General Histology & Embryology - Skeletal Muscle

Skeletal Muscles

Long, cylindrical multinucleated cells with peripherally placed nuclei.

Peripherally

Nasa gilid ang nucleus.

Characteristics of the Muscle

1. Contractible

2. Extensible

3. Elastic

Contractible

Can shorten in length

Extensible

Can extend or stretch

Elastic

Can return to their original shape

Contraction Types

1. Voluntary

2. Involuntary

Voluntary Muscles

Movements that can be consciously controlled.

Examples of Voluntary Muscles

Skeletal muscles (e.g., moving your arms, legs, chewing during mastication).

Involuntary Muscles

Movements that cannot be consciously controlled.

Cardiac muscles (e.g., heartbeats), smooth muscles (e.g., muscles in the digestive tract).

Examples Involuntary Muscles

Skeletal muscle fibers

Arranged into bundles called fascicles.

Four Different Connective Tissue Coverings

1. Deep fascia

2. Endomysium

3. Epimysium

4. Perimysium

[DEEP]

Deep fascia

Surrounds entire skeletal muscle and extends beyond its length. (Grayish structure all over our body).

Epimysium

Closely surrounds skeletal muscle, binds fascicles together.

Perimysium

Surrounds each fascicle.

Endomysium

Surrounds each muscle fiber (cell).

Tendon

Muscles that connect to the bone.

Sarcolemma

Skeletal muscle fibers

Myofibril

Thin filaments within muscle fiber.

Striated muscle

Muscle tissue that has a banded appearance due to the presence of repeating dark (A bands) and light (I bands) bands. This pattern is most commonly seen in skeletal and cardiac muscles.

Sarcomere

• The basic functional unit of a myofibril and the fundamental unit of muscle contraction.

• It is responsible for the muscle's ability to contract, with the interaction of actin and myosin filaments playing a significant role in this process.

Malaki ang participation sa contraction.

Myosin

Thick filament that acts as a motor by hydrolyzing adenosine triphosphate (ATP) to release energy.

Actin

The thin myofilaments have binding sites to which the heads of the thick myofilaments attach.

Skeletal Muscle Contraction

“All or none” response

Different Degree of Contraction

1. Changing the frequency of stimulation.

2. Changing the number of muscle cells stimulated to contract.

Tetanus

Puro contraction lang kaya nag la-lockjaw. Bacteria caused by: Clostridium tetani.