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The Sliding-Filament Theory

Gross and Microscopic Structure of Skeletal Muscle Including Ultrastructure of a Myofibril

Roles of Actin, Myosin, Calcium Ions and ATP in Myofibril Contraction

Striations In Skeletal Muscle Are Caused By Filaments Of Two Protein Actin And Myosin

Structure Of Actin And Myosin Filament

Neuromuscular Junction


Muscles As Effectors

Role of ATP and Phosphocreatine in Providing the Energy Supply During Muscle Contraction

Stimulation Of Muscle Fibres By The Nervous System

Cycle Of Events During Contraction Of A Myofibril

Energy In Active Muscle Cells

Table 16-9-1: Structure, location and general properties of slow and fast skeletal muscle fibres


Fast muscle

Slow muscle

- Role in body

- Rapid, powerful movements
- Short-lasting

- Slow movement
- Long-lasting

- Diameter of fibres
- Capillaries
- Sarcoplasmic reticulum
- Mitochondria

- Large
- Few
- High
- Few

- Small
- Many
- Low
- Many (ETC, Krebs cycle)

- Speed of contraction
- Rate of pumping Ca2+

- Fast
- High

- Slow
- Slower

- ATPase activity
- Respiration
- Glycogen content
- Myoglobin content
- Resistance to fatigue

- High, split ATP quickly
- Anaerobic
- High
- Low
- Low

- Low, split ATP slowly
- Aerobic
- Low
- High
- High


Arms and legs
(running and throwing)

Back and neck
(postural muscles)

Slow muscles contain myoglobin in sarcoplasm → appears bright red