Connective Tissue (M2) Flashcards
what are the 4 general classes of tissues
muscle
nerve
epithelial
connective
function of connective tissue
provide and maintain form throughout the body.
matrix that connects tissues and organs together
what are the 4 types of connective tissue
dense CT (fibrous)
loose (areolar) CT
reticular CT
elastic CT
structure of dense CT
collagen fibers arranged in bundles with elongated fibroblasts in between fibers and at their edges
2 orientations of dense CT
dense regular CT: specific (parallel) orientation
- provides resistance to stress occurring in same direction
- ex. cornea
dense irregular CT: lack of a definite orientation
- provides resistance to stress in all directions (hard to deform)
- ex. sclera
why does dense CT offer more resistance and protection
fewer cells, more collagen fibers than loose CT.
lack of ‘open’ space = less flexibility
forms of dense CT
dermis
ligaments (bone to bone)
tendon (muscle to bone)
most common CT in the body
loose (areolar) CT
composition of loose CT
collagen
reticular and elastin fibers
fibroblasts
macrophages
functions of loose CT
fill space between muscle cells
support epithelial tissues as lamina propria and sheathing blood vessels
features of loose CT
delicate in consistency
flexible
well-vascularized
not very stress resistant
examples of loose CT
choroid
iris
ciliary body
composition of reticular CT
delicate loose connective tissue.
reticular fibers and fibroblasts
features of reticular CT
forms sponge-like network that allows blood cells and fluids to travel through
where is reticular CT found
none in the eye.
hematopoietic and lymphoid organs
ex. bone marrow, spleen, thymus, lymph nodes
composition of elastic CT
dense regular connective tissue with high proportion of elastic fibers.
rich in thick, parallel elastic fibers, with collagen fibers and flattened fibroblasts in between
functions of elastic CT
allows recoil of tissue following stretch.
maintains pulsatile flow of blood
cells of connective tissue
fibroblasts.
macrophages.
mast cells.
plasma cells.
leukocytes.
adipose cells
most common CT cell
fibroblasts
function of fibroblasts
produce components of ECM
what does tropocollagen protein form
type I collagen fibrils
what do proelastin and fibrillin proteins form
elastin fibers
what makes up the ground substance
glycosaminoglycans, proteoglycans, and glycoproteins
what do fibroblasts contain
many mitochondria, abundant rER, and golgi complex
when do fibroblasts become inative
after producing CT, remain in the tissue as fibrocytes
what are fibrocytes and what can they do
fibrocytes: inactive fibroblasts.
may reactivate if there is injury to fill in the injured space - will take a long time to heal and will never be the same because it doesn’t get nutrients the same way
what can fibroblasts become
myofibroblasts - contain actin and myosin filaments
what are macrophages derived from
monocytes
function of macrophages
defense
- phagocytosis of foreign cells
- antigen presentation
- breakdown of tissues no longer needed
- tumor cell-killing
appearance of macrophages
irregular surface due to pinocytosis and phagocytosis
what breaks down hyaloid artery
macrophages in a fetal nucleus.
if not broken down completely the vitreous humor will not be clear
shape of mast cells
oval to round
function of mast cells
inflammatory response.
storage and release of chemical mediators of inflammatory response
what do mast cells contain
secretory granules.
… histamine, heparin, and ECF-A
origin of mast cells
progenitor cells from bone marrow
plasma cells
production and release of antibodies.
differentiated wbc.
abundant rER to support funciton
leukocytes
neutrophils, eosinophils, lymphocytes.
arrive in connective tissue from blood
adipose cells
just a little.
scattered within CT.
similar to fibroblast except it accumulates fat in cytoplasm
most common fiber found in connective tissue
collagen
main types of collagen
types 1 - 4.
type 1 - 3: form fibers
type 4: form meshwork –> reticular fibers
most common type of collagen
type 1
what do fibroblasts produce
tropocollagen proteins –> forms into fibrils extracellularly –> fibril strands make up collagen fibers
where is type 2 collagen found
found in cartilage.
is type 2 collagen more or less organized than type 1 collagen
less
what does type 4 collagen assemble
assembles in a meshwork that builds basal lamina throughout the body (epithelial - not connective tissue)
what does type 7 college form
anchoring fibrils to connect basal lamina to the collagen fibers of the underlying connective tissue
what type of collagen are reticular fibers
specialized type.
mostly type 3 - smaller in diameter than type 1 collagen
what do reticular fibers form
flexible network in organs that undergo changes in form/volume –> prevent rupture
where are reticular fibers found
near basal lamina.
anchoring fibrils of type 7 collagen attach to reticular fibers
what are elastic fibers composed of
elastin and fibrillin proteins.
elastin is the center of the fiber.
fibrillin protein forms microfibrils which surround core
what can fibrin without elastin form
oxytalan fibers.
non-elastic but form suspensory ligaments of the lens
what space does ground substance fill
fills space between fibers and cells in the connective tissue
what is ground substance high in
water content, colorless and transparent
what are the 3 classes of molecules that make up ground substance
- Glycosaminoglycans (GAGs)
- Proteoglycans
- Glycoproteins
most common GAG in ground substance
hyaluronic acid - does not bind with a protein to form a proteoglycan
gags in ground substance besides hyaluronic acid
dermatan sulfate
chondroitin sulfate
keratan sulfate
heparan sulfate
what are proteoglycans
sulfate gags bound around protein core.
take up more space and become more viscous than on their own
function of glycoproteins
adhesive function to neighboring cells, collagen fibers, and GAGs
main function of adipose tissue
stores energy in the form of fat, makes up 15 - 25% of body weight.
thermal insulation of body
unilocular adipocyte
fat is in a single droplet and the remainder of cytoplasm and cell nucleus are pushed to periphery
appearance of unilocular adipocyte
signet ring
what do unilocular adipocytes form
unilocular (common, yellow) adipose tissue –> adipose tissue in the adult
multilocular adipocyte
have multiple lipid droplets in the cytoplasm
what do multilocular adipocytes form
forms multilocular (brown) adipose tissue
what do multilocular adipocytes provide in infants
fat storage and heat
