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Blood and defence > Plasma proteins > Flashcards

Plasma proteins Flashcards

1
Q

What are some functions of plasma proteins?

A 
Transport
Immunity
Detoxification
Colloid osmotic pressure
Coagulation
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2
Q

What proportion of plasma does albumin make up?

A

55%

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3
Q

Different types of globulins, give examples

A

Alpha = alpha 1 antitrypsin
Beta: transferrin, plasminogen, complement C3
Gammma: immunoglobulin

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4
Q

Where are most plasma proteins made, what’s the exception?

A

Liver, gamma globulin

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5
Q

What are the 2 main roles of albumin?

A

Contribute to osmotic balance (between vascular and interstitial compartments)/plasma osmolarity

Binding hydrophobic molecules, trace elements and drugs

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6
Q

What diseases can arise due to abnormal albumin levels?

A

Chronic liver disease, less albumin, symptom= oedema/ascites

Depleted albumin levels (malnutrition) causes Kwashiorkor

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7
Q

Describe the molecules carried by albumin?

A 
Hydrophobic molecules (e.g. fatty acid, sterorid hormones, bilirubin)
Trace elements (e.g. copper)
Drugs e.g. warfarin, digoxin
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8
Q

Where does haem catabolism occur?

A

Liver, spleen, bone marrow

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9
Q

Which organ removes senescent erythrocytes?

A

Spleen

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10
Q

What happens in haem catabolism?

A

Globin protein degraded, AA recycled

Fe2+ is reduced with NADPH and reused

Porphyrin ring opened to give biliverdin (green)

Biliverdin reduced with NADPH to bilirubin (yellow)

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11
Q

How is bilirubin transported to liver in blood?

A

Bound to albumin

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12
Q

What happens to bilirubin in liver, why?

A

Conjugated with glucuronic acid so becomes water soluble for excretion

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13
Q

Where is conjugated bilirubin excreted?

A

In bile into small intestine

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14
Q

What is a sign of hyperbilirubinaemia?

A

Jaundice

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15
Q

What do liver function tests in investigation of causes of jaundice look at?

A

Conjugated or unconjugated bilirubin

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16
Q

What can cause unconjugated hyperbilirubinaemia?

A

Immaturity of conjugating enzymes
Increased bilirubin load (haemolytic anemia)
Genetic defect of conjugating enzyme

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17
Q

What can cause conjugated hyperbilirubinaemia?

A

Hepatocellular disease
Intra/extra hepatic biliar obstruction
Genetic defects of biliruin excretion (e.g. Rotor syndrome)

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18
Q

Is it unconjugated or conjugated hyperbilirubinaemia where bilirubin is excreted in urine?

A

Conjugated

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19
Q

Where is Fe used in body?

A

Hb (60%)
Myoglobin
Cytochromes

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20
Q

Describe the size of iron stores in body, how much do men and women require per day, how much is absorbed as a proportion of this?

A

Total body iron is 2.5-3.5g
Men- 8.5mg
Women 14.5mg
~1mg absorbed

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21
Q

What proportion of Fe2+ is stored?

A

25%

22
Q

Why do females have smaller stores of iron + larger daily losses?

A

Blood loss in menstruation

23
Q

What happens to non haem iron as it is absorbed?

A

Reduced from Fe3+ to Fe2+

24
Q

What ensures excess iron isn’t absorbed?

A

Mucosal block (at level of gut mucosal cells) limits excess iron at level of enterocytes

25
Q

True of false, no mechanism for Fe excretion once taken up by body

A

True

26
Q

What does hepcidin do?

A

Blocks dietry iron absorption increases iron in macrophages and decrease iron in GI.

27
Q

What is hepcidin, where is it made?

A

Peptide hormone made by hepatocytes

28
Q

How can iron be lost form body?

A 
Menstruation
Cell shedding from gut/skin
Bile
Sweat
Pregnancy
Haemorrhage
29
Q

What can happen to Fe2+ once in an enterocyte?

A

Stored as complex of Fe3+ and ferritin

Basolateral transport released and binds transferrin

30
Q

What does transferrin do?

A

Iron binding blood plasma glycoprotein controlling level of free iron in plasma - carries it from intestinal mucosa to peripheral tissue with transferrin receptors

31
Q

Where is transferrin synthesised?

A

Liver

32
Q

Where does transferrin transport iron to and from?

A

From duodenum and macrophages to tissue (e.g. liver)

33
Q

Why is transferrin important in defence against bacteria?

A

Bacteria use free iron in plasma for growth

34
Q

What is a consequence of iron deficiency?

A

Anaemia - fatigue, weakness, chest pain

35
Q

Give an example of a serine antiprotease

A

Alpha 1 antitrypsin

36
Q

What are lipoproteins?

A

Biochemical assembly that transports hydrophobic lipid molecules in water e.g. blood or extracellular fluid

37
Q

What are some major lipoprotein fractions?

A

Chylomicrons, vLDL, HDL, LDL

38
Q

What is the role of the LDL receptor?

A

Mediates endocytosis of cholesterol rich LDL so maintains plasma LDL levels (mainly in liver)

39
Q

What regulates LDL receptor?

A

Synthesis regulated by level of free intracellular cholesterol.

40
Q

Whys is it wrong to say HDL, LDL etc are good/bad type of cholesterol?

A

They aren’t cholesterols. They are proteins that transports lipids e.g. cholesterol

41
Q

Describe the formation of chylomicrons

A

Formed in ER of absorptive cells of small intestine. Join lymph to become chyle which is carried to venous systemic system

42
Q

When is transferrin production upregulated?

A

When low iron intake

43
Q

In what state is iron uptake maximised?

A

Fe3+

44
Q

How does copper benefit iron uptake?

A

Keeps it in Fe3+ state

45
Q

What happens to conjugated bilirubin in the gut?

A

Not reabsorbed mostly, colonic bacteria deconjugate and metabolism into urobilongens

46
Q

What is alpha-1 antitrypsin?

A

Protein protease inhibitor (elastase inhibitor)

47
Q

Where is alpha-1 antitrypsin made?

A

The liver

48
Q

What is the function of alpha-1 antitrypsin?

A

Forms a protective layer on top of healthy lung tissue, protecting the lungs from neutrophil elastase, an enzyme that can disrupt connective tissue (proteases, normally to kill bacteria).

49
Q

The body iron store is controlled mainly by

A

intestinal mucosa

50
Q

Fe3+ It is taken up into cells by

A

receptor-mediated endocytosis

Blood and defence (5 decks)

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