Histology: Connective tissue (lecture)

Question 1

What type of connnective tissue surrounds vessels and nerves?

Answer 1

loose CT (acts to fill and pack around)

Question 2

T or F: dense CT has thinner fibers than loose CT?

Answer 2

False

Question 3

What type of connective tissue is characterized by loose packing of its fibers?

Answer 3

Loose CT

Question 4

What type of CT has large, closely packed fibers and contains cells that are mostly fibroblasts?

Answer 4

Dense CT

Question 5

What are 4 areas where dense irregular CT can be found?

Answer 5

Stroma of organs
dermis of skin
periosteum and perichondrium
capsules of organs

Question 6

What are 3 areas where dense regular CT can be found?

Answer 6

tendons
ligaments
aponeurosis

Question 7

What does dense regular CT consist of?

Answer 7

fibroblasts in linear rows and paralel-oriented collagen fibers

Question 8

What type of collagen is typically found in dense regular CT?

Answer 8

type I - resisted tensile stress

Question 9

Where can reticular connective tissue be found? (5 places)

Answer 9

bone marrow
lymph nodes
lymph nodules
spleen
tonsils

Question 10

T or F: reticular cells are modified fibroblasts?

Answer 10

True

Question 11

What type of collagen makes up reticular fibers?

Answer 11

type III collagen

Question 12

What allow special stains to be used in reticular fiber visualization?

Answer 12

Lots of carbohydrates

Question 13

Compare reticular cells to fibroblasts

Answer 13

they are branching and have much more cytoplasm (they lie along the length of the reticular fiber)

Question 14

What type of cells and fibers are most important in lymph nodes and blood forming organs?

Answer 14

Reticular cells

Question 15

What is the earliest CT in the embryo?

Answer 15

mesenchyme - undifferntiated and can form all kinds of CT

Question 16

T or F: mesenchyme contains sparse reticular fibers in an abundant ground substance?

Answer 16

True

Question 17

T or F: Mesenchymal cells are non-existent in adulthood

Answer 17

False - they are more common in children but a smaller amount persist into adulthood

Question 18

What is a pericyte?

Answer 18

adult mesenchymal cell that can give rise to fibrolasts and participate in new vessel formation during wound healing

Question 19

How does CT participate in tissue repair in the body most often?

Answer 19

fibroblasts become myofibroblasts and mesenchymal stem cells

Question 20

Describe what scar tissue is.

Answer 20

dense irregular CT that may compromise function (e.g. cornea)

Question 21

What are myofibroblasts derived from?

Answer 21

fibroblasts

Question 22

What cells are partly responsible for wound contraction?

Answer 22

myofibroblasts

Question 23

T or F: myofibroblasts are intermediates between fibroblasts and smooth muscle because they contain actin.

Answer 23

True

Question 24

How do myofibroblasts work?

Answer 24

They have proteins attached to collagen outside of cell and actin in the cell. The proteins move along actin and grip onto collagen to pull cells together

Question 25

What happens as a clot forms in the skin?

Answer 25

macrophages and neutophils invade and clean up debris, dead cells, degrade ECM and collagen

Question 26

What are growth factors in the wound produced by?

Answer 26

macrophages

Question 27

What do growth factors in the wound stimulate?

Answer 27

fibroblasts and mesenchymal stem cells proliferate and re-synthesize ECM (sometimes scar = hyperprolferative)

Question 28

T or F: collagen metabolism is low in adults

Answer 28

True - degration and deposition = usually equal

Question 29

In what adult tissue is collagen metabolized at a higher rate?

Answer 29

scar tissue

Question 30

What types of cells modulate collagen degradation?

Answer 30

Fibroblasts, macrophages, neutrophils = collagenases

Question 31

What affect does scruvy have on collagen deposition and degradation?

Answer 31

It increases the rate of collagen degradation by collagenases Scars begin to open

Question 32

What causes scurvy?

Answer 32

Lack of Vit. C - cofactor needed for the hydroxylation of proline and lysine in collagen

Question 33

What is the disease that causes overproduction of tissue as a result of minor injury?

Answer 33

Keloids - collagen sythesis out of control

Question 34

What are common causes of liver fibrosis?

Answer 34

viral infections, alcohol

Question 35

T or F: there is a great amount of ECM in fat cells?

Answer 35

False

Question 36

Where are 4 places that adipose connective tissue is commonly found.

Answer 36

subcutaneous tissue (skin) around kidney around vessels of the heart in mesenteries (abdomin)

Question 37

What type of cells contain only a single droplet of fat?

Answer 37

White adipose tissue

Question 38

How are triglycerides and very low density lipoproteins (VLDL) delivered to fat cells?

Answer 38

transported by blood from intestin and liver and broken down into fatty acids and glycerol that diffuse into adipocyte to reform triglycerides

Question 39

What is leptin?

Answer 39

adipokine that regulates appetite in mice

Question 40

Why might leptin be unaffective in humans?

Answer 40

target cells in hypothalmus etc. may have insufficient receptors or post-receptor signal transduction

Question 41

What factors characterize metabolic syndrome?

Answer 41

``` central obesity high BP (cardiovascular disease) High triglycerides low HDL insulin resistance (diabetes) ```

Question 42

What does metabolic syndrome look like?

Answer 42

lots of weight around the belly

Question 43

What type of adipose tissue is multilocular?

Answer 43

Brown adipose

Question 44

where is brown adipose tissue most commonly found?

Answer 44

hibernating animals and infants because it helps regulate body temp

Question 45

Is multilocular fat associated with disease?

Answer 45

NO

Question 46

What do mast cells look like?

Answer 46

Oval cells with a small oval nucleus | Filled with small membrane bound granules

Question 47

Where are mast cells found in the largest numbers?

Answer 47

along the course of small blood vessels

Question 48

Why are granules not typically seen in sectioned material?

Answer 48

because they are water soluble

Question 49

What do mast cell granules contain?

Answer 49

Heparin (anticoagulant), Histamine Slow reactive Substance of Anaphylaxis (SRSA)

Question 50

What are the biological effects of histamine?

Answer 50

vasodilation | increased capillary and venule permeability

Question 51

What are the biological effects of SRSA?

Answer 51

increases smooth muscle contraction

Question 52

What do endothelial cells do in the presence of histamine?

Answer 52

develop gaps between them and they leak fluid from vasculature into the tissue (edema)

Question 53

What are Hurler, Sanfillipo, and Morquio syndromes?

Answer 53

Ground substance diseases where deficiency in lysosomal enzymes (Hydrolases) that degrade proteoglycans and glycosaminoglycans resulting in intracellular accumulation of these thing

Question 54

What are symptoms Hurler, Sanfillipo, and Morquio syndromes?

Answer 54

mental retardation, growth and heart abnormalities, shortened lifespan

Question 55

What causes Marfan Syndrome?

Answer 55

genetic defect in fibrillin gene causing abnormal elastic fibers

Question 56

T or F: people with marfans have an additional risk of aorta rupture and blurred vision?

Answer 56

True - aortic rupture = due to lack of elastic recoil

Question 57

T or F: elastic fibers are generally thinner than collagen fibers?

Answer 57

T

Question 58

What are elastic fibers composed of?

Answer 58

fibrillin and microfibrils

Question 59

where is elastin located?

Answer 59

Dermis of the skin, CT of lung (recoil during exhalation), elastic cartilage, larger arteries

Question 60

What is Ehlers-Danlos and what are its symptomes?

Answer 60

genetic disorder of CTs, people typically have overly flexible joints, stretchy fragile skin, fragile BVs, propensity for dislocations

Question 61

What type(s) of collagen are affected by classical ehlers-danlos syndrome?

Answer 61

Type V

Question 62

What type(s) of collagen are affected by hypermobility ehlers-danlos syndrome?

Answer 62

Type III, Tenascin-XB (extracellular protein)

Question 63

What type(s) of collagen are affected by vascular ehlers-danlos syndrome?

Answer 63

Type III