Ls2 afet unit 6 support systems in animals

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2. 1. DIFFERENT TYPES OF SKELETONS The three main types of skeletons are: Hydrostatic skeletons (lack hard parts) Exoskeletons (external hard parts) Endoskeletons (internal hard parts) 3. Hydrostatic Skeletons A hydrostatic skeleton consists of fluid held under pressure in a closed body This is the main type of skeleton in most cnidarians, flatworms, nematodes, and annelids Annelids use their hydrostatic skeleton for peristalsis, a type of movement on land produced by rhythmic waves of muscle contractions. 4. HYDROSTATIC SKELETONS NEMATODEANNELIDACNIDARIAFLATWORMS 5. Exoskeletons An exoskeleton is a hard encasement deposited on the surface of an animal Exoskeletons are found in most molluscs and arthropods Arthropod exoskeletons are made of cuticle and can be both strong and flexible The polysaccharide chitin is often found in arthropod cuticle 6. EXOSKELETONS MOLLUSCARTHROPODS 7. ENDOSKELETONS An endoskeleton consists of hard supporting elements, such as bones, buried in soft tissue Endoskeletons are found in sponges, echinoderms, and chordates A mammalian skeleton has more than 200 bones Some bones are fused; others are connected at joints by ligaments that allow freedom of movement. 8. ENDOSKELETONS SPONGESECHINODERMATACHORDATA 9. 2. THE HUMAN SKELETON 10. 2. THE HUMAN SKELETON 11. a. AXIAL SKELETON: i)Human Skull Consist of 28 bones It consists of flat bones that are connected on the sides by immovable joints called sutures. In babies not all the bones of the skull make contact with each other and fontanels are formed. The lower jaw bone (Mandible) is the only movable bone of the skull Upper jaw (Maxilla) is not moveable. The large opening at the base of the skull is called the foramen magnum it is where the spinal cord enters the skull. 12. Human Skull 13. a. AXIAL SKELETON: ii)VERTEBRAL COLUMN Consists of 33 bones called vertebrae. 24 vertebrae are individual single bones. 9 vertebrae are fused to form the sacrum and coccyx. Cartilage disks are found between vertebrae. The s-shaped structure of the vertebral column and the disks absorb shock and help to protect the spinal cord. The first vertebrae Atlas carry the weight of the skull, allows the head to nod. 2nd vertebrae Axis allows head to move to the side 14. a. AXIAL SKELETON:ii) VERTEBRAL COLUMN Vertebrae is divided into 7 Cervical vertebrae 12 Thoracic vertebrae 5 Lumbar vertebrae 5 fused vertebrae = sacrum 4 fused vertebrae = coccyx 15. a. AXIAL SKELETON: iii) THORAX Consists of the sternum, 12 pairs of ribs and thoracic vertebrae. It protects the heart and lungs. First 7 pairs of ribs are directly attached to the sternum by cartilage called true ribs. Next 5 pairs false ribs last 2 pairs of false ribs are not attached to the sternum called floating ribs Intercostal muscles found between ribs aid in breathing process. 16. a. AXIAL SKELETON: iii) THORAXTrue ribssternumFalse ribsFloating ribs 17. b. APPENDICULAR SKELETON Made up of the shoulder (pectoral girdle), arms, hips (pelvic girdle) and legs. 126 bones. Function: Movement 18. b. APPENDICULAR SKELETON i) Pectoral girdle and arm 19. b. APPENDICULAR SKELETON i) Pelvic girdle and leg 20. 3. FUNCTIONS OF A SKELETON Support Movement Protection Blood cell production Storage Endocrine regulation 21. a. Support The skeleton provides the framework which supports the body and maintains its shape. The pelvis, associated ligaments and muscles provide a floor for the pelvic structures. Without the ribs, costal cartilages, and intercostal muscles, the heart would collapse. 22. b. MOVEMENT The joints between bones permit movement. Movement is powered by skeletal muscles, which are attached to the skeleton at various sites on bones. Muscles, bones, and joints provide the principal mechanics for movement, all coordinated by the nervous system. 23. c. Protection The skeleton protects many vital organs e.g.: The skull protects the brain, the eyes, and the middle and inner ears. The vertebrae protects the spinal cord. The rib cage, spine, and sternum protect the lungs, heart and major blood vessels. 24. d. Blood cell production The skeleton is the site of haematopoiesis, which takes place in red bone marrow. Haematopoiesisis the formation of blood cellular components. 25. e. Storage Bone matrix can store calcium and is involved in calcium metabolism. The bone marrow can store iron and is involved in iron metabolism. Bones are not entirely made of calcium, but a mixture of chondroitin sulfate and hydroxyapatite, the latter making up 70% of a bone. 26. f. Endocrine regulation Bone cells release a hormone called osteocalcin, which contributes to the regulation of blood sugar (glucose) and fat deposition. Osteocalcin increases both the insulin secretion and sensitivity. 27. 4. STRUCTURE OF A LONG BONE A long bone is an elongated bone consisting of a body (diaphysis) and two terminal parts (epiphyses), such as found in the leg and arm bones (femur, radius, phalanges and others). 28. 4. STRUCTURE OF A LONG BONE 29. 5. DIFFERENT JOINTS In the human body, there are joints where two or more bones meet in the skeleton. Immovable joints do not allow movement and Synovial joints are movevable joints and allow movement of the bones. Ligaments hold bones together. Tendons attach muscle to bone,. 30. STRUCTURE OF A SYNOVIAL JOINT 31. Different types of synavial joints are: Ball and socket joint Hinge joint Pivot joint Gliding joint 32. BALL AND SOCKET JOINT: Joints of the hips and shoulders Allows rotating movement of arms and legs 33. HINGE JOINT: Joints of the elbows, knees, fingers and toes Only allows movement in one direction. 34. PIVOT JOINT: Joints between atlas and axis One bone turns on another 35. GLIDING JOINT: Joints of the wrist and ankles The flat surface of one bone glides over the surface of a bone next to it. 36. JOINT DISORDERS Do research (self study) on the following disorders, you have to be able to briefly explain what each of them are (will not be marked but there will be question in the exam and semester test about it) Dislocation Sprains Arthritis Osteoarthritis Rheumatoid arthritis 37. 6. MACRO STRUCTURE OF SKELETAL MUSCLES Epimysium: Surrounds entire muscle Perimysium: Surrounds bundles of muscle fibres (Fascicles) Endomysium: Surrounds individual muscle fibres 38. 6. STRUCTURE OF SKELETAL MUSCLES 39. MICRO STRUCTURE OF SKELETAL MUSCLES Sarcolemma: Muscle cell membrane Myofibrils: Threadlike strands within muscle fibres Actin (thin filament) Myosin (thick filament) 40. SKELETAL MUSCLES Muscles are attached to bones by means of tendons. Skeletal muscles produce movement by contracting. This exerts a force on tendons, which in return, pulls on bones. Muscles occur in pairs which work antagonistic against each other. When one contracts the other relaxes. 41. MOVEMENT OF THE ARM