Chapter 1 - Applied Anatomy And Physiology (Paper 1) Flashcards
Where does the energy we use for muscle contractions come from?
Adenosine triphosphate (ATP)
What is Adenosine Triphosphate (ATP)?
The only useable form of energy in the body.
How do we get Adenosine Triphosphate?
The food we eat such as carbohydrates is broken down to release energy that is used to form ATP.
What does ATP consist of?
One molecule of Adenosine and three phosphates.
How is the energy from ATP released?
It is released by breaking down the bonds that hold the compound together.
What is the enzyme that breaks down Adenosine triphosphate?
ATPase
What does ATPase break ATP down into?
It breaks down ATP into Adenosine di-phosphate (ADP) and an inorganic phosphate (Pi)
How does the body rebuild ATP?
It converts ADP and Pi back into ATP.
What are the three ways we can re-synthesise ATP?
1) Aerobic system
2) The ATP-PC system
3) Anaerobic glycolytic system
How are the energy systems fuelled?
Food or phosphocreatine which is found in the muscles.
What determines what energy system is used?
The type of exercise regarding the intensity, duration and whether oxygen is present.
The higher the intensity of the activity the more the individual will rely on the … energy production
Anaerobic
The lower the intensity and the longer the duration of the activity the more the individual will rely on the … system
Aerobic
When is the aerobic system used?
When exercise is low and oxygen supply is high.
Give an example of an activity that uses the aerobic system.
Jogging
What is broken down in the aerobic system?
This system breaks glucose into carbon dioxide and water which, in the presence of oxygen, which is much more efficient.
The complete oxidation of glucose can produce up to how many molecules of ATP?
38
Using the aerobic energy system what can also be broken down?
Fats in the form of fatty acids and proteins in the form of amino acids can be broken down. The products of fat and protein metabolism are reduced to the molecule acetyl coenzyme A that enters the Krebs cycle.
What are the three stages of the aerobic system?
1) Glycolysis
2) Krebs cycle
3) Electron transport chain
Define glycolysis.
A process in which glucose is converted into pyruvate to produce energy.
What is the sarcoplasm?
The fluid that surrounds the nucleus of a muscle fibre and is the site where anaerobic respiration takes place.
What is the Krebs cycle?
A series of cylindrical chemical reactions that take place using oxygen in the matrix of the mitochondria.
What happens during glycolysis? How many ATP molecules are formed?
Glycolysis is the breakdown of glucose to pyruvic acid. For every molecule of glucose undergoing glycolysis, a net of of two molecules of ATP is formed.
What is unusual about glycolysis?
It is anaerobic taking place in the sarcoplasm of the muscle cell.
Where does glycolysis occur?
In the sarcoplasm of the muscle cell.
Before the pyruvic acid produced in glycolysis can enter the next stage (Krebs cycle) what happens?
The pyruvic acid is oxidised into two acetyl groups and is then carried into Krebs cycle by coenzyme A.
What happens during the Krebs cycle?
The two acetyl groups diffuse into the matrix of the mitochondria and a complex cycle of reactions occurs. The acetyl groups combine with oxaloacetic acids, forming citric acid. Hydrogen is removed from the citric acid and the rearranged form of citric acid undergoes ‘oxidative carboxylation’ which simply means that carbon and hydrogen are given off. The carbon forms carbon dioxide which is transported to the lungs and breathed out and the hydrogen is taken to the electron transport chain. The reactions that occur result in the production of two molecules of ATP.
What is the electron transport chain?
Involves a series of chemical reactions in the cristae of the mitochondria where hydrogen is oxidised to water and 34 ATP are produced.
What happens in the electron transport chain?
Hydrogen is carried to the electron transport chain by hydrogen carriers. This occurs into the cristae of the mitochondria and the hydrogen splits its hydrogen ions and electrons and they are charged with potential energy. The hydrogen ions are oxidised to form water while the hydrogen electrons provide the energy to re-synthesise ATP.
What is the product of the Electron Transport Chain?
34 ATP are formed.
What is stored fat broken down into to be transported by the blood?
It is broken down into glycerol and free fatty acids.
What is beta oxidation?
It is a process that converts the fatty acids into acetyl coenzyme A, which is the entry molecule for the Krebs cycle.
What provides a higher ATP yield glucose or fatty acids?
Fatty acids which is why in long duration, low-intensity exercise, fatty acids will be the predominant energy source.
Name three advantages of the aerobic system.
- More ATP can be produced: 36 ATP
- There are no fatiguing by-products (carbon dioxide and water)
- Lots of glycogen and triglycerides stores can last for a long time.
Name two disadvantages of the aerobic system.
- This is a complicated system so cannot be used straight away. It takes a while for enough oxygen to become available to meet the demands of the activity and ensure glycogen and fatty acids are completely broken down.
- Fatty acid transportation to muscles is low and also requires 15% more oxygen to be broken down than glycogen.
What is phosphocreatine (PC)?
An energy-rich phosphate compound found in the sarcoplasm of the muscles.
What is the fuel for the ATP-PC system?
Phosphocreatine (PC)
Give examples of activities that use the ATP-PC system.
Its rapid availability is important for a single maximal movement such as the long jump take-off or shot putt.
How long can PC stores be used?
5-8 seconds
How is PC replenished?
During low intensity work when oxygen is available.
How does the ATP-PC system work?
It is an anaerobic process that re-synthesises ATP when the enzyme creatine kinase detects high levels of ADP. It breaks down the phosphocreatine in the muscles to phosphate and creatine, releasing energy. This energy is then used to convert ADP to ATP in a coupled reaction.
What does anaerobic mean?
A reaction that can occur without the presence of oxygen.
What is a coupled reaction?
When energy required by one process is supplied by another process.
What is the equation that represents the breakdown of phosphocreatine?
Phosphocreatine (PC) -> Phosphate (Pi) + Creatine (C) + energy
What is the equation that represents energy is used to make ATP?
Energy -> Pi + ADP -> ATP
How many ATP molecules are produced from one phosphocreatine molecule?
1 ATP molecule
Why is the ATP-PC system not very efficient?
It is because one molecule of phosphocreatine makes 1 molecule of ATP.
Name 4 advantages of the ATP-PC system.
- ATP can be re-synthesised rapidly using the ATP-PC system.
- Phosphocreatine stores can be re-synthesised quickly (30s = 50% replenishment and 3 mins = 100%)
- There are no fatiguing by-products.
- It is possible o extend the time the ATP-PC system can be utilised through use of creatine supplementation.
Name 3 disadvantages of the ATP-PC system.
- There is only a limited supply of phosphocreatine in the muscle cell, i.e. It can only last 10 seconds.
- Only one mole of ATP can be re-synthesised for every mole of PC.
- PC re-synthesis can only take place in the presence of oxygen i.e. When the intensity of the exercise is reduced).
For high intensity activity lasting less than three seconds, how will energy be provided?
Energy will be provided from just the breakdown of ATP.
What is the short-term lactate anaerobic system/anaerobic glycolytic system?
Produces high powered energy for high intensity events such as the 400m.
What determined the length the short-term lactate anaerobic system/ anaerobic glycolytic system can be used?
This depends on the fitness of the individual and how high the intensity of the exercise is.
How does the short-term lactate anaerobic system/ anaerobic glycolytic system work?
When PC stores are low, the enzyme glycogen phosphorylase is activated to break down glycogen into glucose, which is further broke down to pyruvic acid by the enzyme phosphofructokinase. This process is called anaerobic glycolysis and takes place in the sarcoplasm of the muscle cell where oxygen is not available. Since this is an anaerobic process, the pyruvic acid is then further broken down into lactic acid by the enzyme lactate dehydrogenase (LDH). During anaerobic glycolysis, energy is released to allow ATP re-synthesise.
How many ATP molecules are produced from glucose during the short-term lactate anaerobic system/ anaerobic glycolytic system?
The net result is two molecules of ATP are produced for one molecule of glucose broken down.
How long does the the short-term lactate anaerobic system/ anaerobic glycolytic system last?
Up to 3 mins but can peak at 45 seconds.
What are the key points about glycolysis?
- Breakdown of glucose to pyruvic acid.
- Produces two molecules of ATP.
- During intense exercise, pyruvic acid converted into lactic acid.
Name 3 advantages of the anaerobic glycolytic system.
- ATP can be re-synthesised quite quickly due to very few chemical reactions and lasts for longer than the ATP-PC system.
- In the presence of oxygen, lactic acid can be converted back into liver glycogen or used as a fuel through oxidation into carbon dioxide and water.
- It can be used for a sprint finish (i.e. To produce an extra burst of energy).
Name two disadvantages of the anaerobic glycolytic system.
- Lactic acid as the by-product! The accumulation of acid in the body de-natures enzymes and prevents them increasing the rate at which chemical reactions take place.
- Only a small amount of energy can be released from glycogen under anaerobic conditions (5% as opposed to 95% under aerobic conditions).
What is the energy continuum?
A term which describes the type of respiration used by physical activities. Whether it is aerobic or anaerobic respiration depends on the intensity and duration of the exercise.
Do the energy systems work independently?
No, they all contribute during all types of activities, but one of them will be the predominant energy provider.
What determines which energy system will be the predominant?
The intensity and duration of the activity.
The energy continuum is often explained in terms of threshold. Explain what this means.
The ATP-PC/anaerobic glycolytic threshold is the point at which the ATP-PC energy system is exhausted and the anaerobic glycolytic system takes over (8-10 seconds). The anaerobic glycolytic/aerobic threshold is the point at which the anaerobic glycolytic system is exhausted and the aerobic system takes over (3 mins).
Describe the ATP generation by slow twitch muscle fibre.
- The main pathway for ATP production is in the aerobic system.
- It produces the maximum amount of ATP available available from each glucose molecule (up to 36 ATP).
- Production is slow but these fibres are more endurance based so less likely to fatigue.
Describe the ATP generation of fast twitch muscle fibres.
- The main pathway for ATP production is via the lactate anaerobic glycolytic energy system (during glycolysis).
- ATP production in the absence of oxygen is not efficient - only two ATP produced per glucose molecule.
- Production of ATP this way is fast but cannot last for long as these fibres have least resistance to muscle fatigue.
What energy system is predominantly used for long periods of time at a low intensity? Explain why.
The aerobic system. This is because at low intensity exercise, the demand for oxygen can easily be met and glucose can be broken down much more efficiently when oxygen is present.
What source of food are used for energy at a low intensity?
Fats are used for energy at a low intensity, but as intensity increases there usage becomes limited because they require more oxygen than glucose in their breakdown. As soon as oxygen supplies become limited, fat use for energy drops.