Notes For Class 11 Chapter 20 Locomotion And Movement Download In Pdf
Arthritis : an enflamm atory joint diease characteresed by enflammation of joints.
Coccyx : tail bone formed by fusion of four coccygeal vertebrae in man.
Dicondylic Skill : A Skull with two occipital condyles.
Endo Skeleton : A skeleton present outside the body.
Fascicule : Bundles of muscles febers held together by connective tissue.
Fascia : Collagenous connective tissue layer that surrounds muscle bundles.
Floating ribs : The ribs that remain free anteriorly.
False ribs : The ribs whose sternal part are join to sternal part of a true rib.
Myoglobin : A red coloured pigment present in sarcoplasm of muscle.
Sarcolema : A portion of myofibril between two successive ‘Z’ lines.
Sarcocolema : The plasma membrane of a muscle. Gout : Inflammation of joints due to accumulation of uric acid crystal. Suture : immovable joints between skull bones.
Synovial joints : Freely movable joints between limb bones. Patella : A sesamoid bone acting as kneecap
Intervertebral disc : Fibro carti lagenous pad present between the vertebrae and act as shock absorbers.
L.M.M : Light meromyosin
HMM : Heavy meromysoin
1. Amoeboid movement : These movement takes place in phagocytes where leucocytes and macrophages migrate through tissue. It is affected by pseudepodia formed by the streaming of protoplasm (as in amocba)
2. Celiary movement : These movement occurs in internal organs which are lined by ciliary epithelium.
3. Muscular Movement : This movement involve the muscle fibers, which have the ability to contract and relex.
(a) Skeletal muscles or striated muscles :- These involved in locomotion and change of body postures. Thes are also known as voluntary muscles.
(b) Visceral muscles or smooth muscles :- These are located in inner wall of hollow visceral organ, smooth in appearance and their activity are not under control of nervous system.
(c) Cardiac muscles :- The muscles of heart, involuntary in nature, steriated and branched, These are uni nucleated.
• Each myofibril consist of alternate dark and light band.
• Dark band :- contain myosim protien and is called A-band or Anisotroic band.
• Light band : - Contain actin protien and is called I Band or Isotropic band.
• I Band is bisected by an elastic fiber called ‘Z’ line. Actin filament (thin flament) are firmly attached to the ‘Z’ lines.
• Myosin filament (thick filament) in the ‘A’ Band are also held together in the middle of ‘I’ Band by thin fibrous membrane called ‘M’ line.
• The portion between two successive ‘Z’ lines is considered as functional unit of contraction and is called a sarcomere.
Mechenism of Muscle contraction : Sliding filament theory.
The contraction of musle fiber takes place by the sliding of actin (thin flament) on myosin ( thick filament).
• Muscle contraction is initiated by a signal sent by the CNS via a motor neuron.
• Impulse from motor nerve stimulates a muscle fiber at neuro muscular junctions.
• Neurotransmitter releases here which generates an action potential in sarcolema.
• These causes release of Ca ++ into sarcoplasm.
• These Ca binds with troponin, thereby remove masking of active site.
• Myosin head binds to exposed active site on actin to form a cross bridge, utilising energy from ATP hydrolysis.
• This pulls the acin filament towards the centre of ‘A’ band. ‘Z’ lines also pulled inward thereby causing a shortning of sarcomere i.e. contraction. ‘I’ band get reduced, whereas the ‘A’ band retain the length.
• During relexation, the cross bridge between the actin and myosin break. Ca pumped back to sarcoplasmic cesternae.
• Actin filament slide out of ‘A’ band and length of ‘I’ band increases.
• This returns the muscle to its original state.
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