Provide the framework and internal core structure for the attachment of muscles
Bone is a living rigid tissue which forms the support structures for the rest of
the body. The process of bone formation is called
ossification.
The matrix of bone contains a dense arrangement of collagen fibres together with
mineral salts of calcium, magnesium and phosphates.
The calcium salts give bone its hardness and rigidity while collagen fibres give
bones its flexibility and strength.
Functions of bone
To serve as a firm
support framework for the whole body.
To
protect such delicate structures as the brain and spinal cord
To serve as levers, working with attached muscles to
produce movement.
To serve as a
storehouse for
calcium salts , which may be reabsorbed into the blood if there is not enough calcium in the
diet,
To
produce blood cells in the red marrow.
Microscopic structure of a long bone
Numerous hollow tunnels called
Haversian canals occur within the matrix of bone tissue and run parallel with the length of the
bone. Under the microscope they appear as black circles against a lighterbackground.
Each Haversian canal is surrounded by concentric rings of compact bone called
lamellae
Each of these layers contains a ring of fluid-filled cavities called
lacunae. Each of these lacuna will contain a number of bone cells called
osteocytes.
The lacunae are linked to each other and to the Haversian canal by a system of
very tiny interconnecting canals called
canaliculi. Strands of cytoplasm extend through these canals which supply the osteocytes
with oxygen and nutrients and remove waste products
The Haversian canals, lacunae, osteocytes and canaliculi together form a unit
called a
Haversion System and a number of these systems make up compact bone.
Apart from osteocytes which are embedded in the lacunae of bone there are two
other types of bone cells
Osteoblasts : Bone forming cells. These cells allow the bone to change and remodel its shape
as the organism grows and responds to stresses. If a bone is broken
or if strengthening is needed, bone cells lay down new tissue and repair damaged
tissue
Osteoclasts: Special bone cells for destroying and reabsorbing bone tissue.
Cartilage
Main features
cartilage is a tough semi-transparent flexible tissue
it is enclosed by a fibrous capsule called the
perichondrium
consists of living cells called
chondrocytes which secrete a rubbery protein matrix called
chondrin
chondrocytes occur in small fluid-filled spaces called
lacunae which are scattered throughout the matrix.
There are
no blood vessels or nerves in the matrix.
Cartilage and bone
Infant and young children do not have bones like those of adults. Their bones
are made mostly of
cartilage, a firm elastic fibrous material.
As the individual grows and matures, the cartilage is gradually replaced by bone
cells which deposit crystals of calcium carbonate and calcium phosphate.
This process called
ossification greatly increases the strength of the bone.
Bones usually continue to grow through adolescence. During this time a layer of
cartilage still exists between the head and shaft at either end of thebone.
The growth of the bone does not interfere with the way joints fit together.Eventually once all the cartilage has become ossified bone growth will stop
Types of cartilage
Hyaline Cartilage:
Appearance: glass-like, bluish-white in colour, few fibres present
Location:
at the ends of bones as articular cartilage
where the ribs are joined to the sternum
forms rings in the trachea
larynx and tip of nose
as temporary cartilage in bones.
Functions:
reduces friction at the joints.
allows a degree of movement during breathing
keeps the trachea open.
Forms permanent structures
Allows for bones to increase in length.
Fibrocartilage
Appearance: has numerous white collagen fibres in the matrix.
Location:
as cartilaginous discs between the vertabrae
in the rim of sockets of ball and socket joints
between the pubic bones
Functions:
act as shock absorbers
make the cavity deeper without hampering movement
allows for limited movement
Elastic cartilage
Appearance: has a network of yellow elastic fibres in the matrix.
Location:
in the pinna of the ear
in the epiglottis
Functions:
maintains the shape of the ear but also allows for changes in shape.
strengthens the epiglottis which prevents food from entering the trachea.
Ligaments
Ligaments consist of white collagen fibres and a network of yellow elastic
fibres.
The collagen fibres are less orderly and more randomly arranged than in tendons
and ligaments have varying amounts of elastic fibres.
Ligaments join bone to bone and they also control the degree of movement allowed
between the two bones. This is achieved by the amount of elasticity in aligament i.e. a ligament will only stretch enough to allow a particular
movement to happen.
The more elastic fibres in the ligament the greater the articulation between two
bones. Thus the attachment of ligaments between bones keep the bones of a jointin position.
By restricting bone movement ligaments will prevent any dislocation during
normal actions.
Tendons
Attach muscles to bones and facilitate the various positions of the body related
to movement and balance.
Tendons consist of non elastic collagen fibres only.
These are densely packed, arranged in parallel bundles and are extremely strong,
less flexible and more resistant to stress
The fibres give tendons a white shiny appearance.
There is a minimal amount of matrix present.
Questions & Answers
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
