Aerobic System

Complete table below on the ATP-PC and Glycolytic system Do Now Task Complete table below on the ATP-PC and Glycolytic system Type of Reaction Anaerobic Site of Reaction Food Fuel used Controlling Enzyme ATP YIELD Specific Stages By-products Intensity of activity Duration of System

Learning Objectives D – Recall the stages of aerobic glycolysis and identify sporting examples for this system C/B – Explain the process of aerobic glycolysis A – Critically evaluate the aerobic energy system

Aerobic System The aerobic system kicks in during low- moderate intensity activity as the arrival of sufficient oxygen enables energy production. The aerobic system utilises around 95% of the potential energy in glucose through three distinct stages: 1. Aerobic glycolysis 2.Kreb cycle 3. ETC

Aerobic Glycolysis Aerobic glycolysis is the first stage of the aerobic system. It occurs within in the sarcoplasm where glucose is converted into pyruvic acid with the enzyme PFK catalyzing the reaction. This releases enough energy to resynthesise two moles of ATP. As glucose stores are limited within the blood stream the enzyme GPP is released which coverts stored glycogen to glucose. However as oxygen is now in sufficient supply, the pyruvic acid is no longer converted into lactic acid. Pyruvic acid goes through a link reaction which is catalyzed by coenzyme A, which produces acetyl CoA. Which factors determine whether oxygen is present? Acetyl CoA allows access to the power house of the muscle cell, the mitochondria.

Total Recall In pairs please recall the stages of the energy systems we have covered. Enzymes Fuels Process

The Kreb’s Cycle Acetyl CoA combines with oxaloacetic acid to form citric acid. This is oxidised through a cycle of reactions. Within the Kreb’s cycle, CO2 , hydrogen and enough energy to resytnthesise two moles of ATP are released. This process occurs within the matrix (intracellular fluid) of the mitochondria. Summarise your learning and draw a flow diagram of the two stages of the aerobic system.

Electron transport chain (ETC) The hydrogen atoms are carried through the ETC along the cristae of the mitochondria by NAD and FAD(hydrogen carriers) splitting into ions (H+) and electrons (H-). Hydrogen ions are oxidised and removed as H20. Pairs of hydrogen electrons carried by NAD (NADH2 ) release enough energy to resynthesize 30 moles of ATP and those carried by FAD (FADH2) release enough energy to resynthesize 4 moles of ATP. The overall energy yield of the ETC is 34 moles of ATP When all three stages are combined, one glucose molecule yields 38 moles of ATP. Which sports/activities would the aerobic energy system be suited to?

The aerobic system and FFAs Glycogen stores are large and will fuel the aerobic system for a significant period of time. However, long distance performers will want to reserve glycogen stores as they can be broken down both aerobically and anaerobically. Why is this important? Triglycerides or fats can also be metabolised aerobically as FFAs, providing a huge potential fuel source. The enzyme lipase is released and breaks down triglycerides into FFAs and glycerol. FFAs are converted into acetyl CoA and follow the same path through the Kreb’s cycle and ETC as pyruvic acid. FFAs have a higher energy yield and are therefore preferable for long distance athletes whose events last more than an hour. However FFAs require around 15% more oxygen to metabolise.

Total Recall In pairs please recall the stages of the aerobic energy systems we have covered using the lesson resource. Draw a flow diagram and describe each stage including: Enzymes Fuels Site of reaction

Questions What type of sportsperson would work predominantly in the Lactic Acid Energy System? Explain How long can we work in the Lactic Acid Energy System? High Intensity – Low Duration! Can this be changed and how?

Type of Reaction Aerobic Site of Reaction Sarcoplasm, matrix and cristae of mitochondria Food Fuel used Glycogen/glucose and triglycerides (FFAs) Controlling Enzyme GPP,PFK, co-enzyme A and lipase ATP YIELD 1 mole of glycogen yields up to 38 moles of ATP Specific Stages Aerobic glycolysis Kreb cycle Electron transport chain Glucose + 6O2  6CO2 + 6H2O + energy (exothermic) Energy + 38P + 38ADP  38ATP (endothermic) By-products CO2 and H2O Intensity of activity Low-moderate/ sub-maximal intensity Duration of System Three minutes onwards

Critical Evaluation Advantages: Large fuel stores; Trigylicerides, FFAs, glycogen and glucose High ATP yield and long duration of energy production No fatiguing by-products Disadvantages: Delay for oxygen delivery and complex series of reactions Slow energy production limits activity to sub-maximal intensity Trigylerides or FFAs demand around 15 per cent more O2 for breakdown.

Exam Question Critically evaluate the use of energy systems to resynthesize ATP (20marks.)