Exam3Lec3Digestive3 Flashcards
(49 cards)
What is the largest gland in the body?
Liver
What is the hepatic lobule made up of?
cells, CT, blood vessels, sinuses + biliary tree
What are the structures of the hepatic lobule?
- Classic Lobule
- Portal Lobule
- Liver Acinus
Classic lobule
1. Shape
2. Central vein lxn
3. Portal triad lxn
- Shape: hexagonal
- Central vein lxn: at the center
- Portal triad lxn: at each point of the hexagon
Portal lobule
1. Shape
2. Central vein lxn
3. Portal triad lxn
- Shape: triangular
- Central vein lxn: at each point of the triangle
- Portal triad lxn: at the center
Liver Acinus
1. Shape
2. Central vein lxn
3. Portal triad lxn
- Shape: oval (elliptical)
- Central vein lxn: horizontal ends
- Portal triad lxn: vertical ends
List the location and fxn of each zone of the liver acinus
1. Zone 1
2. Zone 2
3. Zone 3
- Zone 1: = closest to center (axis) -> receive nutrients + toxins first
- Zone 2: Zone 2 = middle ->receive nutrients + toxins 2nd
- Zone 3: furthest from center (axis) receive nutrients + toxins last
Toxins mainly affects which zone of the liver acinus? Oxygen depletion mainly affects which zone of the liver acinus?
toxins mainly affect zone 1; oxygen depletion mainly affects zone 3
What are the 3 types of liver cells?
Hepatocytes, Hepatic Stellate Cells (Ito cells), Kupffer cells
What are hepatocytes?
large polygonal cells w/ microvilli
What is the endocrine and exocrine fxn of hepatocytes?
What is the exocrine fxn regulated by?
What do the organelles do?
Endocrine fxn = make + secrete proteins/lipoproteins into the blood
Exocrine fxn = make + secrete bile into bile ducts and gallbladder
Exocrine fxn regulated by CCK
Organelles degrade toxins (sER) + store lipofuscin pigment (lysosomes)
Granules store glycogen + lipids stain acidophilic (pink)
Hepatic Stellate Cells = Ito Cells
1. Lxn
2. Fxn
- Lxn:Space of Disse
- Fxn: store fat + vitamin A & produce type I collagen fibers
Kupffer Cells
1. Lxn
2. Fxn
- Lxn: inside sinusoids (capillaries)
- Fxn: breakdown of damaged RBCs forms bilirubin (pigment)
Can act as macrophages (phagocytic cells) in the sinusoids
What is the space of disse?
The space b/n the hepatocytes & the endothelial cells of the sinusoid
What structures are extended/secreted into the space of disse?
- Microvilli of hepatocytes extend into this space for absorption
- Processes of Kupffer cells extend into this space + act as macrophages
- Ito cells secrete type I collagen fibers into this space
What is the CT of the liver comprised of?
- Glisson capsule (dense CT)
- Fibroblasts + type I collagen= around the portal triads
- reticular (type III collagen)= perisinusoidal space and around the central vein
What can occur if there is damage to hepatocytes? What does each liver cell do?
causes them to release cytokines to recruit cells to the area
Kupffer cells can act as macrophages to breakdown damaged cellular material
Ito cells become activated ->transform into myofibroblasts -> produce type I collagen fibers into the space of Disse
An increase in fibrosis around the portal vein ____ blood flow, which leads to ____ blood pressure. This can lead to ____
An increase in fibrosis around the portal vein decreases blood flow, which **increases **blood pressure. This can lead to portal HTN.
What is cirrhosis?
What is it caused by?
* Can hepatocytes regenerate?
* death of hepatocytes leads to what?
- Progressive hepatocyte destruction leads to the destruction of normal liver unit structure
Causes: alcohol toxicity, some forms of viral infection, and autoimmune liver disease. - Hepatocytes can regenerate…but NOT their portal system connections
- Increase in fibrocollagenous tissue (type I collagen) leads to formation of “scar tissue”
chronic liver damage
What are 3 causes of cirrhosis?
alcoholism, certain viral infections, autoimmune disease
What makes up the vascular system of the liver (5)?
- Portal vein
- Hepatic vein
- Interlobular vessels in triads
- Sinusoids
- Central vein
portal vein → hepatic vein → interlobular vessels → sinuses → central vein
What are the blood vessels of the liver unit and list the fxn for each?
- Portal vein: brings deoxygenated blood from the intestines, pancreas + spleen to the liver = 75% of blood
- Hepatic artery: brings oxygenated blood from the heart to the liver = 25% of blood
- Interlobular vessels: branch off from the hepatic artery and deliver blood to the sinusoids
- Sinusoids: (=discontinuous capillaries) deliver blood to the central vein
- Central vein: travels alone in the center of the liver unit (i.e., lobule)
Central vein: In the center of the lobule = not in triad
Portal triad = ____ + ____ + ____
portal triad = portal vein +hepatic artery + bile duct
What is the order of the biliary tree?
Bile Canaliculi ->Bile Ductule (interlobular ducts = in portal triad) -> Common Bile Duct
