Connective Tissue Flashcards Preview

Histology > Connective Tissue > Flashcards

Flashcards in Connective Tissue Deck (40):
1

What does connective tissue do?

Provides structure, Defends against infection/antigens, helps to repair injuries, stores lipids/fat (stores energy), means for diffusion of nutrients & waste (helps maintain other tissues), attaches muscle to bone or bone to bone`

2

What would you expect to see in tendon tissue? And why?

Many fibers
Few cells
Little ground substance
Why?: Function: attaches muscle to bone

3

What is Connective tissue made of?

Extracellular matrix: Fibers produced by fibroblasts and ground substance

Cells: Fibroblasts, myofibroblasts, macrophages, mast cell & basophils, adipose cells, mesenchymal stem cell & pericyte, lymphocytes, plasma cells, eosinophils, monocytes & neutrophils

4

What would you expect to see in dense connective tissue?

Lots of collagen fibers
Little ground substance
Thin inactive fibroblasts
Flat nuclei

5

Types of connective tissue

Embryonic connective tissue, Connective tissue proper, Specialized connective tissue

6

Mesenchyme: what is it and what do you expect to see?

-Primative connective tissue which can differentiate into many different things (i.e. muscle, serous membranes, vascular system, urogenital system, various connective tissue)
-Viscous
-Collagen bundles
-Fibroblasts
-Cells wont look orderly because it will differentiate into different cells

7

Mucous Connective Tissue

Gelatin-like ECM present in the umbilical cord. Component of Wharton's jelly.

8

Loose Connective Tissue (areolar)

-Important in diffusion of Oxygen and nutrients
-Various/diverse number of cells
-Fewer collagen fibers
-A lot of ground substance
-Highly vascularized: Blood vessles (for nutrients & place for immune cells to interact with antigens)
-More nuclei (spread out)
-Underneath epithelium that covers body surfaces & lines internal surfaces of the body
-Site of inflammatory and immune reactions

9

Dense connective tissue

-Fewer cells
-Lots of fibers
-Minimal ground substance
-Poorly vascularized
-Provides strength to stand up to stress (Irregular: interlacing patters and regular: parallel arrangements)

10

Dense irregular connective tissue

-Found in submucosa of hollow organs and the dermis layer of integument
-Mostly collagen fibers with elastin mixed in
-Few cells, normally fibroblasts
-Little ground substance

11

Dense Regular connective tissue

-Found in many places
-Densely packed fibers (type depends on function) --> for strength
-Ordered array

12

Tendons

-Attach muscle to bone
-Dense regular connective tissue
-Collage type I
-Bundles of collagen fibers and rows of tendinocytes

13

Ligaments

-Attach bone to bone
-Dense regular connective tissue
-Fibers & fibroblasts arrange less regularly than in tendons (more elastic)
-

14

Aponeuroses

-Dense regularconnective tissue
-orthogonal array in the cornea of the eye
-Collagen fibers arranged in layers at right angles

15

ECM of Connective Tissue

Fibers (collagen, reticular, elastic)
Ground Substance (Proteoglycans, glycosaminoglycans, & multiadhesive glycoproteins)
-Structural network that supports the cells within the CT.

16

Collagen

-Triple helix composed of alpha chains
-Molecules align head to tail in overlapping rows (make up fibril)
-Fibrils (subunits) form bundles that make up a fiber
-Has a 68-nm banding pattern
-Flexible and high-tensile strength
-Pink in slides
-Covalent bonds between fibers (gives molecule strength)

17

Procollagen

-Made intercellularly and then exocytosed
-Precurser to collagen
-Triple helix
-Lots of proline & Lysine because collagen needs to be hydroxylated

18

Collagen Type I

Connective tissue of skin, bone, tendons, ligaments, and organ capsules (90% of body collagen)

19

Collagen Type II

Hyaline and elastic cartilages

20

Collagen Type III

In LCT and smooth muscle, nerve fibers, and blood vessels

21

Collagen Type IV

Major component of basal lamina

22

Collagenophathies

Occur when there is an abnormality in a specific collagen and has wide effects due to the number of locations in the body it is found.

23

Collagen degradation

Proteolytic degradation: Proten clips collagen (enxymes secreted by cells)
Phagocytic degradation: Macrophages and fibroblast cells eats collagen
Many cancer cells produce enzymes to degrade collagen this plays a role in invasion and metastasis (measurement may be a biomarker for degree of malignancy)

24

Reticular Fiber

-Collagen type III fibers that are highly glycosylated (not hydroxylated like collagen fibers are)
-Stain silver
-Arranged in a meshlike pattern/network
-Found in loose CT and embyonic tissue
-Also found in stroma of hemopoietic and lymphatic tissue
-branched and thinner than collagen
-initial tissue that forms in wound healing (after, more mature collagen I forms)
-Kinks, wispy, branched, a lot of cells, no bundles/thick fibers

25

Exception for reticular fibers

Usually produced by fibroblasts except in:
Peripheral nerves (schnwann cells secrete reticular fibers)
Blood vessels and alimentary canal (smooth muscle cells secrete reticular fibers)
Reticular cells in hemopoietic and lymphatic tissues

26

Elastic Fiber

-Elastin forms core fiber which is surrounded by fibrillin microfibrils
-Arranged in a branching pattern interwoven with collagen
-Protein is rich in glycine and proline which makes a hydrophobic molecule that randomly coils (kinks)
-Fibrillin-1 organixes elastin into fibers
-Major substances in vertebral ligaments, larynx, and elastic arteries
-stain dark purple
-coiled and kinky

27

Ground substance

-Tissue fluid that contains salts, ions & soluable protein
-Lost in routine H&E preparation (stains white bc when making slides-->dehydrate and therefore it isn't well preserved
-clear viscous substance
-three groups of molecules (glycosaminoglycans (GAGs), proteoglycans, multiadhesive glycoproteins)

28

Glycosaminoglycans

-Most abundant component in ground substance
-Long unbranched polysaccharides
-Each polysaccharide contains repeating units of N-acetylgalactosamine or N-acetylglucosamine and a uronic acid
-GAG's are SULFANATED which gives a NEGATIVE CHARGE which HELPS ATTRACT WATER
-This allows diffusion of nutrients, waste, and movement of cells (dynamic property to connective tissue)

29

Hyaluronic Acid

-GAG protein
-very long rigid molecule made by enzymes on the cell surface (no sulfate)
-Proteoglycans bind using link proteins to form aggregates
-Help to maintain specific proteins in a location within ECM
-Clinical correlation: Strept & Staph emit hyaluronidase to make an entry point for bacteria

30

Proteoglycans

Found in ground substance of all CT
Types: Decorin, Versican, Aggrecan (responsible for hydration of ECM), Syndecan (links cells to extracellular matrix molecules)

31

Multiadhesive glycoproteins

Important for stabilizing and linking ECM to cell surfaces (interact with receptors)
Modulate cell movement, proliferation, and differentiation (fibronectin)

32

Resident Cells

-Derived from mesenchyme and are always present in cells of connective tissue
-Fibroblasts, adipocytes, macrophages, mast cells, mesenchymal stem cells

33

Migratory cells

-Move in response to signal through and function in connective tissue
-Neutrophils, lymphocytes, plasma cells, eosinophils, basophils, monocytes.

34

Fibroblasts

Make and maintain fibers and carbs in ground substance (chondrocytes, osteoblasts, pericytes)
-Primary cell connectors
-can phagocytos
-elongated nucleus; cytoplasm tails

35

Myofibroblasts

-Fibroblast with characteristics of smooth muscle
-lacks basal lamina
-exists as an isolated cell
-able to contract

36

Macrophages

Differentiated monocytes from blood stream migrate to CT and differentiate into macrophages
-Use neutral proteases and GAGases to migrate
-Function: Phagocytosis of antigens or cell debris, fuse to form Langerhans cells

37

Adipocytes

Differentiate from mesenchymal cells and store fat in their cytoplasm
Yellow fat (unilocular): single droplet of triglycerides, minimal cytoplasm, nucleus conforms to contour of fat droplet
Brown fat (multilocular): numerous droplets, large #'s of mitochondria, mostly present in postnatal life in humans and abundant in hibernating animals for heat protection

38

Mast cells & Basophils

-Part of adaptive immunity
-Triggers histamine release and other inflammatorymediators during degranulation
-Basophils start immediate hypersensitivity rxn and anaphylaxis
Not found in central nervous system
-Granules with histidine in cytoplasm

39

Pericytes, Stem and Plasma cells

Pericytes: fond around capilaries and venules
Mesenchymal stem cells: source of new cell in wound healing
Plasma cell: immune cell found in GI and respiratory tract, clock faced, comet's tail (nucleus off to the side with cytoplam trailing behind)

40

White blood cells (leukocytes), neutrophils, eosinophils

Migrate through and function in connective tissue
Accumulate at sites of inflammation: T-cells (cell mediated immunity) B-cells (antibody mediated immunity, Natural Killer cells: Cell mediated immunity
Neutrophils: Polymorphonuclear leukocytes are high phagocytic & at infection sites
-Eosinophils: cytoplasmic granules stain brightly with eosin, modulate inflammatory process