MUSCLE STRUCTURE

WHAT IS SKELETAL MUSCLE? Muscles are composed of strands of proteins grouped together in fibres. 70% of tissue is water Creates movement around a joint Properties of muscle: Extensibility- stretch Elasticity- return to normal length Excitability- respond to a stimulus Contractibility- ability to shorten

Skeletal muscle is made of individual fibres and group together to form bundles. The muscle is covered with connective tissue which gives it strength. There are two proteins in the muscle fibres: Actin and myosin

MUSCLE FIBRE TYPES WHY CAN SOME PEOPLE RUN FASTER THAN OTHERS? There are different types of muscle fibre with distinct characteristics 3 types Type 1 Slow Oxidative fibres Type 11a Fast oxidative Glycolytic fibres Type 11b Fast glycolytic fibres

Write down a definition of aerobic and anaerobic respiration, explaining the difference between the two.

Type 1 Slow Oxidative Fibres Structure Red Small Many mitochondria Many capillaries High myoglobin Low glycogen Mitochondria- ATP is produced- cope With prolonged periods of exercise Greater blood flow to the working Muscles more O2- work for longer Myoglobin

FUNCTION Contraction- slow Contractile strength- slow Fatigue resistance-high Aerobic capacity- high Anaerobic capacity- low Produce a small amount of force over a longer period of time Have the enzymes to break down fats, carbohydrates to Water and CO2- so less lactic Acid and fatigue They have a slower form of ATPase which is an enzyme that splits, releasing ATP.

SPORTING EXAMPLE: Marathon Runners (aerobic events) Long distance cycling Highly trained distance runners- 80% of the muscle is made up of slow twitch fibres (SO) You can’t predict how good someone is just from their % of muscle fibres- depends on training, efficiently of CV and respiratory system.

Type 11a fast Oxidative Glycolytic Fibres Red Many mitochondria Many capillaries High myoglobin Intermediate glycogen Structure Lighter- fast twitch

FUNCTION Contraction- fast Contractile strength- intermediate Fatigue resistance-moderate Aerobic capacity- moderate Anaerobic capacity- high Produce energy aerobically and anaerobically Suited to more anaerobic Respiration- release energy quickly

Example 1500 metre runner Any activity involving walking, running and sprinting

Type 11b fast Oxidative Glycolytic Fibres White Few mitochondria Few capillaries Low myoglobin High glycogen STRUCTURE Fill out the functional characteristics, using the information above.

FUNCTION Contraction- fast Contractile strength- High Fatigue resistance-low Aerobic capacity- low Anaerobic capacity- high Rely on anaerobic respiration Energy is released quick but the muscle tires Produce a large amount of force over a short period of time

Example 100 metre sprinter Any activity requiring speed and power A sprinter has 76% fast twitch fibres compared to 24% slow twitch fibres

EXAM QUESTION Identify the predominant muscle fibre being used during the biceps curl to produce one maximum lift. Give one structural and one functional characteristic of that Fibre type. (3 marks) Fibre type Structural characteristic Functional Characteristic