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Physiology Test 3 > Liver > Flashcards

Liver Flashcards

1
Q

What are the liver’s functions?

A
  • Regulation of protein, carbohydrate, and lipid metabolism
    • “taking good stuff and saying, what do I need to do with this”
  • Regulation of cholesterol production and excretion
    • liver makes cholesterol
      • some people have increased cholesterol level despite diet d/t HMG CoA making cholesterol working overtime
  • B-oxidation of fatty acids
    • alternative energy source when bile not present
  • Bile acid production
    • ​necessary for effiicent lipid absorption
  • Degradation of hormones
    • ​produce and secrete hormones into blood including insulin-like growth factor, angiotensinogen, cytokines
  • Detoxification and excretion of drugs and toxins
    • ​via Kupffer cells
  • vitamin storage
    • ​store B12, iron
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2
Q

What is source of blood flow to liver? Blood flow rate? % C.O?

A
  • Liver is provided blood flow via hepatic artery and portal vein
  • Blood flow 450 mL/min in hepatic artery
    • this is arterial source for hepatocytes
  • Portal vein= 1L/min
    • portal vein varries venous blood from intestine
    • nutrients, bacteria and foreign bodies processed here
    • causes “first pass” effect
  • 30% CO into liver
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3
Q

Normal liver will have very ___ capillary and venous pressure

A

low

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4
Q

What is portal HTN?

A
  • Increase in pressure somewhere along portal tract
    • prehepatic-
      • portal V, thrombosis, congestion, atresia (biliary ducts aren’t formed, creating extra pressure before liver)
    • intrahepatic
      • cirrhosis, fibrosis, wilson’s disease
    • post-hepatic
      • any obstruction b/w liver and Right heart
        • hepatic vein thrombosis, CHF, Pericarditis
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5
Q

The blood from hepatic artery and portal vein ____ in liver

A

mix

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6
Q

What are kuppfer cells (littoral cells)?

A
  • Attached to sinusoidal membrane present throughout liver
  • Scoop up waste and present to liver cells
  • phagocytose bacteria and damaged RBC
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7
Q

What is the space of disse?

A

Interstitial space of liver

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8
Q

Hepatcocytes are major producers of ____ which is secreted into space of Disse.

A

lymph

Eventually absorbed into lymphatic vessels–> thoracic duct

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9
Q

What are 3 symptoms that can occur with any obstruction of blood flow?

A

Ascites

Hepatomegaly

Jaundice

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10
Q

What is ascites?

A
  • Ascites is fluid formation in peritoneal space
  • Increased hepatic vein pressure (increased right vena cava pressure, increased portal venous pressure causes…
  • increased pooling of blood in capillaries causes…
  • increased hydrostatic pressure in capillaries
  • exudation of fluid from plasma and space of disse into peritoneal cavity of abdomen
    • causes ascites (contains both fluids and proteins)
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11
Q

Is ascites a part of the ECF?

A

No, outside of ECF

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12
Q

What is hepatomegaly?

A
  • Increase in liver size due to fluid retention
    • can also enlarge from excess fat
  • Liver normally has 400mL of blood and can increase to 1L in pathological condition
  • this can affect CV system since it will have to keep BP up with 0.5 L circulating elsewhere
  • can happen along with ascites
  • can detect on physical exam by palpation
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13
Q

What is bilirubin

A
  • End-product of RBC degradation, incorporated into bile and excreted in feces (metabolite also secreted by kidneys)
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14
Q

What is obstructive jaundice?

A
  • Obsturciton of bile ducts (cirrhosis, gallstones, biliary atresia, CA)
  • bile not secreted so nothing to get rid of bilirubin, bilirubin absorbed into blood causing yellowing
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15
Q

What is hepatic jaundice?

A

Results from acute or chronic hepatitis, drug hepatotoxiicty and cirrhosis

  • Reduces ability of cells to metabolize bilirubin
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16
Q

What is hemolytic jaundice

A

nothing to do with liver itself!!

  • Results from anything that increases hymolysis of RBC (malaria, sickle cell, genetic disease)
  • this causes an increase in bilirubin production faster than the bile can excrete it
17
Q

What is neonatal jaundice?

A
  • Uusally not pathologic
  • results from metabolic changes as liver and GI function aren’t perfect after birth
    • not able to secrete enough bile just yet to get rid of bilirubin
  • Can resolve by UV light
    • UV light turns bilirubin to make it more hydrophilic, get through kidney, make urobilin and be excreted
  • sometimes will find it’s a problem with the biliary tree–> this will have to be treated sx
18
Q

What is cirrhosis?

A

Destruction of liver by scarring

19
Q

In what ways does liver affect carbohydrate metabolism?

A

“blood glucose monitor”

  • Glycogen storage and glycolysis
  • Gluconeogenesis
  • Conversion of monosaccharides to glucose
  • formation of chemical compounds
    • pyruvic acid, lactic acid, succinic acid, acetyl coA that can be used in other metabolic pathways
20
Q

What is glycogen storage and glycolysis in liver?

A
  • excess monosaccharaides not used is polymerized and stored as glycogen
    • glucokinase convertes glucose to glycogen
  • stored hepatic glycogen can provide glucose for 12-17 hours during fasting
  • when blood glucose levels low, glucagon and other hyperglycemic hormones (such as epinephrine and growth hormone) stimulate glycolysis to break down glycogen and release glucose into blood
    • through phosphorylase
  • If glycogen not used, converted to triglycerides and transported to adipose tissue for storage
21
Q

What is gluconeogenesis?

A
  • Amino acids and glycerol (from TG) are converted to glucose by gluconeogenesis
  • provides alternate energy soruce during fasting and starvation
22
Q

What are GLUT2 transporters?

A

Transporters in liver that are insulin independent for glucose

  • This allows high capacity transport
  • also found in brain, pancras, kidneys, and basolateral side of enterocytes
23
Q

The liver converts _____ to glucose

A

​Monosaccharides

  • Conversion of monosaccaharides to glucose
    • ATP allows galactose and fructose to enter glycolytic pathway and be stored as glycogen , or undergo glycolysis
24
Q

What role does liver play in lipid metabolism?

A

Building blocks, cholesterol regulation, energy

  • High rate of beta oxidation of fatty acids
  • Forms most lipoproteins
    • VLDL
    • LDL
    • HDL
  • Synthesizes lots of cholesterol and phospholipids
  • converts unused glycogen to TG
25
Q

How do lipids first come into liver?

A

Via systemic circulation (NOT portal, like most other nutrients)

26
Q

What is b-oxidation of fatty acids?

A

​TG are hydrolyzed to fattyacids and glycerol–> mitochondira–> b-oxidation–> acetyl CoA–> citric acid cycle

  • provides energy when you need it
  • in cases of fasting/used up glycogen store
  • happens while gluconeogenesis happens
27
Q

What are the various lipoproteins formed by liver?

A
  • Purpose- carrier proteins that shuttle lipid to other parts of body
  • VLDL- high triglycerides, some cholesterol and phospholipids
    • take triglycerides to adipose tissue
  • LDL: high cholesterol, phospholipids, little TG (theses are the bad guys)
    • implcated in CV disease
  • HDL: 50% protein, less chol and phospholipids (good guys)
    • transport lipid from tissue to liver
    • beneficial in terms of CV health
28
Q

How does liver synthesize cholesterol and phospholipids?

A

HMG CoA Reductase

  • Acetyl CoA molecules combine to form sterol nucelus–> side chains added–> cholesterol
    • HMG CoA reductase catalyzes the reaction and is the target of statin drugs
29
Q

How does liver convert unused carbs to triglycerides?

A
  • Glucose–> glycolysis–> acetyl CoA–> TG polymers made using malonyl coa and nadph–> packed into VLDL–> adipose tissue
30
Q

Role of liver in protein metabolism?

A
  • Deamination of amino acids
  • production of urea
  • synthesis of plasma proteins
  • intervoncersion of amino acids
31
Q

What is the deamination of amino acids?

A

First step in removal of excess amino acids; aminotransferases remove amino group form amino acids creating ammonia

  • Ammonia can be transferred again, or released as ammonia
    • excess ammonia can be removed by production of urea
32
Q

How does the liver produces urea?

A

NH3 combines with CO2 to form urea

Critical process to get rid of toxic NH3

33
Q

Role of liver in synthesis of plasma proteins?

A
  • 90% of plasma proteins are made by liver (albumin, globulins, fibrinogen)
34
Q

What is role of liver in interconversion of amino acids?

A

Transamination cna convert certain amino acids to others that may be needed

35
Q

What are other metabolic function of the liver?

A
  • VItamin storage
  • formation of blood coagulation products
  • iron storage
  • drug, hormone, waste removal

Physiology Test 3 (9 decks)

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