NCERT Solutions for Class 11 Biology Chapter 20 Locomotion and Movement to Study online as well as to download in PDF form free. Download NCERT Solutions of Chemistry, Maths, Business Studies and other subjects also.
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Locomotion and Movement: Solutions
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Important Notes on Locomotion and Movement
Types of Muscles
- Skeletal muscles or striated muscles: These involved in locomotion and change of body postures. These are also known as voluntary muscles.
- 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. They are called involuntary muscles.
- Cardiac muscles: The muscles of heart, involuntary in nature, striated and branched, These are uninucleated.
White muscle fibres
- These are pale or whitish due to presence of less content of myoglobin.
- These contain fewer mitochondria
- Sarcoplasmic reticulum is more/high
- During strenuous exercise, lactic acid accumulates in large quantity so muscle fatigues
Red muscle fibres
- These are red in colour due to presence of high content of myoglobin.
- These contain plenty of mitochondria.
- Sarcoplasmic reticulum is less in these fibres.
- Show slow but sustained contractions for longer periods.
Types of Movement
- Amoeboid movement: These movements takes place in phagocytes where leucocytes and macrophages migrate through tissue. It is affected by pseudopodia formed by the streaming of protoplasm (as in amoeba)
- Ciliary movement: These movement occurs in internal organs which are lined by ciliary epithelium.
- Muscular Movement: This movements involve the muscle fibres, which have the ability to contract and relax.
Structure of Actin and Myosin Filament
- Actin filament: An actin filament is made of two ‘F’ actins which are helically wound to each other. Two filaments of tropo myosin protein also run close to ‘F’ actins throughout its length. A complex protein Troponin is distributed at regular intervals on tropomyosin which mask the actin binding site for myosin.
- Myosin filament: Each myosin filament is a polymer of meromyosin. Each meromyosin has two components a globular head with a short arm and a tail. Head is made of heavy meromyosin while tail is made of light meromyosin. The head with its short arm project outward at regular distance and angle from each other and is known as cross arm. The head has an active site for actin and binding site for ATP.