lecture 2: connective tissue Flashcards
what germ layer is most connective tissue derrived from?
the mesoderm
what is the difference between totipotent, pluripotent, and multipotent?
toti-can become anything (anyone!) pluri-any kind of the three germ layers, multi- any cell that is of the germ layer that cell has already initiated
the mesenchyme can differentiate into what four types of precursor cells?
fibroblasts, osteoblasts, chondrochondroblasts, hematopoetic cells
Besides cells, another component of connective tissue is important to contributing to type and function
fibers, ie collagen, elastic fibers, reticular fibers
type I collagen: where is it found, and what might a disorder of this cause?
tendons, ligaments and bones, and stratum fibrosum, lead to very fragile body if defective
type II collagen, where is it found?
found in the hyaline cartilige and annulus fibrosis
type III cartilige, where is it found
skin and the stratum synovium
type XI cartillige, where is it found?
articulating surface of joints
epidermolysis bollusa is a disease of what?
collage VII: anchoring collagen
what is the role of loose connective tissue, like areolar tissue?
packages organs, surrounds capillaries, under epithelia of body, role in inflamation, cushion, moisture management
in what way is the composition of dense connective tissue different than loose?
more collagen, makes it stronger
irregular, dense connective tissue eg are
fascia, capsules, periostium, perichondrium
regularly arranged tissue eg
ligaments and tendons
what about the arrangement of the collagen fibers is different between tendons and ligaments
ligs are less parallel, can withstand small force
What are the two layers of the joint capsule?
stratum fibrousum, stratum synovium
which layer of the joint capsule is rich in blood supply and poorly innervated?
the synovial layer
what is hemarthrosis?
bleeding into the joint space
what characterizes the stratum fibrosum?
poor vask, rich innerv esp for pain, inflex, guides!
name three functions of tendons, and how its suited to this role
attach muscle to bone, transmit tensile forces for movement, do this efficiently, collagen make up of fiber– inelastic means force is not diminished
what makes an apponeuresis so powerful
represents a muscle with a large origin and small insertion
what is an example of an elastic ligament?
ligamentum flavum or nuchae
cartilage is a modified connective tissue. how does it differ from other CT?
made up of different cells, these differentiate very early in development (chondroblasts) different, stiffer matrix
in cartilage, where are the cells (the chondrocytes)?
in lacunae
cartilage is avascular. how does it receive nutrients?
either via the perichondrium, or via the synovial fluid
what are the two stages of cartilage cell growth?
Interstitial and appositional growth, i, active dividing, ap= no dividing just hypertrophy
what surrounds the hyaline cartilage, providing nutrients during development (except for articular cart?
perichondrium
two reasons to have articular cartilage
reduces friction and distributes the load
difference between osteoarthritis and rheumatoid arthritis
mechanica, restricted to one, vs chronic systemic autommune
where would you find elastic cartilage?
ear, epiglottis
purposes of bone:
ion resevoir, produce RBC, atatchment for muscles, protection
bone can develop two ways, a common and less common way, give examples of each
endochondral, long bones etc, intramembranous ossification where bone dev directly from bone (mandible, scull, clavicle,)
in intramembranous ossification, what happens?
precursours (osteoblasts) develop from the mesodermal stem cells. osteoblasts secrete osteoid, which traps them, they become osteocytes.
describe endochondral ossification:
from a cartilige model, there is primary and secondary ossification. During primary, chondrocytes differentiate into osteoblasts, begin to deposit bone matrix. there is still a growth plate (cartilige interface)
what is the direction of secondary growth in endochondrial ossification?
towards center: chondrocyte layer towards the end, hypertrophic zone towards center of bone=leaves cartilage at the end (articular)
different roles for osteoblasts, clasts and cytes
blasts make bone, clasts break it down, cytes sense pressure
most of the dry weight of bone is
mineral and collagen
volksmans canals, haersian canals=
v passes into bone, h goes along side
in mature bone, where are osteoblasts located for growth and repair?
in the inner layer of the periosteum, osteogenic layer
what are the two types of bone?
compact, spongy
compact bone charicteristics:
found in the diaphysis, has haversian system, support and strength
spongy bone charicteristics
composed of trabiculae, found in the epiphysis, red marrow, light weight, make bones springy
what is wolfes law?
normal pulling of tendons, weight bearing will shape bones
how can movement initiate osteogenisis rather than adipogenisis?
mechanical loading through the bones can make cells preferentially differentiate into bone rather than fat
evidence of wolf’s law?
weight lifters develop thickenings of insertion on stressed muscles, tennis players hae increased cortical layer on dominant arm
what type of fracture is most likely to have severe soft tissue dammage, least?
crushing or penetrating-explosive, tapping
tensile force will produce this type of fracture:
transverse
axial compression will produce this type of fracture:
oblique
spiral fracture is produced by this kind of force
torsion
bending force will produce this type of fracture
transverse with small butterfly
axial compression and bending will produce this type of fracture
transverse oblique with large butterfly
how do blastocytes sense mechanical load?
processes extend into ECM, pressure allows this mechanical signal to be translated into a chemical signal
