Tissue Organization

Question 1

What are the two principle types of tissues?

Answer 1

Cellular (muscle/epithelia)

Connective (cartilage/bone/tendon)

Question 2

What are cellular tissues’ integrity and properties from? (2 types of interactions)

Answer 2

cell-cell interactions

cell-extracellular matrix interactions

Question 3

What are crucial for cellular tissue integrity?

Answer 3

cell junctions

Question 4

What are the properties and of connective tissue derived from?

Answer 4

extracellular matrix (ECM) composition

Question 5

What is the role of the ECM in connective tissues?

Answer 5

anchorage point for cells - connective tissues are primarily comprised of ECM

Question 6

What main molecules interact in adhering/anchoring junctions?

Answer 6

actin microfilament cytoskeleton, intermediate filament cytoskeleton

Question 7

What are the 3 basic components of a junction?

Answer 7

1. Transmembrane glycoprotein
2. linker proteins
3. cytoskeleton

Question 8

what do linker proteins do?

Answer 8

stabilize link from tissue to cytoskeleton

Question 9

what are the two types of actin-filament (MF) based anchoring junctions?

Answer 9

adherens junction = cell-cell

focal junction = cell-ECM

Question 10

what transmembrane protein do adherens junctions use?

Answer 10

cadherins

Question 11

what transmembrane protein do focal junctions use?

Answer 11

integrins

Question 12

What are the two types of intermediate filment based anchoring junctions?

Answer 12

desmosome = cell-cell
hemi-desmosome = cell-ECM

Question 13

what transmembrane protein do desmosome junctions use?

Answer 13

cadherins

Question 14

what transmembrane protein do hemi-desmosomes use?

Answer 14

integrins (alpha6/beta4)

Question 15

are cadherins and integrins homo- or heterophilic?

Answer 15

cadherins = homophilic
integrins = heterophilic

Question 16

what are the two blistering disorders associated with anchoring/adhering junctions?

Answer 16

Pemphigus - autoimmune - antibodies to cadherins

Epidermolysis bullosa simplex - defects in intermediate filament (keratin) assembly

Question 17

What are the two functions of tight junctions?

Answer 17

1. permeability barrier at epithelial sheets (ex. SI)

2. maintain cell polarity (ex. mem proteins)

Question 18

What are the 4 types of junctions in cellular tissue?

Answer 18

1. Actin-Filament based anchoring junctions
2. Intermediate Filament based anchoring junctions
3. Tight junctions
4. Gap junctions

Question 19

what is the function of gap junctions and where are they used/what for?

Answer 19

communication btw neighboring cells

electric conduction in cardiac cells

Question 20

When a gap junction is CLOSED, what are the intracellular conditions?

Answer 20

High Ca2+

Low pH

Question 21

When a gap junction is OPEN, what are the intracellular conditions?

Answer 21

Low Ca2+

high pH

Question 22

What single protein comprises a gap junction?

Answer 22

Connexin

Question 23

what does the ECM confer connective tissues?

Answer 23

tensile strength
elasticity
permeability

Question 24

what are the three types of ECM?

Answer 24

1. Fibrillar proteins
2. Bulky fillers
3. Cross-linkers

Question 25

What are the fibrillar proteins of connective tissue?

Answer 25

collagen elastin fibrillin

Question 26

What are the bulky fillers of connective tissue?

Answer 26

proteoglycans

Question 27

what are the cross-linkers of connective tissue?

Answer 27

fibronectin, laminin

Question 28

What type of protein is collagen?

Answer 28

Fibrillar protein

Question 29

What is Ehlers-Danlos syndrome?

Answer 29

defect in collagen/fibrillar proteins | hyperextensible skin and joints

Question 30

what does collagen confer?

Answer 30

tensile strength | resistance to stretching

Question 31

how is non-fibrillar collagen different from fibrillar collagen?

Answer 31

non fibrillar pro-peptide is not cleaved - cannot form fibrils non-fibrillar collagen is found in basil lamina

Question 32

what type of collage is found in the basal lamina?

Answer 32

non-fibrillar collagen

Question 33

what component of elastin makes it elastic?

Answer 33

proline!

Question 34

what does fibrillin do?

Answer 34

stabilizes elastin - resists stretching

Question 35

What do mutations in fibrillin do?

Answer 35

Marfan syndrome --> aortic rupture possible

Question 36

What are characteristics of glycosaminoglycans?

Answer 36

protein backbone | sulfated, carboxylated

Question 37

what do cross-linking proteins (fibronectin, laminin) do?

Answer 37

integrate cellular and connective tissue

Question 38

What do cross-linking proteins have multiple binding sites for?

Answer 38

integrins

Question 39

where would cross-linking proteins be found?

Answer 39

loose connective tissue, blood clots, wound repair, cell migration, development

Question 40

what are the 4 functions of the basal lamina?

Answer 40

1. supports muscle cells (role in DMD) 2. supports epithelial sheets (cell prolif) 3. molecular filter for kidney 4. guidance pathways - development (Periph NS)

Question 41

What are the 4 factors of growth control?

Answer 41

1. Cell lineage (apoptosis, telomere length) 2. External/diffusible factors (GF) 3. cell-ECM interactions 4. cell-cell interaction (growth inhibition)

Question 42

What are cell lineage factors of growth control

Answer 42

apoptosis | telomere replication - too short --> senescence

Question 43

what differences do transformed (cancer) cells have in terms of growth control?

Answer 43

do not senesce (inactive telomerase or p53) lack GF dependence lack anchorage dependence no cell-cell contact inhibition

Question 44

in which two types of genes to cancerous mutations occur?

Answer 44

oncogenes | tumor suppressor genes