Download The Skeletal System The skeletal system also called the human

The Skeletal System
The skeletal system also called the human skeleton is comprised of bones joined together with cartilage
an tendons attached to muscle to give us our body structure an allow us to stand upright and provide
movement, an also to protect our vital organs such as the brain, heart, and lungs.
There are three types of joints 1-ball and socket joint such as the hip or pelvic bone and allows a wide
range of motion, 2-hinge joint like the knee bone that provides movement in a single plane, and pivot
joint which is found in the neck bones to allow freedom of movement with the head.
The bones can be made up of two parts, the axial skeleton which supports the trunk like the scull,
sternum and vertebra, and the appendicular skeleton that make up the limbs like the arms, legs and hip
bones.
Sex Differences
Men are on average 5.9 inches taller than women do to longer puberty starting later an lasting longer in
men than women. Men normally have longer legs an arms which transmits to more power an force
along with faster speeds than women.
Women tend to have a longer torso than men allowing them to have a lower center of gravity, which
means they may be able to control their balance more, women have smaller frontal, temporal (skull)
and mandible (jaw bone) bones in the head. Women also have flatter, broader pelvis (two ossa coxae),
Greater spinal curvature (do to a tipped pelvis), larger, rounder pelvic inlet to allow the possibility of a
baby through, shorter long bones and also an increased Q angle cause of the wider hips in women.
Bone Structure
The outer layer called the periosteum which covers all the of the outer bone except where capped by
cartilage, an consists of a dense fibrous membrane, it includes an outer fibrous layer along with an
inner cellular layer (cambium). The outer layer is mostly composed of collagen that contain nerve
fibres that cause pain when the tissue is damaged, and also contains blood vessels that branches to
penetrate the bone to supply osteocytes (bone cells) they pass perpendicular through the bone in a
channel called the volkmann canals to the vessels in the haversian canals, which run the length of the
bone. The fibers from the inner layer also penetrate the underlying bone helping the blood vessels to
bind the periosteum to the bone as sharpey fibres.
Compact bone known as cortical bone makes up 80% of our body, is dense compact bone, that has a
matrix solidly filled with organic ground substance and inorganic salts, leaving only tiny (lacunae)
spaces containing the osteocytes (bone cells).
Spongy bone called cancellous bone which has numerous large spaces found in the marrow space the
medullary cavity of the bone.
Bone Marrow called Myeloid tissue
The marrow fills the cavities of the bones an is either red or yellow depending upon the preponderance
(red – Hematopoietic) marrow, which forms all of the blood cells with the exception of lymphocytes
that are produced in the marrow and reach their mature form in the lymphoid organs, red marrow also
contributes to the destruction of red blood cells with the liver and spleen. Red marrow also consists of
a delicate, highly fibrous tissue containing stem cells, that differentiate into various blood cells. The
stem cells first became precursors, or blast cells of various kinds like normoblasts that give rise to the
red blood cells called erythrocytes , then myeloblasts become granulocytes a type of white blood cell
called leukocyte. Platelets that are small blood cell fragments that involve clotting, form from giant
marrow cells called megakaryocytes. New blood cells are released into the sinusoids, a large thinwalled vessels that drain into the veins of the bone.
Remodeling, Growth, Bone resorption and Renewal
The renewal of bone occurs on a tissue level, old bone must be precede new bone deposition.
Remodeling mostly occurs during the years of active growth in kids, teens an into adult hood.
Resorption, the osteoclasts that either erode free bone surfaces or form “cutting cones” that tunnel
through compact bone and create cylindrical cavities that may be subsequently filled by osteons, the
osteoclasts secrete enzymes and hydrogen ions onto the bone surface, dissolving the mineral and
digesting the matrix at virtually the same moment, the resorption process is said to be more rapid than
formation. When calcium levels in the bloodstream are low osteoclasts break down bone and release
calcium into the bloodstream. Osteoblasts are responsible for the synthesis and deposition on bone
surfaces of the protein matrix of new intercellular material, the unmineralized matrix constitutes an
osteoid seam or border, averaging 6 to 10 microns in thickness during active bone formation, along
with helping bone tissue regenerate itself. When calcium levels in the blood are high Ostoeclasts,
remove calcium from the blood and use it to make new bone.
Calcium is delivered to the bloodstream in response to the effects of the parathyroid hormone, that’s
produced by the parathyroid glands, the release of this hormone signals the kidneys to decrease the
amount of calcium secreted in the urin and therefore stimulates the breakdown of bone, so the stored
calcium is released into the blood, while the thyroid gland secretes another hormone called calcitonin,
which decreases the concentration of calcium within the blood when the level rises too high.
Osteonecrosis – bone tissue death
also called necrosis of bone, the death of bone tissue that may result from infection, as in osteomyelitis,
or deprivation of the blood supply like in a fracture, dislocation, caisson disease (decompression
sickness), or radiation sickness, the blood circulation in the affected area ceases and the bone cells die,
and the marrow cavity becomes filled with debris. The surrounding bone resorbs and replaces necrotic
bone over a period of months or years, with wide spread damage, orthopedic treatment may be
required, such as replacement of dead bone.
Photos to help
As I advance further into my career, my findings an knowledge I have learned thus far
in this material I have studied I hope will enable me to do so, along with the further
advancement into bones an the structures of cells and fibers contained within them,
my study is mainly on this topic, im going into radiology, although most people think
it's mainly about taking pictures of bones, id like to understand it in more depth, never
know maybe a bone DR. or something.
Calcium an bone structure – some cited from Human Biology-BIOL 1090-Salt Lake Community
Collage, Custom Edition- Taken from:Biology:Science for life, with physiology, Third Edition by
Colleen Belk and Virginia Borden Maier – Human Anatomy, Fourth Edition by Elaine N. Marieb, Jon
Mallatt, and Patricia Brady Wilhelm.
compact bone 2011. Encyclopedia Britannica Online. Retrieved 05 December, 2011, from
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