Gi 05: Anatomy And Histology Of The Liver, Gallbladder, And Pancreas

Front 1

What is the largest glandular tissue in the body? Size?

Back 1

Liver
- 1200g to 1800g
- 12-15 cm top to bottom
- 15-18 cm across
- Males: 1.8 kg (avg weight)
- Females: 1.4 kg (avg weight)

Front 2

What are the lobes of the liver? Which are the biggest?

Back 2

- Right
- Left
- Quadrate
- Caudate

R and L lobes make up the bulk

Front 3

What blood does the liver receive? Origin?

Back 3

Receives mainly venous blood, arriving directly from the spleen, pancreas, and intestine

Front 4

What are the implications of the liver receiving venous blood from the spleen, pancreas, and intestine?

Back 4

It is the first organ to encounter any ingested toxic substances as well as nutrients

Front 5

What kind of tissue makes up the liver?

Back 5

- Bulk is uniform parenchymal cells = hepatocytes
- Sparse connective tissue

Front 6

What are the functions of the liver?

Back 6

- Detox metabolic waste products
- Synthesize plasma lipoproteins
- Synthesize blood clotting factors
- Synthesis, secretion, and storage of carbs and lipids
- Destruction of spent RBCs and recovery of constituents
- Synthesis and secretion of bile

Front 7

What are the two types of properties of the liver? How do they differ?

Back 7

Endocrine
- From hepatocytes directly into the hepatic blood
- Includes: albumin, fibronectin, transferrin, prothrombin, lipoproteins, α-1-antitrypsin, glucose (after glycogen breakdown), and thyroxin (highly active form)

Exocrine
- Production of bile

Front 8

What happens to endocrine secretions from the hepatocytes? Which ones?

Back 8

- Directly enter the hepatic blood
- Albumin, fibronectin, transferrin, prothrombin, lipoproteins, α-1-antitrypsin, glucose (after glycogen breakdown), and thyroxin (highly active form of thyroid hormone)

Front 9

What compound is produced by hepatocytes to be released for exocrine function?

Back 9

Bile

Front 10

What are the four functional groups of liver components?

Back 10

- Connective tissue
- Large vessels (including blood vessels, lymphatic vessels, nerves, and bile ducts)
- Sinusoidal capillaries (sinusoids - which line the plates of hepatocytes and are responsible for blood flow through the liver)
- Hepatocytes

Front 11

What surrounds the hepatocytes and sinusoids in the liver?

Back 11

Reticular fibers composed of Collagen Type III

Front 12

What is the only connective tissue in the lobules of the liver? Organization? Functions?

Back 12

Reticular Fibers made of Collagen Type III
- Sparse
- Extends outward from the central vein
- Supports the hepatic parenchyma
- Contributes toward keeping sinusoids open to allow normal blood flow

Front 13

What is the origin of the reticular fibers (collagen type III) that surround hepatocytes and sinusoids?

Back 13

Stellate / Ito cells found in the Space of Disse

Front 14

Where are Stellate / Ito cells found? Function?

Back 14

- Space of Disse
- Form the reticular fibers (collagen type III) that surrounds hepatocytes and sinusoids

Front 15

What can disrupt the reticular fiber network surrounding hepatocytes and sinusoids? How can you assess this?

Back 15

- Liver disease can cause disruption of this network
- Staining for Reticulin can aid diagnosis

Front 16

What are the fiver major vessel systems in the liver?

Back 16

- Hepatic artery
- Hepatic portal vein
- Central veins
- Bile ducts
- Lymphatic vessels

Front 17

What is the function of the hepatic artery? Origin?

Back 17

- Carries oxygenated arterial blood into the liver
- Arises from the celiac trunk

Front 18

What is the function of the hepatic portal vein?

Back 18

- Carries venous blood into the liver (high in nutrients)
- Brings blood from the intestines (contains many nutrients and toxic substances), pancreas (contains endocrine secretions like insulin and glucagon), and spleen (contains breakdown products of blood cells)

Front 19

What is the function of the central veins?

Back 19

Carries blood away from the liver toward the hepatic veins and eventually into the IVC

Front 20

What is the function of the bile ducts?

Back 20

Transports bile from the liver

Front 21

What is the function of the lymphatic vessels in the liver?

Back 21

Carries lymph away from the liver

Front 22

What are the contents of the hepatic portal vein blood from the intestine?

Back 22

Nutrients and toxic substances

Front 23

What are the contents of the hepatic portal vein blood from the pancreas?

Back 23

Endocrine secretions like insulin and gluagon

Front 24

What are the contents of the hepatic portal vein blood from the spleen?

Back 24

Breakdown products of the blood cells

Front 25

How does blood gain access to the hepatocytes?

Back 25

Arterial capillaries and inlet venules carry blood from the hepatic artery and portal veins into a network of sinusoidal capillaries (sinusoids)

Front 26

What is the portal triad? How much blood is contributed by these components?

Back 26

Combination of branches of:
- Hepatic artery (30%)
- Hepatic portal vein (70%)
- Common bile duct

(also associated with lymphatic vessels)

Front 27

What is the flow of blood through the portal triad and the hepatocytes?

Back 27

- Blood from hepatic arteries and portal veins flows through the sinusoids toward the central vein
- Efferent blood leaves through the central vein to join the vena cava
- Flow past the hepatocytes allows for exchange of substances

Front 28

What kind of capillaries are in the hepatocytes? Function?

Back 28

Sinusoidal (type III) - allows the exchange of substances between the blood and hepatocytes

Front 29

What are the types of cells in the sinusoids of the liver?

Back 29

- Endothelial cells (sometimes called sinusoidal cells)
- Sinusoidal macrophages (Kupffer cells)

Front 30

What are Kupffer cells derivatives of? Function?

Back 30

- Monocytes (they are aka sinusoidal MACROPHAGES)
- Possibly involved in breakdown of senile RBCs

Front 31

Which cells are possibly involved in the breakdown of senile RBCs?

Back 31

Kupffer cells (aka sinusoidal macrophages)

Front 32

What are the characteristics of the endothelium lining the sinusoids?

Back 32

- Discontinuous to
- Allows unobstructed transfer of plasma and its substrates to the hepatocytes and endocrine secretions from the hepatocytes to the blood
- Large spaces are evident between endothelial cells and there is no continuous basal lamina

Front 33

What is found within the sinusoidal lining?

Back 33

Large numbers of fenestrae that are arranged as sieve plates

Front 34

Where does exchange of substances between blood and hepatocytes take place?

Back 34

Peri-sinusoidal Space of Disse

Front 35

Where is the peri-sinusoidal Space of Disse?

Back 35

Lies between the basal surface of the hepatocyte and the sinusoid

Front 36

What special feature is found on hepatocytes? Function?

Back 36

Microvilli on basal surface which increases the surface area available for substance exchange

Front 37

Why do hepatocytes have microvilli?

Back 37

To increase the surface area available for substance exchange

Front 38

What is commonly found in the peri-sinusoidal Space of Disse?

Back 38

Stellate cells (Ito cells / adipose / lipocytes)

Front 39

What is the structure and function of Stellate cells (Ito cells / adipose / lipocytes)?

Back 39

- Commonly found in peri-sinusoidal Space of Disse
- Often contain large lipid droplets
- Major site of vitamin A storage

Front 40

What is the term for the "functional units" of the liver? What are the types?

Back 40

Lobules:
- Classic lobule
- Portal lobule
- Liver acinus

Front 41

What is the shape of the Classic Lobule? Organization?

Back 41

- Hexagonal block of tissue
- Single central vein at core
- Portal triad at each of the 6 corners
- Sinusoids and hepatic plates radiate toward the portal triads

Front 42

How do you identify the classic lobule in pig livers? Human livers?

Back 42

- Pigs: presence of CT surrounding each lobule
- Humans: very little interlobular CT, which makes it difficult to identify

Front 43

What is at the center of a classic lobule?

Back 43

Single central vein

Front 44

What is at the corners of the hexagonal classic lobule?

Back 44

Portal triad: branches of the portal vein, hepatic artery, and bile duct

Front 45

What radiates from the central vein to the portal triad at each corner of the hexagonal classic lobule?

Back 45

Sinusoids and hepatic plates

Front 46

What is the shape of the liver acinus? Organization?

Back 46

- Lozenge shaped
- Short axis formed between two adjacent portal triads
- Long axis formed between adjacent central veins

Front 47

What does the liver acinus correlate with?

Back 47

- Liver acinus closely correlates with blood perfusion, metabolic activity, and liver pathology
- It allows description of patterns of hepatocyte cell death and regeneration following toxicity

Front 48

What is the flow of oxygenated nutrient / toxin rich blood through the classic lobule?

Back 48

- Blood perfuses from the terminal vessel toward the central vein
- Produces a gradient of nutrients and substances encountered by hepatocytes

Front 49

What is the organization of the zones in the acinus?

Back 49

Three concentric zones surrounding a terminal vessel
- Zone 1: encounters afferent blood first
- Zone 2: second
- Zone 3: last (most susceptible to ischemia)

Front 50

How do the three zones of the acinus differ?

Back 50

Differ with respect to metabolic activity, glycogen storage, and presence of organelles

Front 51

Acetaminophen toxicity damages which part of the acinus?

Back 51

Zone 3

Front 52

What is the principal functional cell of the liver?

Back 52

Hepatocyte

Front 53

How are hepatocytes organized?

Back 53

- Makes up the liver parenchyma
- Arranged in anastomosing plates 1-2 cells thick separated by sinusoids
- Plates of hepatocytes run from central vein out toward the portal triads

Front 54

What shape are hepatocytes? Size?

Back 54

- Large polyhedral cells
- 30 µM wide
- Six surfaces - two faces the perisinusoidal space and four face other hepatocytes and the bile canaliculi

Front 55

What do the peri-sinusoidal surfaces of hepatocytes face?

Back 55

They represent the basal aspect of the cell

Front 56

What sides of the hepatocytes face other hepatocytes?

Back 56

Lateral surfaces

Front 57

What sides of the hepatocytes face bile canaliculi?

Back 57

Apical surfaces

Front 58

Where does transfer of substances between sinusoids and hepatocytes occur?

Back 58

Across the basal surface (peri-sinusoidal surface)

Front 59

What is the shape/organization of the nuclei in hepatocytes?

Back 59

- Large spherical nucleus located in the center of the cell
- Majority are binucleate and are tetraploid (contain 4n DNA)

Front 60

What are the features of the organelles in hepatocytes?

Back 60

- Extremely rich in organelles
- Reflects their high metabolic activity
- Particularly high in RER and mitochondria
- Glycogen granules are deposited throughout the cytoplasm
- Lipid droplets are also prevalent

Front 61

How can we prove that liver regeneration occurs?

Back 61

Partial hepatectomy (in rodents):
- Intact lobes of the liver are removed, leaving a single intact lobe behind
- Cells in the remaining lobe re-enter the cell cycle and begin to proliferate
- Dissected lobes do not grow back, instead the residual lobe enlarges enough to make up for the mass of the removed lobes

Front 62

What cells regenerate after a partial hepatectomy?

Back 62

All liver cell types:
- Hepatocytes
- Biliary epithelial cells
- Sinusoidal endothelial cells
- Kuppfer cells
- Stellate cells

Front 63

How long does the regeneration process from a partial hepatectomy take in rats?

Back 63

5-7 days

Front 64

How does liver regeneration occur in humans?

Back 64

- During regeneration, normal liver function is maintained
- Liver mass is precisely regulated by both positive and negative signals
- Several growth factors have been identified that play crucial roles in regulating regeneration

Front 65

What are the problems with hepatocyte transplantation?

Back 65

- Recovering enough normal donor hepatocytes that are acceptable by the host
- Donor hepatocytes from another individual will be rejected by the host without prolonged immune suppression

Front 66

What would be the ideal way to transplant hepatocytes?

Back 66

- Isolate hepatic stem cells from an afflicted individual
- Expand them in culture
- Genetically modify to correct the defects
- Corrected cells could be returned to the patient whereby they could replace diseased hepatic tissues

Front 67

Where are oval cells found? Characteristics?

Back 67

- Rare population of cells present in the biliary epithelium
- Characteristics of a stem cell, an undifferentiated cell capable of self renewal, proliferation, and production of differentiated progeny
- Bipotential - differentiate to form both biliary epithelial cells and hepatocytes

Front 68

What can oval cells become? Why?

Back 68

They can differentiate to form both biliary epithelial cells and hepatocytes because they are bipotential

Front 69

What happens during chronic liver damage when hepatocyte function and replication is severely compromised?

Back 69

Oval cells proliferate and differentiate

Front 70

How does bone marrow relate to oval cells?

Back 70

- Transplanted BM has been shown to give rise to oval cells
- May provide a source of hepatic stem cells that are bipotential (can proliferate into biliary epithelial cells and hepatocytes)

Front 71

More recently, what have pluripotent stem cells been derived from? How can this be used for liver regeneration?

Back 71

- Pluripotent stem cells have been derived from human fibroblasts
- They have been used to generate hepatocyte-like cells that could one day be used to treat human hepatic disease

Front 72

What is the main exocrine function of the liver?

Back 72

Production of bile

Front 73

What are the functions of bile salts?

Back 73

- Emulsification - decreases surface tension and breaks fat globules into smaller size particles
- Forms micelles (soluble in chyme) and helps absorption of fat breakdown products (FA, monoglycerides, and cholesterol)

Front 74

Where is bile produced? How is it excreted?

Back 74

- Hepatocytes produce bile
- Bile is actively secreted by ATPases across their apical surface into the bile canaliculi

Front 75

What is found in the bile canaliculi (where bile is excreted after being produced by hepatocytes)?

Back 75

ATPases - which means that bile secretion is an active process

Front 76

What is the organization of bile canaliculi?

Back 76

The canaliculi join together to form small terminal ductules called Canals of Herring

Front 77

What are bile ducts made of?

Back 77

- Biliary epithelial cells
- Cuboidal epithelium which forms a ductule

Front 78

How does bile flow compare to blood flow?

Back 78

Bile flows in the opposite direction of the blood, i.e., away from the central vein toward the portal triad

Front 79

Where do bile ducts lead?

Back 79

Lead from the portal triad to join the hepatic duct that carries the bile to the gallbladder

Front 80

How much bile is secreted by the liver per day?

Back 80

1 L

Front 81

What is the function of the gallbladder?

Back 81

- Concentrates the dilute bile that comes from the liver 5-10x
- Stores up to 100 mL of bile / day

Front 82

What stimulates gallbladder contraction and release of bile into the duodenum?

Back 82

- The presence of lipid in the duodenum induces secretion of the hormone CCK
- CCK: cholecystokinin-pancreozymin

Front 83

What is the function of CCK?

Back 83

Cholecystokinin-pancreozymin stimulates gallbladder contraction and forces concentrated bile out

Front 84

What is the shape/structure of the gallbladder?

Back 84

- Muscular sac
- Empty or distended GB has numerous deep mucosal folds

Front 85

What type of epithelium lines the gallbladder? Characteristics?

Back 85

- Mucosa made of simple columnar epithelial cells
- Resembles the absorptive cells of the intestine
- Cells have numerous short apical microvilli
- Basally located nucleus

Front 86

How are the cells of the epithelium in the gallbladder connected?

Back 86

Junctional complexes to produce a barrier between the luminal and intercellular compartments

Front 87

What is the function of the epithelium of the gallbladder?

Back 87

- Concentrate bile by actively absorbing water into a capillary rich network in the lamina
- Maintain a barrier between the luminal and intercellular components

Front 88

How big is the adult pancreas?

Back 88

- 100-150 g
- 20-25 cm

Front 89

What are the parts of the pancreas? Location?

Back 89

- Head: nestles within the concavity of the duodenum, which is C-shaped
- Body
- Tail
- Main pancreatic duct: traverses the length of the organ and joins the common bile duct before entering the duodenum

Front 90

What is the pancreas made of?

Back 90

- Highly lobular
- Loose collagenous tissue separates the lobules as septa

Front 91

What is the path of the main pancreatic duct?

Back 91

Transverses the length of the pancreas and joins the common bile duct before entering the duodenum

Front 92

What are the functions of the pancreas?

Back 92

Exocrine (blue):
- Releases enzymes for digestion

Endocrine (green):
- Secretes hormones that control carbohydrate metabolism

Front 93

What is the organization of the exocrine pancreas?

Back 93

- Consists of densely packed Acini (blue)
- Secretes into a system of ducts: intercalated, intralobular, interlobular, and pancreatic
- Ducts channel the pancreatic secretions into the pancreatic duct that leads to the dudoenum

Front 94

What is the organization of the endocrine pancreas?

Back 94

Consists of randomly distributed Islets of Langerhans (green) throughout the exocrine tissue (blue)

Front 95

What does the exocrine pancreas release?

Back 95

Enzymes involved in digestion in small intestine:
- Secretin
- Cholecystokinin

Front 96

What hormones are released when the duodenum contains food? Function?

Back 96

- Secretin
- Cholecystokinin

- Induce secretion of pancreatic juice from the exocrine pancreas: contains alkaline fluid and enzymes and proenzymes (zymogens) required for digestion

Front 97

How are digestive enzymes stored in the exocrine pancreas?

Back 97

Zymogen granules within the cytoplasm of acinar cells
- Granules allows them to be rapidly released into the gut after a meal
- Zymogen form prevents their auto-digestion of pancreatic tissues
- Stored with proteolytic inhibitors that block any errant activation of proenzymes in the pancreas

Front 98

How are the zymogen forms of digestive enzymes activated?

Back 98

Proteolytic cleavage in the intestine

Front 99

How does the pancreas ensure there is no auto-digestion of its tissues?

Back 99

- Digestive enzymes exist in their proenzyme state (inactive) that only are activated in the intestine by proteolytic cleavage
- Proteolytic inhibitors are secreted by acinar cells to block any errant activation of the proenzymes

Front 100

What is the functional unit of the exocrine pancreas? Shape?

Back 100

Acinus - roughly spherical containing 40-50 pancreatic acinar cells surrounding the lumen of a small ductule

Front 101

What induces acinar cells to secrete pancreatic enzymes into the lumen?

Back 101

Cholecystokinin, stimulated by fatty foods in the duodenum

ACh from vagus nerve is a weaker stimulus

Front 102

What is the organization and function of centroacinar cells?

Back 102

- Extend from the end of the duct into the acinus as a discontinuous epithelium
- Low squamous epithelial cells responsible for secretion of alkaline fluid component of pancreatic juice

Front 103

What induces centroacinar cells to secrete the alkaline fluid component of pancreatic juice?

Back 103

Secretin

Front 104

What is the function of Cholecystokinin?

Back 104

- Results in gallbladder contraction and emptying in under 1 hour
- Induces acinar cells to secrete pancreatic/digestive enzymes in the form of zymogen granules into the lumen
- Relaxes Sphincter of Oddi

Front 105

What is the function of Secretin?

Back 105

- Stimulates secretion of alkaline fluid, rich in sodium bicarbonate, from the centroacinar cells
- Helps neutralize acids and optimizes pancreatic function

Front 106

What is the importance of the alkaline fluid released from centroacinar cells?

Back 106

- Solubilization of zymogen granules
- Helps neutralize acidic chyme as it enters the duodenum (prevents inactivation of enzymes and protects epithelium)

Front 107

What is the shape and organization of the acinar cells of the pancreas?

Back 107

- Pyramidal shape
- Basally located nucleus
- Cells are extremely active so the basal cytoplasm is packed with RER to synthesize exported proteins
- Proenzymes are modified in the Golgi to form zymogen granules

Front 108

How are the zymogen granules released into the lumen?

Back 108

Exocytosis at the apical surface of the acinar cell

Front 109

How is pancreatic juice transported to the duodenum?

Back 109

Network of pancreatic ducts:
- After entering the centroacinar lumen, juice moves through a series of Intralobular ducts
- These ducts merge and transport the uice into the larger interlobular lobes
- These then join the main pancreatic duct to transport the fluid to the duodenum

Front 110

What is the organization of the bile ducts in the liver and gallbladder?

Back 110

- R hepatic duct drains R lobe and L hepatic duct drains L lobe
- R and L hepatic ducts combine to form Common Hepatic Duct
- Gallbladder drained by the Cystic Duct
- Cystic Duct and Common Hepatic Duct combine to from the Common Bile Duct

Front 111

What does the round ligament separate? What is it a remnant of?

Back 111

- Anatomically, the round ligament divides the left part of the liver into medial and lateral sections.
- The round ligament represents the remnant of the fetal umbilical vein.

Front 112

What does the coronary ligament of the liver do?

Back 112

The coronary ligament of the liver refers to parts of the peritoneal reflections that hold the liver to the inferior surface of the diaphragm

Front 113

What is the porta hepatis?

Back 113

Gateway to the liver - where the portal triad enters the liver (portal vein, hepatic artery, and common bile duct)

Front 114

What separates the right and left lobes of the liver?

Back 114

Obliterated ductus venosus and and obliterated umbilical vein

Front 115

What area of the liver is not covered in peritoneum? What does this part attach to?

Back 115

- The superior bare area on the right lobe
- Attaches directly to the diaphragm

Front 116

What are the functions of the ligaments on the liver?

Back 116

- Keeps the liver from moving around
- Fastens it to the diaphragm and posterior abdominal wall

Front 117

What is the function of the Left Triangular Ligament?

Back 117

- Fold that connects the posterior part of the upper surface of the left lobe of the liver to the diaphragm
- Anterior layer is continuous with the left layer of the falciform ligament

Front 118

What is the location and function of the Right Triangular Ligament?

Back 118

- Situated at the right extremity of the bare area
- Small fold which passes to the diaphragm
- Formed by the apposition of the upper and lower layers of the coronary ligament

Front 119

If planning to resect part of the liver, how do you approach the task?

Back 119

Hepatic Segments: based on arterial, venous, and biliary supply, in addition to the drainage of the liver

Front 120

What drains the liver?

Back 120

Hepatic veins (right, middle, and left) that empty into the IVC

Front 121

What separates the L and R lobes clinically?

Back 121

Middle hepatic vein

Front 122

What do the segments of the liver represent?

Back 122

- Caudate lobe: segment 1
- L lobe: segments 2, 3, and 4
- R lobe: segments 5, 6, 7 and 8

Front 123

What is special about segment 1 of the liver?

Back 123

- Represents the caudate lobe
- Receives arterial and venous blood from both R and L sides
- Directly empties into the IVC

Front 124

If you are transplanting a liver, which segments do you take?

Back 124

- Adult: R lobe (segments 5, 6, 7 and 8)
- Child: part of L lobe (segments 2 and 3)

Front 125

What is the route of bile from the gallbladder to the small intestine?

Back 125

- Cystic duct drains gallbladder
- Flows into Bile duct
- Empties into Duodenum at the hepatopancreatic ampulla

Front 126

What is the flow of blood leaving the midgut?

Back 126

- Branches of Superior Mesenteric Vein
- Flows into the Portal Vein to the liver
- Flows through Hepatic Sinuses
- Enters IVC via Hepatic Veins

Front 127

What is the flow of blood leaving the hindgut?

Back 127

- Branches of Inferior Mesenteric Vein
- Flows into the Portal Vein to the liver
- Flows through Hepatic Sinuses
- Enters IVC via Hepatic Veins

Front 128

What can happen to the portal circulation if there is liver disease?

Back 128

Liver disease can cause blood flow to back up and reverse direction to the spleen, causing the spleen to enlarge

Front 129

How does fresh blood get to the liver? What percent of the blood comes via this route?

Back 129

- Abdominal aorta supplies the Celiac Trunk
- The common hepatic artery is one of the branches
- The proper hepatic artery and R and L hepatic arteries enter the liver and supply 30% of the total blood

Front 130

Once blood enters the liver via the hepatic artery or the portal vein, how does it flow through the liver?

Back 130

- The blood flows through the hepatic sinuses / sinusoids
- Blood leaves via the hepatic vein to get to the IVC

Front 131

What kinds of cells line the bile canaliculi?

Back 131

Liver cell plates

Front 132

Where is the space of Disse?

Back 132

Located between the sinusoids and the liver cell plates that line the bile canaliculi

Front 133

How does the concentration of bile in the liver compare to that in the gallbladder? How does this change occur?

Back 133

- Liver bile is more dilute than gallbladder bile
- Bile is concentrated once it gets to the gallbladder via absorption of water, Na+, and Cl-
- Leaves concentrated salts, cholesterol, lecithin, and bilirubin
- Volume goes from 500 mL to 50 mL

Front 134

What happens to the volume of bile that leaves the liver to that which is stored in the gallbladder?

Back 134

Volume goes from 500 mL to 50 mL via absorption of water, Na+, and Cl-

Front 135

What happens to cholesterol and lecithin in the gallbladder?

Back 135

They are solubilized by bile salts

Front 136

Where are bile acids reabsorbed?

Back 136

Ileum where they are taken via the portal blood back to the liver

Front 137

What enzymes are released by the pancreas to digest proteins?

Back 137

- Trypsinogen
- Chymotrypsinogen
- Procarboxypeptidase

All released in inactive form to prevent self-digestion

Front 138

How are the enzymes released from the pancreas to digest proteins activated?

Back 138

- Trypsinogen is activated to Trypsin by Enterokinase
- Trypsin further activates Trypsinogen as well as converts Chymotrypsinogen to Chymotrypsin and Procarboxypeptidase to Carboxypeptidase

Front 139

What activates Trypsinogen to Trypsin?

Back 139

- Enterokinase
- Other Trypsin molecules

Front 140

What activates Chymotrypsinogen to chymorypsin?

Back 140

Trypsin

Front 141

What activates Procarboxypeptidase to Carboxypeptidase?

Back 141

Trypsin

Front 142

What prevents activation of the pancreatic enzymes?

Back 142

Trypsin inhibitor prevents activation until secretions reach the small intestine

Front 143

What are the three forms of carbohydrates in our diet?

Back 143

- Starches
- Lactose
- Sucrose

Front 144

How do you digest starches?

Back 144

Starch → Maltose and 3-9 glucose polymers
- Ptyalin from the saliva (20-40%)
- Pancreatic Amylase from the pancreas (50-80%)

Maltose and 3-9 glucose polymers → Glucose
- Maltase and α-dextrinase from the intestine

Front 145

How do you digest lactose?

Back 145

Lactase from the intestine breaks Lactose down into Galactose and Glucose

Front 146

How do you digest Sucrose?

Back 146

Sucrase from the intestine breaks down Sucrose into Fructose and Glucose

Front 147

What is the form of the dietary fats?

Back 147

- Majority are Triglycerides (TG): glycerol nucleus + 3 FA side chains
- Small amounts of Phospholipids, Cholesterol, and Cholesterol Esters

Front 148

What digests Triglycerides?

Back 148

Pancreatic Lipase - can digest all TG it can reach within 1 minutes (requires emulsification by bile salts)

Front 149

What is the function of Pancreatic Lipase?

Back 149

Digests Triglycerides into Free Fatty Acids and 2-Monoglycerides

Front 150

How do you digest Phospholipids?

Back 150

Phospholipase

Front 151

How do you digest Cholester esters?

Back 151

Cholesterol Esterase

Front 152

What happens to the digested fat remnants?

Back 152

Bile salts form micelles and remove monoglycerides and fatty acids and transports them to the brush border for absorption

Front 153

Where is bicarbonate secreted from?

Back 153

Bile ducts and pancreatic ducts

Front 154

How does bicarbonate get formed?

Back 154

- CO2 diffuses in and combines with H2O to form H2CO3
- H2CO3 breaks down to form H+ and HCO3-
- HCO3- goes into the lumen and associates with Na+, which causes a gradient into the lumen with water

Front 155

Which hormone has the greatest effect on Sphincter of Oddi relaxation?

Back 155

Cholecystokinin

Front 156

In a 40-yo male with Hepatitis C, which hepatic acinus zone would be exposed to the greatest number of viral particles?

Back 156

Zone 1 (this receives the greatest amount of blood flow)

Front 157

Which zone of the hepatic acinus would be affected most by ischemia?

Back 157

Zone 3