SESSION 8: SUPPORT SYSTEMS IN ANIMALS PART 1

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1 SESSION 8: SUPPORT SYSTEMS IN ANIMALS PART 1 KEY CONCEPTS hydrostatic skeleton, exoskeleton, endoskeleton examples, advantages & disadvantages human skeleton parts of axial & appendicular skeleton functions of skeleton structure of a long bone X-PLANATION Skeletons have three major functions: 1. Support 2. Movement 3. Protection of internal organs ENDOSKELETON TYPES EXOSKELETON HYDROSTATIC HYDROSTATIC SKELETON: Consists of fluid held under pressure in a closed body compartment Protects body parts by cushioning them from shock Provides body shape, which can be changed by contracting muscles in the body wall Provides resistance for muscle action Earthworms, hydras, are examples of organisms with hydrostatic skeletons Brought to you by Page 1

2 Hydra: Earthworm: EXOSKELETON: - Rigid external skeleton which can be hard or leathery The exoskeleton of arthropods is made of chitin. Brought to you by Page 2

3 ENDOSKELETON (INSIDE THE BODY): Consists of hard or leathery supporting elements situated among a variety of tissues Most echinoderms, including sea stars and sea urchins, have an endoskeleton of hard plates beneath their skin Vertebrate endoskeletons consist of cartilage or a combination of cartilage and bone Sea Urchin: Brought to you by Page 3

4 Starfish: TYPE OF SKELETON ADVANTAGES DISDAVANTAGES HYDROSTATIC No need for specialised Size is limited structures or tissues. EXOSKELETON ENDOSKELETON Very little energy needed for locomotion as it is aided by water or moist land environment Protects animal Good body support Reduces water loss Provides good leverage for muscle action Greater flexibility Must have moist habitat to survive Speed of locomotion limited Animal has to moult in order to grow Growth limited Movement limited to joints No outside protection Can grow much larger than other types Good body support and shape Does not prevent dehydration Movement limited to joints Protects internal organs Provides more positions for muscle attachment more power to muscles Brought to you by Page 4

5 HUMAN SKELETAL SYSTEM AXIAL APPENDICULAR Consists of the bones that lie around the longitudinal axis of the human body Skull bones, auditory ossicles (ear bones), hyoid bone, ribs, sternum (breastbone), and bones of the vertebral column Consists of the bones of the upper and lower limbs (extremities), plus the bones forming the girdles that connect the limbs to the axial skeleton *** Hyoid bone - U-shaped bone in the neck to which the tongue is attached. AXIAL SKELETON Brought to you by Page 5

6 The Skull The Vertebral Column Cervical Vertebrae (7) Thoracic Vertebrae (12) Lumbar Vertebrae (5) Sacrum 5 (fused) Coccyx 4 (fused) Brought to you by Page 6

7 The Thorax The Rib Cage and Sternum Sternum - Manubrium, body, xiphoid process True Ribs (7) False Ribs (3) Floating Ribs (2) Brought to you by Page 7

8 THE APPENDICULAR SKELETON Brought to you by Page 8

9 The Pelvic Girdle Comparing male and female pelvic girdles: General Functions: Support - framework that supports body and cradles its soft organs Protection - for delicate organs, heart, lungs, brain Movement - bones act as levers for muscles Mineral storage - calcium & phosphate Blood cell formation - from bone marrow Brought to you by Page 9

10 Types of bones making up the skeletal system: Long Bones - metacarpals, metatarsals, phalanges, humerus, ulna, radius, tibia, fibula Short Bones - carpals, tarsals Flat Bones - rib, scapula, skull, sternum Irregular Bones - vertebrae, some facial bones X-AMPLE QUESTIONS Question 1: Explain 3 functions of the skeletal system. Brought to you by Page 10

11 Question 2: Complete the table below: Bones of Skeletal System Axial or Appendicular Skeleton Tarsals 1 Vertebrae 2 Ribcage 3 Scapula 4 Pelvis 5 Mandible 6 Question 3: Study the diagrams and answer the questions: Brought to you by Page 11

12 3.1 Identify parts labelled 2, 4 and What is the function of structure labelled 8? 3.3 Why are parts labelled 10 referred to as false ribs? 3.4 Provide the numbers of the following parts: a) floating ribs b) sternum Question 4: Study the following diagram and answer the questions: 1 D A B C Provide labels for parts A,B,C and D. 4.2 In which region (1 or 2) would you find the little toe. Provide a reason for your answer. Brought to you by Page 12