How Movement is Brought About in a Limb

How movement is brought about in a

limb

Azneezal Ar-RashidSmk Sri Aman

95007 Sri Aman, Sarawak

February 2010

• A muscle is attached to at least two bones across joints through tendons

• Tendons :– Strong– Tough– Inelastic

• Antagonistic pairs– One muscle contracts– One muscle relaxes

• Example :– Bending & straightening

the arm

• Arm– Front : biceps

• When biceps contracts, triceps relaxes

– Forearm moves upwards

– Back : triceps

The structure of muscle

• Muscle– Consists of :

• Muscle fibres• Blood vessels• Nerves

• Muscle fibres– Single & long

cylindrical cell– Many nuclei– Made up of myofibrils

• Two types of protein filaments :

– Actin– Myosin

– Note : interaction between actin & myosin causes muscle contraction

• Has nerve ending– Voluntary actions

• Signal from the brain

• Has mitochondria– Energy : ATP for muscle

contractions