Pathophys - Cartilage and Bone Flashcards
(59 cards)
1
Q
mesenchymal stem cell derivatives
A
- muscle cells
- adipocytes
- osteoblasts
- fibroblasts
- chondroblasts
2
Q
what is unique about the derivation of osteoclasts?
A
they come from the monocyte cell line
3
Q
fibroblasts secrete what?
A
components of connective tissue
4
Q
define connective tissue
A
- tissue that connect, supports, binds, or separates other tissues or organs
- typically have relatively few cells embedded in an amorphous matrix
- often has collagen or other fibers like cartilagenous, fatty and elastic tissues
5
Q
what is the most abundant protein in the body?
A
collagen
6
Q
proteoglycans are precursor molecules for what?
A
collagen
7
Q
function of proteoglycans
A
bind collagen fibrils, elastic fibers and reticular fibers together
8
Q
where do elastic fibers predominate?
A
in blood vessels and ligaments
9
Q
reticular fibers predominate where?
A
in lymphatic tissue and basement membranes
10
Q
vitamin C is a cofactor for what process?
A
hydroxylation of proline and lysine
11
Q
the deficiency of vitamin C causes what?
A
- scurvy
- poor wound healing
12
Q
ehlers-danlos syndrome
A
- defective procollagen peptidase results in uncleaved procollagen or in lysyls hydroxylase
- so can’t hydroxylate lysine needed for staggered array of tropocollagen
- hyperelasticity, joint dislocations, vascular wall rupture
13
Q
osteogenesis imperfecta
A
- point mutation in collagen gene resulting in reduction in type 1 collagen
- type 1 collagen is needed for normal ossification
- brittle bones and blue sclera
14
Q
what are the two most important things to remember about osteogenesis imperfecta?
A
- type 1 collagen deficient
* blue sclera
15
Q
goodpasture’s syndrome
A
- auto-antibodies to type IV collagen
- results in renal and or lung basement membrane thickening
16
Q
marfans syndrome
A
- defect in fibrillin 1 gene, chromosome 15
- fibrillin surrounds elastic fiber core
- results in dilation of aorta, mitral prolapse, periosteal changes (elongation)
17
Q
presentation of pt w/ marfan’s
A
- tall stature
- high arched palate
- myopia
- mitral valve prolapse
18
Q
a mitral valve prolapse causes what heart sound?
A
systolic click
19
Q
general overview of collagen production (in terms of cells)
A
- chondroblasts form chondrocytes
- chondrocytes make tropocollagen
- tropocollagen molecules overlap into collagen fibrils
- fibril bind together to form fibers
- fibers bind together to form tendons
20
Q
structure of tropocollagen
A
3 alpha strand proteins arranged in alpha helix
21
Q
functions of ECM
A
- cell adhesion
- cell-cell communication
- differentiation
22
Q
ECM formation
A
- chondroblast form chondrocytes
- chondrocytes secrete ECM
- young collagen from ECM matures
23
Q
ECM is primarily made of what two things?
A
- aggregan
- type II collagen
24
Q
What is the significance of ECM being negatively charged?
A
it holds water
25
cartilage at the end of long bones is what?
articular cartilage
26
what is the the thickest cartilage of the human body and why
- the articular cartilage of the patella
| - d/t the huge stress on the patella-femoral joint during resisted knee extension
27
characteristics of cartilage
- limited repair
- nutrition supplied by diffusion
- very slow turnover in ECM
28
what are the three types of cartilage
- hyaline
- elastic
- fibrocartilage
29
pathophys of osteoarthritis
- there are biomechanical and chemical processes involving the cartilage, synovium, bone and soft tissues surrounding the joint
- they can be sparked by a single traumatic event, repeated microtrauma or genetic, metabolic, or systemic factors affecting the integrity of cartilage
30
what is secreted by chondrocytes during osteoarthiritis progression?
-metalloproteinases (MMPs)
31
MMPs
- inclue collagenase, stromelysin and gelatinase
| - degrade cartilage
32
what could make cartilage more susceptible to MMPs?
inappropriately low levels of tissue inhibitors of MMPs
33
what is a unique property of chondrocytes?
- chondrocytes secrete the things needed to build cartilage
| - but also secrete the MMPs that break it down
34
during cartilage remodeling, what are the levels of matrix and protease/inhibitor ratio during a net increase?
- increased fibroblasts laying down matrix (matrix synthesis)
- decreased protease: inhibitor ratio (MMP)
35
during cartilage remodeling, what are the levels of matrix and protease/inhibitor ratio during a net decrease?
- decreased matrix synthesis
| - increased protease: inhibitor ratio
36
what are the main findings in an XR of a joint w/ osteoarthirits?
- narrowing of joint space
| - subchondral sclerosis
37
cell derivatives for bone formation
- mesenchymal stem cell --> osteoblasts
| - bone marrow --> monocyte --> osteoclast
38
what type of bone growth grows on a cartilaginous template?
endochondrial
39
what are the two parts of endochondrial bone growth?
- osteoclast chase
| - chondrocyte run
40
osteoclast chase
- osteoclasts (from monocytes) enlarge the bone marrow cavity
- creates an invading front of ossification
41
chondrocyte run
- calcification of the cartilage matrix surrounding hypertrophic chondrocytes
- proliferating chondrocytes away from the ossification front increase the length of the cartilage
42
Haversian system
- fundamental functional unit of much compact bone
| - composed of an artery in the middle of an osteon which is filled with osteocytes
43
what signaling system is used by osteoblasts?
RANKL
44
RANKL signaling system
- macrophages are signaled on to make osteoclasts
| - can be used to heal and remodel
45
intramembranous bone growth
-bone grows directly by connective tissue basement membrane developing into bone
46
intramembranous bone growth is important for what two things?
- fracture healing
| - development of the skill
47
mechanism of intramembranous bone growth
- mesenchymal stem cells --> osteoblasts and osteocytes
- secrete type I collagen (osteoid)
- lay down mineralization
48
content of bone
- 50-70% mineral
- 20-40% organic matrix
- 5-10% water
- <3% lipids
49
minerals contained in bone
Ca, Pi, PPi, Mg, K, hydroxyapatitie, and others
50
increase in extracellular PPi has what effect on hydroxyappetite?
decrease
51
decrease in extracellualr PPi has what effect on hydroxyappetite?
increase (i.e increased mineralization)
52
hydroxyapatite function
storage unite for Ca and phosphorus
53
what hormones regulate the mineralization of bone?
- PTH
| - Vit. D
54
describe bone remodeling (aka bone metabolism)
- lifelong process
- mature bone tissue is removed from skeleton (bone resporption)
- new bone tissue is formed (ossification)
- control fracture repair and micro damage
55
what is the main hormone in bone remodeling?
PTH
56
PTH is secreted by the?
parathyroid gland
57
PTH regulates what?
serum Ca
58
PTH is primarily secreted in response to what?
lowered serum Ca
59
function of PTH
- decrease in serum Ca leads to:
- PTH acting on osteoblasts
- this indirectly activates osteoclasts to tear down bone and release Ca
