Muscle Cells (Skeletal, Smooth, Cardiac)

Muscle cells: or myocytes, are elongated tubular cells crucial for movement, support, and internal functions like peristalsis. They share key properties: contractility (forceful shortening), excitability (response to stimuli), extensibility (stretchability), and elasticity (ability to bounce back to original length after stretching).

1. Skeletal muscle tissue constitutes skeletal muscles, which connect to bones or skin and oversee conscious movements, including locomotion. Referred to as voluntary muscle due to its responsiveness to conscious thought, skeletal muscles exhibit a long, cylindrical structure. Microscopically, the striped or striated pattern of skeletal muscle tissue is attributed to the organized alignment of contractile proteins (actin and myosin). Actin, a globular contractile protein, interacts with myosin to facilitate muscle contraction. Additionally, skeletal muscle cells contain multiple nuclei within a single cell.                                                                                               
2. Smooth muscle tissue is present in the linings of hollow organs like the intestines, stomach, and urinary bladder, as well as around passages such as the respiratory tract and blood vessels. Unlike skeletal muscle, smooth muscle lacks striations, is not subject to voluntary control, features a singular nucleus per cell, and exhibits a tapered structure at both ends. This type of muscle is commonly referred to as involuntary muscle.                                                                             
3. Cardiac muscle tissue is exclusive to the heart, responsible for pumping blood throughout the body and regulating blood pressure. While sharing striations with skeletal muscle, cardiac muscle is involuntary, meaning it cannot be consciously controlled. Each cell has a single nucleus, a branched structure, and is characterized by the presence of intercalated disks.