Connective Tissue/CT Proper Flashcards
connective tissue
purposes
physically connects tissues
fills spaces to integrate
forms pathways
mechanical properties to larger structures
structural support
defense and repair
physiological support
metabolic storage
signaling
basically everything
Composition of CT
ECM (fibers + ground sub)
cells (permanent + temporary residents)
Defining characteristics
more ECM than cells mostly
more fibers than ground sub
vascularized
most common fibers
in ECM
collagen I
elastic fibers
reticular (collagen III)
special fibers in blood
fibrin
special fibers in hyaline and elastic cartilage
collagen II
resident cells
aka fixed
develop/remain/perform functions in CT
long lived
from mesenchymal cells
types of resident cells
fibroblasts
adipocytes
chondroblast/chrondrocytes
osteocytes/bone lining
mast cells
macrophage
transient cells
aka free cells
develop in bone marrow
circulate in blood
recruit to CT to perform
temporary/short lived
transient cells examples
plasma cells
leukocytes WBC
origins of CT cells
mesenchyme (from mesoderm)
bone marrow
hematopoietic stem cells
fibroblasts
most abundant and least specialized
low turnover (rarely divide)
active or inactive
cortisol
on fibroblasts
inhibits fibroblast growth and division so no collagen or elastin
active fibroblasts
synthesizing proteins for secretion
euchromatic nuclei
cytoplasm basophilic
elongate oval shape
inactive fibroblasts
fibrocytes
quiescent (synthetically less active)
smaller/flatter nuclei
cytoplasm acidophilic so blends w/ collagen I
can reactivate
adipocytes
syntheize/store/release fats
more efficient and lighter energy store than glycogen
from mesenchymal cells or fibroblasts
terminally differentiated
types of adipocytes
white fat cells
brown fat cells
do white blood cells divide
NO
but can re-differentiate to brown
beiging of white fat
from caloric restrictions (gastric bypass or intermediate fasting)
or repeated cold exposure
white fat cells
unilocular adipocytes
store energy and release fats
produce adipokines (hormones)
1 fat droplet per cell surrounded by external lamina and reticular fibers
adipokines
regulate fatty acid metabolism and body weight
types of adipokines
leptin- reduce appetite
adiponectin-dec glucose release
retinol-binding protein 4- promote gluc release
multilocular adipocytes
brown fat cells
generate heat via decoupling oxidative phosphorylation mainly
more common in newborns bc number declines with age
mostly in or near adrenal glands in adults
multilocular adipocytes
structures
multiple droplets per cell
smaller than white fat cells
nucleus is round/unsquished/euchromatic
have many large mitochondria
cytochromes in mitochondria give brown color
mast cells
initiate type I hypersensitivity rxns
mediate inflammatory proceses
allergic reactions
mast cells
location
from hemopoietic stem cells
circulate in blood until recruited
differentiate @CT proper or mucosa of respir/dig tracts
signature feature of mast cells
secretory granules very large
intensely basophilic/metachromatic/electron dense
contents of secretory vesicles
mast cells
histamine
heparin
enzymes
chemicals to recruit WBC
type I hypersensitivity rxn
step 1
1st exposure to allergen:
plasma cells back IgE antibodies
antibodies bind receptors in membranes of mast cells = sensitized
type I hypersensitivity rxn
step 2
rexposure to antigen/allergen:
binds to IgE antibodies in mast
triggers degranulation
histamine released = inflammatory response
effects of histamine
inc blood flow by lower BP
inc mucus production
causes contraction of smooth muscle in bronchi
inactivated by heparin
macrophages
functions
phagocytosis
present antigens to lymphocytes
promote wound healing
macrophages
appearance
off center nuclues
kidney shaped
euchromatic
have pseudopods and phagosomes
macrophages
derived from
monocytes aka WBC
plasma B cells
from activated B lympocytes
synthesize and secrete antibodies (Ig)
secretion is constitutive/continuous
plasma cell
appearance
intensely basophilic bc lots of RER
large golgi ghose
no granules in cytoplasm
signature clock face
WBCs
leukocytes
exit bloodstream migrate to CT as needed
classifications of CT
embyronic
CT proper
specialized CT
embryonic CT
mucous CT
mesenchyme
only in embryos
CT proper
subtypes
loose/areolar
dense regular
densse irregular
elastic
reticular
physical connection b/t organs and support within
specialized CT
subtypes
adipose (white and brown)
cartilage
bone
blood
physiological support and/or structural support entire body
mucous CT
mostly ECM (ground substance)
only in umbilical cord
firm gel helps resist compression
mesenchyme
in developing embryos and fetus
main type of embryonic CT
many tissues derive from it
mesenchyme
synthesize ECM of embryonic CT
synthesize all 3 fiber types
pluripotent > resident CT cells
loose CT
areolar
cobwebs
mostly collagen I and elastin fibers
vascularized
most common cells = fibroblast, macrophages
loose CT
function
transition b/t epithelia and deeper CT
provides packaging and protection to blood vessels and nerves within
dense regular Ct
many parallel and closely packed collagen I fibers/bundles
consistent orientation and alignment
dense regular CT
function
main CT that forms tendons and ligs
resist strong tensile forces from one direction
not well vascularized = long time to heal
dense irregular CT
many collagen I fibers/bundles in many directions
no consistent orientation
@dermis of skin, organ capsules. epineurium, perichondrium
resist moderate tensile force from many directions
moderately vascularized
elastic CT
little ground substance
densely packed elastic fibers (Y shape) OR broad sheets of elastin (lamellae or laminae)
few collagen I
mainly fibroblasts
reticular CT
little ground substance
fibers form 3D scaffold of:
bone marrow
adipose CT
endomysium (muscle tissue)
supports cells of solid organs and glands
main cell: fibroblast
@ red bone marrow, glands, liver, adipose CT
adipose CT
cells dominate, little ground sub
each cell has external lamina
reticular fibers scaffold b/t adipocytes
white adipose CT
insulation
cushioning
lipid/energy storage
brown adipose CT
heat generation
lipid storage
multilocular
well vascularized and innervated
distinct lobules separated by septa
more abundant in fetuses and newborns
septa
loose or dense irregular CT
nerves and vessels run within
brown vs white fat
smaller lipid droplets
more mitochondria with larger and more cristae
euchromatic nuclei
more capillaries so better vascularized
