Edexcel IGCSE - Human Biology - Chapter 07 - Form & Movement
- 1. Chapter 07: Form & Movement Edexcel IGCSE Human Biology chandimakumara007@gmail.com 1
- 2. Introduction • Vertebrates – The organisms that composed of a vertebral column • Voluntary muscles/ skeletal muscles – Muscles connected to bones – Controlled consciously/voluntarily by the brain chandimakumara007@gmail.com +94713269478 2
- 3. Importance of the skeleton • Support & movement • Protect vital organs – Cranium – Brain, eyes, ears – Vertebrae – spinal cord – Rib cage – heart, lungs • Produce blood products(RBC, platelets) in long bones (sternum, femur, pelvis) chandimakumara007@gmail.com +94713269478 3
- 5. Human skeleton The skeleton is divided in to two parts 1. Axial skeleton – Cranium – Vertebral column – Rib cage 2. Appendicular skeleton – Pelvis – Clavicle – Scapula – Limb bones chandimakumara007@gmail.com +94713269478 5
- 7. Bone Structure • Bone; – is hard – it is made up by Calcium phosphate – Can resist bending, compression forces – Made of cells called osteocytes along with protein fibers • Middle of the bone is composed of spongy bones with fewer Ca2+ salts and spaces • Some larger bones contain cavities fill with bone marrow store fats and produce blood cells • The outside of the bone is made up with compact bone chandimakumara007@gmail.com +94713269478 7
- 8. Bone Structure • Ossification – The process converting cartilages in to bones – Nearly completed once the baby is born • Haversian system – The arrangement of osteocytes around cannels containing blood vessels and nerves – The osteocytes secrete Ca2+ ions and protein fibers in order to make the bone matrix – Watch this link : https://www.youtube.com/watch?v=d9owEvYdouk chandimakumara007@gmail.com +94713269478 8
- 9. Bone Structure • Cartilages – Can be seen at the end of long bones – Act as a cushion between bones – It is tough but, flexible – Consists of cells called as chondrocytes which secrete various proteins • Periosteum – Outer surface of the bone • Long bones stop growing in late teens, but the internal structure can be changed due to; – Hormones – Diet ( ex: Rickets due to Vit. D deficiency, less Ca2+ intake ) – Exercise chandimakumara007@gmail.com +94713269478 9
- 10. Joints • The point where two bones are met/articulated • Features ; – Having a way to avoid dislocation – Having a way to reduce friction – Having a shock-absorbing surface • Movable joints are called as synovial joints • The oily Synovial fluid is secreted by synovial membrane to reduce friction • The cartilage acts as the shock absorber chandimakumara007@gmail.com +94713269478 10
- 11. • The joint is surrounded by tough fibrous capsule and held together by ligaments composed of fibers • Ligaments have tensile strength to resist stretching and have elasticity to bend Joints chandimakumara007@gmail.com +94713269478 11
- 12. Classification of joints Type of joint Movement Example 1. Freely movement joints One plane Hinge joint in elbow Three planes Ball and socket joint in hip & shoulder 2. Partially movable joints Some movement Vertebrae facilitated by cartilages 3. Immovable (fixed) joints No movement Joints in skull Cranium consist of 22 bones12
- 13. Muscles • Muscles are attached to the bones and move them by contracting • Tendons ― attach muscles in to the bones ― have very high tensile strength ― not very elastic • When a muscle is; ―contracted -> the length is shorten ― relaxed -> the length gets longer • Antagonistic pairs - muscles work in pairs; one contracting while other relaxes (Ex : biceps & triceps) chandimakumara007@gmail.com +94713269478 13
- 15. Muscles • In arm; ―flexion – biceps contracts, triceps relaxes ―Extension – triceps contracts, biceps relaxes • When a muscle contracts, ― the bone at one end of the muscle moves and the place where the muscle is attached to the stationary bone is called the origin ―The bone at the other end stays still and the place where the muscle is attached to the moving bone is called as the insertion ― the insertion moves towards origin chandimakumara007@gmail.com +94713269478 15
- 16. Bending the spine • Spine is made of bones called vertebrae • Joined by synovial joints which allow a slight movement • Rectus muscles responsible for bending the spine • Types of vertebrae 1. Cervical vertebrae 2. Thoracic vertebrae 3. Lumber vertebrae 4. Sacrum (five fused vertebrae at the bottom) chandimakumara007@gmail.com +94713269478 16
- 17. Bending the spine https://www.youtube.com/watch?v=178XnTK5uHk 1 2 chandimakumara007@gmail.com +94713269478 17
- 19. Muscle contraction and exercise • Skeletal muscle made up of highly specialized muscle cells or fibres arranged in bundles • Adopted to contraction • Composed of fine protein filaments • Thin filaments slide past the thick filaments, making fibers shorter chandimakumara007@gmail.com +94713269478 19
- 20. Muscle contraction and exercise • Contraction of muscles needs energy comes from respiration • In respiration glucose and O2 are converted into CO2 , water and release the energy • Some energy is lost as heat • In vigorous exercises; – HR increases to provide more oxygenated blood to muscles – RR and volume of breath is increased to receive more O2 and to release more CO2 – Blood in gut is diverted towards muscles – Vasodilatation and sweating happens in the skin chandimakumara007@gmail.com +94713269478 20
- 21. Muscle contraction and exercise • Even when a muscle is relaxed, some of its fibres are contracted and this state of partial contraction called as muscle tone • It keeps muscles taut, but don’t cause movement ( Ex: Sitting & standing) • Regular exercises; ― keeps muscle toned ― develops muscles ― Avoid stiffness and soreness of muscles ―Improves blood circulation ―Keeps joints working smoothly chandimakumara007@gmail.com +94713269478 21