Unit 6 - Energy systems

Question 1

What are the 3 Key Energy (Macro-) Nutrients?

Answer 1

Proteins, Carbohydrates, fats

Question 2

What is each macro-nutrient broken down into?

Answer 2

Proteins - Amino acids
Carbohydrates - Glucose, glycogen
Fats - Fatty acids

Question 3

How many calories per gram does each yield?

Answer 3

Carbs - 4.1 cal/gram
Proteins - 4.3 cal/gram
Fats - 9.3 cal/gram

Question 4

What is the role of Carbs?

Answer 4

• Most abundant organic substance
• Primary source of energy
• Come from veggies, fruit, and grains like bread and pasta
• Is composed of glucose (glycogen)
• Glucose is stored in the skeletal muscles and liver as glycogen and when needed for activity, can be easily transported by the blood throughout the body

Question 5

Where is glucose stored?

Answer 5

It is stored within skeletal muscles in the body, ready to be released when and transported by the blood when needed for activity

Question 6

How many ways is ATP re-synthesized?

Answer 6

Two ways, aerobically and anaerobically

Question 7

What is aerobic respiration?

Answer 7

• In the presence of oxygen (O2)
• All of its metabolic activity will involve O2
• Occurs in the mitochondria
• Leads to the complete breakdown of glucose

Question 8

What is ANaerobic respiration?

Answer 8

• Anaerobically (without oxygen)
• Without the use of oxygen (O2)
• None of its metabolic activity will involve O2
• Utilises chemicals and enzymes; occurs in the muscle fibre
• Short-lived

Question 9

What is the ATP-PC system?

Answer 9

The ATP-CP system is the system that is responsible for very short (i.e. 1-2 repetitions), explosive movements. This energy system is only good for about 6-10 seconds of activity. Using cars as an analogy, the ATP-CP system would be your nitrous boost

Question 10

What is another name for ATP-PC system?

Answer 10

The ATP-PC (adenisine-triphosphate phosphocreatine) system is also known as the phosphagen system

Question 11

Key aspects of the ATP-PC system

Answer 11

• Relies solely on the action of stored ATP and phosphocreatine (Phosphocreatine (PC) is a readily accessible compound stored in the muscles)
• Phosphate is broken off of PC to resynthesize ATP
  this system yields enough ATP for 10–15 seconds of energy because there is only a small reservoir of PC.
• Provides highest rate of ATP synthesis
• The full replenishment of PC requires ATP and occurs during the recovery period (2-5 minutes). It occurs rapidly and is achieved mainly as a result of supplies of ATP being created during aerobic processes.
• Suited for power events such as 50m, 100m, high jump, weight lifting, which only last a few seconds and require a large burst of energy.
• There are no by-products in this system

Question 12

What is the Glycolysis System?

Answer 12

• Second anaerobic energy pathway – good backup due to plentiful glucose/ glycogen levels that are normally in the body
• Also known as the EMP system
• Provides additional 1–3 minutes in high-level performance
• Glycolysis transfers energy from glucose and glycogen to rejoin ADP and phosphate to make ATP
• Yields twice as much ATP (2 molecules of ATP)
• By-product of this system is lactic acid (LA)
• This system is better suited for medium to high intensity activities – 400m, 800m, hockey shift

Question 12

What does the glycolysis system rely on for re-synthesis?

Answer 12

2 ATP

Question 13

What by-products are there in the glycolysis system?

Answer 13

• By-product of this system is lactic acid (LA)
• 2 ATP molecules and 2 Pyruvate

Question 14

What events/activities is the glycolysis system best suited for?

Answer 14

• This system is better suited for medium to high intensity activities – 400m, 800m, hockey shift

Question 15

How does the Cori Cycle work?

Answer 15

• Lactate is transported by the blood to the liver where most of it is converted back to glucose, from which glycogen is formed (gluconeogenesis) – one-sixth is given off as C02.
• The Cori Cycle is the process by which lactic acid is converted to pyruvate for future conversion to glucose and glycogen. In effect, lactate re-enters the cycle as an energy source.

Question 16

What is the Aerobic system?

Answer 16

Cellular respiration is the third energy system and it contains 3 sub sections
- Glycolysis
- Krebs cycle
– Electron transport chain

• This system uses glucose, glycogen, fats, and protein to make ATP
• Lasts 90-120 seconds and beyond
• The by-products are carbon dioxide (C02) and water H20
• In presence of 02 this system can sustain activity for very long periods of time or until other physiological limits are reached
• This system used by our bodies to sustain endurance type activities – marathon, soccer
• This system involves molecular activity in the mitochondria of the cells, referred to as “cellular respiration”. Fats are the predominant energy source in exercise lasting longer than 20 minutes (proteins are used during starvation).
• Produces 36 ATP molecules for every glucose molecule, nearly 20X the anaerobic system.
  Cellular respiration involves 3 sub-pathways:=

1. Glycolysis:
   The first stage is the same as the anaerobic-lactic system except that in presence of 02, pyruvic acid (3 carbons) is converted (oxidized) to acetyl CoA (2 Carbons) instead of lactic acid.
   Acetyl CoA then enters the Krebs cycle (citric acid cycle) which is the central pathway for the metabolism of fats and proteins. (2 ATP)
2. Krebs Cycle (Citric Acid Cycle):
   Highly complex process involving 8 chemical reactions.
   2 ATP molecules are produced here along with compounds capable of storing high-energy electrons.
   These electrons are sent to a process within the mitochondria known as electron transport chain.
3. Electron Transport Chain:
   Final stage of aerobic respiration; extremely complicated process that produces large amounts of ATP (32) are produced with CO2 and H20 as the by-products.
   Free radicals (highly reactive molecules) may also be by-products as the electrons pass down the chain and these may contribute to long-term muscle fatigue.

Question 17

What does the aerobic system rely on for re-synthesis?

Answer 17

O2

Question 18

What events/activities is the aerobic system best suited for?

Answer 18

• This system used by our bodies to sustain endurance type activities – marathon, soccer

Question 19

What are the 3 sub sections of the Aerobic System?

Answer 19

Glycolysis, krebs, Electron transport chain

Question 20

How many ATP is produced in each aerobic system cycle?

Answer 20

36 ATP are produced

Question 21

How many chemical reactions are there (if any) in the aerobic system cycle?

Answer 21

At least 22 reactions

Question 22

Muscle Fibre Types

Answer 22

Fast twitch and slow twitch

Question 23

Slow-Twitch Muscle Fibres

Answer 23

• Red or dark in colour.
• Generate and relax tension relatively slowly.
• Able to maintain a lower level of tension for long durations.
• Feature a type of enzyme called myosin ATPase found attached to the thick filaments (myosin) in the muscle fibre. The body uses myosin ATPase to provide instant energy for muscle contraction.
• Contain low levels of what are known as glycolytic enzymes, which permit the release of glycogen within muscles
• Contain high levels of oxidative enzymes.
• Produce lower tension and/or contraction levels over a longer period of time.
  -Ideal for activities such as long-distance swimming, cycling, and running.

Question 24

Fast-Twitch Muscle Fibres

Answer 24

• Pale in colour.
• Have the ability to tense and relax quickly.
• Generate large amounts of tension with relatively low endurance levels.
• Have a different type of myosin ATPase compared to slow-twitch muscle fibres and contain high levels of glycolytic enzymes.
• Activate at a rate two to three times faster than slow-twitch fibres
• Ideal for the fast, powerful muscle contractions needed for activities such as short sprints, powerlifting, and explosive jumping.

Question 25

The Importance of Myoglobin
(Note: the prefix “Myo” = Muscle)

Answer 25

• Myoglobin is the oxygen storage unit that delivers oxygen to working muscles, thereby enabling energy-producing biochemical reactions to be sustained over a long period of time.
• Slow twitch fibres are high in myoglobin and therefore suited for endurance activities
• Fast twitch fibres have a low myoglobin content and therefore better suited for short bursts of effort

Question 26

Three Muscle Fibre Types

Answer 26

Kinesiologists normally distinguish not just two but three different types of muscle fibre, using a combination of the tension-generating features and the metabolic properties of the fibre.

These types are:
- Type I or Slow-Oxidative (SO): These fibres generate energy slowly, are more fatigue-resistant, and primarily depend on aerobic processes.
- Type IIA or Fast-Oxidative Glycolytic (FOG): These intermediate-type muscle fibres allow for high-speed energy release as well as glycolytic capacity.
- Type IIB or Fast-Glycolytic (FG): These fibres store lots of glycogen and sufficiently high levels of enzymes necessary for quick contraction without requiring oxygen.
- The main reason for the subdivision within the Type II fibres is that there is strong research evidence suggesting that Type IIB fibres can, as a consequence of aerobic endurance training, become Type IIA fibres (whereas Type IIA fibres do not make the transition to Type I fibres).