physiology of the skeletal system Flashcards
what are the structural roles of the skeleton ?
physical support for the body
attachment points for muscles
protection of internal structures
[ ribcage / skull ]
what are some roles of the physiology of skeletal system ?
stores various minerals [ particularly calcium and phosphorus ]
produces blood [ bone marrow ]
what is an osteogenic cells ?
precursors of osteoblasts
what is osteoblasts ?
bulids bone
what is osteocytes ?
osteoblasts which have become encased in bone
maintain mineral level
what is osteoclasts ?
reabsorb bone
what is the mechanism of endochondral ossification ?
bone develops from a precursor made of cartilage
what is the mechanism of intramembranous ossification ?
bone development from general connective tissue
which bones are made from endochondral and intramembranous ossification ?
most limbs = endochondral ossification
face = intramembranous ossification
how is bone produced ?
the osteoid is produced by osteoblasts and maintain by osteocytes [ largely composed of collagen type 1 ]
hardened by hydroxyapatite , a form of calcium phosphate ,modified with added calcium carbonate
what is osteoid characteristics ?
malleable and holds together well
what are characteristics of minerals ?
hard but brittle
what are some characteristics of bone to protect from fractures ?
hard but malleability to reduce risk of fracture
what is old bone broken down by ?
osteoclasts
describe the turnover of bone
osteoblasts produce special form of extracellular matrix
matrix becomes calcified , making bone which surrounds and encases the osteoblasts
encased osteoblasts then become osteocytes
old bone broken down by osteoclast
turnover of bone allows maintenance and reshaping
when matrix becomes calcified what is this known as the process ?
mineralisation
if less force is placed on the bone will the bones be stronger or weaker ?
weaker
what is osteon in bones ?
rings of lamellae
what is lacunae in bones ?
tiny cavities containing osteocytes
when are phosphorous and calcium extracted from the bones ?
when they are low in the blood
how much of the body stores of calcium and phosphorus stored in the bones ?
calcium= 99%
phosphorous = 80%
how are minerals released into the blood stream ?
osteoclasts carry out the breakdown of bone matrix , releasing minerals for the blood stream
this can be triggered by parathyroid hormone [PTH]
where is the hormone PTH released from ?
parathyroid glands , small structures on the back of the thyroid glands
when is the hormone parathyroid released ?
released in response to low blood serum Ca 2+ ions
PTH triggers the activity of osteoclasts , which breaks down the bone matrix and therefore releases its component calcium into the blood stream
Ca2+ increases and results in less PTH being released [ negative feedback ]
what is the name of the process to increase release of Ca2+?
hypercalcemia
what is name of the process to decrease release of Ca2+?
hypocalcaemia
what does the process of haematopoiesis do ?
produces blood cells
where are haematopoietic stem cells [ HSCs ] found ?
bone marrow to produce all forms of blood cells
where does blood cell production occur ?
red marrow
yellow marrow acts as a store of fat but can become red marrow when needed
