Connective Tissue Flashcards
What permanent CT cell is phagocytic and functions as an APC?
Macrophage
define
connective tissue
provides a matrix that supports and physically connects other tissues and cells together
CT composition
cells and ECM
ECM composition
fibers and ground substance (fluid filling space)
define
mesenchyme
a tissue developing from the mesoderm (middle layer of embryo)
CT is derived from __________
embryonic mesenchyme
4 types of permanent/resident CT cells
- fibroblasts
- adipocytes
- macrophages
- mast cells
what is the principal and most prevalent CT cell?
fibroblast
function
fibroblast
- produce & maintain ECM
- synthesize & secrete fibers (collagen, elastic, reticular)
- synthesize complex carbs of ground substance
fibroblast
active vs inactive cells
active cells - fibroblast - larger nuclei
inactive cells - fibrocyte - smaller cells
define
adipocyte
- fat cells found in CT of many organs
- large cells, derived from mesenchyme
function
adipocyte
- energy storage: cytoplasmic storage of lipid
- heat production
- cushion & protect skin & organs
adipocytes are derived from ____
mesenchyme
macrophages are derived from ____
monocytes (type of WBC)
what are tissue histiocytes?
monocytes that enter tissues, known as macrophages
define
macrophages
phagocytic, antigen-presenting cells that play an important role in repair & inflammation after tissue damage
phagocytic cells
turnover of protein fibers, removal of dead cells, tissue debris, foreign matter
antigen presenting cells (APC)
phagocytic
immune system cells with foreign antigens
macrophages are part of what system?
mononuclear phagocytic system
what organelle is very abundant in macrophages?
lysosome
define
mast cells
large, ovoid, heavily grandulated CT cells
what CT cell is associated with allergic reactions known as immediate hypersensitivity reactions?
mast cells
secretory products of mast cell granules
- histamine
- heparin
- serine proteases
- eosinophil & neutrophil chemotactic factors
- cytokines
function
histamine
increase vascular permeability and smooth muscle contraction
function
heparin
anticoagulant
2 types of wandering/transient CT cells
- plasma cells
- other leukocytes (WBCs)
function
plasma cells
product antibodies
describe
plasma cells
- large, ovoid cell with basophilic cytoplasm, large pale golgi apparatus
- nucleus eccentrically placed with peripheral heterochromatin regions giving “clock-face” appearance
examples of other leukocytes (WBCs)
- neutrophils
- lymphocytes
- eosinophils
- basophils
- adult stem cells
- myofibroblasts
adult stem cells
niches of adult stem cells are located in various tissues and organs; typically differentiating into specific cells
myofibroblasts
fibroblasts involved in wound healing; have a well-developed contractile function; contain a form of actin
most abundant CT fiber
collagen
define
collagen
- family of proteins forming various extracellular fibers, sheets and networks with strong resistance to shearing and tearing forces
most abundant protein in the body
collagen
structure
collagen
bundles of fine, threadlike subunits called collagen fibrils
collagen synthesis is the specialty of the ____
fibroblasts
collagen synthesis
- polypeptides produced in RER
- in ER, 3 a-chains folded into triple helix
- triple helix cleaved into a procollagen molecule (tropocollagen)
- different types of procollagen chains produce the various types of collagen w different structures & functions
what produces the various types of collagen with different structures and functional properties?
different combinations of procollagen a-chains
what is a procollagen molecule?
basic subunit from which all fibers or sheets are assembled (AKA tropocollagen)
assembly of type 1 collagen
fibrils->fibers->bundles
type 1 collagen main location
most places in body
type 2 collagen main location
cartilage
type 3 collagen main location
reticular
type 4 collagen main location
basement membranes
reticular fibers are produced by ____
fibroblasts (reticular cells)
function
reticular fibers
- supporting stroma of hemopoietic (bone marrow) and lymphatic tissue –> network called reticulum
reticular fibers consist mostly of ____
type III collagen
what does argyrophilic mean?
“loves silver” - reticular fibers are stained black with silver salts
location
reticular fibers
- delicate loose CT at boundary of CT & epithelium
- surrounding adipocytes, small blood vesselsm nerves, muscle cells
- abundant in embryonic tissue
function
elastic fibers
allow tissues to respond to stretch & distension
elastic fibers are produced by ____
fibroblasts
structure of elastic fibers
composed of fibrillin, forming a network of microfibrils embedded in a large mass of cross-linked elastin
function of elastin
hydrophobic nature allows random coiling of its fibers
in large blood vessels, elastin occurs in fenestrated sheets called ____
elastic lamellae
define
ground substance
part of ECM that occupies spaces between cells and fibers
3 macromolecules of ground substance
- glycosaminoglycans (GAGs)
- proteoglycans
- multiadhesive glycoproteins
how is CT proper classified?
according to amount of collagen & ground substance
3 types of CT proper
loose CT
dense irregular CT
dense regular CT
loose CT
fibers & cells
fewer, loosely arranged fibers (type 1)
abundant cells
dense irregular CT
fibers & cells
abundant fibers (type 2)
few cells
dense regular CT
fibers & cells
ordered, densely packed fibers (type 1) & cells
dense irregular CT
functional properties
- strength
- allows stretch & distension
loose CT
location
beneath epithelia covering body surfaces and lining internal surfaces of body
dense irregular CT
location
dermis of skin, submucosa of hollow organs, capsules surrounding most organs
dense regular CT
location
tendons & ligaments
2 types of specialized CT
mesenchyme
mucoid
mesenchyme
location
primarily in embryo
mesenchyme
function
contains undifferentiated cells capable of differentiating into all CT
mucoid CT
location
umbilical cord (Wharton’s jelly)
nucleus pulposis of IVD
mucoid CT
fibers & cells
fewer cells than mesenchyme, whispy fibers
2 types of adipose tissue
white
brown
white adipose
unilocular/multilocular
unilocular: single large droplets of triglicerides, displace nucleus to periphery
brown adipose
unilocular/multilocular
multilocular: multiple lipid droplets, abundant mitochondria, central nucleus
white adipose
function
energy storage (lipids)
white adipose
appearance
chicken wire
brown adipose
function
thermogenesis
reticular tissue is characterized by abundant ____ and type ____ collagen
abundant fibers
type 3 collagen
reticular tissue
location
bone marrow - hemapoeitic tissue
lymph nodes
