There are three types of muscle tissue.Smooth muscle forms the walls of blood vessels, stomach, intestines, urinary tract.Striated cardiac muscle makes up most of the muscular layer of the heart.The third kind - skeletal muscle.The name of these muscles due to the fact that they are connected to the bones.Skeletal muscles and bones are a uniform system, enabling the movement.

Skeletal muscle is made up of special cells - muscle cells.This very large cells: their diameter ranges from 50 to 100 microns and the length is several centimeters.Another feature of myocytes - the presence of a plurality of cores, the number of which reaches hundreds.

main function of skeletal muscle - contraction.It provides special organelles - myofibrils.They are located next to the mitochondria, because the reduction requires a large amount of energy.

Myocytes are united in complex - myosymplast surrounded by mononuclear cells - myosatellites.They are stem cells divide and begin actively if damaged muscle.Myosymplast myosatellites form and fiber - a structural unit of muscle.

muscle fibers are interconnected by loose connective tissue in the first row of bundles, bundles of which consist of the second row, etc.The beams are covered with rows of common envelope.Connective layer reaches all muscles, which pass into the tendon attaches to the bone.

for cuts implemented by skeletal muscle, you need a large amount of nutrients and oxygen, so the muscles are supplied with an abundance of blood vessels.Yet the blood is not always able to provide the muscles with oxygen: muscle contraction overlap vessels, blood flow stops, so the muscle cells present a protein capable of binding oxygen - myoglobin.

Muscle regulated somatic nervous system department.Each peripheral nerve muscle solution consisting of axonal neurons located in the spinal cord.In the interior of the muscle nerve branches into processes, axons, each of which reaches the individual muscle fibers.

impulses from the central nervous system transmitted by peripheral nerves, regulate muscle tone - of a constant voltage, by which the body maintains a certain position, and the contraction of the muscles associated with the involuntary and voluntary motor acts.

muscle contraction is shortened, the ends come together.The muscle at the same time pulls the bone, to which is attached by a tendon, and bone changes its position.Each skeletal muscle corresponds to the antagonist muscles, which relaxes when it is reducing, and then declining to return the bone to its original position.For example, for example, the antagonist biceps - biceps - it's the triceps, triceps.The first of them acts as a flexor of the elbow joint, and the second - as the extensor.However, this separation is conditional, some motor acts require simultaneous contraction of antagonist muscles.In humans

200 skeletal muscle, differing from each other in size, shape, method of attachment to the bone.They do not remain constant during the life - they increase the amount of any muscle or connective tissue.The increase in the number of muscle tissue promotes physical activity.