L6. Connective Tissues Flashcards
What are the functions of connective tissues
- provide structural support
- lipid storage
- medium for exchange
- protective function
- defence
Where do connective tissues originate from?
mesenchyme / mesenchymal layer
What does the C.T consists of
- ECM
- cells
Which tissue type has the most ECM?
CT
Describe C.T
- made up of ECM and cells
- derived from the mesenchyme
- vascularized
What makes up the ECM
- Ground substances
- Fibers
What are the 3 different types of fibers?
collagen
reticular fibers
elastic fibers
What are the 3 different ground substances?
GAG
proteoglycan
glycoprotein
What is the characteristics of GAG
-vely charged attracts Na+ attracts H2O ; allows high compression long chains of carbohydrate stains blue on HE stain
What is the characteristic of proteoglycan?
hydration allows for diffusion contains GAG chains (long+unbranched) attracts water 90% of weight is due to GAG compressive stains blue in HE keeps CT hydrated and gel like
What is the function of glycoprotein?
- acts as an adhesive
- link components of the ECM together
- link ECM to cells
- up to 60% of mass is due to short branched sugar chains
What is the characteristic of collagen?
- collagen type 1 fibers have more tensile strength
- thick , appear in bundles
- consists of tropocollagen ( 3 interwoven collagen peptide helices) to make fibrils
- appears STRIATED
What is the characteristic of reticular fibers?
Forms a reticular net
found in highly cellular organs
type 3 collagen fibers that are highly glycosylated
What is an example of proteoglycan?
aggracan
What is an example of glycoprotein
fibronectin
What is the characteristic of elastin?
distensible elastin polymers
glycoprotein wrapped around elastin polymers
found in tissues where stretch /coil is needed
What structure will have elastin?
vessels ( like artery)
What structure will have reticular fibers?
lymphoid nodes
What progenitor cells can be found in the ECM in CT?
hematopoietic stem cells
mesenchyme stem cells
What cells are derived from the mesenchyme stem cells
fibroblast
adipocytes
pericytes
What cells are derived from the hematopoietic stem cells
plasma cells
mast cells
macrophages
What are the characteristics of fibroblast?
- large nucleus
- extensive ER and golgi
- derived from undifferentiated mesenchymal cells
- most abundant cell in CT
What are the characteristics of pericytes?
- attach to vessels stabilize them
- contractile
- pleuripotent stem cell properties
What are the characteristics of adipocytes?
- cytoplasm filled with lipid droplets
- separated by dense irregular CT called septae
- nuclei is eccentric
- lipids are washed out during dehydration
What are the characteristics of mast cells?
-part of inflammation response
secretes histamine (vasodilator, broncho constrictor) and heparin(anti-coagulant)
sensitive to pollen, foreign particules
What are the characteristics of macrophages?
numerous vacuoles, vesicles, endosomes,lysosomes
kidney shaped nucleus
motile phagocytic
derived from monocytes
What are the characteristics of plasma cells?
clock face nucleus
prominent golgi apparatus ( pale staining)
prominent RER ( STAINS BLUE)
differentiated lymphocytes
What is the 5 types of connective tissue
- loose connective tissue
- regular dense connective tissue
- irregular dense connective tissue
- reticular C.T
- adipose C.T
Describe the loose connective tissue
high cells
high Ground substance
low fibers
high diffusion index, flexible, mallaeble
Describe the regular dense connective tissue
resistant to stress in one direction
low cell , low ground substance
lots of collagen type 1 fibers
high amount of fibers
Describe the irregular dense connective tissue
high amount of fibers
resistant to stress in all directions
may contain elastin fibers and collagen type 1 fibers
fibers are irregularly arranged in all directions
Describe the reticular C.T
highly cellular many reticular fibers ( type 3 collagen)
Describe the adipose C.T
high number of adipocytes in groups ( lobules)
lobules are separated by sleeves of irregular connective tissue
Where do we find loose connective tissue
lamina propria
Where do we find regular dense connective tissue
found in tendons, muscles, ligaments
Where do we find irregular dense connective tissue
found in dermis of skin and covering os some organs
Where do we find reticular C.T
found in lymphoid structures
Where do we find adipose C.T
dynamic, found in many CT sites ( hypodermis)
What is the parenchyma
epithelial secretory unit
what is the stroma (for epithelial morphogenesis and support)
surrounding connective tissues in gland
What is a gland?
surface epithelial cells that penetrate underlying connective tissues and secrete substances they syntehsize
Unicellular glands are
single secretory cells that embed in a surface epithelium
Multicellular glands are
clusters of secretory cells surrounded by CT
secrete into a duct
What are the 2 types of multicellular gland systems
- simple : only 1 duct ( no branch)
2. compound: more than 1 duct ( branch)
What are the 2 shapes of a secretory unit
- tubular
2. alveolar
What are the 2 types of secretory glands ( what they secrete)
- serous gland
2. mucous gland
What is a serous gland
secrete a enzyme-rich fluid,
cytoplasm of parenchymal binds to eosin
(eg. pancreas)
What is a mucuos gland
secrete glycoprotein and proteoglycans that form a lubricant;
bind to heotoxylin ( blue- due to -ve charge)
(eg. salivary gland)
Give an example of a serous gland
pancreatic duct
Give an example of a mucous gland
salivary gland
What are fixed cells in the C.T?
mast cells adipocytes fibrocytes pericytes (sometimes macrophages)
What are transient cells in the CT?
numerous WBC, plasma cells
