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MHT-CET : Biology Entrance Exam

MHT - CET : Biology - Locomotion Page 1

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Locomotion:

 

The movement of an organism from one place to another is called loco-motion.

Joints

 

  1. The movement of an entire organism from one place to another is called locomotion.
  2. In all higher animals, the movement is brought about by the coordinated action of joints, bones and muscles.
  3. The articulation of two or more bones is called a joint.

Types of Joints

Depending on the mobility, joints can be classified into three main types:

  1. Fibrous joints - immovable
  2. Cartilagenous joints - slightly immovable
  3. Synovial joints - movable

Fibrous Joints (Synarthrosis)

  1. In this case, the articulating bones are held together by a tough non-elastic fibrous
    tissue, as a result of which no movement is possible between them.
  2. They are of two types:
    1. Sutures: They are present between the flat bones in the skull.
    2. Peg and Socket Joint: It is present between the bones of jaw and teeth.

Cartilagenous Joints (Amphiarthrosis)

  1. The joints in which the bones are connected by a layer of cartilage and allow slight
    movement to the articulating bones are called cartilagenous joints.
  2. They are of two types:
    1. Symphysis: It is present between the pubic bones of the pelvic girdle (Pubic symphysis).
    2. Intervertebral Joint: It is present between the vertebrae of back bone. (Intervertebral disc)

Synovial Joint (Diarthrosis)

  • These joints allow free movements to articulating bones and are sometimes called
    perfect joints.
  • Synovial cavity is present between the articulating bones.
  • The joint is lined by a synovial membrane which secretes a lubricating fluid
    called synovial fluid in the synovial cavity.
  • Types of Synovial Joints:

    The classification is based on the degree of movement provided by the synovial joints.
    1. Hinge Joint: In this joint, the movement is like that of a hinge of a door and is in one plane only. Example: Knee joint and the elbow joint.
    2. Ball and Socket Joint: In this type of joint, the ball like head of one bone fits into the cup-shaped socket of the other bone. This allows rotatory movement in all directions. Example: Shoulder joint and the hip joint.
    3. Pivot Joint: In this type of joint, only rotatory movement is possible. For example, the joint between the first vertebra (atlas) and the odontoid process of the second vertebra.
    4. Gliding Joint: In this type of joint, the bones are joined by flat articulating surfaces and can glide or slide over each other. For example, between the bones of wrist (carpals), and bones of ankle (tarsals).
    5. Condyloid Joint: It is like a hinge joint but permits movements in two planes and is therefore more flexible. Example: Wrist joint (between the bones of fore arm and the carpals).
    6. Saddle Joint: In this type of joint, the articulating surfaces of the two bones are saddle like (concave - convex). It permits movements in many directions. For example, the thumb joint between the first metacarpal and carpal of the wrist.

 

 

Muscle Movements

 

The muscular movements are of two types:
i) Voluntary muscle movements
ii) Involuntary muscle movements

Voluntary Muscle Movements
i) These movements are carried out according to our will. Example: Walking, running, playing, etc.

ii) They are carried out by striated or skeletal muscles which are attached to the bones by tendons.

iii) For example the elbow movement is brought by biceps and triceps present in the upper arm.

iv) These muscles work antagonistic to each other.

v) The contraction of biceps and relaxation of triceps brings about folding movement of the forearm (flexion).

vi) The contraction of triceps and relaxation of biceps straightens the forearm (extension).

Some other examples of antagonistic muscles are as follows:

Types of Muscle and Result of their Contraction:

  1. Flexors: They bring about flexing or bending of the arm or leg.
  2. Extensors: They bring about extension or straightening of the arm or leg.
  3. Adductor: They bring about the movement of the limb towards the median axis of the body.
  4. Abductor: They bring about the movement of the limb away from the median axis of the body.
  5. Protractor: They bring about the movement of pulling the leg forward.
  6. Retractor: They bring about the movement of pulling the leg backward.
  7. Pronator: They rotate the forearm to turn the palm downwards or backward.
  8. Supinator: They rotate the forearm to turn the palm upwards or forward.

    Involuntary Muscle Movements
    These movements are not under control of our will. They are of two types:

    i) Cardiac Movements:
    • These are carried out by cardiac muscles.
    • Cardiac muscles are stimulated by the nerve endings of autonomous
      nervous system.
    • They are capable of generating their own rhythmic contractions.



ii) Visceral Movements:

    • These movements are carried out by smooth or unstriated muscles which
      form the internal lining of visceral organs like urinary bladder, blood vessels, alimentary canal, etc.
    • Their response is slow and long lasting and under the control of
      autonomous nervous system.
    • They utilise very little energy and do not fatigue easily.

 

 

 

 

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