Skeletal and Muscular Systems Quiz

Human Skeletal System

• The axial skeleton forms the central axis of the body, providing structural support and protection for the brain, spine, and thoracic organs.
• The femur is the longest and largest bone in the human body, crucial for weight-bearing and locomotion.
• An adult human skeletal system typically consists of 206 bones, varying in number during development and age.
• Cortical bone, also known as compact bone, forms the hard, outer shell of bones, providing strength and stability.

Functions and Structure of the Skeleton

• The skeleton serves multiple functions including support, protection of vital organs, movement facilitation, mineral storage, and hematopoiesis (blood cell production).
• The atlas (C1 vertebra) is responsible for the pivot joint in the neck, allowing for head rotation.

Bone Cells and Remodeling

• Osteoclasts are specialized cells that break down bone tissue through the process of bone resorption, helping to regulate calcium levels in the body.
• Osteoblasts are the cells that regenerate bone tissue via bone deposition, essential for growth and repair.
• Bone remodeling's main function is to maintain bone strength and mineral homeostasis, adapting to mechanical stresses and repairing micro-damages.

Gender Differences in Skeleton

• Common skeletal differences observed between men and women include variations in pelvic structure, bone density, and overall size, usually attributed to hormonal influences and evolutionary factors.
• The Q angle refers to the angle formed between the quadriceps muscle and the patellar tendon, significant for assessing knee function and potential injury risk.

Muscle Interaction with Bones

• Skeletal muscle interacts with bones to produce voluntary body movements, under conscious control and influenced by the nervous system.
• In muscle contraction, the power stroke occurs when myosin changes shape and pulls actin filaments toward the center of the sarcomere, leading to muscle shortening.

Neuro-muscular Function and ATP Role

• When an action potential travels down a motor neuron, it triggers a release of neurotransmitters at the muscle cell membrane, leading to muscle contraction initiation.
• ATP is essential in muscle contraction for providing the energy required for myosin heads to detach from actin and reset for the next contraction cycle.

Hormones and Muscle Mass

• Testosterone is the hormone responsible for the differences in muscle mass between men and women, influencing muscle size and strength characteristics.
• The main symptom of muscular dystrophy is progressive muscle weakness and degeneration, leading to mobility issues and complications.

Myosin and Actin Interaction

• When a myosin head binds to an actin molecule during muscle contraction, it forms a cross-bridge, allowing contraction to occur as part of the sliding filament theory.
• Muscle cell and tissue death in muscular dystrophy are often caused by genetic mutations that disrupt the production of proteins needed for muscle integrity, leading to muscle degeneration.