Locomotion And Movement Class 11 Notes Biology Chapter 20 - CBSE

Chapter : 20

What Are Locomotion And Movement ?

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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

Joints

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.