Unit 3

Energy Systems Muscle Fibres Nervous System Cardiovascular System Respiratory System

Energy Systems & Muscle Fibres

PSE4U

Energy Systems

Carbohydrates: Most abundant

organic substance in nature they are essential for human an animal life

Glucose: Is broken down to form ATP

(adenosine triphosphate) Is stored in muscles and

liver as GLYCOGEN – can be broken down under conditions of stress or the demands of muscular activity Created by photosynthesis

CO2 + H2O + sunlight E C6H12 O6 + O2

Law of Conservation of Energy Energy is neither created nor destroyed

only transformed from one form to another ▪ Ex. Light energy from the sun is “captured” by plants

during the process of photosynthesis and converted to chemical energy (food)

CHEMICAL ENERGY (food) – is used to make ATP (free energy)

Adenosine adenosine Triphosphate diphosphate phosphate ATP -------------> ADP + P

A-P - P - P -------------> A- P-P + P

ATP

Energy Energy In Out

ADP

2 Methods for Resynthesis of ATP

1. ANAEROBIC (without oxygen) – short high intense activity

2. AEROBIC (with oxygen) – endurance

These two systems coexist, overlap and interact in various combinations

Most activities rely on a combination of both systems

ANAEROBIC

Occurs relatively quickly in the muscle fibres, utilizing chemical and enzymes readily at hand for powerful but relatively short lived activitites

Anaerobic can be broken down into 2 systems: ▪ PATHWAY 1: Anaerobic Alactic (ATP-PC)▪ PATHWAY 2: Anaerobic Lactic (Glycolosis)

PATHWAY 1: Anaerobic Alactic

Name ATP-PC(Anaerobic Alactic System)

Location of Activity CytoplasmEnergy Source Creatine Phosphate (PC)Uses Oxygen or Not Anaerobic (without oxygen)ATP created 1 moleculeDuration 10-15 secondsNumber of Chemical Reactions

1-2

By-Products None

PATHWAY 1: Anaerobic AlacticName ATP-PC

(Anaerobic Alactic System)Basic Formula PC + ADP ATP + creatine Type of Activities Power surges, speed eventsTypes of exercise that rely on this system

Sprints, jumps, weightlifting

Advantages Very quick surge of powerLimitations of energy system

Short duration, muscles store small amounts of ATP and creatine phosphate

Muscle fibre type recruited Type IIB (fast-twitch• Is important as it provides the highest rate of ATP

synthesis that cannot be matched by other, more complex energy systems

• Recovery Period of PC 2-5 min – requires ATP to resynthesize PC

PATHWAY 2: Anaerobic Lactic

Name Glycolysis(Anaerobic Lactic System)

Location of Activity CytoplasmEnergy Source Glucose (Glycogen)

* Glycolysis is the first step in the breakdown of glucose

Uses Oxygen or Not Anaerobic (without oxygen)ATP created 2 molecules per glucose moleculeDuration 15 seconds to 3 minutesNumber of Chemical Reactions

11* Has a lot more steps but yields twice as much ATP over Anaerobic Alactic sytem

By-Products Lactic Acid

Name Glycolysis(Anaerobic Lactic System)

Basic Formula C6H12O6 + 6O2 + 36ADP + 36 P 6CO2 + 6H2O + 36 ATP

Type of Activities Intermediate activities/sprint finishes

Types of exercise that rely on this system

200-800 metre runs, shift in hockey

Advantages Quick surge of power

Limitations of energy system

Buildup of lactic acid causes pain and fatigue

Muscle fibre type recruited

Type IIA (fast twitch)

PATHWAY 2: Anaerobic Lactic

PATHWAY 2: Anaerobic Lactic

PYRUVATE is the by-product of glycolysis when oxygen is not present it continues to breakdown into LACTIC ACID▪ LACTIC ACID –decreases muscles ability to

contract

GLUCOSE

PYRUVATE (without O2) LACTIC ACID(with O2) (Kreb’s Cycle)

Name Cellular Respiration (Aerobic System)

Location of Activity MitochondriaEnergy Source Glycogen, Fats, ProteinsUses Oxygen or Not Aerobic (with Oxygen)ATP created 36 Molecules per glucose molecule Duration 120 seconds and beyondNumber of Chemical Reactions

Glycolysis Kreb’s CycleElectron Transport Chain

By-Products Water and Carbon Dioxide

AEROBICPathway 3: Aerobic Pathway

Name Cellular Respiration(Aerobic System)

Basic Formula C6H12O6 + 6O2 + 36ADP + 36 P 6CO2 + 6H2O + 36 ATP

Type of Activities Prolonged activities

Types of exercise that rely on this system

Marathons, exercise classes

Advantages Long duration, complete breakdown of glucose

Limitations of energy system

Slow, requires large amounts of oxygen

Muscle fibre type recruited

Type I (slow-twitch)

AEROBICPathway 3: Aerobic Pathway

AEROBICPathway 3: Aerobic Pathway

Glucose fuels this system but,▪ Fats can be broken down when exercise occurs for

longer than 20 min▪ Proteins can be broken down in chronic situations –

starvation

Complete breakdown of glucose, unlike anaerobic lactic that stops after glycolysis

This system can be sustained as long as oxygen is present and physiological limits are not reached.

CELLULAR RESPIRATION – 36 ATP

Glucose

Pyruvate (with Oxygen)

Electron Transport Chain

2 ATP are Made

2 ATP are Made

32 ATP are Made

Lactic AcidBlood Lactate Threshold (anaerobic

threshold) Point at which lactate levels in the blood increase

abruptly beyond resting values

Onset of Blood Lactate Accumulation (OBLA)▪ Point at which blood lactate levels begin to accumulate

very rapidly.

Raising the Lactic Acid Threshold – Need to do power training ▪ Raising the lactic acid threshold will allow you to utilize

your anaerobic lactic system for a longer period of time as the build up of lactate will be slower.

Cori Cycle Lactic Acid creation and breakdown

MUSLCE

Glucose

Pyruvic Acid

Lactic Acid

LIVER

Glucose

Pyruvic Acid

Lactic Acid

Can be Stored in liver or

muscles as glycogen

Energy from Fats FATS – ideal as they contain large quantities

of stored energyTriglycerides Fatty Acids

Lipolysis

Fatty Acids Acetyl CoA

Beta Oxidation enter KREB’s CYCLE

Energy from Protein PROTEIN – same amount of energy as

carbohydrates (glucose) but ½ as much as fat

No protein reservoirs in the body like carbs and fats, all proteins are part of existing body tissue or actively engaged as in metabolic systems

Made up of long chains of amino acids

Individual amino acids are broken down further and enter energy system

Muscle Fibres

We have different types of muscle fibres in our body and each type of muscle fibre is more adapted to a certain energy system. Slow Twitch Muscle Fibres▪ Generate and relax tension slowly but are able to

maintain lower levels of tension for a long period of time.

Fast Twitch Muscle Fibres▪ Have the ability to tense and relax quickly and can

generate large amounts of tension but have low endurance levels.

Muscle Fibre Distribution for Athletes in Different Sports

Slow - Twitch Fast – Twitch

Cyclist 61% 39%

Canoeist 61% 39%

Middle – Distance Runner

59% 41%

Swimmer 58% 42%

Weightlifting 46% 54%

Sprinter 26% 74%

Soccer Player 53% 47%

Myoglobin The difference in muscle fibre types are mainly

due to the extent to which a particular muscle relies on oxygen in the production of energy.

MYOGLOBIN – is the oxygen storage unit that

delivers oxygen to working muscles.

The more a muscle utilizes aerobic processes for energy production the more myoglobin it has. ▪ Slow twitch muslce fibres (red) are high in myoglobin ▪ Fast twitch muscle fibres (white) are low in myoglobin

Characteristics of Different Muscle Fibre Types

Type I Slow Oxidative (SO)

Type IIAFast Oxidative Glycolysis (FOG)

Type IIBFast Glycolysis(FG)

Colour Red Red/White WhiteFibre Diameter Small Medium LargeContraction Speed

Slow (110ms) Fast Very Fast (50ms)

Force Production

Low Intermediate High

Energy Efficiency

High Low Low

Myoglobin Content

High Moderately high Low

Myosin ATPase Low High HighFatigue Resistance

High Moderate Low

Aerobic Capacity

High Moderate Low

Anaerobic Capacity

Low High High

Tonic vs. Phasic Muscles

Tonic Muscles – assists the body with maintaining posture or stability during activities such as standing, walking and throwing. ▪ High percentage of Type I fibres

Phasic Muscles – characterised by a higher percentage of Type IIA and Type IIB