Bone/Cartilage Flashcards
is cartilage avascular or vascular
avascular
what percent is cartilage composed of water?
80%
are there nerves in cartilage
no nerves
three types of cartilage and roles/locations
hyaline:
—role: support, flexibility, resilience (weakest, most widespread)
—loc: articular surfaces, costals, respiratory (trachea/larynx), nasal
Fibro:
—role: compressible, high pressure, stretch (strongest)
—loc: intervertebral disks
—no perichondrium
—both type 1 and 2 collagen
elastic:
—role: elasticity and maintain shape
—loc: external ear, nasal tip, eustachian tube, epiglottis
—type 2 collagen and elastin
cartilage cells
chondroblasts: immature/undiff cells
chondrocytes: mature cells (lacunae enclosure)
ground substance of cartilage
proteoglycans (chondroitin sulfates/hyaluronic acid/electrostatic repulsion)
what are the components of cartilage
cells, ground substance, collagen
perichondrium
dense irregular ct that envelopes elastic and hyaline cartilage (not fibrocart)
general bone functions
support/shape
protection
assist homeostasis
blood cell production
is bone vascular or avascular
vascular
compact vs spongey bone
cortical/compact:
— outer layer of bone
—dense
—osteons
—80% of bone
cancellous/spongey:
—inner layer
—trabeculae
bone remodeling cells
osteoclast: resorb bone
osteoblast:build bone
hydroxyapatite comp
39% calcium
18% phosphorous
where is 99% of calcium sored in the body?
bone
calcium homeostasis hormones
parathyroid hormone (PTH)
calcitonin
“activated” Vit D
PTH does what when calcium blood levels are too low
stimulates Ca release from bone
increase Ca absorption from gut
promotes Vit D act
calcitonin does what when calcium blood levels get too high
reabsorption of calcium from bone
osteomalacia/rickets
defective bone matric calcification due to Vit D deficiency (and/or Ca deficiency)
osteopetrosis
impaired osteoclasts (fragile bone)
osteoporosis
excess osteoclast function
Tx: biphosphonates, teriparatide (bone-building drug)
Biphosphonate-associated osteonecrosis of the jaw
biphosphonate therapy for osteoporosis: disfiguring jaw conditions involving serious infection and abnormal build-up of bone
what tissue is composed of 80% water, avascular, no nerve fibers, and flexible?
cartilage
what tissue do chondroblasts reside in?
cartilage
what is the prominent proteoglycan in cartilage/bone?
chondroitin sulfate (electrostatic/proteoglycan repulsion)
chondrocytes vs chondroblasts
chondrocytes are mature cells
chondroblasts are immature cells (undifferentiated)
loss of what contributes to osteoarthritis and joint erosion?
loss of chondroitin sulfate
what fibers are in hyaline cartilage?
Collagen II only
(weakest cartilage)
what fibers are in fibrocartilage?
Collagen I & Collagen II
(strongest cartilage)
what fibers are in elastic cartilage?
Elastin & Collagen II
(springy)
does the perichondrium have a poor or rich blood supply?
rich blood supply
well innervated
what are the layers of perichondrium?
Outer fibrous layer: resist expansion
inner chondrogenic layer: immature chondrogenic cells
what is the most widespread cartilage?
hyaline
articular surfaces
costal cartilages
respiratory cartilages
nasal cartilages
if hyaline cartilage is damaged, what often replaces it?
fibrocartilage
composition of hyaline cartilage
spherical chondrocytes
collagen II only
perichondrium
no nerves/blood vessels
what type of cartilage does not have a perichondrium?
fibrocartilage
*hyaline and elastic have perichondrium
locations of elastic cartilage
external ear
nasal tip
eustachian tube
epiglottis
fibrous covering in cartilage
perichondrium
fibrous covering of bone
periosteum
structural unit of bone
osteon
Areas with higher % trabecular bone are found in the
vertebral column
proximal femur near pelvic girdle
distal radius
what protein attaches osteoclasts to bone?
integrins
what do osteoclasts dissolve?
hydroxyapatite (Ca2+ and Phos)
Collagen
osteoclast vs osteoblast
99% of calcium is stored in the ____
bones
Parathyroid hormone (PTH) is secreted by _____ or the _______ glands
Parathyroid hormone (PTH) is secreted by CHIEF CELLS of the PARAthyroid glands
calcitonin is secreted by what?
Calcitonin is secreted by the PARAFOLLICULAR CELLS of the thyroid gland
what does calcitonin do?
inhibits the resorption of calcium from bone
inhibits osteoclast activity
less calcium in the blood
*oppositive of parathyroid hormone
what two hormones regulate calcium levels in blood?
PTH (parathyroid hormone): increase Ca in blood
Calcitonin: decrease calcium in the blood
What are the four ways in which calcitonin lowers Ca2+ levels in blood?
- inhibits Ca2+ absorption by intestines
- inhibits osteoclasts
- stimulates osteoblasts
- inhibits renal tubular cell reabsorption of Ca2+ (excreted in urine)
glucocorticoids
hormone impacting Ca2+ metabolism
lowers calcium
inhibits osteoclasts
growth hormone on Ca2+
increase calcium in blood
estrogen on Ca2+
prevents osteoporosis
insulin on Ca2+
increases bone formation
rickets or osteomalacia
defective bone matrix calcification due to Vit D deficiency
osteopetrosis
osteoblasts operate unopposed
fragile /distorted bone
osteoporosis
excess osteoclast function
disfiguring jaw condition involving serious infection and osteopetrosis
ONJ
Osteonecrosis of the Jaw (bisphosphonate-associated)
