Download Muscular System

Muscular System
Principles of Anatomy and Physiology
Learning Outcomes
• Recap the types of muscle
• Recap the function of the muscles
• Assignment feedback and workshop
Types of muscle?
• Skeletal
• Smooth
• Cardiac
Skeletal?
• Skeletal or striated muscle, involved in exercise
• -Under conscious control
• Sometimes referred to as voluntary
Smooth?
• Smooth muscle, e.g. digestive tract, artery wall
• Under unconscious control
• Sometimes referred to as Involuntary
Cardiac?
• Striated and involuntary
• Specialist heart muscle
• Under unconscious control
Muscles
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Muscles work in pairs
Front & back
e.g. biceps & triceps
Prime mover/agonist - the muscle responsible for bringing about the
action
Can you think of an example?
Biceps curl – agonist = biceps
Antagonist - the opposite muscle that relaxes for movement to occur
e.g. biceps curl – antagonist = triceps
Muscles general rules?
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Muscles pull
A muscle crosses at least one joint
A muscle contracts along its line of fibre
Muscles work in pairs
Muscle Fibre Types
Principles of Anatomy and Physiology
Muscle structure
Muscle structure
Muscle fibre
Myofibril
Myofilament
Slow Twitch Fibres (Type 1)
• Slow twitch fibres are designed for aerobic exercise, using oxygen
to produce a small amount of tension over a long period of time
• They are very resistant to fatigue as the speed of the contraction
is slow
• They have a higher capacity for aerobic respiration
• They are red in colour because of more myoglobin
• Performers in endurance events tend to have a higher percentage
of slow twitch muscle fibres
Fast Twitch Fibres 2a and 2b
• Subdivided in to two types; Fast Oxidative Glycolytic fibres
(F.O.G.) and Fast Twitch Glycolytic (F.T.G.)
• They are both designed for anaerobic capacity, producing high
contractions in a short period of time
• This however means that they have a low resistance to fatigue
• They are white in colour because of low levels of myoglobin
Relative percentages of fast and slow twitch
fibres in a range of sporting activities
90
80
70
60
50
40
30
20
10
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Non Athlete
Distance Runner
Swimmer
Sprinter
Weight Lifter
90
80
70
60
50
40
30
20
10
0
Non Athlete
Distance Runner
Swimmer
Type 1
Type 2
Sprinter
Weight Lifter
Type 2 fibres
Fast Oxidative Glycolytic
Fibres (F.O.G.) – Type 2a
Fast Twitch Gylcolytic (F.T.G)
– Type 2b
• These anaerobic fibres are more
resistant to fatigue that type 2b
• Type 2b fibres have the greatest
anaerobic capacity
• FOG fibres generate less force than
type 2b fibres though
• Generate largest amount of force of
contraction
• Activities such as a 200m swim or
800m race will rely on type 2a fibres
• Very poor resistance to fatigue
• Expect a Sprinter or Shot Putter to
have large amounts of FTG fibres
Summary of muscle fibre types
Characteristics
Slow Twitch (Type I)
Fast Oxidative Glycolytic
(Type 2a)
Fast Glycolytic (Type 2b)
Fibre Size
Small
Large
Large
Mitochondria density
High
Low
Lowest
No of capillaries
Large
Moderate
Small
Myoglobin content
High
Moderate
Low
PC stores
Low
High
High
Glycogen stores
Low
High
High
Triglyceride stores
High
Moderate
Low
Speed of contraction (ms)
Slow (110)
Fast (50)
Fastest (<50)
Force of contraction
Low
High
Highest
Resistance to fatigue
High
Low
Lowest
Aerobic capacity
High
Low
Lowest
Anaerobic capacity
Low
High
Highest
Activity suited to
Marathon
1500m
110m Hurdler
Colin Jackson – The Making of Me
• https://youtu.be/j-mHQACvZfc