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Section 2
The skeleton

Bone and cartilage

Skeleton ­ hard tissue formed by living cells
Bone and other tissues
Cartilage: hard but more flexible than bone
Hard Bone: is cartilage with more intense amounts of calcium
salts to solidify the bone
Older mammal -> increasing amount of calcified tissue [hard…

Page 2

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Female Skeleton
Broader hips
Narrower shoulders
Knees bent inwards
Arms bent outwards
More easily dislocated lower jaw compared with males

Skull
Protects brain
Backbone
Supports human body in upright position
Forelimb
Movement of this helps in feeding and the use of tools
Pelvic Girdle
Storage for calcium and phosphate
Femur…

Page 3

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Functions of the skeleton



S upport
Hard incompressible bone holds body in position


P rotection
Vital tissues + organs, protected by a covering of bone
Brain protected from shock inside skull
Heart + lungs by rib cage


M ovement
Bones meet at joints ­form levers
Muscles pull on levers to…

Page 4

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Axial Skeleton

Provides central support system of body
Protects internal organs



S KULL


V ERTEBRAL COLUMN [SPINAL]


R IB CAGE


S TERNUM

SKULL

Cranial bones + Facial bones
Cranium =8 flat bones
Immovably joined together by joints call sutures
o Functions
o Protects brain
o Holds + protects sense organs…

Page 5

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o Shaper absorbs jolts and aids in balancing

CERVICLE [NECK]
7 VERTEBRAE

THORACIC [CHEST]
12 VERTERBRAE

LUMBAR [LOWER BACK]
5 VERTEBRAE

SACRUM
5 VERTEBRAE `JOINED TOGETHER'

COCCYX [TAIL]
4 FUSSED VERTEBRAE

SEE DIAGRAM OF VERTEBRAL COLUMN [GET PICTURE]

Page 6

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RIB CAGE

12 pairs of ribs
Extended from thoracic vertebra at back to sternum at front
Upper -7pairs attached to sternum [by flexible cartilage strips]
Middle -3pairs attached to other ribs by cartilage
Lower -2pairs FLOATING RIBS only attached at the back
Intercostal muscle occur between ribs
Allow movement of…

Page 7

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Pelvic girdle
Attached to axial skeleton by some of the strongest ligaments in the body,
forms a very strong base for articulation of legs.

Childhood
Made for ileum, ischium + pubis
[Two bones joined in front by a semi-movable joint
-> Pubis symphysis

Adults
These bones are fussed for strength…

Page 8

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o Microscopic hollow cylinders that run parallel to each other
[lengthways]
o Cylinders are called: HAVERSIAN SYSTEM

Blood vessels + nerves run along central canal of each Haversian system, they
each contain concentric rings of bone material [Matrix] with minute spaces in
it that hold bone cells [osteocytes]

Hard matrix…

Page 9

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Bone Growth

Skeleton starts as cartilage [fibrous connective tissue in foetus]. Cartilage
gradually replaced by bone

Bone increases in length at end =epiphyseal plate [where new cartilage laid
down] the gradually converted to bone.

Mature -bone growth ceases ­ epiphyseal plate converts into fine epiphyseal
line.

Strength of bone

Skeleton…

Page 10

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Strength and lightness
Bones built like tubes. Hard bone on the outside, soft marrow in the
center
End of bone = spongy and interconnecting strips of hard bone separated
by spaces, strips grow according to stresses put on bone and can change
if bone is subjected to different stresses.




Cartilage…

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