Musculoskeletal System – Important Short Answer Questions (SAQs)

The strongest muscle in terms of force is the Masseter (jaw muscle). It is responsible for chewing and can exert a bite force of up to 90 kg (200 pounds).

Skeletal muscles are voluntary, meaning they work under conscious control (e.g., running, lifting). Smooth muscles are involuntary and function automatically without conscious effort (e.g., digestion, blood flow).

The three common causes of sports injuries are:
1. Overtraining
2. Poor technique or form
3. Lack of warm-up or weak flexibility

A sarcomere is the functional unit of contraction in a muscle fiber. During contraction, actin filaments slide over myosin filaments, shortening the sarcomere and producing muscle contraction.

With aging, bone density decreases, increasing the risk of fractures and osteoporosis. Cartilage becomes thin and less flexible, leading to stiffness and osteoarthritis.

Processed foods contain high sugar, unhealthy fats, and excess sodium with fewer nutrients. They increase body inflammation, reduce muscle recovery, lower endurance, and can cause insulin resistance.

- Red fibers: High myoglobin, rich in mitochondria, aerobic respiration, fatigue-resistant.
- White fibers: Low myoglobin, fewer mitochondria, depend on anaerobic respiration, fatigue quickly.

According to the sliding filament theory, contraction occurs when myosin heads form cross-bridges with actin filaments using ATP energy. Calcium ions bind to troponin, exposing actin sites. Actin filaments slide inward over myosin, shortening the sarcomere and causing contraction. The I-band shortens, A-band remains unchanged.

The four major components of the axial skeleton are:
1. Skull
2. Vertebral column
3. Sternum
4. Ribs<

Synovial joints have a fluid-filled cavity between bones, allowing free movement. They enable locomotion and activities like rotation (ball-and-socket), flexion/extension (hinge), pivoting, and gliding.