Muscle tissue �and �Nervous tissue

Muscle Tissue

I. Striated Muscle - regularly arranged contractile units

A. Skeletal Muscle - long, cylindrical multinucleated cells with peripherally placed nuclei. Contraction is typically quick and vigorous and under voluntary control. Used for locomotion, mastication, and phonation.

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B. Cardiac Muscle - elongated, branched cells with a single centrally placed nucleus and intercalated discs at the ends. Contraction is involuntary, vigorous, and rhythmic.

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II. Smooth Muscle - possesses contractile machinery, but it is irregularly arranged (thus, non-striated). Cells are fusiform with a central nucleus. Contraction is involuntary, slow, and long lasting.

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Cont..

• Heart Muscle is known as myocardium.
• The myocardium forms a thick middle layer between the outer layer of the heart wall (the epicardium) and the inner layer (the endocardium), with blood supplied via the coronary circulation.
• It is composed of individual heart muscle cells (cardiomyocytes).
• Cardiac muscle tissue or myocardium forms the bulk of the heart.
• heart muscle diseases known as cardiomyopathies.

Cont..

• The complex junction that joins the cardiac muscle cells are called intercalated discs.
• Intercalated discs have two distinct region:-Transverse region and longitudinal region.

Microscopic view

SKELETAL MUSCLE FIBERS�

• skeletal muscle cells are long and cylindrical, they are commonly referred to as muscle fibers.
• Some other terminology associated with muscle fibers is rooted in the Greek sarco, which means “flesh.” The plasma membrane of muscle fibers is called the sarcolemma, the cytoplasm is referred to as sarcoplasm, and the specialized smooth endoplasmic reticulum, which stores, releases, and retrieves calcium ions (Ca⁺⁺) is called the sarcoplasmic reticulum (SR) .

• The functional unit of a skeletal muscle fiber is the sarcomere, a highly organized arrangement of the contractile myofilaments actin (thin filament) and myosin (thick filament), along with other support proteins.

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Smooth Muscle

• Fusiform, non-striated cells
• Single, centrally-placed nucleus
• Contraction is non-voluntary
• Contraction is modulated in a neuroendocrine manner
• Found in blood vessels, GI and urogenital organ walls, dermis of skin

Nervous Tissue

• Nervous tissue is the term for groups of organized cells in the nervous system, which is the organ system that controls the body’s movements, sends and carries signals to and from the different parts of the body, and has a role in controlling bodily functions such as digestion.
• Nervous tissue is grouped into two main categories: neurons and neuroglia.
• Two Type of cells are found in nervous system:-
• Excitable Cells.:- Neuron
• Non – Excitable cells.:- Neuroglia