Golden Key Points -Chapter-17-Locomotion And Movement

Golden Key Points

Types of Movement:

• Movement is a significant feature of living beings, exhibited by animals and plants in various forms.
• Movement can be categorized into amoeboid, ciliary, and muscular movements.
• Examples include streaming of protoplasm in unicellular organisms, ciliary movements in tubular organs, and muscular movements in human limbs.

Muscle:

• Muscles are specialized tissues of mesodermal origin, contributing to about 40-50% of the body weight.
• Three types of muscles are amoeboid, ciliary, and muscular, each with distinct functions and mechanisms.
• Muscular movement relies on the contractile property of muscles, coordinated by the muscular, skeletal, and neural systems.

Structure of Contractile Proteins:

• Actin (thin) filaments are composed of two filamentous (F) actins wound helically, while myosin (thick) filaments consist of polymerized meromyosins.
• Troponin and tropomyosin regulate muscle contraction by exposing active sites on actin filaments for myosin binding.
• Muscle contraction occurs through the sliding filament theory, where myosin heads bind to actin filaments and slide, shortening the sarcomere.

Mechanism of Muscle Contraction:

• Muscle contraction is initiated by a neural signal from the central nervous system (CNS) via a motor neuron, triggering the release of calcium ions.
• Calcium ions bind to troponin, exposing active sites on actin filaments for myosin binding and cross-bridge formation.
• ATP hydrolysis powers the movement of myosin heads, causing sliding of actin filaments and sarcomere shortening, leading to muscle contraction.

Skeletal System:

• The skeletal system comprises bones and cartilages, providing support, protection, and facilitating movement.
• It is divided into the axial (skull, vertebral column, sternum, ribs) and appendicular skeleton (limbs and their girdles).
• Understanding the structure and function of bones and cartilages is crucial for maintaining skeletal integrity and supporting bodily movements.

Joints:

• Joints are essential for facilitating movement by providing points of contact between bones or between bones and cartilages.
• They are classified into fibrous, cartilaginous, and synovial joints based on their structural forms and mobility.
• Examples include fibrous joints in the skull, cartilaginous joints in the vertebral column, and synovial joints like ball and socket, hinge, pivot, gliding, and saddle joints.

Disorders of Muscular and Skeletal System:

• Disorders include myasthenia gravis, muscular dystrophy, tetany, arthritis, osteoporosis, and gout, each with distinct causes and symptoms.
• These disorders can affect muscle function, bone integrity, and joint health, leading to mobility issues and decreased quality of life.
• Prevention, early detection, and appropriate management strategies are essential for mitigating the impacts of these disorders on overall health.