Least oxygenated

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

False.

Zone 1: Periportal

Highest nutrient content
Most oxygenated
Highest toxin concentration

Where is bile produced and what is it made of?

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

Composed of:

Organic: bilirubin
Inorganic: bile salts

What are cholangiocytes?

Cells lining the bile duct.

short microvilli
one cilium per cell: senses change in flow

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

Intrahepatic bile ducts

How do terminal and intrahepatic bile ducts differ histologically?

Terminal are lined by cuboidal epithelium.

Intrahepatic are lined by columnar epithelium.

The cystic bile duct leads where?

To/from gallbladder

The common bile duct leads where?

To duodenum

What is the function of the gallbladder?

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.

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

True.

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

False. The gallbladder has no muscularis mucosae or submucosa.

Describe the histology of the gallbladder.

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

What is cholecystokinin (CCK)?

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.

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

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

Describe the shape of the exocrine glands in the pancreas.

Tubulo-acinar

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

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

What structure forms the endocrine unit of the pancreas?

Islets of Langerhans

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

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

What are the pancreatic endocrine minor cell types?

- 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)