Biochem Flashcards

(48 cards)

1
Q

Most common cardiovascular diseases

A
  1. Coronary artery disease

2. Stroke

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2
Q

Coronary Artery disease

A
  • Build on wall of artery
  • Leads to narrowing and eventually blockage
  • Blockage after 12 hours leads to cell death
  • Heart attack or MI
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3
Q

Tests for MI

A
  1. Electrocardiogram
  2. Nuclear scan
  3. Coronary angiography
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4
Q

Symptoms of MI

A
  • Chest pain
  • Upper body discomfort
  • Shortness of breath
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5
Q

Diabetes and MI

A

MI can occur without symptoms because of nerve damage

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6
Q

Cardiac biomarkers

A
  • Enzymes
  • Proteins

Show the amount of damage and extent of damage in the heart

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7
Q

Serum enzymes and proteins

A

Serum levels of enzymes and proteins can be a biomarker as it shows damage by showing release of intracellular components

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8
Q

Serial testing of biomarkers are necessary to ensure that:

A
  1. Rise in blood levels is not missed

2. Estimate severity of the heart attack

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9
Q

Ideal cardiac biomarker

A
  • cost effective
  • accurate
  • available
  • early appearance and measurable
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10
Q

List the former cardiac biomarkers

A
  1. Lactate dehydrogenase
  2. Aspartate aminotransferase (AST)
  3. Myoglobin
  4. Creatine kinase
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11
Q

Lactate dehydrogenase

A
  • Non-specific for cardiac tissue

LD1-5

LDH1: Pancreas, kidney, stomach tissue, RBC

LDH2-4: Platelets

LDH1+2: Cardiac tissue

Acute MI - LDH levels rise at about 10 hrs, peak at 24-48 hrs, elevated up for 8 days

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12
Q

Aspartate aminotransferase (AST) is also called:

A

Serum glutamate oxaloacetate transminase (SGOT)

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13
Q

Aspartate aminotransferase (AST)

A
  • an enzyme found in heart and liver
  • non-specific and no longer used as an assessment
  • Catalyzes the reversible transfer of an alpha-amino group between aspartate and glutamate
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14
Q

Myoglobin

A
  • heme protein present in heart and skeletal muscles
  • released from damaged tissues
  • increases occur more rapidly than creatine kinase
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15
Q

Functions of Myoglobin:

A
  1. Reservoir for oxygen

2. As an oxygen carrier

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16
Q

Why is myoglobin not used on it’s own for assessing MI?

A
  1. short plasma half-life (so metabolized quick)

2. Lack of specificity for cardiac tissue

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17
Q

What is Myoglobin paired with for assessment?

A

Troponins and/or CK-MB

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18
Q

Creatine Kinase formally known as:

A

Creatine phosphokinase (CPK)

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19
Q

Creatine Kinase

A
  • an enzyme
  • present in greatest amounts in skeletal muscle, myocardium, brain
  • small amounts occur in other visceral tissues

Catalyses a reversible reaction: creatine –> phosphocreatine

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20
Q

CK subunits:

21
Q

CK isoenzymes:

A

CK-MM (muscle)
CK-BB (brain)
CK-MB (high % in heart)

22
Q

% of CK-MB in muscle, brain, heart

23
Q

CK elevations

A
  • may be from a variety of non cardiac conditions

- an elevation in total CK is not specific to MI

24
Q

List the new cardiac biomarkers

A
  1. CK-MB

2. Troponin

25
CK-MB
- specific for cardiac tissue - rise starts 3-6 hrs after onset of MI - peak at 12-24 hrs - return to baseline 48-72 hrs
26
CK:CK-MB ratio
- improved specificity - higher ratio = more likely MI has occurred Ratios > 2.5-3 have been proposed for MI
27
Troponin 3 subunits:
3 regulatory enzymes: - TnC - TnT - Tnl
28
Troponin attaches to...
Tropomyosin (sits between actin filaments in striated muscle) --> needed for non smooth muscle contraction in the skeletal and cardiac muscle
29
Which troponin is not measured and why?
Troponin C because it doesn't have an isoform specific for the heart (could be heart or skeletal muscle)
30
Which troponin(s) are cardiac specific?
CTnl and CTnT
31
Which serum levels can be used to diagnose people with MI especially when ECG is inconclusive?
CK CK-MB cTnl cTnT
32
Heart-type fatty acid binding protein (H-FABP) function:
- helps intracellular uptake of long chain fatty acids in myocardium - still being evaluated for use in MI diagnosis
33
Where does heart-type fatty acid binding protein (H-FABP) go?
Due to small size (15 kDA) and location (cytoplasm of cardiac myocytes), releases rapidly into the blood after Myocardial damage
34
What could you combine H-FABP with and why for MI?
cTnT because it provides significant improvement in the diagnosis within 4-12 hours
35
CK-MB kinetics
Concentration begins to rise between 3-6 hrs and goes back to baseline at 3-4 days
36
cTnl kinetics
Concentration begins to rise between 3-6 hrs and goes back to baseline at 7-10 days
37
cTnT kinetics
Concentration begins to rise between 2-6 hrs and goes back to baseline at 7-10 days
38
Myoglobin kinetics
Concentration begins to rise at 2-3 hrs and goes back to baseline a little after 24 hrs
39
Are troponin levels in serum high or low and why?
Normally low because they are intracellular and only released from dead myocytes after 12 hours of chest pain if troponin levels are still low then heart attack is unlikely
40
What is Angina?
Chest discomfort caused by poor blood flow through the blood vessels of the heart muscle with normal cardiac troponin levels
41
Elevated CK-MB levels may be seen in:
- skeletal muscle injury | - cardiac injury other than MI
42
Elevated troponin levels may be seen in:
- ischaemia - myocarditis - arrhythmia - pulmonary embolism - high blood pressure
43
Mycarditis
inflammation of the heart muscle
44
Arrhythmis
abnormal heart rhythm
45
Pulmonary embolism
blood clot lodged in the lung
46
High blood pressure
hypertension
47
Definition of MI
- evidence of significant increase in troponin (or CK-MB) concentration with time - evidence of ischaemia with symptoms of MI - new ECG changes
48
Ischaemia
sudden reduction of heart muscle blood supply