support systems in animals 1 · axial appendicular axial skeleton consists of the bones that lie...

Life Sciences Grade 10

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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

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

TYPES

ENDOSKELETON

HYDROSTATICEXOSKELETON


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Hydra:

Earthworm:

EXOSKELETON:

- Rigid external skeleton which can be hard or leathery

The exoskeleton of arthropods is made of chitin.


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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:


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Starfish:

TYPE OF SKELETON ADVANTAGES DISDAVANTAGES

HYDROSTATIC No need for specialised structures or tissues. Very little energy needed for locomotion as it is aided by water or moist land environment

Size is limited Must have moist habitat to survive Speed of locomotion limited

EXOSKELETON Protects animal Good body support Reduces water loss Provides good leverage for muscle action

Animal has to moult in order to grow Growth limited Movement limited to joints

ENDOSKELETON Greater flexibility Can grow much larger than other types Good body support and shape Protects internal organs Provides more positions for muscle attachment – more power to muscles

No outside protection Does not prevent dehydration Movement limited to joints


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HUMAN SKELETAL SYSTEM

AXIAL APPENDICULAR

AXIAL SKELETON

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

*** Hyoid bone - U-shaped bone in the neck to which the tongue is attached.

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


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The Skull

The Vertebral Column

Cervical Vertebrae (7)

Thoracic Vertebrae (12)

Lumbar Vertebrae (5)

Sacrum 5 (fused)

Coccyx 4 (fused)


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The Thorax

The Rib Cage and Sternum

Sternum - Manubrium, body, xiphoid process True Ribs (7) False Ribs (3) Floating Ribs (2)


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THE APPENDICULAR SKELETON


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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


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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.


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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:


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3.1 Identify parts labelled 2, 4 and 5. 3.2 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:

4.1 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.

A

B C

D

1

2

support systems in animals 1 · axial appendicular axial skeleton consists of the bones that lie...

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