Gastrointestinal: accessory glands Flashcards
What are the 2 major parts of the GI system?
GI tract
Accessory gland
What is the GI tract?
Several organs joined in series to process food and digestion products
What are the accessory glands?
Secrete various fluids and enzymes to aid the digestive process
What are the 4 types of GI gland types and give an example of them?
Surface glands - goblet cells
Deep, tubular glands - gastric glands
Mucosal/sub mucosal glands - crypts of Liberkuhn
Specialised glands - salivary glands
What is the role of an accessory gland and give 3 examples:
Secrete products via ducts into lumen of the GI tract:
- Salivary glands, saliva
- Pancreas, pancreatic juice
- Liver, bile
What are the 2 characteristics of saliva and what are the 2 enzymes in it?
Rich in bicarbonate ions
Contains mucus
enzymes: salivary amylase, lysozyme
What are the 2 types of secretions in saliva?
Serous secretion (salivary amylase) Mucous secretion (mucins)
What are the glands that secrete into gastric juice and what do they secrete? (3)
Cardiac glands: mucous
Oxyntic/gastric glands: HCl, pepsinogen, mucous
Pyloric glands: pepsinogen, mucous
What are the 3 main cells that secrete from the glands?
Chief cells - pepsinogen
Parietal cells - HCl
Neck cells - mucous
What is the pH of the stomach?
1.0 - 3.5
What causes peptic ulcers? (5)
Excess acidity - lining the stomach Excess pepsin Poor mucous secretion - no bicarbonate layer Irritation of mucosa Infection of mucosa
What are the symptoms of peptic ulcer disease? (3)
- Chronic, rhythmic and periodic burning pain in the stomach
- Relieved by drinking milk or antacids
- bleeding due to acid and pepsin attacks on blood vessels
How is the stomach protected from acid? (3)
- Luminal membrane of gastric mucosal cells are impermeable to H+ - HCl can’t pentrate
- Cells are joined by tight junctions that prevent HCl penetrating between them
- A mucus coating over the gastric mucosa offers further protection
What is a helicobacter pylori? (3)
- Gram negative bacteria found in the mucus lining in stomach
- Triggers ulcer by activating immune response that destroys tissue - makes lining vulnerable
- Secretes urease enzyme - neutralises HCl
What does the pancreas release exocrinely into the GI system?
Pancreatic juice: bicarbonate, enzymes (pancreatic amylase, lipases, proteases, nucleases)
What is a zymogen? (3)
- Inactive form of digestive enzymes
- Stored in zymogen granules of acinar cells in cytoplasm
- Activated by proteolytic enzymes in lumen of intestinal tract
What is the endocrine role of the pancreas? (3)
- Consists of isolated islands of there endocrine tissue (islets of Langerhans)
- Produce hormones - insulin and glucagon
- Exocrine and endocrine derived from different tissues
What are the functions of the liver? (7)
Secreting bile Processing of nutrients Storing glycogen Removal of old RBC Elimination of wastes and toxins Synthesis of plasma proteins Secretion and modifications of hormones
What is the biliary system comprised of?
Liver, gall bladder and associated ducts
What does the biliary system do?
Liver synthesises bile
Gallbladder stores bile
Common bile duct transports bile from liver to duodenum
What is the liver anatomy and what do they do? (4)
Sinusoids: take up materials to make bile from blood
Hepatocytes secretes bile into bile canaliculi
Canaliculi drain into bile ducts
Bile ducts drain into common hepatic duct
