T1 L8 Secretions of liver, intestines, gallbladder & pancreas Flashcards
What are the 3 main sections of the small intestine?
Duodenum
Jejunum
Ileum
What are the functions of the duodenum?
Receives stomach contents, pancreatic juice & bile Neutralises stomach acids Emulsifies fats Increase in pH will inactivate pepsin Has pancreatic enzymes
What is the histology of the duodenum?
Brunner glands - empty into intestinal glands & secrete an alkaline fluid
Villi have a leaf-like shape
What is the function of the jejunum?
Nutrient absorption
What is the histology of the jejunum?
Extensive intestinal folds
Villi have a finger-like shape
Plicae circulares are well developed
What are peyer’s patches?
Aggregated lymphoid nodules found in the ileum
Small masses of lymphatic tissue that form part of immune system by monitoring intestinal bacterial problems & preventing growth of pathogenic bacteria in the intestine
What is the histology of the ileum?
Villi are shorter compared to the jejunum
Peyer’s patches extend throughout lamina propria & submucosa
What is the brush border?
Found on cells of small intestine & are made of microvilli.
Help with final stages of digestion
What is a crypt-villus unit?
Functional unit of the small intestine
Immature cells in the crypts of Lieberkuhn, which secrete fluid
At the tip the cells are well differentiated
What is the maturation zone in the crypt-villus unit?
Intermediate zone where cells are moving towards the tip of the villus & beginning to express enzymes & absorptive membrane transport proteins
What is the crypt?
Contains rapidly dividing stem cells that force migration of cells up the side of a villus
Crypt cells are a source of intestinal fluid secretion
What is the definition of chemical digestion?
Complex series of enzymatic reactions that convert dietary macromolecules into their corresponding sub units that fan then be absorbed by enterocytes
What cells are found in the crypts of lieberkuhn?
Paneth cells - lysozyme
Enterocytes
Enteroendocrine cells
What are the 3 types of enteroendocrine cells?
I - CCK stimulates the gallbladder to release bile
D - somatostatin
S - secretin stimulates pancreas to release bicarbonate
What cells are in the villi?
Goblet cells - secrete mucus, which lubricates & protects intestinal surface
Enterocytes - brush border which contains enzymes
What is coeliac sprue?
A malabsorption syndrome characterised by hypersensitivity to wheat gluten & gliadin
Results in immune-mediated destruction & denudation of small intestinal villi
Symptoms include diarrhoea, steatorrhoea, abdominal bloating & flatulence
What is the function/anatomy of exocrine glands in the pancreas?
80% of pancreas volume
Digestive function
Similar structure to salivary glands
Made of acinus (secrete digestive enzymes) & duct cells (secrete bicarbonate)
Delivers digestive enzymes & isotonic HCO3- rich solution into intestinal lumen
What is the function/anatomy if endocrine glands in the pancreas?
Metabolic function
4 types of Islet cells that release hormones such as insulin & glucagon
What is type 1 diabetes?
Beta cells on the pancreas no longer make insulin
Body’s immune system has attacked & destroyed beta cells
Have to take insulin daily
What is type 2 diabetes?
Usually begins with insulin resistance
Insulin production declines over time
What are the functions of exocrine secretions from the pancreas?
Alkaline fluid that neutralises acidic chyme entering small intestine
Secretes enzymes to break down the macromolecules in food & produce smaller nutrient molecules for intestinal absorption
What is the composition of exocrine secretions from the pancreas?
Water Electrolytes Proteolytic enzymes Lipolytic enzymes Amylolytic enzymes Nucleases Other enzymes - procolipase, trypsin inhibitor
What are some examples of proteolytic enzymes secreted by the pancreas?
Trypsin 1,2 & 3
Proelastase 1 & 2
Procarboxypeptidases A1, A2, B1, B2
What are some examples of lipolytic enzymes secreted by the pancreas?
Lipase
Phospholipase A
Pancreatic lipase
What is the mechanism for secretion by the pancreas?
1) Pancreatic enzymes synthesised as inactive proenzymes on ribosomes
2) Transferred into rough ER
3) Move to Golgi complex
4) Form acidic condensing vacuoles
5) Released as zymogen granules
6) Fusion & exocytosis of zymogen granules