GENERAL HISTOLOGY

MUSCLE

SKELETAL MUSCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The contractile unit of a muscle is called the ____
A
Sarcolemma
B
Sarcoplasmic reticulum
C
Sarcoplasm
D
Sarcomere
Explanation: 

Detailed explanation-1: -A sarcomere is the basic contractile unit of a myocyte (muscle fibre). A sarcomere is composed of two main protein filaments (thin actin and thick myosin filaments) which are the active structures responsible for muscular contraction.

Detailed explanation-2: -A sarcomere is the functional unit (contractile unit) of a muscle fiber. As illustrated in Figure 2-5, each sarcomere contains two types of myofilaments: thick filaments, composed primarily of the contractile protein myosin, and thin filaments, composed primarily of the contractile protein actin.

Detailed explanation-3: -What Is a Sarcomere? When muscle cells are viewed under the microscope, one can see that they contain a striped pattern (striations). This pattern is formed by a series of basic units called sarcomeres that are arranged in a stacked pattern throughout muscle tissue (Figure 1).

Detailed explanation-4: -A sarcomere (Greek sarx “flesh", meros “part") is the smallest functional unit of striated muscle tissue. It is the repeating unit between two Z-lines. Skeletal muscles are composed of tubular muscle cells (called muscle fibers or myofibers) which are formed during embryonic myogenesis.

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