Energy Stores In The Cell Pt 2 Flashcards
1
Q
What are the Key concepts about energy stores in cells?
A
- ATP is a universal currency not a store
- When supply exceeds demand, energy is most often stored in the form of polymer macromolecules of fuel molecules e.g. glycogen (glucose stores), triglyceride (fatty acid stores).
- Some cell types need to increase metabolic activity very quickly (e.g. skeletal muscle).
- need a reserve of high energy stores that can be used immediately
- Use creatine phosphate (phosphocreatine)
2
Q
What is the reaction that forms creatine phosphate?
A
Creatine + ATP -(creatine kinase)- phosphocreatine (creatine phosphate) + ADP
- When ATP levels are high, ‘phosphate bond energy’ may be stored in phosphocreatine.
- If ATP concentration falls suddenly, the reaction reverses providing short term boast in ATP concentration.
Pg 4-5
3
Q
How is creatine kinase a marker of myocardial infarction?
A
- creatine kinase is made up of two subunits.
- Different isoform combinations are found in different tissues.
- one isoform combination is specific to the heart muscle
- CK-MM at 70% and CK-MB at 25-30%
- CK is released from cardiac myocytes (cells) when damaged, myocardial infarction (heart attack)
- Appears in the blood after a few hours.
- Diagnostic in myocardial infarction
4
Q
How is Creatinine produced?
A
- Creatine and phosphocreatine can spontaneously breakdown to form creatinine
- The breakdown is spontaneous and is non-enzymatic and occurs at a constant rate for each compound
5
Q
How is creatinine a useful clinical marker?
A
- Produced by a spontaneous reaction at a constant rate - unless muscle is wasting
- excreted via the kidneys
- because there is a constant production of creatinine from skeletal muscle, creatinine excretion per 24h is proportional to the muscle mass of the individual.
- provides a measure of muscle mass
- creatinine concentration in the urine is a marker for urine dilution
- can be used to estimate true urinary loss of many substances e.g. hormone in pregnancy
