نشاط (6-6) تثبيت المفاهيم الرئيسة - كتاب أنظمة جسم الإنسان - الصف 12 - الفصل 1 - المملكة العربية السعودية

--- SECTION: نشاط (6-6) تثبيت المفاهيم الرئيسة --- نشاط (6-6) تثبيت المفاهيم الرئيسة.--- SECTION: 6-6 --- مستعينا بالشكل أعلاه وضح المقصود بقولنا: "عدد الألياف العضلية المرتبطة بكل خلية عصبية ونوعها، يعتمد على طبيعة العمل المطلوب من ناحية الدقة والقوة".2023 - 1447--- VISUAL CONTEXT --- **DIAGRAM**: Untitled Description: A diagram illustrating the concept of motor units and their relation to muscle function, showing two main parts. The upper part depicts muscle fibers and their innervation by nerve cells, while the lower part shows human leg movements. Data: The upper section shows two motor units. The left motor unit depicts a single nerve cell innervating a larger bundle of muscle fibers, labeled 'وحدة المحرك' (Motor Unit). The right motor unit shows a single nerve cell innervating a smaller bundle of muscle fibers, labeled 'الليف العضلي' (Muscle Fiber). This visually implies that different motor units control different numbers of muscle fibers. The lower section illustrates two leg postures. The left leg is shown standing on the tips of the toes, with a label 'الارتكاز على أطراف أصابع القدم' (Support on the tips of the toes), indicating a movement requiring precision. The right leg is depicted in a running motion, labeled 'جري' (Running), indicating a movement requiring strength. Context: This diagram visually supports the understanding that the number and type of muscle fibers associated with each nerve cell (motor unit) depend on the nature of the required action in terms of precision and strength. For example, fine motor control (like standing on toes) involves motor units with fewer muscle fibers, while powerful movements (like running) involve motor units with many muscle fibers.