Category: Biology Second Paper Lecture Sheet

It is located in alimentary canal, blood vessel, trachea, urinary tract, uterus etc.

Involuntary muscles are squash-shaped in appearance. That is, it is wide in the middle and narrow at both ends. Its length is 15-200 micrometers and diameter is 8-10 micrometers.
1. Sarcolemma: The muscle sheath is called sarcolemma. The sarcolemma is indistinct in involuntary muscles.
2. Sarcoplasm: Cytoplasm of muscle is called sarcoplasm. Cytoplasm contains mitochondria. Its cytoplasm is called sarcoplasm. Each cell has a nucleus and numerous fibers called myofibrils.
3. Nucleus: Each muscle cell has a nucleus. It performs biological functions of cells.
4. Myofibril: Myofibril fibers are present along the length of the cell. Myofibril fibers are composed of actin and myosin filaments. Actin and myosin filaments together are called sarcomere.

Muscles whose actions are not controlled by the will of the animal are called involuntary muscles. They are also called visceral muscles because they are present in the walls of various organs (vessels).

1. Human movement is through these muscles.
2. Controls body organs through contraction and expansion.
3. Regulates body posture and muscle tension.
4. Regulates body temperature.

Optional muscles are located in the eyes, tongue, pharynx etc. of animals.

Muscle fibers are arranged in clusters. Each bundle is called a fasciculus. Each fasciculus is covered by perimycium. Many fasciculi join together to form large clusters. Each large cluster is covered by epimycium.

Myofibril fibers are present along the length of the cell. Myofibril fibers are composed of actin and myosin filaments. Actin and myosin filaments together are called sarcomere. Myofibrils have two types of lines or bands. anisotropic band (A) and isotropic band (I). Darker bands are called anisotropic or A bands and lighter bands are isotropic or I bands.

It is a long and cylindrical muscle. Its length is 1-4 cm and diameter is 10-40 micrometers. It is also called muscle fiber because the cells look like fine fibers.
1. Sarcolemma: Muscle tissue is covered by a sheath called sarcolemma.
2. Sarcoplasm: Its cytoplasm is called sarcoplasm. Cytoplasm contains mitochondria. Because these cells require a lot of energy.
3. Nucleus: Multiple nuclei in each muscle cell. It performs biological functions of cells.
4. Myofibril: Myofibril fibers are present along the length of the cell. Myofibril fibers are composed of actin and myosin filaments. Actin and myosin filaments together are called sarcomere. Myofibrils have two types of lines or bands. anisotropic band (A) and isotropic band (I). Darker bands are called anisotropic or A bands and lighter bands are isotropic or I bands.
5. Transverse lines: Several transverse lines are seen in optional muscles. These lines are called linear muscles or marked muscles.
6. Fasciculus: Muscle fibers are arranged in clusters. Each bundle is called a fasciculus. Each fasciculus is covered by perimycium. Many fasciculi join together to form large clusters. Each large cluster is covered by epimycium.

It is a long and cylindrical muscle. Its length is 1-4 cm and diameter is 10-40 micrometers. It is also called muscle fiber because the cells look like fine fibers.
1. Sarcolemma: Muscle tissue is covered by a sheath called sarcolemma.
2. Sarcoplasm: Its cytoplasm is called sarcoplasm. Cytoplasm contains mitochondria. Because these cells require a lot of energy.
3. Nucleus: Multiple nuclei in each muscle cell. It performs biological functions of cells.
4. Myofibril: Myofibril fibers are present along the length of the cell. Myofibril fibers are composed of actin and myosin filaments. Actin and myosin filaments together are called sarcomere. Myofibrils have two types of lines or bands. anisotropic band (A) and isotropic band (I). Darker bands are called anisotropic or A bands and lighter bands are isotropic or I bands.
5. Transverse lines: Several transverse lines are seen in optional muscles. These lines are called linear muscles or marked muscles.
6. Fasciculus: Muscle fibers are arranged in clusters. Each bundle is called a fasciculus. Each fasciculus is covered by perimycium. Many fasciculi join together to form large clusters. Each large cluster is covered by epimycium.

Muscles whose functions are controlled by the will of the animal are called voluntary muscles. It is also called skeletal or linear or smooth or striated muscle. There are 656 voluntary muscles in the human body.