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CBSE Class 11th Biology Notes for Chapter 20 Locomotion and Movement

Chapter 20 Locomotion and Movement
The voluntary movements that result in a change of place or location are called locomotion.

  1. Amoeboid movements: Some specialized cells in our body like leucocytes in blood exhibit amoeboid movement. It is affected by pseudopodia formed by the streaming of protoplasm.
  2. Ciliary movements: These occur in most of our internal tubular organs which are lined by ciliated epithelium.
  3. Muscular movements: Movement of our limbs, jaws, tongue, etc. require muscular movements.

Muscle is a specialized tissue of mesodermal origin. They have properties like: excitability, contractility, extensibility and elasticity.
There are three types of muscles present in our body:

  1. Skeletal muscles: These are attached to skeletal elements. They appear striated and are voluntary in nature.
  2. Visceral muscles: These are present in the inner walls of visceral organs. They are non-striated and involuntary.
  3. Cardiac muscles: These are the muscles of the heart. They are striated, branched and involuntary.

Muscle fibre is the anatomical unit of muscle. Each muscle fibre has many parallelly arranged myofibrils. Each myofibril contains many serially arranged units called sarcomere which are the functionally units.

Repeated stimulation of muscles leads to fatigue. Muscles are classified as Red and White fibres based primarily on the amount of red coloured myoglobin pigment in them.

Bones and cartilages constitute our skeletal system. The skeletal system is divisible into axial and appendicular. Skull, vertebral column, ribs and sternum constitute the axial skeleton. Limbs bones and girdles form the appendicular skeleton. Three types of joints are formed between bones or between bone and cartilage- fibrous, cartilaginous and synovial. Synovial joints allow considerable movements and therefore, play an important role in locomotion.

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