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Physiology II Exam III > Liver And Pancreas > Flashcards

Liver And Pancreas Flashcards

1
Q

Liver cell plates are composed of ____ layers of hepatocytes. Where does the bile canaliculi lie?

A
  • 2

- lies between two layers of hepatocytes in each cell plate

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2
Q

What are sinusoids lined with?

A
  • endothelial cells

- Kupffer cells

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3
Q

Where is the space of Disse found?

A

-between endothelial cells and hepatocytes

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4
Q

Liver has high blood flow and low vascular resistance, what is the percentage of blood received from resting cardiac output?

A
  • 27% of resting cardiac output

- 1050mL from portal vein + 300mL from hepatic artery flows into sinusoids each minute

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5
Q

What is the portal pressure? What is the pressure from liver to vena cava?

A

9 mm Hg

0 mm Hg

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6
Q

How does cirrhosis affect blood flow to the liver?

A

-increase blood resistance to blood flow

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7
Q

What is the effect of a clot blocking portal vein or a major branch?

A
  • blockage of return blood from spleen and intestines

- increase in capillary pressure in intestinal wall -> loss of fluid -> death

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8
Q

What will high pressure in the right atrium result in the blood flow to the liver?

A

-high pressure of right atrium -> back pressure on liver -> increased blood volume in liver up to 1.5L
+may occur during cardiac failure with peripheral congestion

-therefore liver can store blood in times of excess and supply blood in times of diminished volume

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9
Q

Hepatic sinusoids are ________ permeable to proteins.

A
  • highly

- efferent lymph has a protein concentration of 6g/dL (almost equivalent to plasma concentration)

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10
Q

What happens with there is higher than normal pressure in the hepatic veins?

A
  • back pressure causes fluid to transfuse into lymph
  • fluid leaks through liver capsule into abdominal cavity
  • fluid is almost pure plasma
  • large amounts of fluid in abdominal cavity -> ascites
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11
Q

What is the function of the liver in terms of carb metabolism?

A
  • stores glucose as glycogen
  • converts galactose and fructose to glucose
  • gluconeogenesis
  • forms many intermediate products of carb metabolism
  • releases stored glucose into the circulation
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12
Q

What are the functions of the liver in terms of fat metabolism?

A
  • oxidation of FAs for energy
  • synthesis of cholesterol, phospholipids, lipoproteins
  • synthesis of fats from proteins and carbs
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13
Q

What are the functions of the liver in terms of protein metabolism?

A
  • deamination of aas
  • formation of urea
  • formation of plasma proteins
  • inter conversion of various aas and synthesis of other compounds from aas
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14
Q

What vitamins does the liver store?

A
  • vitamin A
  • vitamin D
  • vitamin B12
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15
Q

What’s another liver function not yet mentioned?

A

-immune function

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16
Q

What coagulation factors does the liver form?

A
  • fibrinogen
  • prothrombin
  • accelerator globulin
  • factors VII, IX, X
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17
Q

What does the liver do in terms of waste removal?

A
  • detoxifies or excretes I tot he bile: sulfonamides, penicillin, ampicillin, and erythromycin
  • excretes excess Ca into the bile
  • detoxification and removal of ammonia and ethanol
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18
Q

Potentially toxic substances are presented to the liver via the __________.

A

Portal system

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19
Q

Phase I rxns are catalyzes by what?

A

P-450 enzymes

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20
Q

Phase II reactions conjugate products from Phase I reactions.

A

:)

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21
Q

What stores bile?

A

Gallbladder

22
Q

What are the components of bile?

A

-bile acids
+colic and chenodeoxycholic acids (synthesized by hepatocytes)
+deocxycholic acid and lithocholic acid (converted by bacteria)

  • water and electrolytes
  • cholesterol and phospholipids
  • pigments and organic molecules -> bilirubin
23
Q

What is hemoglobin released from?

A

Damaged RBCs

24
Q

What is the reticuloendothelial system?

A
  • hemoglobin is phagocytized by macrophages
  • split into globin and heme
  • heme ring is opened to free Fe
  • heme is transported in the blood by transferrin
  • straight chain of pyrrole nuclei is formed
  • heme is converted by heme oxygenase into biliverdin
  • biliverdin is converted to free bilirubin
25
Q

How is free bilirubin transported?

A

-in the blood stream attached to plasma albumin to liver hepatocytes

26
Q

How is conjugated bilirubin excreted?

A
  • secreted into the intestine

- excreted into the urine

27
Q

What is jaundice?

A
  • refers to a yellowish tint to the body tissues
  • usually caused by quantities of bilirubin in the extracellular fluids

-common causes:
+increased hemolysis
+obstruction of the bile ducts or damage to the liver

28
Q

What are the major types of islet cells?

A

-alpha, beta, delta

29
Q

What do alpha cells do?

A
  • secrete glucagon

- 25% of total cells

30
Q

What do beta cells do?

A

-secrete insulin and amylin
+insulin inhibits glucagon secretion
+amylin inhibits insulin secretion

-60% of total cells

31
Q

What do delta cells do?

A

-secrete somatostatin

+inhibits insulin, glucagon, and gastrin secretion

32
Q

What are the two communication channels between the islet cells?

A
  • gap junctions

- islet portal blood supply

33
Q

What communicates with what via gap junctions?

A
  • beta cells to beta cells
  • alpha cells to alpha cells
  • beta cells to alpha cells
34
Q

What communicates via the islet portal blood supply?

A

-beta cells to alpha and delta cells

35
Q

Insulin not bound to receptors are destroyed where?

A

Liver

36
Q

What happens when insulin is bound to a receptor?

A
  • increased uptake of glucose (decrease blood glucose)
  • increased permeability to aa, K, and P ions (decrease aa and K)
  • increase uptake of FAs
  • increased activity levels for many enzymes
  • changes in rates of translation and transcription
37
Q

What is an insulin receptor?

A
  • found on target tissues for insulin
  • intrinsic tyrosine kinase activity autophosphorylates the beta subunits, which then phosphorylate intracellular proteins

-insulin down regulates its own receptor
+increased in starvation
+decreased in obesity

38
Q

Most of the glucose absorbed after a meal is stored as glycogen where?

A

-in the liver

39
Q

What is the glucose uptake mechanism for the liver?-I

A
  • insulin inactivated liver phosphorylase
  • insulin activates glucokinase and enhances uptake of glucose from blood
  • insulin increases activities of enzymes needed for glycogenesis
40
Q

Outline the events that causes the liver to release glucose into the blood.

A
  • decreased blood glucose resulting in decreased insulin secretion
  • lack of insulin reverses glycogen synthesis pathway
  • lack of insulin activates phosphorylase which splits glycogen into glucose phosphate
  • glucose phosphatase removes phosphate from glucose and allows it to diffuse back into blood
  • insulin inhibits gluconeogenesis
41
Q

How does blood flow through the liver lobule?

A

Portal vein -> sinusoids -> central vein -> hepatic veins -> hepatic artery -> sinusoids -> central vein -> hepatic veins

42
Q

What does insulin promote excess glucose into?

A

-converted excess glucose into FAs and decrease utilization of fat

43
Q

Explain how insulin works on fat storage physiologically.

A
  • increases transport of glucose into liver creating excess
  • excess glucose in converted to acetyl CoA
  • FA synthesis is initiated
  • newly synthesized FAs are converted into triglycerides and transported from liver as lipoproteins
  • triglycerides are split into FAs in capillaries and taken up into fat cells
  • insulin promotes uptake of glycerol by fat cells
44
Q

What happens when there are low amounts of insulin?

A

-large amounts of glycerol and FAs are released into the blood

45
Q

Explain how lack of insulin effects fat storage physiologically.

A
  • large amounts of acetoacetic acids are formed in the liver
  • carnation transport mechanism in the liver is activated
  • B-oxidation results in excess acetyl CoA
  • excess acetoacetic acids cause acidosis
  • increase of ketone bodies in blood
46
Q

What are the major effects of glucagon? What does it work on?

A
  • works on liver and adipose tissue
  • break down of liver glycogen
  • increased gluconeogenesis
47
Q

Explain physiologically how glucagon works.

A
  • activates adenyl cyclase in hepatic cell membrane which causes formation of cAMP
  • activates protein kinase
  • activates phosphorylase b kinase
  • converts phosphorylase b into phosphorylase a
  • promotes degradation of glycogen to glucose-1-phosphate
  • increases lipolysis -> increase in blood FAs -> increase blood keto acids -> increase in blood glucose
  • increases urea production (due to deamination of aas used for gluconeogenesis)
48
Q

What does somatostatin do? What secretes this?

A
  • secreted by delta cells
  • inhibits secretion of insulin, glucagon, and gastrin
  • decreases motility of stomach, duodenum, and gallbladder
  • decreases secretion and absorption of GI tract
49
Q

What are the negative effects of increased blood glucose levels?

A
  • increased osmotic pressure in extracellular fluid
  • loss of glucose in urine
  • osmotic diuresis (dehydration and loss of electrolytes)
  • damage to tissues and blood vessels
50
Q

What causes Type I diabetes? What are some effects of it?

A
  • caused by lack of insulin secretion

- injury to beta cells via viral infection and autoimmune disorders

51
Q

What causes Type II diabetes? What are some risk factors?

A
  • due to insulin resistance
  • obesity is a major risk factor
  • preceded by metabolic syndrome
52
Q

What is metabolic syndrome?

A
  • obesity (esp abdominal fat)
  • insulin resistance
  • fasting hyperglycemia
  • increased lipid triglycerides
  • decreased HDL levels
  • hypertension

Physiology II Exam III (9 decks)

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