Connective Tissues Flashcards
connective tissue cells are separated from each other by
extracellular matrix
extracellular matrix (ECM)
- what is it
- what is it like in bone
- what does it carry
gel-like substance with embedded protein fibers
- in bone it is mineralized
- carries O2, CO2, nutrients, and wastes
3 types of adult fibrous connective tissues
loose (areolar)
dense regular
dense irregular
6 functions of connective tissues
- structural framework of body
- protection
- supports and interconnects tissues
- energy storage (adipose)
- transports fluids, cells, chemicals
- defense against microorganisms
fibroblasts
- what do they produce
produce collagens, proteoglycans, glycoproteins
mesenchymal cells
connective tissue stem cells
adipocytes
store and release fats
chondrocytes
produce and maintain cartilage components
osteoblasts
produce bone components
hematopoietic stem cells
produce red blood cells and immune cells
- macrophages
- mast cells
- lymphocytes
- plasma cells
function of collagens in ECM
resists tension
function of elastins in ECM
stretchable fibers, assembly of tropoelastin, fibulin-1, fibrillins 1/2
function of reticular fibers in ECM
forms supportive meshwork
type 1 collagen fibers
aligned and cross-linked to increase tensile strength
Ehlers-Danlos syndrome
abnormal collagen synthesis leading to weak collagen fibers
Scurvy
due to vitamin C deficiency; vitamin C is a cofactor in cross-linking collagen fibers
- weakens connective tissue
Marfan’s syndrome
autosomal dominant disorder where elastin is weak; caused by mutation in fibrillin-1 gene
- targets ocular, skeletal, and cardiovascular systems
- patients tend to be tall with long arms/legs
features of embryonic connective tissue
rich in ECM and mesenchymal stem cells; some collagen and reticular fibers
“Warton’s Jelly”
embryonic connective tissue in the umbilical cord
adult mesenchymal stem cells
multipotent stem cells that differentiate into a variety of cell types:
- fibroblasts
- muscle cells
- osteoblasts
- chondroblasts
- adipocytes
areolar tissue
a type of loose connective tissue; low density tissue with both fixed and wandering cells; widespread
adipose tissue
a type of loose connective tissue; fat containing tissue
reticular connective tissue
a type of loose connective tissue; rich in reticular fibers; forms an open framework to create a supportive mesh for holding free cells
- meshwork also houses blood cells and immune cells outside blood and lymph vessels
dense irregular connective tissue
- how are the fibers arranged
- example
fibers are deposited in a random pattern
- ex: dermis of skin
dense regular connective tissue
- how are the fibers arranged
- function
- vascularization?
- example
fibers are deposited in a highly regular patterns; resists pulling forces; poorly vascularized
- ex: tendons connecting skeletal muscle to bone
elastic connective tissue
dense connective tissue rich in elastin fibers; allows recoil of tissue following stretching
what are the three types of fixed cells in loose areolar connective tissue
fibroblasts
adipocytes
mesenchymal cells
what are the four types of wandering cells in loose areolar connective tissue
macrophages
mast cells
leukocytes/lymphocytes
plasma cells
functions of loose connective tissue
- support and bind other tissues
- hold body fluids
- defense against infection
where is loose connective tissue found
- beneath membranous epithelia
- around blood vessels, muscles, and nerves
function of adipose connective tissue
- provides reserve energy source and insulates against heat loss
- supports and protects organs
where is adipose connective tissue found
under skin, around organs, within abdomen, breasts and buttocks
white fat
- functions
functions in energy storage, insulation, cushioning vital organs, and hormone secretion
brown fat
- functions
- babies vs adults
key thermogenic tissue, abundant in newborns, greatly reduced in adults
where is reticular connective tissue found
liver, bone marrow, lymph nodes, spleen
where is dense irregular connective tissue found
dermis of skin, capsules surrounding internal organs, perichondrium and periosteum, fascia
what is the principle cell type of dense regular CT
fibroblasts
where is elastic CT found
blood vessel walls, bronchiole tubes, special ligaments (ligamentum nuchae)
function of fibroblasts
produce the collagen, elastin, reticular fibers, proteoglycans, and glycoproteins in the ECM
adipocytes
- micrograph appearance
- function
closely packed cells with nuclei pushed to the side by large fat droplet; removes lipids from blood and stores it and releases it into the bloodstream when needed
- provides reserve energy source
macrophages
differentiate from monocytes; function is phagocytosis and destruction of bacteria/damaged cells/sick cells, removal of debris, and antigen processing and presentation
mast cell
secrete chemicals such as histamine that mediate the allergic response and heparin (an anti-coagulant of blood)
plasma cells
differentiate from B-lymphocytes; produce antibodies that mediate immunity
3 types of proteoglycans
- chondroitin sulfates
- heparan sulfates
- keratan sulfates
hyaluronan
links proteoglycans into large link
- found a lot in cartilage
integrin receptors
transmembrane linkers between ECM and cells
- used by migrating cells and epithelial cells
syndecans
single transmembrane domain proteins that are thought to act as coreceptors
CD44
cell surface adhesion receptor that is highly expressed in many cancers
dystroglycans
cell adhesion receptor that connects ECM to cells
