Lecture 7: The Pancreas Flashcards
What causes diabetes type II?
insulin resistance
What is an acinus and what is its function?
the main pancreatic unit responsible for synthesizing and secreting enzymes and proenzymes.
What is the function of glucagon?
It is secreted in response to a low glucose (during fasting); its action is to raise the blood glucose by stimulating glucose synthesis and glycogen breakdown
Describe acinar cells
- highly polarized
- pyramidal in shape
- basal nuclei
- abundant RER
- apical
- contains membrane bound zymogen
What percentage of an islet is comprised of A (alpha) cells?
5-30%
What are the main cell types found in islets?
A (alpha), B (beta), and D (delta cells)
What is the exocrine pancreas responsible for?
It produces the pancreatic juice, which is the most important of the digestive secretions
What polypeptide do beta cells secrete?
insulin
What are the function of D (delta) cells?
they secrete somatostatin in response to an increased blood glucose, which inhibits hormone relase from A and B cells.
What causes acute pancreatitis?
proenzymes are activated early (in the pancreas) and they eat the tissue of the pancreas
What is the role of a centroacinar cell?
they secretes water and elctrolytes and are the first cells of the intercalated ducts
What type of hormones are secreted by the islet cells found in the endocrine pancreas?
polypeptides
What is the pancreas?
A mixed endocrine and exocrine gland with acinar cells that form most of the gland’s volume
What type of epithelium is found in an intercalated duct?
low cubodial or simple sqaumos
Describe a centroacinar cell
pale, cubodial cells with elongated central nuclei and abundant mitchondria
What are the main differences between an islet cell and an acinar cell?
islet cells are smaller and contain small membrane bound secretory granules
How are islets arranged in the pancreas?
they are scattered throughout the exocrine pancrease with cells arranged in cords or clusters
What are islet cells?
regions of the pancreas that contain the endocrine (hormone-producing) cells.
What is the interlobular duct?
the location where the intralobular duct drains
What type of epithelium lines an intralobular duct?
cubodial epithelium
How much of the pancreatic volume is made up of islets?
about 1-2 %
What is trypsinogen?
the inactive precursor of trypsin
What type of cells are found in an intercalated duct?
pale, low cubodial centroacinar cells
Where are acinar found?
in the exocrine pancreas
What are intralobular ducts?
intercalated ducts that are joined together
What are the proenzymes that are found in the pancreatic juice?
Zymogens
Describe an islet cell
they are made up of parenchymal cells that are derived from the endoderm of the developing duodenum; Islets are very vascular
What is the function of insulin?
it is released in response to an increased blood glucose (after eating) and acts to lower blood glucose by stimulating glucose uptake and glycogen synthesis in liver and muscle
What color do alpha cells stain with aldehyde fuchsin?
brilliant red or orange
What is the main function of the intercalated ducts of the pancreas?
they secrete large amounts of bicarbonate ions which neutralize acid from the stomach
What is parenchyma?
the specific (functional) tissue of an organ as distinguished from the connective tissue or stroma
Why are amylase, lipase, and trypsinogen significant to the pancrease?
They are enzymes of the pancreas that are capable of digesting the main components of ingested food(carbs, proteins, nucleic acids, lipids, and phospholipids). To prevent this, they are stored as inactive precursors of the pancreas.
Where are the intralobular, interlobular, and intercalated ducts found in the pancreas?
in the exocrine part of the pancreas
What causes Diabetes type I?
primary insulin deficiency
What makes up the structure of the exocrine pancreas?
- It is classified as compound tubuloacinar gland
- It has sparse stroma
- a thin capsule
- and a delicate connective tissue septa that divide the gland into distinct lobules
What polypeptide do A (alpha) cells secrete?
glucagon
What type of stroma (connective tissue) is the endocrine pancreas made up of?
sparse reticular connective tissue
What are pancreatic islets?
regions of the pancreas that contain the endocrine
What makes up the pancreatic juice found in the exocrine pancreas?
enzymes and proenzymes that are activated in the intestine
How many acinar cells are found in an acinus?
about 50
What color do B (beta) cells stain with aldehyde fuchsin?
dark purple
What is one difference between a parotid gland and a pancreatic gland?
they are no striated ducts or myoepithelial cells in the pancreas
What is another name for a pancreatic islet?
Islets of Langerhans
What percentage of an islet cell is comprised of B (beta) cells?
60-80 %
What enzymes are found in the pancreatic juice?
amylase-carbohydrates, lipase-fats, trypsin-proteins,
What is insulin responsible for?
keeping the sugar content of the blood at a constant level
What is the endocrine pancreas responsible for?
produces several polypetide hormones such as insulin
True or False
The Endocrine pancreas acinar cells take up most of the space in the pancreas
FALSE
The acinar cells are found in the exocrine pancreas, which takes up most of the space in the pancreas
