Locomotion And Movement

Locomotion and Movement – CBSE Class-11: One of the most important characteristics of living things is movement. Animals and plants move in a variety of ways. Humans can move their limbs, mouths, eyes, tongues, and so on. Some of the motions cause a shift in position or location. Locomotion refers to such voluntary motions. Walking, running, climbing, flying, and swimming are all locomotory actions. Hydra’s tentacles may be used to capture prey as well as for mobility. We utilize limbs to adjust our bodily postures and move about. Streaming of protoplasm is a primitive kind of movement in unicellular organisms such as Amoeba. Many creatures exhibit movement of cilia, flagella, and tentaclesLocomotory structures do not have to be distinct from those affecting other forms of movement. Cilia, for example, aids in the flow of food through the cytopharynx and in motility in Paramoecium.  The abovementioned facts imply that motions and locomotion cannot be investigated independently. It is possible to connect the two by asserting that all locomotions are movements, but not all movements are locomotions.

Locomotion

Locomotion is the process through which an organism moves from one location to another. The movement of appendages like limbs, wings, and flagella is a part of this process. Some creatures, including fish, whales, and sharks, move by contracting their muscles in waves, which is how they move. An organism uses locomotion to obtain food, avoid bad weather, and flee from predators, and other things.

Locomotion includes activities like walking, running, swimming, etc. Contrarily, movement refers to any form of motion that is not always localized.

TYPES OF MOVEMENT

Cells of the human body exhibit three main types of movements, namely amoeboid, ciliary, and muscular.

• Amoeboid Movement: Specific specialized cells in human bodies, such as macrophages and leucocytes in blood, demonstrate amoeboid motility. It is influenced by pseudopodia generated by protoplasm streaming.
• Ciliary Movement: Most of our internal tubular organs, which are lined by ciliated epithelium, have ciliary movement. The synchronized motions of cilia in the trachea aid in the removal of dust particles and some foreign chemicals ingested together with the ambient air. The ciliary movement also aids in the passage of eggs through the female reproductive system.
• Muscular Movement: Muscular action is required for the movement of our limbs, mouth, tongue, and so on. Humans and the bulk of multicellular creatures employ the contractile characteristic of muscles for locomotion and other activities. Locomotion necessitates the precise coordination of muscular, skeletal, and neurological systems.

TYPES OF MUSCLE

There are three types of muscle. These are:

• Cardiac muscles: The heart is striated and involuntary.
• Skeletal muscles: Striated and voluntary, responsible for the locomotion and movement of appendages.
• Visceral muscles: They are also involuntary, supporting many inside organs and participating in tasks like as digestion and reproduction.

Anatomy of Muscle Fibre and Sarcomere

Skeletal muscles are the most abundant muscles. They are made up of bundles of muscle fibers wrapped around connective tissue.

Muscle Fibres

Muscle fibers are lengthy cells. They are grouped together into fascicles. Muscle fiber properties are as follows:

• Skeletal muscle fibers are all long, cylindrical, and striated.
• The plasma membrane of the muscle fiber is known as the sarcolemma.
• Sarcoplasm is the muscle fiber’s cytoplasm.

Myofibrils

Several myofibrils run lengthwise and parallel across the sarcoplasm of each muscle fiber. Myofibrils’ continuous dark and light-colored bands give the muscle a striated look. Each myofibril is made up of even smaller structures known as myofilaments.

Myofilaments

Filaments that are thin and thick. Muscle contraction requires the attachment of thin and thick filaments.

Muscle bundle

A biceps muscle is made up of several muscle bundles (fascicles) that are bound together by fascia, a connective tissue layer. Several muscle fibers are found in each fascicle.

Microfilaments

As they are made up of two entangled strands of the globular protein known as actin, microfilaments are also known as actin filaments. 

• Actin filament: In muscle fibers, a protein called actin creates fine filaments. The movement of the cell membrane and the development of the pseudopodia that cells employ to migrate are both mediated by actin filaments.
  
• Myosin filament:  In muscle fibers, a protein called myosin creates dense filaments. Myosin filaments attach to actin filaments and pull them together to cause muscle contraction.
• Sarcomere: The fundamental units of contraction in skeletal muscles are called sarcomeres. They are distributed in a repeating pattern along the length of the muscle fiber and are made up of actin and myosin filaments.

Mechanism of Muscle Contraction

• Actin and myosin filaments slide over one another to cause muscle contraction.
• The sliding filament model was suggested by Andrew and Hugh Huxley.
• Sliding produces an increase in the overlap of the thick and thin filaments and shrinkage of the sarcomere. Muscles contract as a result of this. 

Muscle Contraction Steps

1. The brain or spinal cord (CNS) sends a signal to motor neurons to initiate muscle contraction.
2. The neurological signal causes the neurotransmitter acetylcholine to be released at the neuromuscular junction’s synaptic cleft. Acetylcholine binds to receptors located on the muscle fiber and induces depolarization of sarcolemma.
3. The created action potential spreads across the muscle fiber. The sarcoplasmic reticulum releases Ca2+ ions into the sarcoplasm. Another protein, dystrophin, regulates Ca2+ release. The dystrophin coding gene is the human body’s longest gene.
4. Following the connection, the myosin head releases phosphate, resulting in the “power stroke.” Myosin filaments stretch and pull fibers towards the center of the sarcomere, causing the sarcomere and muscle to shrink. During the procedure, ADP is released.
5. The procedure is repeated in the presence of high levels of Ca2+ ions. 

Muscle Relaxation

When the neuronal signal stops. Acetylcholinesterase is a protein that deactivates acetylcholine in the synaptic cleft. Muscle fibers enter a condition of rest. Ca2+ ions are returned to the sarcoplasmic reticulum. In the absence of Ca2+ ions, the troponin-tropomyosin complex re-covers the actin filaments’ myosin-binding sites. 

Skeletal System

The skeletal system serves as our body’s structural framework and aids in movement and mobility. It shields the interior organs from harm. Our skeletal system is made up of many types of connective tissues, such as bones and cartilage.

Bones

An adult human being has a total of 206 bones. Because of Ca salts in the matrix, bones are hard, whereas cartilage includes chondroitin salts.

• Axial skeleton (80 bones)- skull, vertebral column, ribs, and sternum.
• Appendicular skeleton (126 bones)– pectoral and pelvic girdle and limbs.

Joints

A joint, which is a connection between two bones in the skeletal system, is often referred to as an articulation or an articular surface. Motion is made possible by joints. A joint’s degree and nature of movement are determined by its type and properties. Joints can be grouped according to their structure and function.

Types of Joints

• Pivotal Joints: One bone has tapped into the other in this kind of joint, making it unable to rotate fully. This joint facilitates movement in both directions. In the neck.
• Hinge Joints: Similar to door hinges, hinge joints allow only backward and forward movement. The ankle, elbow, and knee joints are examples of hinge joints.
  
• Condyloid Joints: Condyloid joints have two axes and allow for both up-and-down and side-to-side motions. The base of the index finger, the wrist’s carpals, the elbow, and the wrist joints all contain condyloid joints. Condylar, or ellipsoid, is another name for this joint.
  
• Ball and Socket Joints: In this instance, one bone hooks into the hollow of another bone. This kind of joint facilitates rotational movement. The shoulders are an example of a ball and socket joint.
• Gliding Joints: A typical class of synovial joint is the gliding joint. A plane or planar joint is another name for it. This joint enables the unrestricted movement of two or more round or flat bones next to one another without any bone friction or crushing. 

Difference Between Locomotion and Movement

Locomotion	Movement
Locomotion is the movement of an organism away from its starting point.	Movement can take place with or without a change in the posture of an organism.
At the level of the organism, locomotion occurs.	There is movement at the biological level.
Locomotion doesn’t  require energy	Movement requires energy.

Disorders of the Muscular and Skeletal System

• Muscular dystrophy: Skeletal muscle degeneration is mostly caused by a hereditary disease.
• Tetany:  Rapid spasms (wild contractions) in muscle due to low Ca++ in body fluid.
• Osteoporosis: Age-related condition characterized by decreasing bone mass and increased fracture risk. A typical reason is low estrogen levels.
• Myasthenia gravis An autoimmune illness that affects the neuromuscular junction, causing tiredness, weakness, and paralysis of skeletal muscle.

FAQS on Locomotion and Movement

Question 1:  Where in the body is the ball and socket joint present?

Answer:

They are present between the humerus and pectoral girdle – the shoulder joints, hip joints, and femur bone in the socket of the pelvic girdle.

Question 2: What is locomotion?

Answer:

Locomotion is an organism’s capacity to move from one location to another. 

Question 3: How is locomotion different from movement?

Answer:

Locomotion is the movement of a body from one location to another. Movement, on the other hand, is defined as the displacement of a body or a part of a body from its initial location.

Question 4: What is arthritis? 

Answer:

Arthritis is a disease that causes inflammation in one or more joints, as well as pain and stiffness that worsens with age.

Question 5: What causes fatigue of muscle fibers? 

Answer:

Accumulation of lactic acid causes fatigue of muscle fibres.