Download Function of Bones

Part A
Skeletal Cartilages, Classification
of Bones, and Functions of Bones
Without Bones
We would look
like Slugs
Skeletal Cartilages
• Cartilage tissue consists primarily
of water
– Accounts for its resilience (ability
to spring back to its original shape
after being compressed)
• Contains no blood vessels or nerves
• Surrounded by the perichondrium
Perichondrium
• Surrounds skeletal cartilage
• Made from dense irregular
connective tissue
• Resists outward expansion when
cartilage is compressed
• Contains blood vessels from which
nutrients diffuse through matrix
to reach cartilage cells
– This limits cartilage thickness
Skeletal Cartilages
• Three types of Skeletal
Cartilages
– Hyaline
– Elastic
– Fibrocartilage
• All contain chondrocyte cells and
an extracellular matrix of ground
substance and fibers
• Looks like frosted
glass when freshly
exposed
• Provides support,
flexibility, and
resilience
• Is the most
abundant skeletal
cartilage
• Contains fine
collagen fibers
Hyaline
Cartilage
Hyaline Cartilage
• Is present in these cartilages:
– Articular – covers the ends of
long bones
– Costal – connects the ribs to the
sternum
– Respiratory – makes up the larynx
and reinforces air passages
– Nasal – supports the nose
Hyaline Cartilage in Blue
Figure 6.1
Elastic Cartilage
• Similar to hyaline
cartilage but
contains more
elastic fibers
– Better able to
stand repeated
bending
Elastic Cartilage
• Found in the
external ear and
the epiglottis
– Epiglottis is the
flap that covers
the opening of
the larynx when
we swallow
Elastic Cartilage in Green
Figure 6.1
Fibrocartilage
• Highly
compressible
with great
tensile strength
• Contains thick
collagen fibers
Fibrocartilage
• Found in sites
subjected to
both heavy
pressure and
stretch
– menisci of the
knee
– intervertebral
discs
Fibrocartilage in Red
Figure 6.1
Growth of Cartilage
• Cartilage grows in two ways
• 1. Appositional – Growth from
outside
– cells in the perichondrium secrete
matrix against the external face
of existing cartilage
Growth of Cartilage
• Cartilage grows in two ways
• 2. Interstitial – Growth from inside
– lacunae-bound chondrocytes
inside the cartilage divide and
secrete new matrix, expanding
the cartilage from within
Growth of Cartilage
• Typically cartilage growth ends
during adolescence (same time as
skeleton)
• Calcification of cartilage occurs
under certain conditions
– During normal bone growth in
youth
– During old age
Growth of Cartilage
• Calcified cartilage is not bone
• Calcification is when calcium salts
are deposited in the matrix and
harden
Classification of Bones
• Two basic types
of bone tissue
– Compact Bone
• Homogeneous
• Dense - looks
smooth and
solid to the
naked eye
Classification of Bones
• Two basic types
of bone tissue
– Spongy Bone
• Honey comb of
small needlelike pieces of
bone
• Many open
spaces
Classification of Bones
• The 206 named bones of the human
skeleton are divided into two
groups:
– Axial skeleton
– Appendicular skeleton
Axial Skeleton
• Includes bones of the skull,
vertebral column, and rib cage
• Most involved in protecting,
supporting, or carrying other
body parts
Axial Skeleton in dark tan
Figure 6.1
Appendicular Skeleton
• Includes bones of the upper and
lower limbs, shoulder, and hip
Appendicular Skeleton
• Locomotion
– Helps us move
– Helps us manipulate our
environment
Appendicular Skeletons in yellow
Figure 6.1
Classification of Bones
by Shape
•
•
•
•
Long Bones
Short bones
Flat bones
Irregular bones
Long Bones
• Longer than
they are
wide
• Has a shaft
with heads
at both ends
• Contains
mostly
compact
bone
Figure 6.2a
Long Bones
• Examples of
long bones
– Humerus
– Femur
– The bones
in your
fingers
Figure 6.2a
Short Bones
• Contains mostly
spongy bone
• Cube shaped
– Wrist and
ankles
• Carpals –
Tarsals
Short Bones
• Sesamoid bones
– shaped like a
sesame seed
– Special bones
that form
within tendons
• Example:
Patella
• Thin &
Flattened
• Usually
curved
• Thin layers
of compact
bone around
a layer of
spongy bone
Flat Bones
Figure 6.2c
Flat Bones
• Examples
– Sternum
– Ribs
– Scapulae
– most skull
bones
Figure 6.2c
Irregular Bones
• Irregular
shape
• Bones with
complicated
shapes or
ones that
do not fit
into other
categories
Figure 6.2d
Irregular Bones
• Examples
– vertebrae
– hip bones
Figure 6.2d
Function of Bones
• Support
• Protection
• Movement
• Mineral storage
• Blood cell formation
Function of Bones
• Support of the body
– form the framework that
supports the body and cradles
soft organs
• Protection of soft organs
– provide a protective case for the
brain, spinal cord, and vital organs
• Movement due to attached skeletal
muscles
– provide levers for muscles
Function of Bones
• Storage of minerals and fats
– reservoir for minerals, especially
calcium and phosphorus
• Blood cell formation
– hematopoiesis occurs within the
marrow cavities of bones
Study Guide
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complete pages 120122 of the study guide
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