Skeletal Muscle Tissue & The Muscular System: Structure, Function, and Anatomy

Chapter 9: Skeletal Muscle Tissue

Functions of Skeletal Muscle Tissue

Skeletal muscle tissue is essential for various physiological processes in the human body. It is responsible for movement, posture, protection, and metabolic functions.

• Body Movement: Skeletal muscles attach to bones via tendons, enabling voluntary movement of the body through contraction and relaxation.

• Posture and Body Position: Muscles maintain posture and stabilize joints, allowing the body to remain upright and balanced.

• Support of Soft Tissue: Muscles support the weight of visceral organs and protect internal tissues from injury.

• Control of Body Openings/Passages: Sphincter muscles regulate the opening and closing of body passages, such as those in the digestive and urinary systems.

• Maintenance of Body Temperature: Muscle contractions produce heat, which helps maintain normal body temperature (thermogenesis).

• Storage and Movement of Nutrients: Muscles store nutrients and can break them down to synthesize ATP for energy production.

Characteristics of Skeletal Muscle Tissue

Skeletal muscle tissue comprises a significant portion of total body mass and is specialized for voluntary movement.

• Percentage of Body Mass: Skeletal muscle accounts for approximately 40% - 45% of total body mass.

• Cellular Features:

  • Mitochondria: Abundant in muscle cells, mitochondria generate ATP required for muscle contraction.

  • Myoglobin: A protein that stores oxygen within muscle cells, facilitating aerobic respiration.

• Stimulus: Skeletal muscle contraction is under conscious (voluntary) control, unlike smooth and cardiac muscle tissues.

• Comparison with Other Muscle Types:

  • Smooth Muscle Tissue: Found in internal organs, under involuntary control.

  • Cardiac Muscle Tissue: Found in the heart, also under involuntary control.

Chapter 10: The Muscular System

Anatomy of the Muscular System

The muscular system consists of various muscles that attach to bones and other structures, enabling movement and providing structural support.

• Muscle Attachment:

  • Origin: The fixed attachment of a muscle to a bone or structure that does not move when the muscle contracts.

  • Insertion: The movable attachment of a muscle to a bone or structure that does move when the muscle contracts.

• Example:

  • Biceps Brachii: Originates at the scapula (shoulder blade) and inserts at the radius (forearm bone). When the biceps contracts, the forearm moves upward.

  • Gastrocnemius: Originates at the femur and inserts at the calcaneus (heel bone) via the Achilles tendon. Contraction causes plantar flexion of the foot.

Key Terms and Concepts

• Tendon: A strong, fibrous connective tissue that attaches muscle to bone.

• Aponeurosis: A broad, flat tendon that connects muscles to each other or to bones.

• Voluntary vs. Involuntary Control: Skeletal muscle is under voluntary control, while smooth and cardiac muscles are involuntary.

Comparison Table: Muscle Tissue Types

Muscle Type	Location	Control	Main Function
Skeletal Muscle	Attached to bones	Voluntary	Movement, posture
Smooth Muscle	Walls of internal organs	Involuntary	Move substances through organs
Cardiac Muscle	Heart	Involuntary	Pump blood

Important Equations

• ATP Production in Muscle Cells:

$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$

• Muscle Contraction Principle:

$\text{Force} = \text{Mass} \times \text{Acceleration}$

Additional info: Expanded explanations and examples were added for clarity and completeness, including the comparison table and equations relevant to muscle physiology.