musculoskeletal system Flashcards
how is micro damage dealt with by bone cells? ex = run
if you go for a run and you your shins are a bit sore and you feel you’ve got shin splints,
our bones are designed that actually these BONE BUILDING cells called osteoblasts will sort of rush in to
the site of micro damage and they’ll lay down some new bone and then periodically some BONE CHEWING cells,
osteoclasts will sort of come in behind and and tidy up any mess and make things a bit more organised.
fibro dysplasia
where tissue soft tissue should be generated,
bone tissue is mistakenly generated.
And so these bony protrusions result.
=> additional bones, bone fusion,…
functions of bone
structural support => allows us to stand
Enables movement – attachment of muscles
Protection of vital organs
Storage of minerals
(Ca2+ = 99% storage of it => can capture and sequester it into circulation, PO43- , Mg)
Haematopoiesis
red Blood cell formation (in bone marrow, some long bones, adolescence mostly adulthood)
what is bone?
Collagen fibre framework in a mucopolysaccharide-rich semisolid gel “ground substance”
gives bone its tensile strength
without collagen/ lack of / bones that fracture easily = brittle
Hardened by precipitation of calcium phosphate (hydroxyapatite) crystals within matrix
gives bone its compressional strength
(cartilage is similar to bone but
not calcified)
=> without/ lack of minerals = bendy bones
Made of osteoblasts, osteoclasts
osteocytes = ‘mature blood cells’
Supplied by blood vessels & nerves
Contains bone marrow
long bone structure
head = epiphysis => covered by hyaline cartilage => contains spongy bone
Metaphysis (between epiphysis and diaphysis (region of growth in childhood)
shaft = hallow cylinder = medullar cavity with compact bone around is called the diaphysis -> contains bone marrow
periostem = protective tissue covering the bone => contains lots of these active precursor cells that can be triggered to migrate to other parts of the bone to repair damage => fibroblasts synthesize collagen/
mesenchymal cells that can differentiate into osteoblasts and chondroblasts/
osteoclasts
trabecular/ cancellous
=> spongy
trabecular, which are these sorts of lines of bone lay down along the lines of stress, and they’re there in order to direct the stress from the head of the bone, down through the shaft of the bone.
if these trabecular were not there, you would quickly result in a situation where if you’ve got a vertical stress bone = going to shatter, it’s going to splinter or break of
gives supporting strength to the ends of the weight-bearing bone
really important site of metabolic activity for ion exchange
cortical
solid
will transmit the stresses,
applied to the bone through to other regions of the bone.
bone on the outside forms the shaft of the long bone
provides stiffness and strength
blood supply to bone
volkman’s canals carry blood horizontally through bone
haversian’s canals run vertically through bone
macro level => bring blood into and out of bone, the bone cells within compact bone.
Compact bone units = osteons => inside these osteocytes dont have a direct blood supply => oxygen can be transmitted through the bone matrix to cells that are not in direct contact with a blood supply for metabolism to occur,
and equally, waste products can be shipped out of bone.
osteon
compact bone arranged in osteons
central blood vessel and then around it osteocytes are arranged in sort of increasing circles.
Haversian canals carry blood along bone
Cells arranged in concentric circles (like onions)
Inside each layer are collagen fibres
Fibres in each layer can be oriented differently - very flexible
trabecular bone arrangement
not arranged in concentric circles.
=> easier for
Various agents to be able to access the surface of the trabecular bone.
Fewer lamellular layers in the “spongy” trabecular region
Less coordinated (weaker and more flexible) than compact bone
More open, less dense, site of haemopoiesis in bone marrow
rickets
Vitamin D deficiency failure of Ca2+ absorption
scurvy
Vitamin C deficiency lack of collagen
osteoblast
bone forming cell, cover the surface of bone ….forming an osseous matrix in which it becomes enclosed as an osteocyte
When stimulated to form bone will deposit organic matrix (collagen) then hydroxyapatite
Some become entombed during this process mature in to osteocytes
osteoclast
osteophage; a large, multinucleated cell derived from haematopoietic cells…In response to mechanical stresses and physiological demands they resorb bone matrix by demineralization
Release H+ and hydrolytic enzymes to dissolve the mineral, liberate calcium and break down the extracellular matrix
Regulated by hormones (e.g., oestrogens) and osteoblasts
osteocyte
bone cell – trapped, “retired” osteoblasts. Mature bone cells - embedded in lacunae, relatively inactive. Maintain bone matrix through cell-to-cell communication (via projections in canaliculi) and influence bone remodelling. Mechanosensing
Embedded within lacunae
Communicate via finger-like projections in canaliculi
