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Skeletons
B5a In good shape
Figure 5a.1 The human skeleton.
An exoskeleton made ofchitin covers an insect’s body.
attachment ofmuscle to theskeleton
flexiblemembrane
The insect’s musclesare attached to theinside of theskeleton.
chitinous exoskeleton
Figure 5a.2 An insect’s exoskeleton.
Muscles in the body wall squeezein on the fluid, keeping the wormin shape.
The spaces inside anearthworm’s body arefilled with fluid.
Figure 5a.3 An earthworm’s hydrostatic skeleton.
orbit
lower jaw
clavicle
sternum
rib
pelvic girdle
femur
patella
metatarsals
phalanges
cranium
vertebral column
scapula
humerus
ulna
radius
carpals
metacarpalsphalanges
fi bula
tibia
tarsals
© Cambridge University Press www.cambridge.org
Cambridge University Press978-0-521-70904-0 - Gateway Separate Science for OCRDavid Acaster, Mary Jones and David SangExcerptMore information
2 B5a In good shape
Which is the best kind of skeleton?
Figure 5a.4 This dragonfly was a water-living nymph less than an hour before this photo was taken. Now it has to wait until its new exoskeleton has hardened before it can fly.
Time /days
0
10
20
30
Leng
th o
f h
ind
fem
ur
/ mm
0 10 20 30 40 6050
Figure 5a.5 Changes in the length of a locust’s leg as it grows to an adult.
© Cambridge University Press www.cambridge.org
Cambridge University Press978-0-521-70904-0 - Gateway Separate Science for OCRDavid Acaster, Mary Jones and David SangExcerptMore information
B5a In good shape 3
Bone growth
layer of cartilagecovering the surface
head – the toppart of the bone,which forms ajoint with thepelvis
shaft – the mainpart of the bone
outer layer ofhard, compactbone
inner spacefilled with softbone marrow
blood supply to allparts of the bone
Figure 5a.6 The structure of a long bone.
H
Figure 5a.7 An X-ray of some of the bones of a child.
Bone and cartilage
part of pelvis (hip bone)
head of femur, covered with cartilage
growth plate, where cartilage cells divide and make new cells, which eventually turn to bone
femur
© Cambridge University Press www.cambridge.org
Cambridge University Press978-0-521-70904-0 - Gateway Separate Science for OCRDavid Acaster, Mary Jones and David SangExcerptMore information
4 B5a In good shape
Broken bones
Types of fracture
simple fracture
compound fracture
greenstick fracture
Figure 5a.8 Three types of fracture.
Figure 5a.9 A hard plaster holds a limb firmly in place so that the broken bone cannot move and gradually heals in the correct position.
H
H
© Cambridge University Press www.cambridge.org
Cambridge University Press978-0-521-70904-0 - Gateway Separate Science for OCRDavid Acaster, Mary Jones and David SangExcerptMore information
B5a In good shape 5
Osteoporosis
Figure 5a.10 This X-ray shows a broken collar bone. You can feel where your collar bone should be by feeling just below your shoulder. A broken collar bone is a common injury caused by a fall from a horse or a bicycle.
Bone loss in space
Figure 5a.11 Working leg muscles against a machine that provides mechanical resistance can avoid some of the worst effects of weightlessness.
© Cambridge University Press www.cambridge.org
Cambridge University Press978-0-521-70904-0 - Gateway Separate Science for OCRDavid Acaster, Mary Jones and David SangExcerptMore information
