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Block 2 Biochem Exam
Block 2 VCOM 2011
56
Biochemistry
Graduate
10/30/2011

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Term
osteoid
Definition
includes proteoglycans, glycoproteins, and collagen. contributes flexibility and tensile strength
Term
Type I collagen
Definition
kind of collagen seen in bone and the strongest
Term
intramembranous ossification
Definition
forms directy from mesenchyme. makes most of the bones of the skull and the clavicle.
Term
endochondral ossification
Definition
bones are first modeled in hyaline cartilage
Term
osteon
Definition
unit of compact bone. represents a weight-bearing pillar
Term
haversian canal
Definition
central canal in an osteon
Term
endosteum
Definition
a thin layer of connective tissue that lines the surface of the bony tissue that forms the medullary cavity of long bones
Term
periosteum
Definition
a membrane that lines the outer surface of all bones. osteoblasts just under it secrete new matrix
Term
volkmann's canal
Definition
transverse canals that connect the vascular supply of periosteum to those of the haversian canal and the medullary cavity
Term
canaliculi
Definition
spaces in bone where extensions of neighboring osteocytes are located. they have gap junctions at the ends that allow communication between osteocytes
Term
trabecular bone
Definition
located at epiphyses and along medullary cavity. irregularly shaped. no osteons.
Term
Parathyroid hormone (PTH)
Definition
stimulates osteoblasts to secrete M-CSF, IL-6, and RANK Ligand
Term
Vitamin D
Definition
sensitizes osteoblasts to PTH. also increases absorption of Ca2+ and Pi by small intestine
Term
Macrophage-CSF
Definition
stimulates stem cells to differentiate into multinucleated osteoclasts
Term
RANK Ligand
Definition
promotes differentiation and activity of osteoclasts
Term
Osteoprotegrin
Definition
secreted by osteoblasts. binds to RANK Ligand to prevent it from binding to RANK receptor and stimulating osteoclast activity, so it is protecting bone from degradation.
Term
Glucocorticoids
Definition
increase osteoblast secretion of RANK Ligand and decrease its secretion of osteoprotegrin, resulting in more bone loss
Term
sealing zone
Definition
integrins on osteoclast bind to vitronectins on bone surface to make this
Term
calcitonin
Definition
binds to osteoclasts and leads to activation of PKA which inhibits bone reabsorption (opposite of PTH)
Term
8-12 weeks
Definition
how long fracture repair takes
Term
Woven bone
Definition
found in newly formed bone such as in fracture repair or bone-forming tumors. always pathologic if found in an adult
Term
hematogenous osteomyelitis
Definition
primarily affects the metaphyseal area of the long bones because of loop in arterioles giving bacteria time to penetrate walls of the blood vessels
Term
osteoporosis
Definition
metabolic bone disease resulting in decreased mineralized bone, but a normal ratio of mineralized to non-mineralized matrix
Term
Type I Primary Osteoporosis
Definition
due to an absolute increase in osteoclast activity as a result of estrogen withdrawal
Term
Type II Primary Osteoporosis
Definition
reflects decrease osteoblast activity with old age
Term
Osteomalacia
Definition
inadequate mineralization of bone matrix caused by a Vitamin D deficiency which reduces calcium available to mineralize osteoid
Term
Osteopetrosis aka Albers-Schonberg Disease or marble bone disease
Definition
autosomal recessive malignant type and autosomal dominant benign type. resulting in reduced osteoclastic bone resorption making bones very dense
Term
Scurvy
Definition
inability of osteoblasts to manufacture collagen. from Vitamin C deficiency
Term
Looser's zones
Definition
pseudofractures characteristic of osteomalacia
Term
Primary Hyperparathyroidism
Definition
adenoma causes excessive PTH production which causes osteoporosis, neuromuscular excitability, kidney stones, and phosphaturia
Term
Brown's tumor
Definition
typical of hyperparathyroidism
Term
myofibrils
Definition
filaments inside each muscle cell (muscle fiber)
Term
fasicules
Definition
bundles of muscle fibers
Term
tropomyosin
Definition
molecules consisting of two alpha helices that coil and sit near the two grooves formed by actin strands. at rest, they are blocking the myosin binding site on actin
Term
troponin
Definition
heterotrimer that binds Ca2+ and induces tropomyosin to move off the myosin binding sites so that contraction can occur
Term
synoatrial node
Definition
where action potentials are initiated in the heart
Term
intercalated disks
Definition
combination of mechanical juctions (fascia adherens and desmosomes) and electrical juctions
Term
Na-Ca antiporter
Definition
3 Na+ In, 1 Ca2+ Out. Helps get Ca2+ out of the cell
Term
Sarcolemmal Ca2+ Pump
Definition
uses ATP to extrude Ca2+ from the cell
Term
phospholamban
Definition
protein associated with SERCA. phosphorylated by PKA when epinephrine binds beta-adrenergic receptors
Term
thick filament regulated
Definition
smooth muscle requires an alteration in myosin before it can interact with actin
Term
thin filament regulated
Definition
requires movement of troponin-tropomyosin complex before myosin can bind to actin
Term
single-unit smooth muscle
Definition
cells are electrically coupled. causes a wave of contraction
Term
multi-unit smooth muscle
Definition
cells are isolated
Term
Calcium Induced Calcium Release
Definition
in smooth muscle, the Ca2+ that enters the cytoplasm through channels in the caveoli cause release from SR channels
Term
calmodulin
Definition
binds 4 Ca2+ which activates it to activate myosin light chain kinase which ultimately results in muscle contraction
Term
myosin light chain
Definition
when phosphorylated, it is able to bind to actin and act as molecular motor for contraction
Term
MLC phosphatase
Definition
cleaves off phosphate from MLC making it inactive
Term
phasic, twitch-like contraction
Definition
Ca2+ mobilization followed by cross-bridge phosphorylation and cycling
Term
sustained, tonic contraction
Definition
prolonged stimulation
Term
bursa
Definition
sacs of lubricant lined with synovial membrane that secrete synovial fluid. reduces friction during joint activity
Term
tenon sheath
Definition
elongated bursa that wraps completely around a tendon
Term
retinaculum
Definition
confine tendons to a specific line of pull
Term
collagen
Definition
triple helix of 3 alpha chains have gly-x-y sequence
Term
fibrillar collagens
Definition
I, II, III, V, and IX
Term
basement membrane collagen
Definition
IV
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