Introduction to Locomotion and Movement
Here, we will get a good understanding of Locomotion and Movement class 11 chapter 20. Let’s get started!
All living organisms like we, human beings, can bend, jump, stretch, run and walk, exhibit movement which is one of their characteristic features. We must be aware that movement in plants is different from that in the animals. The simplest form of movement is protoplasmic streaming which is found in unicellular organisms such as amoeba. Some organisms have different structures for movement such as cilia in Paramecium, Flagella in Chlamydomonas and Tentacles in Hydra. Other organisms like domestic and wild animals including humans can move their eyelids, tongue, jaws, hands and legs. And many times, this movement results in change in location or place and such voluntary movement is called locomotion. The different types of locomotory movements are swimming, walking, flying and running.
Besides, the parts of the bodies that help in locomotion also help in other activities such as cilia in Paramoecium help in movement of food through cytopharynx, tentacles in Hydra are used for capturing prey and also for locomotion and humans use limbs for changing body postures and locomotion as well. So, it is clear that movements and locomotions are related and can be studied together. Also, one should understand that all locomotions are movement but all movements are not locomotion. This is because locomotion is concerned with the change in location or place whereas movement can be associated with only that of any body part and the whole body still remains constant. Likewise, it is well explained in Locomotion and Movement class 11 NCERT books.
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Why do Organisms Perform Locomotion?
Animals need to perform locomotion for various reasons including for the search of food, mating, shelter, breeding ground and favourable climatic condition and safety from predators or enemies. Therefore, the different methods of locomotion that animals perform depend upon their habitats and demand of the situation.
Types of Movement
As explained in locomotion and movement NCERT book, three different types of movement are known, namely:
Amoeboid Movement - It is seen in some specialized cells such as macrophages and white blood cells. Pseudopodia are responsible for this type of movement in Amoeba due to protoplasmic streaming and microfilaments are cytoskeletal elements are also responsible for this kind of movement.
Ciliary Movement - It occurs in most internal tubular organs lined by ciliated epithelium. Example, in trachea, cilia move in coordinated manner to move foreing substances inhaled and dirt by moving. Another example is seen in the movement of eggs through the female reproductive tract which is lined by cilia.
Muscular Movement - It can be seen in the eyelids, tongue, jaws, hands and legs. Contractile muscles help in bodily movements and locomotion of an organism.
Locomotion is brought about by the coordination of three kinds of systems in organisms, namely muscular system, skeletal system and neural system. Let’s discuss it more in detail.
Muscular System
Muscles help in body movements as well as that of internal organs. It helps in stretching, bending, walking and other physical activities.
Muscles constitute 40 -50 percent of the body weight of a person. Muscle is a specialized tissue originating from the mesoderm. It is the only tissue consisting of properties including contractility, extensibility, excitability and elasticity.
Muscles are classified according to their location (Skeletal, Visceral or Cardiac), Appearance (Stripped or Smooth) and Nature of Regulation (Voluntary or Involuntary).
Skeletal System
This system comprises bones giving shape to the body. An adult skeletal system consists of 306 bones and a few cartilages. On the other hand, a new born baby consists of around 300 bones which are fused later on. Bones and cartilages are specialized connective tissues. The latter is softer in appearance.
The axial skeleton consists of 80 bones comprising skull, vertebral columns, ribs and sternum. The skull is having facial and cranial bones. Hyoid bone which is U-shaped is also present in the skull as well as ear ossicles are there in the skull.
The appendicular skeleton consists of 126 bones which includes bones of limbs and supporting girdles. Each limb consists of 30 bones; bones of hand include humerus, ulna, radius, carpals, metacarpals and phalanges. Similarly, the hind limb or leg consists of femur, tibia, fibula, tarsals, metatarsals and phalanges, Knee cap called patella is found in the knee. Pectoral and Pelvic girdle are known which form the remaining 6 bones.
The point at which two bones or bone and a cartilage make contact are called joints. The functions of joints are in locomotion and bony parts of my body. Joint acts as fulcrum and are classified into fibrous, cartilaginous and synovial. Fibrous joints are immovable such as cranial bones that form cranium via fusing. Synovial joints have synovial fluid and allow a considerable amount of movement. Many joints like hinge joints and pivot joints fall under synovial joints. Arthritis is an example of disorder or joints and another is osteoporosis caused due to decrease in bone mass.
Besides all points discussed here, students can refer to the locomotion and movement NCERT books of class 11 in chapter 20. Students can also learn about disorders of muscular and skeletal systems.
Different Types of Locomotion
With the presence of various muscles, bones, cartilages, ligaments, tendons and joints, different types of locomotion and movement are possible. Locomotion is the ability to move from one place to another and the three types of locomotion which are performed by living organisms include flight locomotion, swimming locomotion and land locomotion. Flight locomotion is flying which includes the motion of an organism through the air, example: birds.
FAQs on Locomotion and Movement
1. What is the main difference between locomotion and movement?
Movement is any change in the position of a body part, like blinking your eyes or moving your hand. Locomotion, however, is a specific type of movement that results in a change of place for the entire organism, such as walking, swimming, or flying. Therefore, all locomotion is a form of movement, but not all movements result in locomotion.
2. What are the functions of the pectoral and pelvic girdles in our skeleton?
The pectoral and pelvic girdles are essential components of the appendicular skeleton that connect our limbs to the central part of the body.
- The pectoral girdle, or shoulder girdle, connects the arms to the axial skeleton and allows for a wide range of motion.
- The pelvic girdle, or hip girdle, connects the legs to the axial skeleton. It is much stronger and more robust as it bears the full weight of the upper body and is crucial for stable locomotion like walking and running.
3. How do the three types of muscles—skeletal, smooth, and cardiac—differ in their roles?
The three main types of muscles are distinguished by their location, appearance, and how they are controlled.
- Skeletal muscles are attached to bones and are under our conscious control (voluntary). They are responsible for body movements like walking and lifting.
- Smooth muscles are found in the walls of internal organs like the stomach and intestines. They work automatically (involuntary) to perform functions like digestion.
- Cardiac muscles are found only in the heart. They are also involuntary and work continuously to pump blood throughout the body.
4. How does the sliding filament theory explain muscle contraction on a microscopic level?
The sliding filament theory explains that a muscle contracts when its thin filaments (actin) slide past its thick filaments (myosin). This sliding action pulls the ends of the muscle's basic unit, the sarcomere, closer together, causing the entire muscle to shorten and generate force. This entire process is initiated by a nerve impulse and requires energy, which is supplied by ATP.
5. What are the different types of joints, and how do they affect our movement?
Joints are primarily classified by the amount of movement they permit. The three main categories are:
- Fibrous Joints: These are immovable joints held together by dense fibrous tissue, like the sutures found in the skull.
- Cartilaginous Joints: These allow for only slight movement, as the bones are connected by cartilage. The joints between the vertebrae in the spine are a key example.
- Synovial Joints: These are freely movable joints and are the most common in the body. They contain synovial fluid for lubrication and include types like the hinge joint (knee) and ball-and-socket joint (shoulder).
6. Why are the bones in a baby's skull not completely fused at birth?
A baby's skull bones are separated by flexible fibrous joints known as fontanelles, or 'soft spots'. This has two major advantages. Firstly, it allows the bony plates of the skull to compress and overlap, which helps the baby's head to pass more easily through the birth canal. Secondly, this flexibility accommodates the very rapid growth of the brain during the first few years of life.
7. What is actually happening in the body when a person gets arthritis?
Arthritis is a general term for the inflammation of one or more joints, which causes pain and stiffness. In osteoarthritis, the most common form, the protective cartilage that cushions the ends of bones gradually wears down. In rheumatoid arthritis, the body's own immune system mistakenly attacks the lining of the joint capsule, leading to painful swelling and inflammation that can eventually cause joint deformity.
