Higher Human Biology Unit 1 Human Cells KEY AREA 8: Energy Systems

Human Cells Learning Intentions KEY AREA 8 – Energy Systems 1.Energy Systems in muscle cells 2.Lactic Acid Metabolism (Anaerobic Respiration) 3.Types of Skeletal Muscle Fibres

8a) Energy Systems in muscle cells ATP is the source of immediately-available chemical energy required for muscular contraction During intense muscular activity, muscle cells break down ATP  ADP + Pi + energy Each muscle only stores sufficient ATP for a few contractions Energy needed for repetitive muscular contraction comes from a chemical called creatine phosphate During strenuous muscular activity, creatine phosphate in muscle cells breaks down, releasing energy and phosphate, which is used to convert ADP to ATP by phosphorylation Creatine phosphate system can only support strenuous muscle activity for around 10 seconds, and then the creatine phosphate supply runs out. Creatine phosphate is restored when energy demands are low

8b) Energy Systems in muscle cells Creatine Phosphate System

8c) Lactic Acid Metabolism (Anaerobic Respiration) After 10seconds of intensive exercise creatine phosphate store is depleted and if the intensive exercise continues the cells start to respire anaerobically because they do not receive an adequate supply of oxygen from the blood for aerobic respiration During Anaerobic Respiration, the only stage of respiration that can occur is Glycolysis In Glycolysis in Anaerobic Respiration Glucose  Pyruvate  Lactic Acid This conversion involves the transfer of hydrogen from NADH NAD is regenerated Lactic Acid gathers in muscle cells and causes fatigue and an oxygen debt builds up The oxygen debt gets repaid when exercise comes to a halt, and energy made from Aerobic Respiration is used to convert lactic acid back to pyruvic acid and glucose

8d) Lactic Acid Metabolism (Anaerobic Respiration)

8e) Types of Skeletal Muscle Fibres FeatureType 1 Slow-TwitchType 2 Fast-Twitch Muscle contraction speedSlowFast Length of time for which contraction lasts LongShort Speed at which fibre becomes fatiguedSlowFast Respiratory Pathways to make ATPAerobic RespirationGlycolysis Number of mitochondriaManyFew Blood supplyLargeSmall Concentration of myoglobin in cellsHigh concentrationLow concentration Storage fuels usedFats Glycogen/Creatine phosphate ActivitiesLong distance running, skiing Sprints, Weightlifting Body movements are brought about by the action of skeletal muscle fibres Skeletal muscle fibres fall into two categories based on the duration of their twitches Type 1 (Slow-twitch muscle fibres) Type 2 (Fast-twitch muscle fibres)

Human Cells Questions KEY AREA 8 – Energy Systems 1.Testing Your Knowledge 2Page 116Q’s What You Should KnowPage Quick Quiz