The Muscular System What do skeletal muscles do

The Muscular System • What do skeletal muscles do? • How do muscles work?

Functions of Muscle Tissue • Produce movement – Muscle pulls tendons to move the skeleton • Maintain posture and body position - Continuous muscle contraction • Support soft tissue -Support weight of visceral organs • Movement of substance around the body - Encircle openings to digestive and urinary tracts: sphincters - Regulate blood flow, movement of food, enzyme, propel urine…. • Maintain body temperature – Energy from contraction is converted to heat

Types of muscles tissue

Skeletal Muscle • Muscles are bundles of cells and fibres. • Muscles work in a very simple way; all they do is contract or relax. • Muscles can only pull, they never push. • Muscles generally work in pairs to produce movement: when one muscle contracts the other relaxes. • There are 630 active muscles in your body

Muscle Action • Skeletal muscles produce movement by exerting force on tendons, which pull bones. • When muscle contracts it shortens and pulls two jointed bones together. • However the two bones do not move equally in response to the force, one is held in place by other muscles which brace it so that the other bone will move towards it.

Ø Muscles which cause the movement of a joint are connected to two different bones; muscle contraction pulls them together. Ø An example would be the contraction of the biceps and a relaxation of the triceps. This produces a bend at the elbow, an action called flexion Ø The contraction of the triceps and relaxation of the biceps produces the effect of straightening the arm.

• Muscle contractions require energy – Blood vessels deliver oxygen and nutrients to produce ATP – ATP is the cellular energy molecule produce in the mitochondria • Muscle contractions are under stimulation from the CNS – Voluntary control – Axons connect to individual muscle fibers

Anterior View

Posterior View

The muscular system • BBC MUSCLE GAME