17.1 What makes up the skeleton? (Book 3, p.4)

Transcription

1 17 Locomotion in humans 17.1 What makes up the skeleton? (Book 3, p.4) Structure of the skeleton (Book 3, p.4) The skeleton is made up of: (1) bones ( ) (2) cartilage Bones (Book 3, p.4) Bones are hard tissues made up of (3) living cells and (4) minerals, e.g. calcium phosphate. (5) Blood vessels run through the bones so that oxygen and nutrients are supplied for the growth and development of the bones, and carbon dioxide and other waste are removed. (6) Nerves are also present to provide sensations from the bones. Cartilage (Book 3, p.4) Cartilage is made up of (7) living cells. As it contains a smaller amount of minerals, it is (8) softer than bones. It can be found between bones to reduce (9) friction as the surfaces of the bones move against one another. It also gives shape to structures such as Ear Nose Oxford University Press

2 The general plan of our skeleton (Book 3, p.5) The skeleton is divided into the (1) axial skeleton (Š ) and the (2) appendicular skeleton (òí ). A (5) collar bone D B (3) sternum (6) shoulder bone (í ) (4) rib (7) humerus ( ) (í ) C (8) radius E (9) ulna F (10) femur (í ) (11) knee cap ( ) G (12) tibia (13) fibula The human skeleton Note: There are three types of skeletal systems: external (exoskeleton), internal (endoskeleton) and fluid-based (hydrostatic skeleton). The human skeleton is an endoskeleton. 2 Oxford University Press 2005

3 Axial skeleton (Book 3, p.6) The axial skeleton forms the central axis of the body. It is mainly for (1) support and protection of (2) internal organs. It includes: Structure Function A (3) Skull Protects the brain Protects sense organs such as eyes and ears B (4) Rib cage ( ) Protects the lungs and the heart Allows the breathing movement (5) Vertebral Supports the body weight C column Protects the spinal cord Provides surfaces for muscle attachment to maintain an upright posture Appendicular skeleton (Book 3, p.6) The appendicular skeleton lies on either side of the body. It allows (6) movement of the body. It includes: Structure Function D (7) Pectoral girdle (í ) Forms the shoulders Joins the arms to the axial skeleton E (8) Fore limb (õí) Allows locomotion F (9) Pelvic girdle Forms the hips Joins the legs to the axial skeleton G (10) Hind limb (þí) Allows locomotion Oxford University Press

4 Functions of the skeleton (Book 3, p.7) Function Description Support Allows the body to stand (1) upright and gives shape to it Movement Bones act as (2) levers during movement Bones provide hard surfaces for attachment of (3) muscles which can contract and relax in a coordinated way Protection of the internal organs Skull protects the (4) brain and some sense organs Rib cage protects the lungs and the (5) heart Vertebral column protects the (6) spinal cord 4 Oxford University Press 2005

5 Function Production of blood cells Description (1) Bone marrow in long bones produces red blood cells, white blood cells and blood platelets bone marrow Storage of minerals Store minerals such as (2) calcium ( ) and phosphorus calcium phosphate 17.2 What is the muscular system? (Book 3, p.8) The muscular system is made of many different sets of (3) muscles ( ) all over the body. Muscles are the body s (4) principal effectors for locomotion. When stimulated, they contract to bring about movement of the bones. Each muscle is attached to its associated bones through (5) tendons ( ), which transmit the pulling force produced by muscle contraction to the bones, to allow muscles to control the way bones move. tendons shoulder bone tendons muscles ulna radius humerus tendons Tendons attach the muscles to the bones Oxford University Press

6 17.3 How do humans move? (Book 3, p.10) A(1) joint is the place where two or more bones meet. The structure of a joint (Book 3, p.10) A B C Movable joint Structure Function (2) Ligament Prevents (3) dislocation ( ±) A Allows the limb bones at the joint to move in a controlled way B (4) Synovial membrane Secrets (5) synovial fluid to reduce friction between the ends of the bones (6) Cartilage Absorbs (7) shock C Reduces friction between the ends of bones Protects the bones from wearing away Note: 1 Some joints are immovable, i.e. do not allow any movement, e.g. the joints between the bones of the skull. 2 Ligament is a short band of tough connective tissues composed of collagen fibres. 6 Oxford University Press 2005

7 Action of muscles on bones (Book 3, p.11) Muscles are attached to the limb bones across joints through tendons. They usually work as pairs of (1) opposing muscles ( ). The alternate contraction and relaxation of the pair of muscles bring about movements of the limb bones. A muscle which bends a limb when it contracts is called a (2) flexor. A muscle which straightens the same limb when it contracts is called an (3) extensor. In the movement of the forearm, (4) biceps ( ) is the flexor and the (5) triceps ( ) is the extensor. Arm model Bending the arm Extending the arm tendons tendons triceps biceps triceps biceps forearm elbow joint forearm Biceps (6) Contract / Relax (9) Contract / Relax Triceps (7) Contract / Relax (10) Contract / Relax Forearm (8) Raised /Lowered (11) Raised /Lowered Oxford University Press

8 The lever principle of movement (Book 3, p.12) Bones at joints act as (1) levers during movement. The forearm acts as a lever during movement: Lever Forearm effort contraction of the biceps fulcrum load weight of the forearm joint Fulcrum ( ) (2) Joint (3) Load Weight of the forearm Effort ( ) (4) Contraction of the biceps Go To Practical 17.1 Examination of an arm model (Student s Book 3 p.12; Activity Book 3 p.1) Types of movable joints (Book 3, p.13) Different types of movable joints allow different degrees of movement. Hinge joint (Book 3, p.13) Hinge joints ( ) allow movement of bones in (5) one plane only. Examples include the elbow joint hinge and the knee joint. Hinge joint 8 Oxford University Press 2005

9 Ball and socket joint (Book 3, p.13) Ball and socket joints ( ) allow movement of bones in (1) three planes. Examples include the shoulder joint and the hip joint. ball socket Ball and socket joint Go To STS connection 17.1 Health issues related to the skeleton and muscles (Student s Book 3 p.14; Activity Book 3 p.3) Quick check (Student s Book 3 p.14) 17.4 How do we keep our skeleton and muscles healthy? (Book 3, p.15) Keep correct posture. Avoid poorly fitting shoes. Avoid carrying heavy schoolbags. Avoid poor working conditions like dim light and low work surfaces. Go To STS connection 17.2 Occupational safety (Student s Book 3p.15;Activity Book 3 p.7) Review (Student s Book 3 p.16) Summary concept diagram (Student s Book 3 p.17) Oxford University Press

10 Practice question The diagram below shows the knee joint of a human. a i Name the type of joint to which the knee joint belongs. (1 mark) Hinge joint (1m). ii What is the difference in the degree of movement provided by the knee joint and the shoulder joint? (2 marks) The knee joint allows movement of bones in one plane only (1m) while the shoulder joint allows movement of bones in three planes (1m). b Name structure A and give a function of it. (2 marks) Ligament (1m). To prevent dislocation of the joint during movement (1m). c i If structure B wears away and exposes the bones underneath, how would the movement at the joint be affected? (2 marks) The friction between the ends of bones increases (1m). The movement at the ii joint becomes more difficult (1m). Who will have a higher chance of having structure B worn away? Give two examples. (2 marks) Athletes and the elderly (1m x 2). END Total: 9 marks 10 Oxford University Press 2005