Digestive System III Flashcards
How many lobes does the liver have?
4 lobes of unequal shape and size
What divides the right and left lobes of the liver?
Falciform ligament
What are the two lobes that are not the right and left lobes of the liver?
Quadrate
Cuadate Lobes
What is the functional unit of the liver? Do all lobes have this?
Lobules
All lobe has this
What surrounds the liver?
Fibrous capsule
Aka Glisson’s capusle
What surrounds the Capsule of the liver? What is its purpose?
Serous coat of mesothelium
Reduces friction
What is the shape of the lobules?
Hexaganol
What 3 components make up the portal triad? Where is the portal triad located?
- Hepatic portal ven
- Hepatic Artery
- Bile duct
Found on the edges of lobules
What lies in the center of the lobules of the liver?
Central Vein (actually a venule) Blood flow through sinusoids
What the the 6 most important functions of the liver?
- Removal of toxins
- Metabolize nutrients
- Store starches as long term glycogen stores
- Kupffer Cells (macrophages) phagocytose pathogens/debris
- Produce clotting factors and plasma proteins
- Production of bile
Where are Kupffer cells located?
Line sinusoidal capillares
Macrophages of the liver
What type of plasma proteins does the liver produce?
alpha and beta globulins
albumin
fibrinogen
What is bile important for (2)?
- Digestion of food
2. Absorption of vitamins A, D, E, K
75% of the blood that comes to the liver is _____ supply from the _____, the other 25% is _____ supply from the ______
Venus supply, hepatic portal vein
Arterial supply, hepatic artery
What does the venule blood supply contain (3)? What other organs does the blood go through before coming to the liver?
Contains nutrients (glucose, metabolites), toxins, byproducts of medications Goes through GI tract, pancreas, spleen
What important thing does the hepatic artery bring the liver?
Oxygen
What are the lobe of the liver divided into?
Layers of hepatocytes
What are the hepatocytes seperated by? What is the significance of this?
Sinusoidal capillaries
The discontinuous basal lamina allows for large molecules (nutrients, toxins, metabolites) to flow in/out of the sinusoids and in/away from hepatocytes
What line the sinusoidal wall of the capillaries in the liver? What two functions does the cell perform?
Kupffer cells
Reinforce wall
Phagocytosis
What is the overall shape of the hepatocyte?
Cuboidal - has 8 sides
What separates the hepatocytes on their laminal sides? What is their function?
Bile Canaliculus
Tuber space between that act as the beginning of the bile ducts
Do the bile ducts move in the same or opposite way as the blood flow? What are all the tubes called (4)?
The bile ducts flow in the opposite direction
Bile canaliculi > bile ductule @ portal triad > larger bile ducts > main bile duct
The liver has the enrichment of what 3 organelles in its cells? What is the implication of this?
- sER
- peroxisomes
- Lysosomes
All are important for digestion, breakdown, and detoxification
What are Ito cells? Where are they found? What is their function?
Found in the liver
Important for storage of vitamin A
What do Ito cells have to do with vision?
Release vitamin A as retinol bound to retinol-binding protein > travels to retina > becomes rodoxin = important for eyesight
How can a damaged liver lead to decreased eyesight?
Liver damage > Ito cells become myofibroblasts > scar tissue > decreased storage of vitamin A > decreased retinol > decreased rodoxin > decreased eyesight
What is the space of disse?
Part of the hematocyte that faces the sinusoidal wall
Contains microvilli that increase absorption, synthesis, and secretion of materials into the sinusoid
What do the microvilli in the space of disse in the liver synthesize?
Clotting factors etc
Does the gallbladder have a lot of interaction with the body? Why?
No, it is a blind sac attached to the visceral surface of the liver
What is the only place the gallbladder interacts with the body?
The cystic duct which connects with the hepatic duct
What is the function of the gallbladder?
Concentrates and stores bile
Talk me through bile secretion
Bile released through common hepatic duct > cystic duct > gallbladder removes 90% of the water > bile becomes enzymatically active > CCK from small intestine > secrete out enzymatically active bile into the duodenum
How does the anatomy of the gallbladder reflect its main function of water removal? (3) (first 2 modification in mucosa)
- Mucosa is lined with simple columnar epithelium with microvilli
- Mucosal Folds increase surface area
- Lots of Na/K ATPase pumps on the lateral side of cells to allow for the lateral transport of water across the membrane so it can be taken up by the blood vessel in the LCT and returned to the body
What does the muscularis externa tell us about the gallbladder?
Has 3 layers of smooth muscle to allow for large contractions > release of bile into the cytsic duct
What two layers does the gallbladder lack? What does this mean for the lamina propria?
lacks muscularis mucosa and submucoa Lamina propria (LCT) runs continuously with muscularis externa
Does the gallbladder have adventitia or serosa?
Adventitia at point of attachment to the liver
Serosa at unattached surfaces
What are the 3 regions of the pancreas?
- Head
- Body
- Tail
What is the capsule of the pancreas?
LCT
enters into the tissue to create CT septa which created the rough-looking exterior of the pancreas
What are the two ducts important in the pancreas? What do they drain into?
- Main pancreatic duct (Duct of Wirsung): drains into duodenum
- Accessory duct (duct of Santorini): only in some individuals, different entry point (not same as bile duct)
What are pancreatic acini cells? Where are they located? What is their function? Is this an exocrine or endocrine function?
Granular cells found in the pancreas
Produce digestive enzymes; exocrine function
What are Islets of Langerhans? Where are they located? What is their function? Is this an exocrine or endocrine function?
Found dispersed throughout acini cells in the pancreas
Produce insulin and glucagon; endocrine function
What 4 things do the zymogen granules of acini cells contain? What is the significance of this?
- Proteolytic endo and exopeptidases
- Amyloytic enzymes
- Lipases
- Nucleolytic enzymes
Something to breakdown and digest each of the 4 macromolecules
What are centroacinar cells? Where are they located? What is their function?
Found in the center and extending from acinar cells - like a lollipop
Eventually becomes intercalated duct > intralobular duct > main duct
What is the function of enteroendocrine cells of the DNES system in the pancreas?
Hormonal Control
- Secretin
- CCK
What does secretin do in the pancreas?
Acts on acinar cells > release of digestive enzymes into intercalated duct
What does CKK do in the pancreas?
Act on centracinar cells and intercalated duct cells > make alkaline buffer > mixes with digestive enzymes > duodenum enzymes
Talk me from centroacinar cells to the duodenum
Centroacinar cells > intercalated duct > intralobular duct > interlobular duct > main pancreatic duct > duodenum
What do the pancreatic ducts make? What is its function?
Make bicarbonate buffer
Increased the pH of the duodenum (in addition to secretion from duodenum glands) + alkaline > neutralization of chyme AND created perfect pH conditions to active zymogen enzymes
What are the three types of cells found in the Islets of Langerhans? And what do they produce?
- Alpha > glucagon
- Beta > Insulin
- Delta > Somatostatin
What does glucagon do?
Contracts insulin
Stimulates glucose production and increase blood glucose levels
What does insulin do?
In response to high blood glucose levels it acts on cells to increase the uptake of glucose > glucose storage
What does somatostatin do?
Inhibits both glucagon and insulin
What is acute hemorrhagic pancreatitis? What causes it? Symptoms on the cellular and whole-body level? How long do symptoms last?
Heavy meals or excessive drinking > inactive proenzymes become prematurely active > destruction of pancreatic acini > Necrosis and Hemorogining
Abdominal pain, nausea, vomiting
Lasts a few days
What can cystic fibrous do to your pancreas?
Mucus obstructs ducts > destroy pancreatic acini and tissue overtime > pancreatic failure > death
What can repeated (chronic) pancreatitis lead to? In what individuals do we see this in?
Can lead to acute hemorrhagic pancreatitis
See this in alcoholics
