DIGESTIVE SYSTEM 2 Flashcards by humaira afzal

what are the digestive accessory organs?

salivary glands
liver
gallbladder
pancreas

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what do the salivary glands do?

secrete lubricating fluid & enzymes that break down carbs

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what does the the liver do?

Bile production; storage

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what does the gallbladder do?

Stores & concentrates bile

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what does the pancreas do?

Exocrine cells (fluid & enzymes), endocrine cells (hormones)

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where are the small salivary glands?

Situated in submucosa of oral cavity + tongue

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how are the small salivary glands grouped?

Lingual
Labial
Buccal
Molar
Palatine

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what are the 3 types of large salivary glands?

sublingual
submandibular
parotid

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where is the sublingual gland?

Beneath tongue

Many ducts

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where is the submandibular gland?

Floor of mouth
Along inner surface of mandible
Ducts behind teeth

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where is the parotid gland?

Largest, empties into mouth at the second molar

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what kind of glands are all the salivary glands?

All tubulo-acinar glands

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what are the large salivary glands?

Glands close to oral cavity secrete mucus

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what so the Sublingual glands secrete?

Mainly mucus acini

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what do the Submandibular glands secrete?

Serous and mucus acini

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what do the Parotid glands secrete?

Almost exclusively serous acini

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what is the liver?

Largest gland of body (and largest internal organ)

Highly vascularised

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what are the 4 lobes of the liver?

2 major – left + right (largest)

2 minor – caudate + quadrate

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what is the liver surrounded by?

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what does the liver function as?

an exocrine gland (secretes onto an epithelium via a duct)

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where does the liver receive blood from?

2 vessels
Hepatic artery (oxygenated, from aorta)
Hepatic portal vein (from digestive system + spleen)

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what is the percentage of arterial blood in the liver?

25%

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what is the percentage of venous blood in the liver?

75%

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where is blood discharged from the liver?

into small vascular channels called sinusoids (sinusoidal capillaries)

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what are kupffer cells?

Sinusoidal macrophages Destroy bacteria Degrade worn-out blood-cells

where does the blood flow out of the liver in order?

capillaries, central vein, hepatic vein, inferior vena cava

what are hepatic sinusoids lined by?

discontinuous sinusoidal epithelium

what is the liver lobule?

Basic functional unit of the liver

what are the specialised epithelial cells in the liver?

hepatocytes

what is a lobule composed of?

Terminal hepatic venule Interconnecting plates of hepatocytes Peripherally arranged portal triads

what is the lobule delimited by?

by CT, called interlobular septum

what are the 3 hepatocyte zones of the liver lobule?

periportal mid zone centriolobular

what is the periportal hepatocyte zone?

Highest nutrient component Most oxygenated Highest toxin conc.

what is the mid zone hepatocyte zone?

no sharp boundaries

what is the centriolobular hepatocyte zone?

Lowest nutrient component, but larger glycogen + fat deposits Least oxygenated

what is the organic composition of bile?

bilirubin

what is the inorganic composition of bile?

bile salts

what is bile produced by?

hepatocytes

where does bile pass into?

bile canaliculi

where do canaliculi carry bile?

to bile duct (counter-current to blood flow)

what is the bile duct lined by?

cholangiocytes

what are the features of cholangiocytes?

Short microvilli One cilium per cell Senses change in flow (mechanosensory)

what are the Terminal bile ducts lined with?

cuboidal epithelium

what are the Intrahepatic bile ducts?

Coalesce into left + right hepatic ducts | Unite to form common hepatic duct

what are the Intrahepatic bile ducts lined by?

Columnar epithelium

where does the cystic duct travel to and from?

to/from gallbladder

where does the common bile duct travel to?

to the duodenum

what is the gallbladder?

``` Ovoid sac with muscular wall Can distend (swell) ```

what is the function of the gallbladder?

Concentrates and stores bile

where are H2O + ions absorbed?

by mucosa

where does the gallbladder receives watery bile from?

the hepatic duct

where does the gall bladder empty thick, concentrated bile into?

the common bile duct

what are the 3 layers of the gallbladder?

mucosa muscularis externa adventitia

what is the mucosa layer of the gallbladder made of?

Columnar epithelium with microvilli

what does the mucosa layer of the gallbladder not contain?

No mucus producing cells | No muscularis mucosae or submucosa

what is the mucosa layer of the gallbladder arranged in?

in plicae

how is concentrated bile expelled in the mucosa layer of the gallbladder?

by contraction of smooth muscle wall

what is Cholecystokinin in the gallbladder?

CCK is a peptide hormone released from inclusion cells in duodenum

what does CCK do?

Reduces digestive motility + gastric emptying

where is the pancreas located?

behind the stomach

what is the pancreas?

Elongate organ | Retroperitoneal

what is the structure of the pancreas?

No distinct capsule | Covered by a thin layer of connective tissue

what does the pancreas function as?

Endocrine and exocrine functions

what is the exocrine part of the pancreas composed of?

tubulo-acinar glands

what does the exocrine part of the pancreas secrete?

pancreatic juice Alkaline fluid composed of enzyme precursors

what is the exocrine function of the pancreas made of?

Single layer of epithelial cells form secretory acini

what are the ducts of the pancreas?

acini, interlobular, pancreatic, bile duct

what is the acini duct?

1st part of intercalated duct

what is the interlobular duct made of?

columnar epithelium

what is the pancreatic duct made of?

columnar epithelium

what does the bile duct secrete into?

the duodenum

what does the endocrine part of the pancreas contain?

islets of langerhans

where do the islets of langerhans secrete products to?

into pancreatic ducts

what do the islets of langerhans contain?

Contain a variety of neuroendocrine cells

what are Beta cells?

Secrete: insulin + amylin | Stimulates glycogen, protein and fatty acid synthesis

what are Alpha cells?

Secrete: glucagon | Generally opposite actions of insulin

what are Delta cells?

Secrete: somatostatin Locally acting hormone Inhibits other endocrine cells

what are PP-cells (pancreatic polypeptides)?

Stimulates gastric chief cells | Inhibits bile secretion

what are Epsilon cells?

Secrete: Ghrelin | Stimulates appetite

what are EC (enterochromaffin) cells?

Secretes: Secretin: controls secretion of other hormones Motilin: stimulates gastric activity Substance-P: wide range of functions

what are D1 cells?

Secrete: VIP (Vasoactive Intestinal Peptide) Relaxes stomach and gallbladder Reduces arterial BP