Bone from website Flashcards
function of bone
- protect vital organs 2. store minerals such as calcium 3. store lipids (white bone marrow) 4. Make blood cells (haemopoesis)
when the body needs calcium
the bone releases calcium
calcium necessary for
muscle cotnraction, blood clotting, nerve conduction.., strength of bones andf teeth
osteoclasts break down bone to
free calcium
osteoblasts deposit
calcium in bone, remaking it
bone cells are called
osteocytes
osteocytes are found within
lucunae in each lacuna you will find one osteocyte
canaliculi
connect lacuna allowing osteocytes to communicate with eachother via their processes (filapodia)
two types of bone
compact cancellaneous (spongy)
compact bone found
under the periosteum and in the diaphyses of long bones, where it provides support and protection.
compact bone arranged into many
osteons- very regular pattern
overview of osteon structure
The osteocytes sit in their lacunae in concentric rings around a central Haversian canal (which runs longitudinally).
The osteocytes are arranged in concentric rings of bone matrix called lamellae (little plates), and their processes run in interconnecting canaliculi.
The central Haversian canal, and horizontal canals (perforating/Volkmann’s) canals contain blood vessels and nerves from the periosteum.
down the centre of an osteon is the
haversion canal
what is found within the haversion canal
blood vessels, nerves and lymphatic vessels
horizontal canals that flows between osteons
Volkmann canals - larger blood vessels and nerves - means there is a blood supply for all the bone tissue
two kinds of bone including compact, whoch is the other
Cancellous bone
cancellous bone
also known as spongy or trabecular bone, is one of the two types of bone tissue found in the human body. Cancellous bone is found at the ends of long bones, as well as in the pelvic bones, ribs, skull, and the vertebrae in the spinal column
difference between Cancellous (spongy bone) and compact bone
much less dense and less regular
what is the outer most layer of bone (continous with ligaments and tendons)
periosteum
down the centre of the long bone is the
medullary cavity
medullary cavity contains
yellow bone marrow
contains largest blood vessels/ nerves
blood vessels and nerves in the medullary cavity
enter the bone tissue and allow for noruishment of individual osteocytes
endosteum
The endosteum (plural endostea) is a thin vascular membrane of connective tissue that lines the inner surface of the bony tissue that forms the medullary cavity of long bones.
outline the gross structure of a long bone
epiphysis
metaphysis
diaphysis
where is red bone marrow found
at the proximal and distal end sof the bone within spongy cancellous bone
outer layer of bone composed of
compact bone
compact bone
dense material with low porosity
spongy cancellous (trabecular) tissue
red bone marrow
makes blood cells- haemopoesis
yellow bone marrow
shape of osteocyte
star shaoed- long projections (filipodia/ processes) that prokect into canaliculi
structure of spongy bone looks like
honeycombe
each rod of bone in spongy bone that looks like honeycomb is called
a trabecula or spicule
trabeculae (in spongy bone) dont contain
osteons
haversian
matrix of spongy bone
o contain lamellae, or layers of bone matrix, but the lamellae are parallel to each other. The matrix contains lacunae and canaliculi, as well as osteocytes, osteoblasts, and osteoclasts.
when the amount of bone manufacture equals the amoutn of disintegrations
the mass of a bone stays the same
how do osteoblasts form new bone
osteoblasts move over the matrix of a bone and deposit a protein mixture called osteoid. The osteoid contains a protein called collagen as its major component. Then the osteoblasts deposit minerals—including calcium—into the osteoid to make bone. The new material fills in the cavity formed by osteoclasts.
osteocytes
Some osteoblasts become trapped in the bone matrix and are transformed into osteocytes inside lacunae. Osteocytes are thought to be sensory cells that are involved in signaling processes inside the bone. They connect to other osteocytes through their projections, which extend through the canaliculi. They are the most abundant cells in bone and also appear to have the longest lifespan.
osteoclasts
Unlike osteoblasts, osteoclasts contain more than one nucleus. They are large cells produced by the fusion of several smaller ones. Osteoclasts travel over the surface of the bone matrix and secrete acids and enzymes to disintegrate it, forming a little pit on the surface of the bone.
- absrob mineral- which is later relased intot he tissue fluid located between cells
- fromt here the ions enter the blood
which hormone stimulate sthe action of osteoclasts
parathyroid hormone
parathyroid hormone
stimulates the action of osteoclasts when the amount of calcium in the blood falls. The hormone causes the transfer of calcium from bone to blood.
which thryoid hormone is produced which slows the activity of osteoclasts- decreasing the bone breakdown
calcitonin
what can help increase bone production
when someone performs regular weight-bearing exercise
when someone is bedridden the net effect is
bone loss
which hormones in men and women help maintain bone strength
testosterone- men
oestrogen- women
osteoporosis summary
Osteoporosis is a disorder in which the bones become unusually porous and brittle and bone density decreases. The condition generally appears in older people, although it occurs in young ones as well. In osteoporosis the amount of bone resorption is much higher than the amount of bone production.
Osteoporosis can occur in both males and females, but it’s most common in post-menopausal women. After menopause the amount of estrogen in a women’s body decreases significantly, increasing the risk of weakened bones.
general cause of osteoporosis
amount of bone resorption is much higher than the amount of bone production
