Skeleton

HideShow resource information
Preview of Skeleton

First 229 words of the document:

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
bone] for strength and support
Baby -> parts of the skeleton made of cartilage =soft =movement
during birth
Types of skeleton
Endoskeleton =[hard skeletal muscle + connective tissue on the
outside] e.g. Vertebrates
Exoskeleton =[hard, protective material on outside of body -> softer
tissues is on the inside] e.g. Crustacean, insects
o Limits growth therefore the molt
Hydro skeleton =[Soft bodied animals such as slugs use body fluid]
Bones can be fragile
Manufacture of bone by the body requires
Calcium
Amino acids
Vitamin d
Phosphate
Hormones
o Older ­the bones are more fragile
Osteoporosis: cavities appear in bone
Women are protected by it by estrogen until menopause
supplied by hormone replacement therapy [HRT]
Vertebrate skeleton
1. Axial Skeleton
Skull/backbone/ribcage
2. Appendicular Skeleton
Limbs/girdles ­connect them to the axis
Total bones: 206
Largest: Femur
Smallest: Middle of the ear

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

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
Bone cells are manufactured in the bone marrow
Exoskeleton
Muscle
Is on the inside
Chitin
On the outside
Prevents water loss
Protects soft tissue from predators
Must be shed + replaced as insect grows [would…read more

Page 3

Preview of page 3

Here's a taster:

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 move body
S torage
Calcium and Phosphate are stored in bones
M anufacture of blood cells
The bone marrow generates blood cells [only some bones]
S urface area
For muscle attachment
C onduction of sound…read more

Page 4

Preview of page 4

Here's a taster:

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 and supplies surface area for
attachment of head.…read more

Page 5

Preview of page 5

Here's a taster:

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]…read more

Page 6

Preview of page 6

Here's a taster:

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 rib cage during breathing
o Functions
o Protection of lungs and heart
o Surface for muscle attachment
Appendicular Skeleton
A rms
L egs
P ectoral Girdle ->connect the arms to rest of skeleton
P elvic…read more

Page 7

Preview of page 7

Here's a taster:

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

Page 8

Preview of page 8

Here's a taster:

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 ­has crystals of calcium phosphate, calcium carbonate, magnesium
salts with collagen fibers, which make the bone stronger and more flexible.…read more

Page 9

Preview of page 9

Here's a taster:

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 is subjected to variety of compressive and tensile forces. Designed to
withstand forces + light to allow movement.…read more

Page 10

Preview of page 10

Here's a taster:

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
Hard but flexible tissue made up of cells ­chondrocytes [produce matrix]
With an organic Matrix [consisting of various amounts of collagen fibrils.
Elastic and can withstand compressive forces.…read more

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »