13. Muscular System

Muscle cells are specialized cells responsible for body movement through contraction.

Muscle Cells

Three Main Parts of a Muscle Cell

Nuclei, sarcoplasm, and sarcolemma.

Contain the genetic material of muscle cells and control cellular functions.

Nuclei

The cytoplasm of a muscle cell, which contains contractile proteins and other cellular components.

Sarcoplasm

The plasma membrane that encloses the muscle fiber; it receives electrical signals from the nervous system and propagates them into the cell to trigger contraction.

Sarcolemma

Three Main Types of Muscle

Skeletal muscle, cardiac muscle, and smooth muscle.

Muscles attached to bones and responsible for voluntary movements such as walking.

Skeletal Muscle

Muscle found in the heart and responsible for generating the force that pumps blood.

Cardiac Muscle

Muscle found in the walls of organs and blood vessels and responsible for involuntary movements such as peristalsis.

Smooth Muscle

Located attached to bones; under voluntary control; multinucleated; striated; contains sarcomeres; contracts rapidly and powerfully; uses aerobic and anaerobic respiration; has no intercalated discs; regulated by motor neuron stimulation.

Skeletal Muscle

Located in the walls of organs and blood vessels; under involuntary control; has a single nucleus; non-striated; lacks sarcomeres; contracts slowly and sustainably; primarily uses aerobic respiration; has no intercalated discs; regulated by hormones and the autonomic nervous system.

Smooth Muscle

Located in the heart; under involuntary control; has a single nucleus; striated; contains sarcomeres; contracts rapidly and sustainably; uses aerobic respiration; has intercalated discs for coordinated beating; regulated by intrinsic pacemaker cells.

Cardiac Muscle

Muscle with Multinucleated.

Skeletal Muscle Nuclei

Muscle with Single nucleus.

Smooth Muscle and Cardiac Muscle Nuclei

Striated

Skeletal muscle and Cardiac muscle

Non-striated

Smooth muscle

Intercalated Discs (For beating)

Cardiac Muscle