Locomotion And Movement Class 11 Notes Biology Chapter 20 - CBSE

Chapter : 20

What Are Locomotion And Movement ?

Types Of Movement

Ciliary Movement

  • By cilia
  • Ex- trachea and oviducts

Muscular movement

  • By muscles
  • Ex- limbs

Flagellar Movement

  • By flagella
  • Ex- Spermatozoa, sponges, Protozoa

Types Of Muscles

Skeletal Muscles

  • Attached to skeleton
  • Striations present
  • Voluntary
  • Rich blood supply
  • Fatigue muscle
  • Multinucleate
  • More mitochondria

Visceral Muscles

  • In visceral organs
  • Striations absent
  • Involuntary
  • Poor blood supply
  • Non-fatigue
  • Uninucleate
  • Less mitochondria

Cardiac Muscles

  • In heart wall
  • Striations present
  • Involuntary
  • Rich blood supply
  • Non-fatigue
  • Uninucleate
  • Poor mitochondria

Skeleton Muscles

  • Skeletal Muscle is made up of muscles bundles (fascicles), held together by collagenous connective tissue called fascia.
  • Each muscle fibre has an alternate light and dark band, which contains a special contractile protein, called actin and myosin respectively. Actin is a thin contractile protein present in the light band and is known as the I-band, whereas myosin is a thick contractile protein present in the dark band and is known as the A-band. There is an elastic fibre called z line that bisects each I-band. The thin filament is firmly anchored to the z line. The central part of the thick filament that is not overlapped by the thin filament is known as the H-zone.

Contractile Protein And Muscle Contraction

  • Actin (Thin) Filament: Each actin (thin) filament is made up of two F (filamentous) actins helically wound to each other. Each F actin is a polymer of monomeric G (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length. A complex protein Troponin is distributed at regular intervals on the tropomyosin. In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments.
  • Myosin (Thick) Filament: Each myosin (thick) filament is also a polymerised protein. Actin binding sites ATP binding sites Head Cross arm Tail Myosin monomer (Meromyosin). Many monomeric proteins called Meromyosins constitute one thick filament. Each meromyosin has two important parts, a globular head with
    a short arm and a tail, the former being called the heavy Meromyosin (HMM) and the latter, the Light meromyosin (LMM).

Skeleton System And Its Functions

Axial Skeletal System (80 BONES)

  • Skull (29 BONES):
    • Cranial bones (8): Frontal (1), Parietals (2), Temporals (2), Occipital (1), Sphenoid (1) and Ethmoid (1).
    • Facial bones (14): Nasals (2), Maxillae (2), Zygomatics (2), Lacrimals (2), Palatines (2), Inferior nasals (2), Mandible (1) and Vomer (1).
    • Hyoid bone (1): U-shaped bone seen below buccal cavity.
    • Ear ossicles (3 x 2 = 6): Malleus (2), Incus (2) and stapes (2).
  • Vertebral column (26 BONES): Cervical vertebrae (7), Thoracic vertebrae (12), Lumbar vertebrae (5), Sacral vertebrae (1-fused) and Coccygeal vertebrae (1-fused)
  • Sternum or breast bone (1)
  • Ribs (12 pairs): True ribs (first 7 pairs), false ribs (8th, 9th & 10th pairs).

Appendicular Skeletal System (126 BONES)

  • Bones of forelimbs (30 x 2 = 60): Humerus (1), Radius (1), Ulna (1), Carpals (wrist bones- 8), Metacarpals
    (palm bones-5) and Phalanges (digits-14).
  • Bones of hindlimbs (30 x 2 = 60): Femur (thigh bone- 1), Patella (knee cap- 1), Tibia (1) and fibula (1), Tarsals (ankle bones-7), Metatarsals (5) and Phalanges (digits-14).
  • Pectoral girdles (2x2=4): Clavicle (2) and scapula (2).
  • Pelvic girdles (2): 2 coxal bones


Fibrous (immovable) Joints

E.g. sutures between skull bones

Cartilaginous Joints

(Slightly movable joints)

E.g. Joints between the adjacent vertebrae

Synovial (movable) Joints

They have a fluid filled synovial cavity between articulating surfaces of 2 bones.

Example Of Different Joints

  • Ball and Socket Joints: Joints at shoulders and hip.
  • Hinge Joints: Knee and wrist joints.
  • Pivot Joint: Neck to head joint.
  • Gliding Joint: Tarsal to ankle, carpal to wrist, sternum to clavicle etc.
  • Saddle Joint: Joints between carpal and metacarpal of thumb.

Disorders Of Skeleton And Muscular System

  • Myasthenia Gravis: Auto immune disorder. It affects neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscles.
  • Tetany: Rapid muscle spasm due to low Ca2+ in body fluid.
  • Muscular Dystrophy: Progressive degeneration of skeletal muscles. Mostly due to genetic disorder.
  • Arthritis: Inflammation of joints.
  • Osteoporosis: Age-related disorder characterized by decreased bone mass and increased chances of fractures. Decreased level of estrogen is a common cause.
  • Gout: Inflammation of joints due to accumulation of uric acid crystals.