1. Starter
On the flipchart paper, write down everything you know about the skeletal system.
What helps the skeleton to move?

2. Muscle Structure and Function
Level 3 Anatomy and Physiology for Exercise and Health

3. By the end of this session you will be able to:
Learning outcomes
By the end of this session you will be able to:
Explain the cellular structure of muscle fibres
Describe sliding filament theory
Explain the effects of different types of exercise on muscle fibre types
Describe the ability of muscle fibres to adapt to training

4. What are the different types of muscle tissue?
Smooth
Cardiac
Skeletal
What are the different sources of energy for muscles?
Fat
Carbs
Protein
When does fat become the main energy source for muscles?
After carbs

5. Myocardium (cardiac muscle)
Only found in the heart.
Actin and myosin filaments are arranged similar to the skeletal muscle.
3 differences:
Cannot be controlled (involuntary muscle)
Muscle cells ae connected via intercalated discs to form a single coordinated unit. This is so they can share nutrients equally as well as communicate with each other quickly. Cells contact in a specially organised sequence – single contraction.
Only generated by oxygen

6. Smooth Muscles
Found in the tubes of the body. (digestive, reproductive, respiratory, blood vessels and urinary tracts.
Involuntary muscle.
Contraction leads to decreased in diameter (constriction), whist relaxation leads to an increase (dilation)

7. Skeletal muscle
Bring all the movement of the skeleton and is largely voluntary, though some movements are continuous involuntary and are the postural muscles which adjust skeletal alignment.

8. Muscle structure and function

9. Skeletal muscle structure
A muscle is a large collection of individual fibres packaged together and protected by connective tissues.
Mainly composed by protein collagen fibres, with some elastic tissue.
Muscles are bound together by different fasic made of dense irregular connective tissue.
Composed by mainly collage fibres which run in different directions.
The fascia of the muscle eventually converge to the tendon which attaches to the bone.

10. The tendon is made of dense regular connective tissue.
Collagen fibres in the tendon run in one direction to create a strong connection for the muscle in the direction of pull.
A cover of endomysium surrounds each and every cell. The endomysium is continuous with the fibres membrane. Many fibres are then bundled together and wrapped in the perimyosin.
The bundle of fibres is referred to as the fascicle.
The outer covering of the muscle then surrounds several of these bundles. This is called the epimysium.
Towards the ends of the muscle the irregular collagen fibres of the fascia become more regularly aligned and thickened to form the muscle tendon.
The tendon then fuses with the periosteum of the bone to which it is connected. All the connective tissue in a muscle are continuous with each other.

11. It is this tissue that transmit the pulling forces generated inside the muscle cell to the bony leavers, bringing about movement.
All muscles are well supplied with blood vessels carrying nutrients and oxygen, and nerve fibres that convey the stimulus.

12. Fascia
Location
Endomysium
Around each muscle cell (fibre)
Perimysium
Around the fascicles (bundles of fibres)
Epimysuim
Around the outside of the muscle
An easy way to remember the types of facia is that the epimysium is ‘epic’ as it is the largest layer around the whole muscle; endomysium is the ‘end’ because it is the last and smallest layer; perimysium is simple the one in the middle.

13. Muscle structure Muscle fibre Myofibril Myofilament

14. Muscle Cell Structure
The muscle fibres (cells) are the approximate width of a human hair and often run the full length of a muscle. They are composed of smaller elements known as myofibrils.
Myofibrils are divided along their length into repeating units called sarcomeres.
The sarcomeres given skeletal muscle the striped appearance and shorten to bring about muscle contraction.

15. Muscle structure and function

16. Sliding filament theory Occurs within the sarcomere
The ‘unit’ of muscular contraction
Requires calcium and ATP
Nervous stimulus causes the myosin heads to attach to the actin forming cross bridges
Myosin heads pivot and pull actin towards the centre of the sarcomere
Process is repeated and myosin attaches further along the actin

17. Motor units and recruitment

18. Task
Draw a motor unit.
What is the ‘all or none’ law?

19. Motor units and recruitment
The strength of a muscular contraction will be affected by:
The frequency of nerve impulses coming into the muscle cell
The number of motor units activated

20. Fast glycolytic fibres
Muscle fibre types
Slow twitch fibres
Fast twitch fibres
Type 1
Type 2
Slow oxidative fibres
Fast glycolytic fibres
Red in colour
White in colour
Contain large numbers of mitochondria
Contain low numbers of mitochondria
Endurance type activities
Strength / anaerobic type activities

21. Muscle fibre types The 2 fibres subdivide:
Type 2a – Fast oxidative glycolytic (FOG)
Type 2b – Fast glycolytic (FG)