1.  Clare Hargreaves-Norris Skeletal Muscle Tissue ACCESS HE Human Biology.

2.  Clare Hargreaves-Norris Muscle Tissue Characteristics Muscles are made up of tiny elastic fibres that have the ability to: Shorten or contract. Spring back to the original form after contraction - like elastic. Stretch when relaxed. Respond to stimuli provided by nerve impulses.

3.  Clare Hargreaves-Norris Skeletal (Voluntary) Muscle Tissue Skeletal muscle tissue is controlled voluntarily by the brain and nervous system. When viewed under a microscope, it has visible stripes and is therefore called striated. Each muscle tissue consists of bundles of parallel muscle fibres. Each muscle fibre also has a rich blood and nerve supply. The blood brings fresh oxygen, nutrients, and adrenalin and removes waste products such as lactic acid and carbon dioxide. The nerves carry impulses that stimulate the muscle to contract or relax.

4.  Clare Hargreaves-Norris Actin and myosin fibres Running the length of the muscle tissue are two kinds of protein filaments: Actin filaments: the thinner filaments. Myosin: the thicker filaments. Actin and Myosin filaments are arranged in alternating bands resulting in a striated appearance.

5.  Clare Hargreaves-Norris Structure of a muscle fibre

6.  Clare Hargreaves-Norris How a voluntary muscle contracts 1. Muscle must receive a stimulus from the motor nerve attached to the muscle fibre. 2. Muscle must have a sufficient energy supply. 3. Energy comes from Adenosine triphosphate (ATP), which is rich in glucose and oxygen. 4. Nerve stimulus and ATP results in the actin filaments sliding further in-between the myosin filaments, therefore shortening the muscle fibres. 5. This is the sliding filament theory of muscle contraction. Actin filament Myosin filament