Form 5 Biology (Chapter 2: Locomotion & Support)

Form 5: Chapter 2 – Locomotion and Support 2.1 Support and Locomotion in Humans and Animals

Chapter 2: Locomotion and Support 2.1 Support and Locomotion in Humans and Animals Support System and Locomotion 1. Provided by a skeleton. 2. Types of skeleton: a) Exoskeleton – shell - insects and crabs - importance: i) supports important body organs ii) protects the internal structures from damage iii) allows movement iv) waxy cuticles found on the surface of insects prevents water loss. b) Endoskeleton – bones and cartilage - vertebrates - importance: i) maintaining body shape ii) supporting soft tissue iii) protecting internal organs from injury iv) stores mineral (calcium and phosphorus) v) produce blood cells c) Hydrostatic skeleton – internal watery fluids held under pressure contained within confined spaces in the body surrounded by the muscles. - caterpillar and earthworm The human skeleton 1. Parts: a) axial skeleton b) appendicular skeleton The axial skeleton 1. Consists of: a) skull b) vertebral column c) the ribs d) sternum 2. Skull consist of: a) Cranial bones – enclose and protect the brain b) Facial bones – protect and provide support for the entrances to the digestive system and respiratory system c) Suture – immovable joints which securely hold bones that make up the skull d) Jaw – movable joint

Prepared by: Mr. Gerard Selvaraj

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3. Vertebral column (spine or backbone) a) composed of vertebrae. b) encloses and protects the spinal cord. c) supports the head d) serves as a point of attachment for the ribs, pelvic girdle and the muscles of the back and neck. e) cervical, thoracic and lumbar are moveable. f) sacrum and coccyx are immovable. g) invertebral discs in the vertebrae permits movement of the vertebral column and absorb vertical shock. h) varies in size and shape. i) vertebral foramen encloses the spinal cords.


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4. Cervical vertebrae a) Have transverse formaen through which blood vessels and nerve pass. 5. Thoracic vertebra a) Have spinous processes that are long directed downwards. b) Spinous and transverse processes serve as points of attachment of muscles and ligaments.

6. Lumbar vertebra a) Largest and strongest. b) Have large centrums which bear the weight of the lower back.


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7. Thorax: a) thoracic cage (consists of ribs and the sternum) b) encloses and protects the organs in the thoracic cavity and upper abdominal cavity. The appendicular skeleton 1. Consists of: a) Pectoral girdle – clavicle and scapula b) Humerus – upper arm, longest bone c) Ulna d) Radius e) Carpals - wrist f) Metacarpals – palm of the hand g) Phalanges – fingers and toefingers g) Pelvic girdle – consists of two hip bones which provide strong and stable support for the vertebral column. h) Femur – thigh bone, longest, heaviest and strongest i) Tibia j) Fibula k) Patella – kneecap l) Tarsals - ankle m) Metatarsals – foot The structure of a joint 1. Joint – a place where two or more bones meet. 2. Ligaments – Hold bones together and allow them to move 3. Synovial joint: a) Joint that contains a cavity filled with fluid that allow free movement. b) 4 features – joint capsule (joint enclosure, reinforced and strengthened with ligaments) - lined with thin synovial membrane (inner surface of the capsule) - secretes synovial fluid lubricant which reduces friction between the ends of


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the bones) - covered with cartilage 4. Cartilage cushions the joint, absorbs shock and reduces friction between the ends of the bones. 5. Joints:-

a) Hinge joint – knee, elbow, finger and toe. - allows the leg to swing back and forth (one plane). - 180 degree

b) Ball and socket joint – rotational movement of bones in all directions. - shoulder and hip joint. - 360 degree Prepared by: Mr. Gerard Selvaraj

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How movement is brought about in a limb

1. Skeletal muscle are responsible for voluntary movements of the body. 2. A muscle is attached to at least two bones across joints through tendons. 3. Tendons are tough, strong and inelastic strands of dense connective tissues. 4. Skeletal muscle produce movements by pulling on tendons attached to bones. 5. A muscle can only pull. 6. It pulls when it contracts. 7. A pair of muscle (antagonistic muscle) work together to allow coordinated movement of the skeletal joints. 8. This means when one muscle contracts, the other muscle relaxes. 9. Bending and straightening of the arm a) When the biceps contract. b) The tendons transmit the pulling force produced by the contraction to the forearm. c) At the same time, the triceps relaxes. d) As a result, the elbow joint flexes or bends and the forearm moves upwards. e) This causes the bending and straightening of the arm.


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The structure of a muscle

1. A skeletal muscle such as the biceps consists of bundles of muscle fibres and large supply of nerves and blood vessels. 2. A muscle fibre is a single, long cylindrical cell that contains many nuclei. 3. A muscle fibre is made up of bundles of smaller units called myofibrils. 4. Each myofibril is made up of actin and myosin ( protein filaments). 5. The interaction of both these proteins causes muscle contractions. 6. Muscle contraction involves the nervous systema and requires energy. Consequences of impaired musculoskeletal system on support and locomotion 1. Muscle cramp Definition: sudden contraction of one or more muscles which results in a sudden, intense pain and inability to use the affected muscle. Causes: - common among endurance athletes. - inadequate stretching and muscle fatigue. 2. Muscular dystrophy Definition: Caused by the progressive degeneration and weakness of the skeletal muscles That control movement. Causes: - mutated gene which is found on the X chromosome and mainly affects the boys.


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3. Osteoporosis Definition: Common bone disorder, especially among elderly women. The bones become thinner, more brittle and more porous. Causes: - Loss of bone mass begins after the age of 30 and accelerates greatly around the age 45. - If dietary intake of the of phosphate and calcium is insufficient. - Bone production and bone tissue will suffer resulting in brittle and fragile bones. Symptoms: - fractures of the vertebrae, wrist or hips - loss of height and stooped posture Prevention: - Adequae intake of calcium, phosphorus and vitamin D. - Regular exercise 4. Arthritis Definition: - Decreased production of synovial fluid in joints and cartilage between bones become thinner (osteoarthritis), and ligaments shorten and lose some of their elasticity. - Suffer from a painful and stiff knee which restricts daily activities like walking.


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The mechanism of locomotion in animals Locomotion in an animal with a hydrostatic skeleton (earthworm)

1. Earthworms have a hydrostatic skeleton (the force of contraction is applied to a coelum (fluid filled chamber). 2. Coelom is surrounded by two antagonistic muscle: a) circular muscles – surround the chamber b) longitudinal muscles – extend from one end to the other. 3. Thinner and longer: When circular muscle contract and the longitudinal muscle relax. 4. Shorter and thicker: When circular muscle relax and the longitudinal muscle contract. 5. The muscles contract rhythmically to produce peristaltic waves which begins at the front and move towards the end of the body. 6. Earthworm has chaetae (bristles) which anchor parts of the body to the ground so that other parts can be pulled towards it.


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Locomotion in an animal with exoskeleton (grasshopper)

1. A grasshopper uses three legs to support the body off the ground, while the other three legs move together to make successive steps while walking. 2. The flexor and extensor (antagonistic) muscles are attached to the internal surface of the exoskeleton. 3. Flexor muscles bend a joint. 4. Extensor muscles straighten it. 5. The rear legs of a grasshopper are long and muscular and is adapted for hopping. 6. Sitting position: When the flexor muscle contracts, the lower leg is pulled towards the body. The hind leg is folded in a Z shape and ready for a jump. 7. Jump: When the extensor muscle contracts, the leg jerks backwards, propelling the grasshopper forward and upward into the air.


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Locomotion in an animal with an endoskeleton (fish)

1. Why can a fish swim in a viscous and dense environment: a) body wight is supported by water to overcome gravity. b) sleek and streamlined body to overcome resistance. c) overlapping scales on the body of a fish face backwards to overcome resistance. d) covered by slimy coating to minimize frictional drag and maintains a smooth flow of water. 2. Vertebral column of the fish is moved from side to side by the contraction and relaxation of myotomes.


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3. Myotomes – W shaped muscle blocks that make up each side of the body of a fish and carry out opposite action. 4. Alternating waves of contraction and relaxation pass down the myotomes on either side of the body from the head to the tail. 5. These cause different parts of the body to be swept from side to side pushing water backwards and sideways and the body forwards. 6. Tendency for a fish to become unstable in water during movement, leading to:a) yawing – sideways movement b) pitching – vertical plane movement c) rolling – transverse plane movement 7. Movements are countered by fins. Caudal fin provides thrust and controls the fish’s direction.

8. These movements are countered by:a) yawing – resisted by the median (dorsal and ventral) fin b) rolling – resisted by median fin c) Pitching – resisted by paired pelvic fin and pectoral fin which acts as brakes and rudders. 9. Bony fish have swim bladders to help them maintain buoyancy in the water. 10. The swim bladder is a sac inside the abdomen that contains gas. 11. Controlling the amount of gas in the swim bladder, a fish can change its buoyancy so that it has the same relative density as the surrounding water.


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2.2 Appreciating a Healthy Muscoskeletal System 1. Adequte calcium intake 2. Physical activities and exercise – strengthen joint structures, increase muscular performance and delay the progress of arthritis. 2.3 Support in Plants 1. Why? a) Plant grows and it produces more leaves. b) Grow tall therefore needs to withstand the forces of gravity. c) Spreading of leaves and branches horizontally. 2. Aquatic plants are supported by buoyancy and support. Support in aquatic and terrestrial plants Submerged plants 1. Hydrilla sp. have thin, narrow and flexible leaves. 2. This type of leaves provide little resistance to water flows, plants can be tugged at and pulled by water currents without being damaged. 3. Air sacs inside the leaves and stems keep the plant floating close to the surface to obtain maximum sunlight. 4. Their stems have no woody tissues. Floating plants 1. Water hyacinth (Eichornia crassipes) have broad leaves that are firm but flexible enough to resist tearing by wave action. 2. Aerenchyma tissues (spongy tissues with large air spaces between the cells) in the stems and leaves provide buoyancy so that the plants can float on the surface of the water. Herbaceous plants (Terresterial plants) 1. Support provided by the turgidity of the parenchyma and collenchyma cells. 2. Turgor pressure of the fluid content in the central vacuole pushes the cell membrane and the cell contents against the cell wall, creating support for the stem, root and leaves. 3. The thickening of the cell walls with cellulose and pectin in collenchyma cells provide additional mechanical strength. Woody plants 1. Support provided by sclerenchyma and xylem tissues. 2. Sclerenchyma tissue is composed of cells with secondary cell walls that are usually lignified which support non-growing parts of plants. 3. Two types of sclerenchyma tissue: a) fibres – long, straight and thin


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- found around vascular tissues b) sclereids – short, circular and irregular shaped - found in fruit and seeds 4. During primary growth development, the cell walls of xylem vessels and tracheids are thickened with lignin and forms vessels .

5. Type of vessels: a) annular (ring shaped) vessel b) spiral vessel c) scalariform (ladder like) vessel d) pitted vessel 6. Secondary growth of xylem results in the formation of wood which makes the plant stronger and and provides support.. 7. Other supporting structures: a) Buttress root – roots that come out from the lower part of the trunk and grow into the ground, providing support for the tree. b) Creepers, vines and lianas – use other trees for support.


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Form 5 Biology (Chapter 2: Locomotion & Support)

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