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Movement and locomotion


Animals and plants exhibit a wide range of movements
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There are three
basic types- amoeboid, ciliary and muscular locomotion
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Such voluntary movements are called
locomotion
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Example- zoospores, gamete
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 Walking, running, climbing, flying, swimming are all some forms of locomotory movements
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For
example, in Paramecium, cilia help in the movement of food through cytopharynx and in locomotion as
well
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We use limbs
for changes in body postures and locomotion as well
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 Methods of locomotion performed by animals vary with their habitats and the demand of the situation
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 In multicellular organisms locomotion occurs by means of muscles with or without skeleton and its
joint
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Non muscular movements- It includes streaming of Protoplasm, pseudopodal, flagellar and ciliary
movements of protozoans
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b) Pseudopodal movement- Leukocytes and macrophages move about in the tissues with the help of
pseudopodia
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d) Ciliary movement- Cilia lining trachea, oviduct and vasa efferentia propel dust particles, eggs and
sperms in specific direction by their lashing movements
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Non muscular ciliary locomotion is retained by some animal larvae such as planula larvae of
coelenterates and trochophore larvae of annelids and even some adults such as planarians
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Muscular movements - by alternate contraction and relaxation of muscle fibres
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 Some specialized cells in our body like macrophages and leucocytes in blood exhibit amoeboid movement
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Cytoskeletal elements
like microfilaments are also involved in amoeboid movement
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The
coordinated movements of cilia in the trachea help us in removing dust particles and some of the foreign
substances inhaled along with the atmospheric air
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 Movement of our limbs, jaws, tongue, etc, require muscular movement
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Locomotion requires a perfect coordinated activity of muscular, skeletal and neural systems
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Gathering of information by movement of pinna, eye orbits and neck etc
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Facial expression and gestures
3
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Movement of appendages and Limbs for locomotion 5
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Ingestion of food 7
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Offence and defense 9
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Movement of internal body parts
1
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Movement of diaphragm, ribs and lungs for gaseous exchange 3
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Peristalsis for passage of urine in the urinary
tract 5
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Movement of genital tract and uterine wall during egg laying and
childbirth 7
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Muscle
 Muscle is a specialized tissue of mesodermal origin
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They have special properties like excitability, contractility, extensibility
and elasticity
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Based on their location, three types of muscles are identified: (i) Skeletal (ii) Visceral and
(iii) Cardiac
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They have a striped
appearance under the microscope and hence are called striated muscles
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They are primarily
involved in locomotory actions and changes of body postures
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They do not exhibit any striation and are smooth in appearance
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Their activities are not under the voluntary control of the
nervous system and are therefore known as involuntary muscles
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 Cardiac muscles are the muscles of heart
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Based on appearance, cardiac muscles are striated
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Skeletal muscle structure
 The skeletal muscles connect to bones by tendons
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Each
fascicle is enclosed by tough connective tissue called perimysium which separates one fascicle to other
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Outside epimysium a collagenous connective tissue layer called fascia is located which
separates the muscles
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Skeletal muscle fibres are long cylindrical
multinucleated cells that reach from one end of the muscle to the other
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Outside sarcolemma each muscle fibre is
surrounded by a connective tissue called endomysium
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Sarcolemma has
multiple inward extensions that form a set of T tubules (transverse tubules)
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The endoplasmic reticulum, i
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,
sarcoplasmic reticulum of the muscle fibres is the store house of calcium ions
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Sarcoplasm also
contains a protein pigment called myoglobin which can take up, store and give up oxygen like hemoglobin
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 Each myofibril has alternate dark and light bands on it
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 The light bands contain actin and is called I-band or Isotropic band, whereas the dark band called ‘A’ or
Anisotropic band contains myosin
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 Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick
filaments respectively
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The
thin filaments are firmly attached to the ‘Z’ line
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The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the
myofibrils
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 In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free
ends of the thick filaments leaving the central part of the thick filaments
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 Sarcomere contains four types of proteins namely myosin, actin, tropomyosin and troponin
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 Tropomyosin and troponin are called regulatory proteins as the determine when to contact or not
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Structure of Contractile Proteins- Myosin and Actin
 Actin is a globular protein
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Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins
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 Two filaments of another protein, a double stranded protein tropomyosin also run close to the ‘F’ actins
throughout its length
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 In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments so
that cross bridge formation cannot occur between the actin and myosin to cause contraction
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Troponin-T binds to tropomyosin and two other troponin
components, 2
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3
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 Each myosin (thick) filament is also a polymerized protein
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Two heavy
chains wrap spirally around each other to form a double helix
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 Each meromyosin is splitted by enzyme trypsin forming 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)
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e
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 The globular head (HMM) is an active ATPase enzyme and has binding sites for ATP and active sites for
actin whereas LMM lacks ATPase activity and does not combine with actin



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