Term
| What are the 3 main pathways for supplying energy to muscle fibers? Which is reversible? |
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Definition
Direct phosphorylation of creatine phosphate (rev.)
Aerobic metabolism
Anaerobic metabolism |
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Term
| What are some bodily functions that require ATP? |
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Definition
G actin -> F Actin
contractile process
pumping Ca to initiate muscle relaxation
Maintaining Na/K ion gradients |
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Term
True or False
The ATP in resting muscle is sufficient for sustaining numerous twitches |
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Definition
False
only 1-2 seconds worth can be supported by ATP in resting muscle |
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Term
| What is the immediate source of energy for the conversion of ADP to ATP? |
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Definition
| creatine phosphate (phosphocreatine) |
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Term
| What enzyme recycles ATP? |
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Definition
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Term
| In resting muscles, how much phosphocreatine is present in comparison to ATP? |
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Definition
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Term
| Where does the reaction involving creatine kinase take place? |
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Definition
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Term
| How is creatinine removed from the body? |
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Definition
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Term
| Describe the cycle of muscle contraction using ATP & the enzymatic action of creatine kinase |
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Definition
1. Glucose converted to ATP
2. ATP fuels muscle contraction
3. ATP converted into ADP + Pi
4. Creatine kinase transferrs P from phosphocreatine to ADP to from ATP
5. Creatine product is converted to creatinine
6. Creatinine is excreted via the urine |
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Term
| Where does creatine get rephosphorylated? |
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Definition
| in the mitochondrial membrane |
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Term
| Can phosphocreatine be depleted? |
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Definition
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Term
| How many ATP are produced by the direct phosphorylation of creatine phosphate? |
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Definition
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Term
| What is the primary means of producing ATP? |
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Definition
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Term
| Which macronutrients can be used to synthesized ATP? Which specific molecules? |
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Definition
CHO, proteins, lipids
glucose, pyruvate, free fatty acids, amino acids |
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Term
True or False
ATP synthesis can also occur via degradation products of CHO, lipids & proteins |
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Definition
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Term
| What are the major substrates for aerobic ATP synthesis in the fed state? Fasted state? |
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Definition
Fed: glucose
Fasted: free fatty acids from breakdown of TG's
glycogen |
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Term
| When is glycogen used as a backup substrate for aerobic metabolism? |
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Definition
| when glucose & free fatty acids are not broken down fast enough to meet the demands of the contracting muscle |
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Term
| What happens to 'excess' glucose? |
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Definition
| it is stored in the liver as glycogen |
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Term
| After glucose has been absorbed from the GIT, where does it go? |
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Definition
to the liver, where it is stored as glycogen for future use
to the muscle where it is used for ATP synthesis |
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Term
| How much glycogen is stored in the muscle? |
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Definition
| 1% of muscle weight, enough for a few thousand twitches |
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Term
| Where is glycogen found in the muscle? |
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Definition
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Term
| What is the process for the initial breakdown of glycogen? |
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Definition
| glycogen -> glucose-1-phosphate |
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Term
| What process in aerobic metabolism does not require oxygen? |
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Definition
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Term
| What form of metabolism is used for long term, slow muscle contraction? |
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Definition
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Term
| How many ATP are generated from a single glucose molecule? |
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Definition
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Term
| Where does glycolysis occur in the muscle fiber? |
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Definition
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Term
| What are the products of glycolysis? |
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Definition
2 moles of pyruvate
CO2
H2O
4 NADH
2 ATP (from glucose) or 3 ATP (from glycogen) |
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Term
| Where does the TCA cycle occur in the muscle fiber? |
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Definition
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Term
| What reaction occurs in the TCA cycle? |
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Definition
| pyruvate is convered into acetyla CoA, NADH & FADH2 are produced |
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Term
| Where does oxidative phosphorylation occur? |
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Definition
| in the mitochondria of muscle fibers |
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Term
| Why is aerobic metabolism more efficient than anaerobic? |
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Definition
| anaerobic metabolism is limited to the generation of ATP in glycolysis |
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Term
| What is lost with anaerobic metabolism? |
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Definition
| ability to combine H+ with O2 to produce H2O, releasing energy |
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Term
| How much faster is anaerobic glycolysis vs aerobic? |
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Definition
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Term
| What enzyme is active in anaerobic glycolysis? |
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Definition
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Term
| What happens to the H+ ions in anaerobic metabolism? |
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Definition
| they cannot be removed fast enough so they accumulate in the muscle, LDH adds them to pyruvate to produce lactic acid |
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Term
| What are the two isoforms of LDH? |
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Definition
LDH-1: aerobic metabolism
LDH-5: anaerobic metabolism |
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Term
| What inhibits the action of LDH-1? |
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Definition
| pyruvic acid & lactic acid |
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Term
| Which isoform of LDH is typical for skeletal muscles? |
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Definition
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Term
| What is the fate of the lactic acid produced during anaerobic metabolism? |
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Definition
transported to liver: converted to glucose
transported to heart: used as energy source |
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Term
| What is the limiting factor for a runner in a sprint? |
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Definition
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Term
| What is the effect of high levels of lactic acid in the muscle? |
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Definition
-muscle pH decreases
-glycolysis decreases
-ATP synthesis decreases
-muscle fatigues & stops contracting |
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Term
| Why do muscles fatigue & stop contracting when lactic acid levels are high? |
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Definition
| low pH & lack of energy available in the form of ATP |
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Term
| What is the role of lactic acid in the conversion of muscle to meat? |
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Definition
| no circulatory system to transport lactic acid so it remains in the muscle |
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Term
| When are aerobic metabolism & creatine phosphate able to meet the energy requirements of muscle? |
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Definition
| -if the muscle is working slowly & has adequate O2 |
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Term
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Definition
| the breakdown of glycogen into glucose & glucose-1-phosphate |
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Term
| Is glycogenolysis used in aerobic or anaerobic metabolim? |
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Definition
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Term
| What hormones affect glycogenolysis & why? |
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Definition
adrenalin & epinephrine
-response to an external stressor causes them to be released, stimulates breakdown of glycogen |
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Term
| Where does glycogenolysis occur? |
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Definition
| in the liver (glucose enters blood) & in muscle tissue (glucose is metabolized) |
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Term
| Describe the initiation process of glycogenolysis |
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Definition
1. fight/flight causes adrenaline or epinephrine to be released
2. adenylate kinase is activated
3. a series of steps produces an active phosphorylase enzyme
4. phosphorylase enzyme breaks down glycogen |
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Term
| What else is produced besides chemical energy during nutrient metabolism? |
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Definition
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Term
| What happens if excess heat cannot be removed from the body? |
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Definition
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Term
| What are the energy substrate & product(s) of phosphorylation of creatine phosphate? |
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Definition
S: creatine phosphate
P: 1 ATP |
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Term
| What are the energy substrate & product(s) of anaerobic metabolism? |
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Definition
S: glucose
P: 2 ATP, 2 lactic acid |
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Term
| What are the energy substrate & product(s) of aerobic metabolism? |
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Definition
S: glucose, pyruvate, amino acids
P:36 ATP, CO2, H2O |
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