Connective Tissue

Question 1

What are the 5 main functions of connective tissue?

Answer 1

Support, medium for exchange, protection, reparation, storage of fat

Question 2

What are the main components of the extracellular matrix in CT?

Answer 2

Ground substance and fibers

Question 3

What are the main components of ground substance?

Answer 3

Glycosaminoglycans, Proteoglycans, glycoproteins

Question 4

What glycosaminoglycans are there?

Answer 4

Chondroitin; heparan, keratan, dermatan sulphates, hyaluronic acid

Question 5

What collagen fibers are the most abundant in CT?

Answer 5

I and III

Question 6

What fibers are there in CT?

Answer 6

Collagen fibers, reticular fibers, elastic fibers

Question 7

What is the function of ground substance?

Answer 7

Diffusion of gases and substances and delivering them to cells

Question 8

Name all these about Aggrecan: types of GAG chains, localization, functions

Answer 8

Chondroitin and keratan sulphate, in cartilage, mechanical; forms large aggregates with hyaluronic acid

Question 9

Name all these about Beta-glycan: types of GAG chains, localization, functions

Answer 9

Chondroitin and dermatan sulphate, in cell-matrix interface, binds growth factor TGF-beta

Question 10

Name all these about Decorin: types of GAG chains, localization, functions

Answer 10

Chondroitin and dermatan sulphate, common in CT, connects collagen fibrils and TGF-beta

Question 11

Name all these about Perlecan: types of GAG chains, localization, functions

Answer 11

Heparan sulphate, in basal laminae, structural; filtration

Question 12

Name all these about Syndecan: types of GAG chains, localization, functions

Answer 12

chondroitin and heparan sulphate, on surfaces of cells, cell adhesion, binds growth factor FGF

Question 13

What are the properties of collagen fibers in CT?

Answer 13

Built of collagen type I and III, acidophilus, composed of striated fibrils, thick, form bundles, resistant to stretch and disruption

Question 14

How are collagen fibers produced and assembled?

Answer 14

1. Preprocollagen molecules get translated in RER, 2. The molecules get hydroxylized and glycosylized in RER, 3. Formation of pro collagen triple helix molecules in RER, 4. Pro collagen molecules are transferred to Golgi and secreted through exocytosis, 5. Cleavage of propeptides - formation of collagen, 6. Self-assembly of collagen molecules into collagen fibrils, lateral aggregation of fibrils into fibers

Question 15

What are the main features of reticular fibers?

Answer 15

Built of collagen III, composed of striated fibrils, thin, form a scaffolding for cells and cell groups

Question 16

What is the morphology and location of Collagen type I?

Answer 16

Morphology: coarse striated collagen fibers, Location: dermis, ligaments, fascia, tendon, fibrocartilage, cornea

Question 17

What is the morphology and location of Collagen type II?

Answer 17

Morphology: thin striated collagen fibers, Location: hyaline and elastic cartilage

Question 18

What is the morphology and location of Collagen type III?

Answer 18

Morphology: thin striated reticular fibers, Location: blood vessels, bone marrow, lymphatic organs, smooth muscle, lungs, liver, skin

Question 19

What are the main features of elastic fibers?

Answer 19

Built of elastin microfibrils, thin, form networks or fuse into flat sheets, highly expandable

Question 20

What do desmosine cross-links do?

Answer 20

They give elastin fibers their mechanical properties by straightening under stretch and coiling after cessation of stretch

Question 21

What are the cells of CT proper?

Answer 21

Fibroblasts, macrophages, plasma cells, mast cells, adipocytes, pericytes

Question 22

Which cells have mesenchymal stem cell origin?

Answer 22

Fibroblasts and adipocytes

Question 23

Which cells have hematopoietic stem cell origin?

Answer 23

Macrophages, plasma cells, mast cells

Question 24

What are the main features of fibroblasts?

Answer 24

Produce ECM components, elongated, RER, & Golgi, constitutive exocytosis, get transformed into quiescent fibroblasts in mature tissue

Question 25

What are the main features of macrophages?

Answer 25

Phagocytosis, immune response, stem from monocytes, capable of ameboid movement, numerous lysosomes

Question 26

What are the two functional types of macrophages?

Answer 26

Proinflammatory M1 and antiinflammatory M2

Question 27

What are the main features of plasma cells?

Answer 27

Humoral immunity, stem from B lymphocytes

Question 28

What are the main features of mast cells?

Answer 28

Type I hypersensitivity (proinflammatory mediators), contain granules, located close to blood vessels, scarce microvilli, originate from bone marrow

Question 29

What are the main secretory products of mast cells that are stored in GRANULES?

Answer 29

Histamine (vasodilator), heparin (inactivates histamine), chondroitin sulphate (inactivates histamine), proteases (increase inflammatory response), factors attracting eosinophils and neutrophils to site of inflammation

Question 30

What are the main secretory products of mast cells that are released immediately after activation?

Answer 30

Leukotrienes, cytokines (interleukins), platelet-activating factor, free radicals

Question 31

What are the two types of mast cells and what proteases do they contain?

Answer 31

Connective tissue mast cells (both chymase and tryptase) & Mucosal mast cells (only tryptase + do not contain heparin)

Question 32

How does the activation of a mast cell work?

Answer 32

1. Binding of IgE to its receptor, 2. Binding of antigen to IgE, 3. Activation of signalling pathways

Question 33

What does the activation of signalling pathways in mast cells do?

Answer 33

1. Increases Ca2+ level resulting in massive exocytosis of granule content, 2. Activation of phospholipase resulting in production and release of leukotrienes, 3. Activation of genes encoding cytokines —> production and release of proinflammatory cytokines

Question 34

What are the main features of telocytes?

Answer 34

Are interconnected via their processes forming a signalling network, thus influencing functions of other cells by releasing signalling molecules and by shedding micro vesicles and exosomes

Question 35

What is the classification of CT?

Answer 35

1. Embryonic CT: mesenchymal (embryos, almost no fibers) & mucous (umbilical cord, primitive fibroblasts, very few delicate collagen fibrils), 2. CT proper: loose CT (fibers and ground substance in equal amounts, forms scaffolding in organs) & dense CT (predominant collagen fibers, quiescent fibroblasts) & Reticular Tissue (mainly fibroblasts and macrophages, reticular fibers) & Adipose tissue (white, brown, beige), 3. Supporting CT, 4. Specialized CT: blood, cartilage and bone

Question 36

What are the main features of white adipose tissue?

Answer 36

Unilocular, dense network of capillary vessels, fatty acid homeostasis

Question 37

What hormones does white adipose tissue produce?

Answer 37

Leptins (inhibit appetite), Adiponectin (regulation of fatty acid and glucose metabolism), Resistin (regulation of inflammatory processes and induced insulin resistance)

Question 38

What are the main features of brown adipose tissue?

Answer 38

Multilocular, dense network of capillary vessels, rich Innervation, in neonates, production of heat, numerous mitochondria

Question 39

What are the main features of beige adipose tissue?

Answer 39

Not age-dependent, forms small islets in yellow adipose tissue, almost the same as brown adipose tissue function-wise, induced by e.g. muscular activity, reduces the amount of yellow adipose tissue