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Anatomy Unit 3 > TBL 18 > Flashcards

TBL 18 Flashcards

0
Q

What does initial outgrowth of the liver bud form? And subsequent ventral growth?

A

It forms the bile duct. Ventral growth from the bile duct forms the cystic duct.

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1
Q

What is the liver bud an outgrowth from? What does this outgrowth site mark?

A

The liver bud is an endodermal outgrowth from the second part of the duodenum. The site of outgrowth marks the end of the foregut derived portion of the duodenum.

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2
Q

What forms the gallbladder?

A

Proliferation of the cystic duct epithelium within the septum transversum

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3
Q

What happens to the bile duct distal to the cystic duct? What forms the liver cords?

A

The bile duct divides and forms the left and right hepatic ducts. The liver cords are formed by epithelial proliferation from the hepatic ducts and they proliferate into the septum transversum.

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4
Q

What do the liver cord differentiate into? What makes the liver stroma?

A

Liver cords differentiate into hepatocytes (parenchymal liver cells)
Mesenchymal fibroblasts in the septum transversum generate the liver stroma.

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5
Q

What form the hepatic sinusoids and hepatic veins?

A

Right and left vitelline veins

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6
Q

What causes the duodenum to be C-shaped?

A

It is caused by the stomach’s rotation around its anteroposterior axis.

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7
Q

What forms the dorsal and ventral pancreatic buds? Where do they grow?

A

Adjacent to the bile duct, endodermal outgrowths from the 2nd part of the duodenum forms the dorsal and ventral pancreatic buds.

The large dorsal pancreatic bud grows into the dorsal mesentery and the small ventral bud remains close to the proximal portion of the bile duct.

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8
Q

What happens to the pancreatic buds during rotation?

A

The ventral pancreatic bud moves dorsally to join the dorsal pancreatic bud in the dorsal mesentery.
The rotation of the stomach place the conjoined buds int he retroperitoneal space.

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9
Q

How is an annular pancreas formed, when can it induce vomiting that contains bile, and what creates its characteristic “double bubble” radiographic sign?

A

The ventral pancreatic bud consists of two components that normally fuse and rotate around the duodenum so they come to lie below the dorsal pancreatic bud. Sometimes, however, the right portion of the ventral bud migrates along its normal route but the left migrates in the opposite direction. The duodenum is surrounded by pancreatic tissue and an annular pancreas is formed.

Bile is usually released into the duodenum and reabsorbed in the distal parts of the small intestine. Due to constriction, bile cannot be reabsorbed and is found in the vomit.

The radiograph shows two bubbles. One is the dilation of the stomach in the LUQ and the proximal duodenum in the RUQ.

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10
Q

What forms the main pancreatic duct? Where does it empty into?

A

After the union of the pancreatic buds, the endoderm derived duct systems of the buds fuse to form the main pancreatic duct.

The pancreatic duct empties into the bile duct.

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11
Q

What forms the pancreatic stroma?

A

It is derived from mesenchymal cells of the dorsal mesentery.

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12
Q

What separates the right and left hepatic lobes?

A

The falciform ligament separates the right and left hepatic lobes. The lobes form the convex diaphragmatic surface of the liver.

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13
Q

Where is the subphrenic recess located?

A

It is between the diaphragm and the anterior and superior aspects of the right and left hepatic lobes. The recess is a superior extension of the greater sac.

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14
Q

What is the subhepatic space?

A

It is a portion of the supracolic compartment inferior to the visceral (inferior) surface of the liver.

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15
Q

What is the hepatorenal recess?

A

It is a recess between the right hepatic lobe and the right kidney. It is an extension of the subhepatic space.
In the supine position, fluid in the supracolic compartment drains into the hepatorenal recess.

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16
Q

What forms the hepatoduodenal ligament and what does it do?

A

The free border of the lesser omentum forms the hepatoduodenal ligament and it conveys the bile duct, proper hepatic artery and hepatic portal vein to the liver.

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17
Q

What are the cuadate and quadrate lobes? What are the visceral surfaces of the lobes associated with?

A

cuadate and quadrate lobes are accessory parts of the large right hepatic lobe

visceral surface of the cuadate lobe: IVC
visceral surface of the quadrate lobe: gallbladder

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18
Q

What is the arterial supply of the right and left lobes of the liver?

A

common hepatic artery –> proper hepatic artery (terminal branch) –> bifurcates to right and left hepatic arteries that enter the lobes of the liver with the right and left hepatic ducts

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19
Q

Why would clamping the omental foramen’s anterior border (the Pringle maneuver) rapidly control hepatic hemorrhaging during emergency surgery?

A

It would compress the hepatic artery and hepatic portal vein so hemorrhaging can be controlled.

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20
Q

How is the liver commonly palpated? How do increases in central venous pressure or metastatic carcinomas from the large intestine cause hepatomegaly and where is the liver palpated under the conditions?

A

The liver may be palpated in a supine person because of the inferior movement of the diaphragm and liver that accompanies deep inspiration. Place the left hand posterior behind the lower rib cage. Then, put the right hand on the persons RUQ, lateral to the rectus abdominis and inferior to the costal margin. Ask the person to take a deep breath as the examiner presses postero-superiorly with the right hand and pulls anteriorly with the left hand.

Any rise in central venous pressure is directly transmitted to the liver which enlarges as it becomes engorged with blood.

When the liver is massively enlarged, its inferior edge may be readily palpated below the right costal margin and may even reach the pelvic brim in the RLQ of the abdomen.

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21
Q

What is the pathogenesis of cirrhosis of the liver and why does it cause portal hypertension? Why is metabolic evidence of liver failure late to appear?

A

There is progressive destruction of hepatocytes and replacement of these cells by fat and fibrous tissue in cirrhosis. Alcoholic cirrhosis is the most common cause of portal hypertension because the fibrous tissue surrounds the intrahepatic blood vessels and binary ducts, making the liver firm. This impedes circulation of blood. The liver has great functional reserve therefore the metabolic evidence of liver failure is late to appear.

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22
Q

How is a liver biopsy properly obtained?

A

The liver is located in the right hypochondriac region where it receives protection from the overlying thoracic cage, the needle is commonly directed through the right 10th intercostal space in the midaxillary line. The person is asked to hold his or her breath in full expiration to reduce the costodiaphragmatic recess and to lessen the possibility of damaging the lung and contaminating the pleural cavity.

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23
Q

What is the subcutaneous paraumbilical vein?

A

It originates near the umbilicus and is a tributary of the hepatic portal vein.

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24
Q

What happens to the paraumbilical vein inferior to the sternal xiphoid process?

A

The paraumbilical vein pierces the linea alba and parietal peritoneum to enter the falciform ligament. It courses inferior to the border of the falciform ligament to join the portal vein.

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25
Q

What is the pathogenesis of caput medusa?

A

In severe cases of portal obstruction, the veins of the anterior abdominal wall (normally caval tributaries) that anastomose with the para-umbilical veins (normally portal tributaries) may become varicose and look somewhat like small snakes radiating under the skin around the umbilicus.

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26
Q

Why does a portacaval anastomosis or a splenorenal shunt surgically reduce portal hypertension?

A

It diverts blood from the portal venous system to the systemic venous system by creating communication between the hepatic portal vein and the IVC.

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27
Q

What happens to lymph from the liver?

A

Before reaching the thoracic duct, lymph from the liver is filtered by hepatic lymph nodes in the hepatoduodenal ligament and the celiac lymph nodes around the celiac trunk. Half the lymph entering the thoracic duct is liver lymph.

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28
Q

What forms hepatic triads? Where do they course?

A

Hepatic portal vein
Proper hepatic arteries
Hepatic ducts

They course in the liver stroma.

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29
Q

What creates subunits of the hepatic lobes? What surrounds the margins of these subunits?

A

Polyhedral hepatic lobules create subunits of hepatic lobes. In the lobules, rows of hepatocytes are separated by the hepatic sinusoids that terminate in central veins.

Portal triads form an incomplete ring around the peripheral margins of the polyhedral hepatic lobes.

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30
Q

What is the flow of blood from the portal triads?

A

vessels of the portal triads –> sinusoids –> central veins –> tributaries of the hepatic veins –> left and right hepatic veins –> IVC

31
Q

What do the space of Disse do?

A

It separates sinusoids from adjacent rows of hepatocytes. Loose connective tissue occupies the space of Disse and suspends the sinusoids between the rows of hepatocytes.

Secretory products from the hepatocytes (plasma proteins and glucose) are released into the space of Disse and rapidly traverse the endothelial clefts of the sinusoids to enter the bloodstream.

32
Q

What are Kupffer cells?

A

They are macrophages that partially fill the clefts between endothelial cells lining the sinusoids. When small plasma proteins traverse the clefts into the space of Disse the Kupffer cells remove blood-borne bacteria, viruses and parasites.

33
Q

What is the function of fat-containing cells (of Ito)?

A

In normal liver, they store and regulate transport of 80% of total retinoids (vitamin A) in the body via large lipid droplets that are abundant in their cytoplasms.

Each cell has a small nucleus and many long, branched cytoplasmic processes that embrace endothelial cells of hepatic sinusoids.

They also contain alpha-smooth muscle actin, which via contraction in response to vasoactive substances may regulate blood flow in the sinusoids.

34
Q

Why is hepatic lymph, which originates in the space of Disse, so voluminous?

A

Spaces of Disse allow plasma to flow between sinusoidal lumina and hepatocyte surfaces, which permits the rapid exchange of soluble, noncellular substances between blood and parenchyma. Hepatic lymph originates in these spaces and eventually drains to small lymphatic vessels in portal tracts.

35
Q

Why is excessive alcohol consumption toxic to the liver?

A

It may morphological changes and clinical symptoms including liver cell damage, extensive fibrosis, and inflammation.

Hepatocytes in the alcoholic liver accumulate large amounts of fat and often become distended beyond recognition.

Mitochondria is enlarged and misshapen.

SER is distended.

Mallory bodies: aggregates of intermediate filaments of the cytoskeleton. scattered in the cytoplasm of damaged hepatocytes.

Structural changes parallels functional alterations in cell oxidation and metabolism.

36
Q

What forms bile canaliculi?

A

Cell membranes of adjoining hepatocytes make these canaliculi that convey bile to the bilary ducts of the portal triads.

Hepatocytes secrete bile (used in fat digestion) into the canaliculi at a rate of 30 mL/hr

37
Q

What prevents bile leakage from the canaliculi?

A

Tight junctions which link the cell membranes of adjacent hepatocytes

They also unite cells of simple cuboidal epithelium that lines the bilary duct system!

38
Q

Why does intrahepatic cholestasis cause jaundice?

A

Intrahepatic cholestasis is a pathologic state of reduced bile formation or flow. It leads to jaundice, a yellowing of the skin and sclera of the eyes because of excess circulating bilirubin.

39
Q

What is the liver acinus?

A

It is another concept of liver lobulation

It is an oval-shaped area of parenchyma defined by its blood supply from the vessels of the portal triad.

40
Q

What forms the short axis of the acinus?

A

Vessels of the portal triad.

It is surrounded by 3 concentric, elliptical zones (acinar zones 1, 2,3).

42
Q

What is the functional and pathological relevance of the zones of acinus?

A

Zone 1: most central. It is the first zone to receive oxygen, hormones, nutrients from the bloodstream and most glycogen and plasma protein synthesis by hepatocytes occurs here.

Zone 2: Intermediate

Zone 3: Furthest from the distributing vessels. Zone 3 is poorly oxygenated and is the first to show ischemic necrosis and fat accumulation if metabolism is altered. It is also the site of most drug and alcohol detoxification.

A gradient of metabolic activity exists for many hepatic enzymes in the three zones.

43
Q

What artery supplies the gallbladder?

A

The cystic artery branches from the right hepatic artery to supply the gall bladder.

44
Q

Where does lymph from the gallbladder drain to?

A

hepatic and celiac lymph nodes.

45
Q

Where is the fundus of the gallbladder located in the body?

A

It projects from the inferior border of the liver at the edge of the 9th costal cartilage on the right midclavicular line.

46
Q

What organs is the gallbladder closely associated with?

A

duodenum and transverse colon are in close proximity

47
Q

What causes biliary colic and how could it lead to cholecystitis? How is pain perceived after blockage of the cystic duct?

A

A stone lodged in the cystic duct causes biliary colic (intense, spasmodic pain). If the stone BLOCKS the cystic duct, cholecystitis can occur (inflammation of the gallbladder) because of bile accumulation.

Pain may be felt in the posterior thoracic wall or right shoulder owing to irritation of the diaphragm.

48
Q

Why does a cholecystoenteric fistula involve the 1st part of the duodenum or transverse colon and what is the diagnostic radiographic sign of the fistula?

A

A gallbladder that is dilated and inflamed owing to an impacted gallstone in its duct may develop adhesions with adjacent viscera. Because of their proximity to the gallbladder, the superior part of the duodenum and transverse colon are most likely to develop a cholecystoenteric fistula.

RADIOGRAPHIC SIGN: UNKNOWN

49
Q

What is the most common treatment for gallstones?

A

The most common treatment is laparoscopic surgery.

50
Q

What happens to the mucosal folds when the lumen is distended with bile?

A

They disappear. The simple columnar epithelium absorb water to concentrate bile for luminal storage (up to 50 mL)

51
Q

What does the muscularis externa of the gallbladder contain?

A

It contains longitudinally and diagonally organized bundles of smooth muscle.

52
Q

What is the contractile stimulus of the smooth muscle in the muscularis externa of the gallbladder after dietary fat intake?

A

Cholecystokinin is a hormone that causes the reflex contraction of smooth muscle. It also causes sphincters associated with the common bile duct and the ampulla to relax to permit bile to enter the duodenum.

53
Q

What nerves innervate the foregut derived viscera?

A

The vagus nerves, postsynaptic sympathetic fibers from the celiac ganglion, and visceral sensory fibers from DRG at T5-T9 innervate the foregut derived viscera via periarterial plexuses on branches of the celiac trunk.

54
Q

What does sympathetic and parasympathetic nerve fibers do the gallbladder?

A

Sympathetic: vasoconstriction regulates blood flow to the gallbladder and liver

Parasympathetic: not much! do not affect liver and contraction of the gallbladder is mainly under hormonal control

55
Q

Where is the pancreas located in the body?

A

The pancreas (like the distal duodenum and kidney) is a retroperitoneal organ. It resides on the posterior abdominal wall adjacent to the bodies of vertebrae L2 and L3.

56
Q 
What is the relationship of:
head of pancreas
neck of pancreas 
body of the pancreas
tail of pancreas

to the rest of the abdominal viscera?

A

head of pancreas: C-curve of duodenum, bile duct, and IVC
neck of pancreas: SMA and hepatic portal vein
body of pancreas: abdominal aorta
tail of pancreas: hilium of spleen

57
Q

What is the name of the space separating the stomach and first part of the duodenum from the pancreas?

A

HELP

Is it the pyloduodenal junction?

58
Q

What artery supplies the head of the pancreas? neck, body, and tail?

A

head of pancreas: superior and inferior pancreaticoduodenal arteries

neck, body, tail of pancreas: splenic artery

59
Q

Where does venous blood from the pancreas drain?

A

hepatic portal vein

60
Q

What innervates the pancreas? What do sympathetic fibers do to it? Vagal fibers?

A

periarterial plexuses on branches of the celiac trunk

Sympathetic: vasoconstriction
Vagal fibers: secretomotor (pancreas is mainly under hormonal control)

61
Q

Where does visceral pain of the pancreas that is distended or irritated referred to in the body?

A

epigastric region

62
Q

What (in relation to the pancreas) causes sharp, localized, back pain?

A

The parietal peritoneum covers the anterior surface of the pancreas and activation of somatic sensory fibers that supply the parietal peritoneum causes the back pain

63
Q

What forms the hepatopancreatic ampulla?

A

The union of the main pancreatic duct to the bile duct forms the short, dilated hepatopancreatic ampulla on the descending part of the duodenum.

Demarcates the foregut and midgut derived portions of the duodenum

64
Q

What do smooth muscle sphincters of the bile duct, pancreatic duct and hepatopancreatic ampulla do?

A

They control the flow of bile and pancreatic enzymes into the duodenum and prevents reflux of duodenal content into the ampulla

Tonic contractions of the sphincters normally limits flow into and reflux from the ampulla.

65
Q

What does cholecystokinin activate?

A

gallbladder contraction

relaxes the sphincters

66
Q

Why can spasms of the hepatopancreatic sphincter or obstruction of the hepatopancreatic ampulla by gallstones cause pancreatitis?

A

Bile may back up and enter the pancreatic duct causing pancreatitits.

If the ampulla is blocked, the weak pancreatic duct spinchter may be unable to withstand the excessive pressure of the bile in the hepatopancreatic ampulla.

67
Q

Why can severe, forceful compression of the abdomen rupture the pancreas and why would sharp, local pain result?

A

The pancreas is located centrally within the body and is well protected. However, pancreatic injury can occur from sudden, severe, forceful compression of the abdomen, such as force of impalement on a steering wheel in an automobile accident.

Rupture of the pancreas tears its duct system allowing pancreatic juice to enter the parenchyma of the gland and to invade adjacent tissues. Digestion of pancreatic and other tissues by pancreatic juice is VERY painful.

68
Q

How does pancreatic cancer cause jaundice and why does the cancer have a high fatality rate?

A

Cancer of the head often compresses and obstructs the bile duct and/or the hepatopancreatic ampulla. This causes obstruction, resulting in the retention of bile pigments, enlargement of the gall bladder and obstructive jaundice (staining of most body tissues by circulating bile pigments).

The pancreas’s extensive drainage to relatively inaccessible lymph nodes, and the fact that pancreatic cancer typically metastasizes to the liver early, via the hepatic portal vein, make surgical resection of cancerous pancreas nearly futile.

69
Q

Where does the main pancreatic duct extend in the pancreas?

A

from the tail to the head of the pancreas

70
Q

What do secretory acini do?

A

The dark stained cells of the secretory acini secrete digestive enzymes, mainly under the influence of cholecystokinin (rate of 1-2L/ day)

71
Q

What do exocrine acini do?

A

It secrete into small ducts that empty into the main duct along its entire length

72
Q

What is scattered among the acini of the exocrine pancreas?

A

Pancreatic islets of Langerhans

73
Q

What identifies beta and alpha cells?

A

selective staining of hormones

insulin: beta
glucagon: alpha

74
Q

What is different about secretions of beta and alpha cells of the endocrine pancreas versus the exocrine pancreas?

A

Beta and alpha cells of the endocrine pancreas enter the bloodstream via a network of capillaries, which lie next to each islet cell

75
Q

What does insulin vs. glucagon do?

A

insulin: lowers blood glucose mainly by prompting glucose entry into hepatocytes, adipocytes and skeletal muscle fibers.
glucagon: raises blood glucose mainly by activating hepatocytic glycogenolysis

76
Q

How can acute pancreatitis become life threatening?

A

Inflammatory disorder of the exocrine pancreas often associated with alcoholism.

Usually pancreatic acinar cells are normally protected from harmful effects of digestive enzymes that they secrete. But, acinar cell injury or pancreatic duct obstruction may lead to inappropriate extracellular leakage of activated digestive enzymes and autodigestion of pancreatic acini. This causes edema and progressive fibrosis of the stroma and causes hemorrhage and pancreatic insufficiency.

Anatomy Unit 3 (9 decks)

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