📚 Year 7 Science: Support and Movement | 七年级科学：支撑与运动
All living things face the force of gravity, which constantly pulls their bodies downward. Without some form of support, soft tissues would collapse and vital organs could be damaged. In this unit, we investigate how the human skeleton, muscles, joints, and even plant tissues provide the support and movement needed for survival.
所有生物都受到重力的作用，重力持续将身体向下拉。如果没有某种支撑结构，软组织就会塌陷，重要器官可能受损。本单元我们将探究人体骨骼、肌肉、关节以及植物组织如何提供生存所需的支撑和运动。
1. Why Organisms Need Support | 为什么生物体需要支撑
Support systems allow an organism to maintain its shape, protect internal organs, and move from place to place. Land animals need stronger support than aquatic animals because water provides buoyancy, while air does not.
支撑系统使生物能够保持体形、保护内部器官并移动位置。陆生动物比水生动物需要更强的支撑，因为水能提供浮力，而空气不能。
In humans, the skeleton acts as a framework. Muscles attach to bones and pull on them to produce movement. Without a rigid skeleton, coordinated movement such as walking, running, or writing would be impossible.
在人体中，骨骼起到框架的作用。肌肉附着在骨骼上并牵拉骨骼以产生运动。如果没有坚硬的骨骼，像走路、跑步或写字这样的协调运动就不可能完成。
2. The Human Skeleton: Axial and Appendicular | 人体骨骼：中轴骨与附肢骨
The adult human skeleton has 206 bones and is divided into two main parts. The axial skeleton includes the skull, vertebral column, ribs, and sternum, and it forms the central axis of the body.
成人体内有 206 块骨，分为两大部分。中轴骨包括颅骨、脊柱、肋骨和胸骨，构成身体的中心轴。
The appendicular skeleton includes the shoulder girdle, arm bones, pelvic girdle, and leg bones. It is mainly responsible for movement and for attaching the limbs to the axial skeleton.
附肢骨包括肩带、臂骨、骨盆带和腿骨。它主要负责运动，并将四肢连接到中轴骨上。
3. Bone Structure and Functions | 骨骼的结构与功能
Bone is a living tissue made of cells, collagen fibres, and minerals such as calcium phosphate. The hard outer layer is called compact bone, while the inner spongy bone is lighter and contains bone marrow.
骨是一种活组织，由细胞、胶原纤维和磷酸钙等矿物质组成。坚硬的外层称为骨密质，内部松质骨较轻并含有骨髓。
Bones have several functions: they support the body, protect organs such as the brain and heart, store minerals, and produce blood cells in the bone marrow. The long bones also act as levers for movement.
骨有多种功能：支撑身体、保护脑和心脏等器官、储存矿物质，并在骨髓中制造血细胞。长骨还充当运动的杠杆。
4. Joints: Where Bones Meet | 关节：骨骼相接之处
A joint is a place where two or more bones meet. Joints are classified by how much movement they allow. Fixed joints, such as those in the skull, allow no movement, while slightly movable joints, such as those between vertebrae, allow limited movement.
关节是两块或更多骨相接之处。关节按允许的运动量分类。颅骨中的不动关节不允许运动，而脊椎骨之间的微动关节允许有限运动。
Freely movable joints are called synovial joints. They contain synovial fluid, which lubricates the joint, and cartilage, which cushions the ends of bones and reduces friction.
自由活动的关节称为滑膜关节。它们含有滑液来润滑关节，并有软骨缓冲骨端、减少摩擦。
5. Types of Synovial Joints | 滑膜关节的类型
Different synovial joints allow different types of movement. A hinge joint, such as the elbow or knee, allows bending and straightening in one plane, like a door hinge.
不同的滑膜关节允许不同类型的运动。铰链关节（例如肘关节或膝关节）像门铰链一样，在一个平面内进行屈伸运动。
A ball-and-socket joint, such as the shoulder or hip, allows movement in many directions, including rotation. Pivot joints allow rotation around a single axis, as when you turn your head from side to side.
球窝关节（例如肩关节或髋关节）允许多方向运动，包括旋转。枢轴关节允许绕单轴旋转，例如头部左右转动。
6. Muscles and Antagonistic Pairs | 肌肉与拮抗肌对
Skeletal muscles are attached to bones by tough cords called tendons. Muscles can only contract, or shorten; they cannot push. Therefore, muscles often work in pairs to move a bone in opposite directions.
骨骼肌通过称为肌腱的坚韧索状组织附着在骨上。肌肉只能收缩（缩短），不能推动。因此，肌肉通常成对工作，使骨骼向相反方向运动。
The biceps and triceps in the upper arm form an antagonistic pair. When the biceps contracts, the arm bends at the elbow; when the triceps contracts, the arm straightens. The relaxing muscle is stretched passively.
上臂的肱二头肌和肱三头肌构成一对拮抗肌。当肱二头肌收缩时，手臂在肘部弯曲；当肱三头肌收缩时，手臂伸直。放松的肌肉被被动拉长。
7. How Muscles Create Movement | 肌肉如何产生运动
In a lever system, a bone acts as the lever, a joint acts as the fulcrum, a muscle provides the effort, and the body part being moved provides the load. For example, in the elbow joint, the forearm is the lever, the elbow is the fulcrum, the biceps provides effort, and the hand or weight is the load.
在杠杆系统中，骨充当杠杆，关节充当支点，肌肉提供动力，被移动的身体部位提供负荷。例如，在肘关节中，前臂是杠杆，肘部是支点，肱二头肌提供动力，手或重物是负荷。
The lever principle can be written as effort multiplied by effort arm equals load multiplied by load arm.
杠杆原理可以写作：动力乘以动力臂等于负荷乘以负荷臂。
Effort × Effort arm = Load × Load arm
In the human body, lever systems often sacrifice force to gain speed and a wide range of motion.
在人体中，杠杆系统通常牺牲力量以获得速度和较大的运动范围。
8. Comparing Skeletons in Animals | 比较动物的骨骼
Animals have different types of skeletons. Vertebrates such as humans, birds, and fish have an internal endoskeleton made of bone or cartilage. This grows with the animal and provides strong support.
动物有不同类型的骨骼。人类、鸟类和鱼类等脊椎动物具有由骨或软骨构成的内骨骼。内骨骼随动物生长，并提供强大的支撑。
Arthropods such as insects and crabs have an external exoskeleton made of chitin. It protects the body but must be shed, or moulted, for the animal to grow. Some soft-bodied animals, such as earthworms, use a hydrostatic skeleton, where fluid pressure inside the body maintains shape.
昆虫和螃蟹等节肢动物具有由几丁质构成的外骨骼。外骨骼能保护身体，但动物生长时必须蜕皮。一些软体动物（如蚯蚓）使用流体静力骨骼，即体内的液体压力维持体形。
9. Support in Plants | 植物的支撑
Plants do not have bones, but they still need support to stand upright and reach light. Herbaceous plants rely on turgor pressure, which is the pressure of water inside cells pushing against the cell wall.
植物没有骨骼，但它们仍然需要支撑以直立并获取光照。草本植物依靠膨压，即细胞内水分对细胞壁施加的压力。
Woody plants, such as trees, produce lignin in their xylem vessels, making stems hard and strong. Cell walls made of cellulose also provide structural support for all plant cells.
木本植物（如树木）在木质部导管中产生木质素，使茎坚硬强壮。由纤维素构成的细胞壁也为所有植物细胞提供结构支撑。
10. Investigating Support and Movement | 探究支撑与运动
A simple model of the arm can be built using a ruler as the forearm, a split pin as the elbow joint, and strings as muscles. Pulling each string shows how antagonistic muscles make the arm bend and straighten.
可以用尺子作为前臂、开口销作为肘关节、绳子作为肌肉来制作一个简单的手臂模型。拉动每根绳子可以显示拮抗肌如何使手臂弯曲和伸直。
When investigating grip strength, you could use a hand dynamometer and record repeated measurements. Keep the same hand position and rest time between trials to make the results reliable and fair.
在探究握力时，可以使用手握力计并记录多次测量结果。保持相同的手部位置和试验间隔休息时间，使结果可靠且公平。
11. Common Misconceptions and Exam Tips | 常见误区与考试技巧
A common mistake is to say that muscles push bones. In fact, muscles can only pull. When a bone moves in one direction, one muscle contracts; to return the bone, a different muscle contracts.
一个常见错误是说肌肉推动骨骼。事实上，肌肉只能牵拉。当骨骼向一个方向移动时，一块肌肉收缩；要使骨骼回到原位，另一块肌肉收缩。
Another misconception is that bones are dead or inactive. Bone is living tissue that remodels itself and contains blood vessels and nerves. In exams, always use precise terms such as 'contract', 'relax', 'tendon', 'ligament', 'cartilage', and 'synovial fluid'.
另一个误区是认为骨骼是死的或不活跃的。骨是活组织，会自我重塑，并含有血管和神经。考试时，务必使用准确术语，如收缩、放松、肌腱、韧带、软骨和滑液。
When answering questions about movement, describe the antagonistic pair together. For example: 'The biceps contracts and the triceps relaxes to bend the arm at the elbow.'
在回答有关运动的问题时，要一起描述拮抗肌对。例如：'肱二头肌收缩，肱三头肌放松，使手臂在肘部弯曲。'
Published by TutorHao | Year 7 Science Revision Series | aleveler.com
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