Skeletal System Flashcards
function of the skeletal system
storage of calcium, lever system, protection for vital organs
red marrow
hematopoietic stem cells (immature cells) that make RBCs, WBCs, and osteoclasts
yellow marrow
mesenchymal stem cells that make osteoblasts, osteocytes and adipocytes
osteoclasts
cells that can help degrade bone and release calcium from bones, multinucleated
osteoblast
help build bone, deposit calcium in bone to make it stronger, single nucleated
osteocytes
bone cells
adipocytes
fat cells (yellow and in yellow marrow)
modeling
chondrocytes –> cartilage –> osteoblasts –> osteoid + hydroxyapatite
chondrocytes
lay down more cartilage
die and leave cartilage
osteoblasts
form the osteoid that binds to cartilage
growth hormone
stimulates chondrocytes to produce cartilage and osteoblasts
occurs until epiphysial closure occurs –> influenced by genetics
hypothalamus –> pituitary gland –> GHRH
lacunae
areas in canaliculi where osteocytes are housed
canaliculi
canal, allows cells to have access to blood, connect the central canal to cells, connection between cells
lamellae
spaces where cells will reside, concentric layers
haversian canal (central canal)
where there is blood supply and helps keep the osteocyte cells alive
remodeling
osteoblasts and osteoclasts always working
degrade bone
osteoclast activity > osteoblast activity
build bone
osteocalst activity < osteoblast activity
sclerostin (anti-anabolic effect)
secreted by osteocytes
inhibit osteoblast activity
breakdown bone
osteoporosis characteristics
bone shatters when osteoporosis bone is broken and need to replace bone
factors: pickup plate, step of a curb, get out of the shower
1:4 men to women
osteoporosis risk factors
genetics, race (asians more likely), smoking (can limit hunger)
osteoporosis in women vs men
women
- bone loss at age 45
- 3% decline/decade
- menopause at 55-60 years old that causes a 9% decline, osteoblast activity < osteoclast, decrease in estrogen levels
men
- bone loss at age 55
- 3% decline/decade
estrogen
can help lower secretion of sclerostin so no estrogen means secretion of sclerostin and osteoblast activity inhibited, increasing rate of bone loss
mechanosensors
Stimulate osteoblast activity
depositing in more bone to prevent hepisopetate
d = m/v and increase in exercise and decrease in density
deoxygenation
osteoporosis affect of diet
not enough calcium centers, body takes it from the bone
drink milk
osteoporosis preventions
resistance training
increase skeletal muscle tension, increase bone strength
40-60% strength before one breaks
calcium homeostasis (too high)
calcitonin decreases vitamin D levels, thyroid increases
kidneys decrease calcium reabsorption
bones increase osteoblast activity
small intestine decreases calcium absorption
calcium homeostasis (too low)
parathyroid hormone, low calcium levels, increased vitamin D
kidneys increase calcium reabsorption in proximal tubules
bones increase osteoclast activity
small intestine increases calcium absorption
RBC formation (erythropoiesis)
RBCs shelf life is 120 days and can’t replicated because no nucleus
hematopoetic stem cells –> erythroblasts (lose nucleus) –> reticulates –> erythocytes
epo (erythropoietin)
released by kidneys
stimulates erythropoiesis formation
hematopoietic
stem cells in the bone that make RBCs stem cells
RBC death (eryptosis)
changes conformation of cell membrane
apoptosis
a form of programmed cell death usually occurs in the nucleus
macrophage
degrade RBCs and located in the spleen and liver
heme
bilirubin
converted in bile
urobilin –> yellow color
filters by urination
globin
alpha and beta chains
broken down and sent back to bone to reform hb in eryptosis
iron (Fe+)
converted into transferrin –> to transport iron
iron goes to bone to reform hb
liver can store iron as feritin
