Lecture 37: EXERCISE Flashcards
How is ATP used in muscle?
myosin ATPase converts ATP to ADP and Pi (energy for contraction)
How in ATP created in muscle?
ADP + Pi > ATP
Resynthesis by energy metabolism
How much ATP is in muscle?
Only 5 micro mol per gram which is enough for 1 second
What is anaerobic exercise?
High intensity, rapid generation of force for short periods
What are examples of anaerobic exercise?
Sprinting and weight lifting
What is aerobic exercise?
Low intensity, prolonged, sustained exercise
What are examples of aerobic exercise?
Long distance running, swimming and walking
What happens the longer you exercise?
The more aerobic it must be
What are the anaerobic ways of generating ATP in muscle?
phosphocreatine and glycogen
Does anaerobic exercise require oxygen?
No
What are the aerobic ways of generating ATP?
Oxidation of glucose and fatty acids
Does aerobic exercise require oxygen?
Yes
What is phosphocreatine described as?
On site, fast fuel
How much phosphocreatine is present?
20 micro mol per g of muscle which lasts around 10 seconds
What is phosphocreatine?
A high energy phosphate compound
What can be done with the phosphate of phosphocreatine?
It can be transferred to ADP to make ATP
What is phosphocreatine made from?
Gly and Arg
What type of system does phosphocreatine form?
An energy buffering system
What happens during exercise (phosphocreatine)?
Phosphocreatine is converted to creatine and ADP to ATP by creatine kinase
What happens during recovery (phosphocreatine)?
Creatine is converted to phosphocreatine and ATP to ADP by creatine kinase
What is glycogen?
On site store of glucose in muscle
What happens with glycogen?
It is mobilised to glucose-1-phosphate by glycogen phosphorylase
What happens with glucose-1-phosphate?
It is converted to glucose-6-phosphate
What is the fuel for anaerobic glycolysis?
Glucose-6-phosphate
What does adrenaline do?
Binds beta adrenergic receptors (GPCR) of muscle cells
What does adrenaline stimulate?
The mobilisation of glycogen to provide fuel for glycolysis
What is the source of fuel for anaerobic glycolysis?
Muscle glycogen
How is ATP generated in anaerobic glycolysis?
By substrate level phosphorylation
What happens with pyruvate in anaerobic glycolysis?
It is reduced to lactate to regenerate NAD+
How is ATP generation described in anaerobic glycolysis?
Very rapid but for a short time only
What can lactate cause?
Muscle pH to drop and thus fatigue because enzyme activity lowers
What is glycogen mobilisation stimulated by?
Ca2+ and adrenaline (stress hormon)
What is phosphofructokinase activity increased by?
Allosteric regulators - AMP and Pi
How do muscle cells make good use of ATP?
ADP + ADP = ATP + AMP
What enzyme allows muscle cells to make good use of ATP?
Adenylate kinase (myokinase)
What supplies the fuels for aerobic generation of ATP?
The blood
What supplies the oxygen for aerobic generation of ATP?
The blood
What happens in aerobic generation of ATP?
Active citric acid cycle, electron transport chain and oxidative phosphorylation
What must be attempted to do during aerobic generation of ATP?
Must try not to deplete glycogen stores for short bursts of energy if required (sprint finish)
What are the types of muscle fibre?
Type 1 and Type 2
What are the Type 1 muscle fibres?
Red, slow twitch fibres
What are the characteristics of Type 1 muscle fibres?
Slow speed of contraction, low maximum power output, high endurance, high capillary density and high myoglobin content
How is metabolism in type 1 muscle fibres?
Oxidative (Aerobic)
What are Type 2 muscle fibres?
White, fast twitch
What are the characteristics of Type 2 muscle fibres?
Fast speed of contraction, low endurance, low mitochondrial density, high glycogenolytic enzyme activity and high glycolytic enzyme activity
How is metabolism in type 2 muscle fibres?
Glycolytic (anaerobic)
What muscle fibres are selected for in endurance training?
Type 1 (aerobic)
What happens to the number of blood capillaries per muscle fibre in endurance training?
Increases
What happens to the mitochondria in endurance training?
Increase size and number - increased cristae, increased capacity of mitochondria to generate ATP by oxidative phosphorylation, increased capacity to oxidise lipid and carbohydrate
What happens to myoglobin content in endurance training?
Increases
What are some performance enhancing drugs?
EPO doping, anabolic steroids and growth factors
What does EPO do?
Increases red blood cell count and therefore gives more oxygen - recombinant EPO
What do anabolic steroids do?
Give more muscle
What do growth factors do?
More muscle - recombinant IGF-1, GH
What are possibilities of gene therapy?
Turn off myostatin and regulation of transcription factors
What may happen in regulation of transcription factors?
Upregulate PGC-1 or turn on PPAR which controls the number of mitochondria
