Relate the types of myofilaments and describe theirstructures

Muscle cells are specialized for contraction to permit movements like walking along with other processes like digestion, respiration. There are majorly three types of muscle tissue : skeleton, cardiac and smooth muscles. 

Skeletal muscles attach to bones and skin and control locomotive movements which are under our conscious control. They are also called voluntary muscles. 

Smooth muscles occur in the walls of organs like intestines, stomach , bladder and are not under voluntary control. They are tapered at ends and are called involuntary muscles. 

Cardiac muscles are only found in the heart and maintain blood pressure. 

Skeletal muscle fiber is a skeletal muscle cell which is large in size with lengths up to 30cm. The plasma membrane of a skeletal muscle fibre is called sarcolemma. These act as a site of action potential conduction which are responsible for muscle contractions. Within each of these muscle fibres are myofibrils which are long cylindrical structures that lie parallel to the muscle fibers. Myofibrils are found to be running along the entire length of the muscle fibres.

They are striated in appearance because of the bands of proteins present and being repeated. Dark A bands and Light I bands are found to be repeating which cause the appearance to be striated. 

Myofilaments are smaller structures which compose the myofibrils. They are usually of two types : thick and thin , each one having a different composition and location. Thick filaments are found in A band of myofibrils whereas thin filaments attach to a protein in the Z disc which is called alpha actinin. Thin filaments are found across the entire length of the I band and somewhat into the A band.