Term
| what are the functions of the liver? |
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Definition
Largest gland of body.
Metabolizes and stores nutrients
Stores glycogen
Detoxifies chemicals and drugs
Synthesizes blood proteins (e.g., albumin, fibrinogen, lipoproteins) and secretes them into the blood (endocrine secretion)
Synthesizes and secretes bile (exocrine secretion). |
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Term
| what are the stroma in the liver composed of? |
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Definition
| composed of a connective tissue capsule (type I collagen) and a framework of reticular fibers (type III collagen). |
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Term
| what are the parenchyma in the liver made up of? |
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Definition
made up of hepatocytes which are derived embryologically from foregut endoderm.
hepatocytes are arranged into 1-2 cell-thick interconnected plates |
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Term
| what are the 2 blood supplies to the liver? |
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Definition
| the portal vein and hepatic artery |
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Term
| 75% of blood delivered to the liver is from which vessel? |
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Definition
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Term
| 25% of blood delivered to the liver is from which vessel? |
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Definition
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Term
| the portal vein delivers what type of blood to the liver? |
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Definition
| oxygen poor, nutrient rich |
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Term
| the hepatic artery delivers what type of blood to the liver? |
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Definition
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Term
| what are the 3 components of the portal triad? |
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Definition
Branches of the portal vein (portal venules) that lead to inlet venules, that empty into sinusoids
Branches of the hepatic artery (hepatic arterioles) that lead to inlet arterioles, that empty into sinusoids.
The combination of venules and arterioles provides a mixture of arterial (25%) and venous (75%) blood in the sinusoids.
Branches of the bile duct that receive bile from bile ductules (canals of Hering), which drain the bile canaliculi.
Lymphatics are present in the region of the triad but are NOT included as a component of the triad |
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Term
| where is the portal triad located? |
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Definition
| Located at the corners of the classic lobule. There are usually 3-6 per lobule |
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Term
| what are the 3 ways to describe structure of the liver? |
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Definition
| classic lobule, portal lobule, and liver acinus |
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Term
| describe a classic liver lobule |
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Definition
polygonal structure
Although clearly delineated by connective tissue in some mammalian species (e.g. pig), it is not clearly in humans.
The classic liver lobule is based on blood flow direction.
The lobule is composed of a central vein, radiating plates of hepatocytes separated by sinusoids, and portal triads. |
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Term
| describe the portal lobule in the liver |
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Definition
Triangular.
The portal triad is at the center of the portal lobule
Central veins are at the corners.
Contains part of 3 classic lobules.
It is based upon the direction of bile secretion. |
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Term
| describe the liver acinus |
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Definition
Best correlation among blood perfusion, metabolic activity, and liver pathology.
The acinus is diamond-shaped.
Two central veins and two portal triads define its corners.
The center of the acinus has terminal branches of portal venules, hepatic arterioles (distributing vessels), and bile ducts.
It can be divided into 3 zones based on oxygen, nutrient, and toxin levels in blood |
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Term
| describe the liver acinus zone I |
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Definition
closest to the distributing vessels
Exposed to higher oxygen, nutrient and toxin levels.
The cells in the zone have a higher metabolic rate and are more susceptible to toxins.
Cells are the first to show changes following bile duct occlusion.
They are the last to die following circulatory impairment and the first to regenerate. |
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Term
| describe the liver acinus zone 3 |
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Definition
Farthest from the distributing vessels and closest to the terminal hepatic vein.
Cells in Zone 3 are the first to show ischemic necrosis (death due to reduced circulation: centrilobular necrosis).
Also the first cells to show fatty accumulation (see alcoholic liver disease below).
They are the last to respond to toxins.
Pathology is described in terms of the classic liver lobule.
Therefore centrilobular refers to the area closest to the central vein, i.e. Zone 3. |
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Term
| what are the 3 major phases of alcoholic liver disease? |
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Definition
| fatty liver, alcoholic hepatitis, and cirrhosis |
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Term
| describe what occurs during the fatty liver stage of alcoholic liver disease |
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Definition
All chronic alcoholics accumulate fat within their liver cells.
Liver can attain three times normal weight.
Centrilobular hepatocytes are first affected.
With cessation of drinking, reversible and has few functional consequences |
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Term
| what is alcoholic hepatitis? |
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Definition
More severe than fatty liver.
Alcoholic hepatitis presents a significant mortality.
It is an inflammatory, necrotizing disease.
There is a neutrophilic inflammatory response and necrosis of hepatocytes in the central zone (Zone 3, around the central vein). |
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Term
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Definition
A scarring of the liver which can lead to portal hypertension and/or liver failure.
Histologically, fibrous septa form around hepatocellular nodules.
The normal structure and consequently function of the liver is disturbed. |
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Term
| what is cardiac cirrhosis? |
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Definition
Heart failure can cause liver damage that can lead to cirrhosis.
Hepatocytes in zone 3 that normally receive the least oxygen and nutrients, are very susceptible to ischemia and hypoxia.
No noticeable changes are seen in zones 1 and 2. |
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Term
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Definition
Occupy space between hepatic plates or cords.
Receive blood from portal triads
mixed venous (75%) and arterial blood (25%).
Blood flows from portal triads to central vein.
Specialized capillaries that allow for very slow blood flow.
Have dilated lumens
Discontinuous endothelial lining with a discontinuous basal lamina.
Have fenestrae with no diaphragms |
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Term
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Definition
Mononuclear phagocytic cells found in the walls of sinusoids and on their luminal surfaces.
They phagocytose aged RBCs |
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Term
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Definition
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Term
| what is the space of disse? |
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Definition
Narrow space between the endothelium of the sinusoids and the hepatocytes.
Allows blood fluid and macromolecules to come into contact with hepatocyte microvilli.
In the space, there is an exchange of materials between the sinusoids and hepatocytes |
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Term
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Definition
contains bile acids (emulsify fats), phospholipids, cholesterol, bilirubin, water, etc..
Ninety percent of bile is reabsorbed from intestines, 10% is synthesized by hepatocytes. |
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Term
| what are bile canaliculi? |
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Definition
Narrow intercellular channel between hepatocytes.
Formed by shallow "grooves" in the surfaces of adjacent hepatocytes. As such, they have no wall of their own and therefore, their walls are adjacent hepatocytes.
Sealed by tight junctions and receive bile secretion from hepatocytes.
Canaliculi lead to bile ductules (canals of Hering), which terminate in the bile ducts of the portal triads.
The flow of bile is opposite to flow of blood in the sinusoids. |
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Term
| what do bile ductules (canals of Hering) lead to and what are they formed by? |
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Definition
| Formed by cuboidal cells that are not hepatocytes. They lead to bile ducts |
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Term
| what do bile ducts converge to form and what forms them? |
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Definition
Formed by cuboidal or columnar cells, they are a component of the portal triad.
Bile ducts converge to form hepatic ducts |
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Term
| the right and left hepatic duct join to form what? |
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Definition
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Term
| describe the common hepatic duct |
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Definition
| Common hepatic duct joins the cystic duct from the gallbladder to form the common bile duct, which empties into duodenum at the ampulla of Vater. There is a sphincter in the ampulla called the sphincter of Oddi |
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Term
| what are some characteristics of the gallbladder? |
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Definition
Stores and concentrates bile from the liver.
It releases bile into the duodenum in response to CCK.
Mucosa has a simple columnar epithelium with an underlying lamina propria.
Epithelium - absorptive cells with microvilli.
Absorbs water from stored bile.
Mucosal folds are numerous and branched.
Near the cystic duct, invaginations of the mucosa form glands (sometimes called sinuses) that secrete mucus.
Has NO submucosa |
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Term
| what are rokitansky-aschoff sinuses and what does their presence indicate in the gallbladder? |
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Definition
| Rokitansky-Aschoff sinuses are deep invagination of mucosa. Presence of these sinuses may indicate early pathologic changes. |
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Term
| pancreatic acini are formed by which types of cells? |
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Definition
serous cells with spherical nuclei
The cells are polarized with basal RER (basophilic) and apical zymogen granules (acidophilic).
Secrete a wide variety of digestive enzymes, including proteases, lipases, nucleases, etc.
Secretion of enzymes is stimulated by cholecystokinin from enteroendocrine cells of the duodenum or by parasympathetic (vagus) stimulation |
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Term
| describe the duct system in the exocrine pancreas |
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Definition
Duct system cells secrete a watery, bicarbonate-rich fluid in response to secretin from enteroendocrine cells of the duodenum.
The centroacinar cells are light-staining cells in the lumens of acini. The cells are continuous with the initial portion of the intercalated duct.
The intercalated ducts are composed of cuboidal cells. They lead to small intralobular ducts, which lead to interlobular ducts.
The interlobular ducts are composed of columnar cells.
The interlobular ducts lead to main or accessory pancreatic duct (ductus choledocus) which arises in the head of the pancreas.
Terminal ducts empty into the duodenum. The main duct joins the common hepatic duct to empty into the duodenum through the ampulla of Vater. |
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Term
| is the spleen derived from the foregut? |
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Definition
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Term
| describe the spleen and its location |
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Definition
NOT derived from the foregut
Immune organ
Highly vascular – filters blood
Located on left side within greater sac
It lies against the 9th-11th ribs
Trauma to the ribs can rupture the spleen causing profuse internal bleeding |
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Term
| should the spleen go over the midaxillary line? |
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Definition
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Term
| what does white pulp in the spleen contain? |
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Definition
White pulp has lymphoid nodules.
Filters and provides immunologic surveillance of blood. |
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Term
| what is the function of the red pulp in the spleen? |
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Definition
Red pulp acts as the filters and degrades old red blood cells.
Traps them, breaks them down and recycles hemoglobin and iron |
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Term
| describe the compartmentalization of the spleen |
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Definition
Dense connective tissue capsule which send trabeculae into the parenchyma of the spleen.
Incompletely divides the organ into functional units whose main components are white pulp and red pulp, named for their appearance in fresh tissue. |
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