vidéo : le système musculaire 3ème année collège ملخص + PDF (svt bsif)

The muscular system is a complex network of tissues that work together to produce movement. It is made up of three types of muscles: skeletal, cardiac, and smooth. Skeletal muscles are attached to bones and are responsible for voluntary movement. Cardiac muscles are found in the heart and are responsible for pumping blood. Smooth muscles are found in the walls of internal organs and are responsible for involuntary movements, such as digestion and blood flow. The muscular system is controlled by the nervous system. When the brain sends a signal to a muscle, the signal travels through the nerves to the muscle fibers. The muscle fibers then contract, causing the muscle to move. The muscular system is essential for our survival. It allows us to move, breathe, and digest food. It also helps to protect our organs and regulate our body temperature. Here is a more detailed explanation of the muscular system: * **Skeletal muscles** are the muscles that we can control voluntarily. They are attached to bones by tendons and are responsible for movement. Skeletal muscles are made up of long, thin cells called muscle fibers. Each muscle fiber is surrounded by a thin layer of connective tissue called the sarcolemma. The sarcolemma contains many mitochondria, which are responsible for producing energy for the muscle. The sarcolemma also contains myofibrils, which are bundles of protein filaments that contract when stimulated by the nervous system. * **Cardiac muscles** are the muscles that make up the heart. They are involuntary muscles, which means that they contract without our conscious control. Cardiac muscles are made up of short, thick cells called cardiac muscle cells. Each cardiac muscle cell is surrounded by a thin layer of connective tissue called the sarcolemma. The sarcolemma contains many mitochondria, which are responsible for producing energy for the heart. The sarcolemma also contains myofibrils, which are bundles of protein filaments that contract when stimulated by the nervous system. * **Smooth muscles** are the muscles that line the walls of internal organs. They are involuntary muscles, which means that they contract without our conscious control. Smooth muscles are made up of spindle-shaped cells called smooth muscle cells. Each smooth muscle cell is surrounded by a thin layer of connective tissue called the sarcolemma. The sarcolemma contains many mitochondria, which are responsible for producing energy for the smooth muscles. The sarcolemma also contains myofibrils, which are bundles of protein filaments that contract when stimulated by the nervous system. The muscular system is a complex network of tissues that work together to produce movement. It is essential for our survival and allows us to do many things that we take for granted, such as walking, talking, and breathing.