Histo - Connective Tissue

Front 1

what is connective tissue?

Back 1

tissue that provides supporting and connective framework for all other tissues in the body and gives metabolic support to cells as the medium of diffusion for nutrients and wastes

Front 2

composition of connective tissue

Back 2

cells
fibers
ground substance

Front 3

composition of extracurricular matrix

Back 3

fibers + ground substance

Front 4

what is difference between connective tissue and epithelium

Back 4

unlike epithelium , connective tissue is directly supplied by blood and lymphatic vessels and nerves , also cells are widely separated by components of ECM. fewer cels , lots of ECM

Front 5

which embryonic germ layer is connective tissue derive from?

Back 5

from embryonic mesenchyme

Front 6

what is is largest component of ground substance at the embryonic stage?

Back 6

hyaluronic acid

Front 7

which embryonic germ layer is epithelium derived from?

Back 7

all 3 mebryonic germ layers
ectoderm - epidermis
mesoderm - mesothelium ( pleura, pericardium, peritoneum)
endoderm - intestinal epithelium

Front 8

which embryonic germ layer is endothelium derived from?

Back 8

mesenchyme

Front 9

describe euchromatin

Back 9

loosely packaged DNA in an uncoiled state that allows for active transcription; lightly stained

Front 10

describe heterochromatin

Back 10

tightly packaged, coiled DNA that is genetically inactive, darkly stained and often in clumps

Front 11

list main types of cells of connective tissue

Back 11

fibroblasts
plasma cells
macrophages,
mast cells
leukocytes
adipocytes

Front 12

what is origin of connective tissue cells?

Back 12

1 - hematopoietic stem cells in the bone marrow , or
2 - undifferentiated mesenchymal cells

Front 13

what is most common cell type in connective tissue?

Back 13

fibroblasts

Front 14

describe fibroblasts

Back 14

- most common cell type in conective tissue
- responsible for synthesis of ECM components ( collagen, elastin, GAG, proteoglycans, glycoproteins)
- 2 forms active =fibrloblast
inactive = fibrocyte

Front 15

describe macrophages

Back 15

aka histocytes
- derived from circulating monocytes
- phagocytes, antigen presenting cells, cytokine producers
large irregularly shaped cells with large nucleus , many lysosomes, well developed RER and golgi

Front 16

describe epithelioid cells

Back 16

this are activated macrophages resembling epithelial cells
they merge to form multinucleated giant cells and form granulomas in many pathologic conditions ( like TB, leprosy, Crohn)

Front 17

describe mast cells

Back 17

- derived from the same progenitor in the bone marorw as basophils
- large oval cells with basophilic cytoplasmic granules
- produce - histamine, heparin, serine protease, leukotriens, chemotactic factors,

Front 18

what is role of mast cells

Back 18

inflamation,
allergies,
innate imunity,
tissue repair

Front 19

describe histochemical processing requirements for mast cells

Back 19

granules are lost in conventional processing of wax sections, so special stains and plastic embedding material must be used to visualize them ( toluidine blue)

Front 20

describe plasma cells

Back 20

- derived from B lymphocytes
- secrte anibodies,
- large ovoid cells with basophilic cytoplasm
- characteristic clockface ( or carthwheel) nucleus ,
juxtanuclear golgi and cetrioles occupy a region that appears pale

Front 21

list fibers of connective tissue

Back 21

collagen fibers,
reticular fibers,
elastic fibers

Front 22

describe collagen

Back 22

- most abundant protein in human body
- more than 20 types,
- can form long fibrils, anchoring fibrils, or network,
- bundles stain pink with H$E
main function is to provide tensile strength
- EVERY 3 rd amino acid is GLYCINE

Front 23

where can we find type I collagen ?

Back 23

dermis, bone, tendon, dentin, fascias, sclera, organ capsules, fibrous cartilage

Front 24

where can we find type II collagen ?

Back 24

hyaline and elastic cartilages,

Front 25

where can we find type III collagen ?

Back 25

smooth muscle, endoneurium, arteries, uterus, liver, spleen, kidney, lung

Front 26

where can we find type IV collagen?

Back 26

epithelial and endothelial basal laminae and basement membranes

Front 27

describe synthesis of type I collagen

Back 27

- polypeptide procollagen alfa - chains are produces in RER
- hydorxylation of proline and lysine residues by prolyl and lysyl hydroxylase ( requires O2 , Fe , ascorbic acid)
- glycosylation of some hydroxylysines
- triple helix forms consisitng of two alfa1 and one alfa 2 peptide chain ( procollagen) and is secreted by golgi
- end propeptides are removed and polymeric collagen fibrils are assembled
- fibrilar structure reinforced with lysine cross link formation via lysyl oxidase