RBSE Class 11 Biology Notes Chapter 20 Locomotion and Movement

These comprehensive RBSE Class 11 Biology Notes Chapter 20 Locomotion and Movement will give a brief overview of all the concepts.

RBSE Class 11 Biology Chapter 20 Notes Locomotion and Movement

→ One of the essential feature of animals is movement. Some of the movements exhibited by animals are: protoplasmic streaming, cilliary movements, movement of wings, limbs, fins etc.

→ Voluntary movement helps the animal to change its place, it is called locomotion. It is usually done for food, shelter, mate, breeding/protection from adverse climatic conditions. Mass movement of animals is called migration.

→ Movements are of various types. In human body it is amoeboid, cilliary and muscular type. Muscles are of three types: skeletal-attached to skeletal elements. They are striated and voluntary in nature. Visceral muscles are formed in the visceral (internal walls) organs and they are spindle shaped without striations. Cardiac muscles are branched, striated and located in the heart walls. But involuntary in nature keeps contraction through out the life.

→ Muscles have excitability, contractibility, extensibility and elasticity properties.

→ The anatomical unit of muscle is called muscle fibre. Each muscle fibre has myofibrils arranged parallelly. Each myofibril has many serially arranged functional ‘contraction’ unit called sarcomere.

→ Each sarcomere has free central ‘A’- band made up of thick-myosin (protein) filaments. Two half bands on sides of ‘A’-band, the T bands made up of thin actin (protein) filaments. It has ‘Z’ bands on either sides to which attached. These are actin and myosin and contractile polymerised proteins.

→ Myosin filament/proteins has active side on head, ATP has ATP binding sites for action. The active sites on actin are marked by troponin protein.

→ Action potential is generated when the motor neuron carries the signal to muscle fibre and results in release of Ca⁺⁺ from sacroplasmic reticulum. Ca⁺⁺ activates the actin which binds to the myosin head to form a cross bridge.

→ Contraction of sacromere takes place by the action of the crossbridges that pull the actin filaments to slide over the myosin filaments. Ca⁺⁺ ions are then returned back to sacroplasmic reticulum which in activate the action. Resulting in breaking of cross bridges and the muscles relax.

→ Fatigue of muscles is due to the repeated stimulation of the muscles. Due to lack of supply of oxygen and accumulation of lactic acid.

→ Muscles are of 2 types: on the basis of presence of myoglobin a red coloured pigment in muscles,
(a) Red muscles (myoglobin in large quantity along with mitochondria),
(b) White muscles (myoglobin and mitochondria are in less quantity). 

→ Our skeletal system is of endoskeleton type made up of bones and cartilage. It is divisible into:
(a) axial skeleton: skull, vertebral column, ribs and sternum constitute it.
(b) Appendicular skeleton: Limbs and girdles constitute it.

→ Joints are categorised on the basis of its formation:
(a) fibrous joints
(b) cartilagenous joints
(c) synovial joints. Synovial joints provide, considerable movements and therefore, play a significant role in locomotion. Joints are points of articulation between two bones, bones and cartilages.

→ Locomotion: The movement that causes change of place/location.

→ Tube feet: Locomotory organs of Phylum Echinoderms.

→ Sarcomere: The space between ‘Z’ lines of a myofibril.

→ Sarcosomes: Mitochondria present in sarcoplasm of muscles.

→ Unstriped muscles: Involuntary muscles present in organisms.

→ Striped muscles: Voluntary muscles having bands in organisms.

→ Cardiac muscles: Muscles found in heart (wall).

→ Sarcoplasm: The cytoplasm of muscle fibre cell.

→ Sarcolemma: Plasma membrane of mucle fibre cell.

→ Tropomyosin: Protein attached to T-actin, filament.

→ Troponin: Mixture of globular protein.

→ l-band: Actin filaments (thin) that form light bands on striped muscle fibre.

→ A-band: Myosin filaments (thick) that form dark bands on striped muscle fibre.

→ Z-line: A narrow line between the I-bands.

→ H-band: A band between A-band.

→ Intercalated disc: Structure present between the cardiac muscles on regular intervals.

→ Contractile protein: Actin, myosin present in muscle fibre.

→ Myoglobin: Red pigment present in the muscles imparting reddish colour to red muscles.

→ Osteology: The study of bones.