Liver

Question 0

What does the gall bladder do?

Answer 0

Gallbladder stores bile and sucks water out to concentrate all the bile to emulsify fat
CCK is the hormone of the gallbladder

Question 1

What is in the gall bladder besides bile?

Answer 1

other “stuff” from the liver, like bilirubin

Question 2

What is the structure of a liver lobule?

Answer 2

Hexagon with portal triad at each corner and central vein in the center
Contains Kupffer cells (macrophages, live forever)

Question 3

What is the portal triad made up of? Which way do the vessels flow?

Answer 3

Hepatic portal vein (80%) - drains to central vein
Hepatic artery (20%)
Bile duct
Lymphatic vessel - drains away from central vein

Question 4

What is the anatomy of the liver like, how does this relate to its function?

Answer 4

The liver is soft and expandable like a sponge and half the mass is blood, the reticular fibers are weak, blood spends 30 sec here (3 sec in other organs). To be filtered completely, low pressure in the portal vein (9 mmHg, from body to liver), even lower pressure in hepatic vein (0mmHg, from liver to vena cava), overall low resistance to blood flow

Question 5

Why does the liver have sinusoidal capillaries?

Answer 5

These big holes allow for larger particles to pass through the capillaries. This would cause edema in other parts of the body but the hydrostatic pressure keeps this from happening.
Note: the hepatocytes that line the capillaries have microvilli to increase surface area to increase absorption, the capillaries are also lined with endothelial cells and Kupffer cells

Question 6

What are bile canaliculi?

Answer 6

Gaps between hepatocytes that form a small canal for fluid to run between cells, until it gets to the bile ductule and finally the bile duct. The TIGHT junction (zona occludens) surrounding the bile canaliculi makes it water tight so that the fluid can’t ooze through back into the blood.

Question 7

What do Kupffer cells do?

Answer 7

Kupffer cells eat the bacteria so that it doesn’t go to systemic circulation, they detoxify hepatocytes

Question 8

What are the metabolic functions of the liver?

Answer 8

Carb, protein, fat metabolism, and other metabolism

Question 9

How does the liver help with carbohydrate metabolism?

Answer 9

Stores large amounts of glycogen, conversion of galactose and fructose into glucose, gluconeogenesis, and formation of compounds from intermediate products. This is how the liver acts as a buffer in the control of blood sugar.

Question 10

How does the liver help with protein metabolism?

Answer 10

Deamination of amino acids, formation of urea for removal of ammonia from body fluids, formation of plasma proteins, converts and synthesizes other amino acids

Question 11

How does the liver help with fat metabolism?

Answer 11

Oxidation of fatty acids to supply energy to the body (the liver dumps ketone bodies so the rest of the body can break down fatty acids.. so the liver basically does the first step of fat metabolism)
Synthesis of cholesterol, phospholipids, and lipoproteins
Synthesis of fat from proteins and carbs

Question 12

Besides carb, protein, and fat metabolism, what are the other metabolic functions of the liver?

Answer 12

Stores vitamins (A,D,B12), stores iron as Ferritin (can release or hold on to iron based on the body’s needs, considered a blood iron buffer)
Forms blood substances used in coagulation (prothrombin, fibrinogen, factor 7)
Removes/excretes drugs, hormones, and other substances (like calcium, penicillin, thyroxine, estrogen)

Question 13

What is unique about a hepatocyte when looking at it microscopically?

Answer 13

Hepatocytes are busy cells! They have large, light stained nucleus (making a lot of RNA to make a lot of protein), has a lot of RER (to package and send out the plasma proteins), lots of fat in the cell (makes cholesterol)

Question 14

What is unique about the lymph in the liver?

Answer 14

Lymph doesn’t usually have a lot of protein, but in the liver it contains just as much protein as the blood does. About half the lymph you make everyday is in the liver

Question 15

How does the perilobular region of the hepatic sinusoid differ from the centrolobular region (toward the central vein)?

Answer 15

Going from perilobular to centrolobular, the oxygen content falls, making these centrolobular cells more hypoxic and more likely to be injured

Question 16

How is bile salt made and how much of it gets reused?

Answer 16

Bile salts made by cholesterol, 90% reabsorbed in the intestines and recirculated, 10% synthesized bile in the SER and released into the ducts

Question 17

What do bile and bilirubin have in common?

Answer 17

The bili, they both travel through the biliary tract, otherwise they are very different

Question 18

How do size, density, TAGs, location differ between chylomicrons, VLDL, LDL, and HDL?

Answer 18

Chylomicrons: biggest, least dense, most TAGs, comes from GI to the blood (broken down the least)
VLDL: second biggest, second most TAG, from liver to blood
LDL: second smallest, from blood to body and liver
HDL: smallest, most dense, least TAGs, from body to liver

Question 19

What happens to LDL particle when it gets to the cell?

Answer 19

LDL particle binds to LDL receptor, receptor is recycled to pick up more LDL and LDL is endocytosed, lysosome breaks it down so the contents are available to the cell

Question 20

When a RBC is destroyed, how is it broken down and excreted?

Answer 20

It first disassociates to heme and globin. The iron part of heme goes to iron pool, the biliverdin (green bruise) reduces quickly to unconjugated bilirubin (not water soluble) and is released by macrophages into the plasma. This binds with albumin, transporting it to the liver, to get conjugated by sticking glucuronic acid on it (water soluble). It is then dumped, as urobilogen, in feces and 5% in urine