The skeletal system Flashcards
(33 cards)
The yellow (fatty) marrow is found in the _____________ of the bone:
Diaphysis
Spongy bone is mostly found in the…
Epiphysis and metaphysis
What is the functional unit of COMPACT bone called?
An osteon
Osteocytes are arranged in concentric layers called:
Lamellae
What is the extracellular fluid called that holds an osteocyte in place?
Lacuna
What are the interconnected channels called that connect the lacuna, and what do they feed into?
Canaliculi feed into Haversian Canal
Volkmann’s canals run (perpendicular/parallel) to bone
Perpendicular
Osteogenic (osteoprogenitor) cells are in the endosteum and periosteum of growing/injured bone. What do they do?
Either differentiate into osteoblasts OR osteocytes
Osteocytes are mature bone cells that do what?
Transfer bone minerals from the interior to the growth surface
Osteoblasts are modified fibroblasts that:
Synthesize and secrete organic matrix and help calcify is. They CAN become osteocytes too!
Osteoclasts are derived from:
monocytes
What do osteoclasts do?
resorption of bone which releases CA+
The organic matrix of bone (secreted by osteoblasts) is called “Osteoid” and is made up of:
- Type 1 collagen
- Proteoglycans
- Glycoproteins
Inorganic mineral salts (mostly calcium phosphate) are part of extracellular fluid in bone and are brought in by:
osteocytes
A fetal skeleton is made up of _______________ with no minerals
Hyaline cartilage
The formation of the primary ossification center indicates:
Chondrocytes begin to hypertrophy and start secreting alkaline phosphatase
A “periosteal bud” invades the central cavity to do what?
Vascularize the tissue
The formation of the secondary ossification center indicates:
Osteoclasts are further breaking down the cavity to develop it more
What is RANKL?
a protein expressed by osteoblasts that in fact has to do with the formation, function, and survival of osteoclasts!
What is OPG (osteoprotegerin)?
Secreted by osteoblasts, inhibitor of RANKL
What does estrogen do to RANKL?
It limits production of it by osteoblasts
Where is calcitonin made?
Parafollicular cells in thyroid gland
Kidneys and GI system are also involved in _____ homeostasis:
Calcium
Low calcium levels stimulates secretion of what hormone and why?
Parathyroid hormone, because it tells osteoblasts to tell osteoclasts to increase breakdown and release of CA+
