Tiêu đề Locomotion and Movement_(182-218).pdf ✅

NEET ZOOLOGY VOL-I 182 NARAYANA GROUP LOCOMOTION AND MOVEMENT Locomotion and Movement CO N T E N TS * Introduction * Types of Movement * Muscles * Skeletal System * Joints * Disorders of Muscular and Skeletal System  Locomotion and Movement  Types of movement- Amoeboid, ciliary, flagellar and muscular;  Skeletal muscle- contractile proteins and muscle contraction;  Skeletal system and its functions (To be dealt with the relevant practical of Practical syllabus);  Joints  Disorders of muscular and skeletal system-Myasthenia gravis, Tetany, Muscular dystrophy, Arthritis, Osteoporosis, Gout. NEET SYLLABUS 20
NARAYANA GROUP 183 NEET ZOOLOGY VOL-I LOCOMOTION AND MOVEMENT INTRODUCTION * Movement is one of the most important characteristic of living organisms. * The movement of an individual from one place to another is called locomotion. * In higher vertebrates including humans it involves muscles, skeleton and joints for locomotion and body structure. * Movement results from cooperation between muscles and skeleton. * Even when we hold something. steady muscles and skeleton work together. * The muscles provide force and the skeleton offers hard surface for the force to work against. * Animals and plants exhibit a wide range of movements. * Streaming of protoplasm in the unicellular organisms like Amoeba is a simple form of movement. * Movement of cilia, flagella and tentacles are shown by many organisms.Human beings can move limbs, jaws, eyelids, tongue, etc. * Some of the movements result in a change of place or location. Such voluntary movements are called locomotion. * Walking, running, climbing, flying, swimming are all some forms of locomotory movements. * Locomotory structures need not be different from those affecting other types of movements. * For example in, a) Paramoecium, cilia helps in the movement of food through cytopharynx and in locomotion as well. b) Hydra can use its tentacles for capturing its prey and also use them for locomotion. c) We use limbs for changes in body postures and locomotion as well. * The above observations suggest that movements and locomotion cannot be studied separately.  “All locomotions are movements but all movements are not locomotions.” * Methods of locomotion performed by animals vary with their habitats and the demand of the situation. However, locomotion is generally for search of food, shelter, mate, suitable breeding grounds, favourable climatic conditions or to escape from enemies/predators. TYPES OF MOVEMENT * Cells of the human body exhibit three main types of movements, namely, amoeboid, ciliary and muscular. Some specialised cells in our body like macrophages and leucocytes in blood exhibit amoeboid movement. It is effected by pseudopodia formed by the streaming of protoplasm (as in Amoeba). * Cytoskeletal elements like microfilaments are also involved in amoeboid movement. * Ciliary movement occurs in most of our internal tubular organs which are lined by ciliated epithelium. * The coordinated movements of cilia in the trachea help us in removing dust particles and some of the foreign substances inhaled alongwith the atmospheric air.
NEET ZOOLOGY VOL-I 184 NARAYANA GROUP LOCOMOTION AND MOVEMENT * Passage of ova through the female reproductive tract is also facilitated by the ciliary movement. * Movement of our limbs, jaws, tongue, etc, require muscular movement. * The contractile property of muscles are effectively used for locomotion and other movements by human beings and majority of multicellular organisms. * Locomotion requires a perfect coordinated activity of muscular,skeletal and neural systems. MUSCLE  The study of muscles is called Myology * Muscle is a specialised tissue of mesodermal origin. * About 40-50 percent of the body weight of a human adult is contributed by muscles. * They have special properties like excitability, contractility, extensibility and elasticity. * Muscles have been classified using different criteria, namely location,appearance and nature of regulation of their activities. * Based on their location, three types of muscles are identified : (i) Skeletal (ii) Visceral and (iii) Cardiac. i) Skeletal muscles are closely associated with the skeletal components of the body. * They have a striped appearance under the microscope and hence are called striated muscles. * As their activities are under the voluntary control of the nervous system, they are known as voluntary muscles too. * They are primarily involved in locomotory actions and changes of body postures. ii) Visceral muscles are located in the inner walls of hollow visceral organs of the body like the alimentary canal, reproductive tract, etc. * They do not exhibit any striations and are smooth in appearance. * Hence, they are called smooth muscles (nonstriated muscle). * Their activities are not under the voluntary control of the nervous system and are therefore known as involuntary muscles. * For example:They assist in the transportation of food through the digestive tract and gametes through the genital tract. iii) Cardiac muscles are the muscles of heart. * Many cardiac muscle cells assemble in a branching pattern to form a cardiac muscle. * Based on appearance, cardiac muscles are striated. * They are involuntary in nature as the nervous system does not control their activities directly. Structure of a skeletal muscle: * Each organised skeletal muscle in our body is made of a number of muscle bundles or fascicles (singular -fasiculus or fascicle) held together by a common collagenous connective tissue layer called fascia. * Each muscle bundle contains a number of muscle fibres
NARAYANA GROUP 185 NEET ZOOLOGY VOL-I LOCOMOTION AND MOVEMENT Fascicle (muscle undle) b Muscle fibre (muscle cell) Sarcolemma Blood Capillary Figure : Diagrammatic cross sectional view of a muscle showing muscle bundles and muscle fibres * Each muscle fibre is lined by the plasma membrane called sarcolemma enclosing the sarcoplasm. * Muscle fibre is a syncytium as the sarcoplasm contains many nuclei. * The endoplasmic reticulum, i.e., sarcoplasmic reticulum of the muscle fibres is the store house of calcium ions. * A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called myofilaments or myofibrils. * Each myofibril has alternate dark and light bands on it. * A detailed study of the myofibril has established that the striated appearance is due to the distribution pattern of two important proteins – Actin and Myosin. * The light bands contain actin and is called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin. * Both the proteins are arranged as rod-like structures, parallel to each other and also to the longitudinal axis of the myofibrils. * Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively. * In the centre of each ‘I’ band is an elastic fibre called ‘Z’ line which bisects it.  Z lines also known as Z -disc or Krause’s membrane or Dobie’s membrane or Z- line, Z-disc made up of actinin protein. * The thin filaments are firmly attached to the ‘Z’ line.  Accessory pigments such as titin, nebulin, myomesin, dystrophin maintain precise alignment of thin & thick filaments. * The thick filaments in the ‘A’ band are also held together in the middle of this band by a thin fibrous membrane called ‘M’ line.