MUSCLE TISSUE

Muscle Tissue If it contracts, it's muscle: Muscle tissue is categorized on the basis of a functional property: the ability of its cells to contract. consists of the contractile protein fibrils actin and myosin. Muscle is responsible for movement of the body and changes in the size and shape of internal organs. Muscle cells are generally referred to as muscle fibres. Muscle fibres are typically arranged in parallel arrays allowing them to work together effectively

The three types of muscle: Three types of muscle tissue can be identified histologically: 1.skeletal muscle 1.skeletal muscle (striated muscle, voluntary), 2.cardiac muscle 3.smooth muscle 3.smooth muscle (non- striated muscle, involuntary).

Skeletal muscle Skeletal muscle constitutes the muscle that is attached to the skeleton and controls motor movements and posture.

Skeletal Muscle Skeletal muscle fibres (cells) are multinucleated They are filled with longitudinally arrayed subunits called myofibrils. The myofibrils are made up of the myofilaments myosin (thick filaments) and actin (thin filaments). The striations reflect the arrangement of actin and myosin filaments and support structures. The individual contractile units are called sarcomeres.

Skeletal Muscle Summary Summary: Skeletal muscle fibres bear obvious striations, have many peripherally located nuclei, are of the same thickness throughout their length and do not branch.

Skeletal Muscle

Cardiac Muscle Cardiac muscle is the type of muscle found in the heart Cardiac muscle is intrinsically contractile but is regulated by autonomic (unconscious) and hormonal stimuli.

Cardiac Muscle Summary Striations are present (actin and myosin) Greater number of mitochondria present Cardiac muscle cells have only one or two nuclei, which are centrally located. Cardiac muscle cells are joined to one another in a linear array. The boundary between two cells abutting one another is called an intercalated disc. Cardiac muscle fibres are branched

Cardiac Muscle

Smooth Muscle Smooth muscle is the intrinsic muscle of the internal organs, iris of the eye and blood vessels. Like cardiac muscle, smooth muscle fibres are intrinsically contractile but responsive to autonomic and hormonal stimuli. They are specialized for slow, prolonged contraction.

Smooth Muscle Smooth muscle fibres are generally arranged in bundles or sheets (no striations) A single nucleus is located in the central part of the fibre. Fibres do not branch. Smooth muscle fibres lie over one another in a staggered fashion Fusiform Shape with tapered ends

Smooth Muscle

Musclel Tissue Summary

Muscle Tissue Summary