Muscles

3 types

• Skeletal / striated - voluntary
• Cardiac - involuntary
• Smooth -  involuntary 

Myofibrils - single muscle fibre 

• Consist of a series of sub-units called sarcomeres 

Thick filaments 

• Are made up of a protein called myosin 
• Darker in colour 

Thin filaments 

• Made up of a protein called actin 
• Lighter
• Around actin filament there are two other proteins called tropomyosin and troponin 

Secondary form protein
 

Filament arrangement 

• Filaments are arranged in an overlapping pattern 
• Allows them to slide between each other 
   

Sliding filament theory

Troponin, tropomyosin + calcium 

• The movement of muscle is caused by an electrical impulse 
  - Neurons connect to muscles at 
  
•                    Neuromuscular junctions  
• At…