Locomotion & movement

• Movement is a significant feature of living beings
• Animals and plants exhibit a wide range of movements
• Streaming of protoplasm in unicellular organisms like Amoeba is a simple form of movement
• Human beings can move limbs, jaws, eyelids, tongue, etc
• Voluntary movements that result in a change of place or location are called locomotion
• Walking, running, climbing, flying, swimming are forms of locomotory movements
• Locomotory structures can be the same as those affecting other types of movements
• All locomotions are movements but all movements are not locomotions
• Cells of the human body exhibit three main types of movements: amoeboid, ciliary, and muscular
• Amoeboid movement is shown by specialised cells like macrophages and leucocytes in blood
• Ciliary movement occurs in internal tubular organs lined by ciliated epithelium
• Muscular movement is required for movements like limb movement, jaw movement, and tongue movement
• Muscle is a specialised tissue of mesodermal origin
• About 40-50% of the body weight of a human adult is contributed by muscles
• Muscles have special properties like excitability, contractility, extensibility, and elasticity
• Three types of muscles based on location are: Skeletal, Visceral, and Cardiac
• Skeletal muscles are striated and under voluntary control, primarily involved in locomotory actions and changes of body postures
• Visceral muscles are smooth in appearance, not under voluntary control, and assist in functions like transportation of food and gametes
• Cardiac muscles are striated and involuntary, found in the heart
• Muscle fibre is lined by the plasma membrane called sarcolemma enclosing the sarcoplasm
• Muscle fibre is a syncitium with many nuclei in the sarcoplasm
• The sarcoplasmic reticulum of muscle fibres is the storehouse of calcium ions
• Myofibrils contain actin and myosin, giving a striated appearance to muscles
• The sliding filament theory explains muscle contraction by the sliding of thin filaments over thick filaments
• The skeletal system consists of a framework of bones and a few cartilages
• The skeletal system plays a significant role in movement in the body
• Bone and cartilage are specialised connective tissues
• The skeletal system in human beings is made up of 206 bones and a few cartilages
• The skeletal system is grouped into two principal divisions - the axial and the appendicular skeleton
• The axial skeleton comprises 80 bones distributed along the main axis of the body
• The axial skeleton includes the skull, vertebral column, sternum, and ribs
• The skull is composed of cranial and facial bones, totaling 22 bones
• The vertebral column is formed by 26 vertebrae and extends from the base of the skull
• The sternum is a flat bone on the ventral midline of the thorax
• There are 12 pairs of ribs, with different types such as true ribs, false ribs, and floating ribs
• The appendicular skeleton consists of bones of the limbs and their girdles
• Each limb is made of 30 bones, including bones of the hand and bones of the legs
• The pectoral and pelvic girdle bones help in the articulation of the upper and lower limbs with the axial skeleton
• Joints are essential for all types of movements involving the bony parts of the body
• Joints are points of contact between bones and cartilages