Movement is a fundamental property of living organisms, and locomotion is a specialized type of movement that results in a change of place. From the beating of cilia to the coordinated contraction of muscles in humans, locomotion and movement play a vital role in survival, adaptation, and interaction with the environment. In zoology, this chapter is crucial for NEET and other medical entrance exams, as it integrates anatomy, physiology, and clinical aspects of the musculoskeletal system.
Introduction to Locomotion and Movement
Movement: Any visible change in the position of a body part, e.g., bending of arm, contraction of muscles.All locomotion is movement, but not all movement is locomotion. Movements may be voluntary (muscle-controlled) or involuntary (heartbeat, peristalsis).
Types of Movement in Animals
1. Amoeboid Movement – Occurs with the help of pseudopodia in amoeba, macrophages, WBCs.Human Skeletal System
The skeletal system provides structure, support, and aids in locomotion.
- Axial Skeleton – Skull, vertebral column, ribs, sternum (80 bones).
- Appendicular Skeleton – Limbs, pectoral and pelvic girdles (126 bones).
- Total Bones in Human Body – 206.
Functions: Protection of organs, muscle attachment, blood cell production (bone marrow).
Joints
Joints are points of articulation between bones. They are classified into:
- Fibrous Joints – Immovable (e.g., skull sutures).
- Cartilaginous Joints – Slightly movable (e.g., intervertebral discs).
- Synovial Joints – Freely movable (e.g., knee, shoulder, hip).
Muscular System
Muscles are specialized tissues for movement, making up nearly 40–50% of body weight.
Types of Muscles
- Skeletal Muscles – Voluntary, striated, multinucleated.
- Smooth Muscles – Involuntary, non-striated, single nucleus.
- Cardiac Muscles – Involuntary, striated, branched, rhythmic.
Structure of Skeletal Muscle
- Muscle → Fascicles → Muscle fibers → Myofibrils
- Myofibrils contain actin (thin) and myosin (thick) filaments arranged in repeating units called sarcomeres.
Mechanism of Muscle Contraction
- Explained by the Sliding Filament Theory.
- Myosin heads bind to actin filaments forming cross-bridges.
- ATP hydrolysis provides energy for sliding movement.
- Calcium ions and troponin-tropomyosin regulate contraction.
Disorders of Muscular and Skeletal System
- Myasthenia Gravis – Autoimmune disorder causing muscle weakness.
- Muscular Dystrophy – Genetic disorder leading to muscle degeneration.
- Tetany – Muscle spasms due to low calcium levels.
- Osteoporosis – Reduced bone mass leading to fragile bones.
- Arthritis – Inflammation of joints causing pain and stiffness.
Comparative Table of Muscle Types
| Muscle Type | Striation | Control | Location | Example |
|---|---|---|---|---|
| Skeletal | Striated | Voluntary | Attached to bones | Biceps |
| Smooth | Non-striated | Involuntary | Internal organs | Intestine walls |
| Cardiac | Striated, branched | Involuntary | Heart | Myocardium |
Importance of Locomotion and Movement
- Essential for food gathering, escaping predators, and reproduction.
- Maintains posture and balance.
- Enables interaction with the environment.
- In humans, supports complex activities like sports, speech, and creativity.
- Exam perspective: Frequently tested in NEET via questions on sliding filament theory, types of joints, and skeletal bones.
FAQs on Locomotion and Movement
Q1. What is the difference between movement and locomotion?
Movement is any change in position of a body part, while locomotion involves movement that changes the organism’s position or place.
Q2. Which is the functional unit of muscle contraction?
Sarcomere is the functional unit of muscle contraction.
Q3. What are synovial joints?
They are freely movable joints with synovial fluid, e.g., knee, shoulder.
Q4. How many bones are present in the adult human body?
There are 206 bones in the adult human skeleton.
Q5. Which ion is essential for muscle contraction?
Calcium ions (Ca²⁺) are essential for muscle contraction.