Lectures 6-7: Connective Tissue Flashcards
basic functions of connective tissue (5)
-structural framework
-conducts and translates muscle contractions into movement
-forms stroma of glands and organs
-medium for metabolic exchange
-site of fat and mineral storage
general characteristics of connective tissue (4)
-highly vascular
-low cell density
-extensive ECM
-retain stem and mitotic cells for tissue growth
2 components of ECM
-ground substance
-fibers
function of ECM
-determine physical properties
ground substance features
-colorless, transparent, gel like
-highly hydrated
2 macromolecules present in ground substance
-proteoglycans
-glycosaminoglycans
glycosaminoglycans features
-repeating disaccharide units
-negatively charged
what ion is attracted to glycosaminoglycans
sodium
what is the hydrating element of ground substance
glycosaminoglycans
proteoglycans definition
glycosaminoglycans covalently bonded to core protein
proteoglycans functions (2)
-cushion against compression (think sponge)
-aid in material exchange
large aggregates of proteoglycans function
-enhance role of glycosaminoglycans
-occupy large volume
-resist fluid movement
2 fibers in ECM
-collagen
-elastic
what is the most common protein in the body
collagen
collagen function
tensile strength (flexible not elastic)
collagen organization (smallest to largest)
fibrils –> fibers –> bundles
what determines the type of collagen
length and color of fibril bands
periodicity
-rate at which the collagen stripes exist
-results from presence of overlap and gap regions between collagen fibrils
which type of collagen is most common
type 1
type 1 collagen has highest ____________
tensile strength
type 1 collagen under light microscopy
-pink fibers and bundles with H and E
-acidophilic
type 2 collagen definition
slender fibrils found in cartilage
type III collagen fibers aka
reticular fibers
type III/reticular fibers function
filter fluid
how are type III fibers stained
silver
how do type III/reticular fibers appear
-branching, delicate like meshwork
core of elastin surrounded by
sheath of microfibrils
elastic always accompanies
collagen
elastic fibers vs collagen under miscroscope
-elastic: stringy, black
-collagen: thicker, dark pink
elastic vs reticular fibers appearance
reticular fibers branch, elastic don’t
example of connective tissue cell that originates in and permanently resides in CT
fibroblasts
examples of CT cells that migrate into CT to perform functions
-host defense, WBCs
-mast cells, macrophages, plasma cells, leukocytes
what is the most abundant and widely distributed fixed cell
fibroblast
fibroblast appearance
elongated, oval nucleus
fibrocyte
inactive version of fibroblast
2 types of adipocytes
-unilocular
-multilocular
most common adipocyte
unilocular
unilocular adipocyte
-large white cell
-thin rim of cytoplasm
-single lipid droplet
where are multilocular adipocytes located
brown adipose tissue
multilocular adipocyte: definition
-fat stored in multiple lipid inclusions (many small droplets)
multilocular adipocyte: function
-non shivering thermogenesis (heat production)
multilocular adipocytes most present in who
infants
when are mast cells released
after exposure to sensitized antigens
granules present in mast cells (3)
-histamine
-heparin
-leukocyte chemotactic factors
histamine function
blood vessel permeability, makes cell swell
heparin function
anticoagulant
leukocytic chemotactic factors function
attract WBCs
where are mast cells found and why
-near blood vessels in skin, digestive system and respiratory system
-need to react quickly, come in contact with pathogens/antigens
mast cell: normal inflammatory response
-antigen exposure –> mast cells release histamine and leukocyte chemotactic factors –> surrounding epithelial cell opens to allow WBCs to come through
macrophages originate where
bone marrow
precursor to macrophages called
monocyte
macrophages undergo which form of endocytosis
phagocytosis
macrophages use/have __________ for phagocytosis
pseudopodia
what gives macrophages bubbly appearance
phagosomes and lysosomes
plasma cells function
synthesize and secrete antibodies
what organelle is required to make antibodies
rough ER (protein)
plasma cells are made by what cells
B cells
where are plasma cells mainly found
GI and respiratory tract
general types of connective tissue (4)
-loose
-dense
-adipose
-reticular
loose CT aka
areolar
loose CT appearance
-sparse, loosely arranged fibers
-looks open
-a lot of ground substance
where is loose CT located
-beneath epithelium
-near lumen
loose CT is the primary site for what kind of reactions
immune and inflammatory
dense CT appearance
-many bundled fibers
-little ground substance
-looks compact
different types of dense CT (2)
-dense
-irregular
irregular vs regular CT
-irregular is disorganized, strong is all directions
-regular is linear (nuclei one after the other)
reticular tissue appearance
delicate, lattice work of reticular fibers
where is reticular tissue found
-organs that filter = blood or lymph
-endocrine glands
How to identify loose connective tissue histology
Very few fibers present
Abundance of cells/nuclei
How to differentiate skeletal vs cardiac vs smooth muscle under microscope
Skeletal = peripherally located, flat nucleus (towards top of striations)
Cardiac = centrally located nucleus, intercalated discs, branching
Smooth = centrally located nucleus, no striations
how to identify macrophage under microscope
-psuedopodia
-lysosomes
how to identify plasma cell under microscope
-weird shaped nucleus
-extensive euchromatin in nucleus
