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MCT > Connective Tissue > Flashcards

Connective Tissue Flashcards

1
Q

3 cell types responsible for making connective tissue matrix

A

fibroblasts
chondrocytes
osteocytes

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2
Q

fibers (collagen, elastin, fibronectin, etc) in a hydrated gel (glycosaminoglycans + H2O) and growth factors / support proteins

A

matrix

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3
Q

How does ECM regulate cell behavior?

A

Cells adhere to and migrate differently on different ECM
ECM can bind and regulate growth factors
**ECM can itself act like growth factors. Cell have receptors for, and respond to ECM.

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4
Q

Densely packed collagen fibers, somewhat wavy but mostly parallel. Scanty fibroblasts wedged between fibers.
(tendons and ligaments)

A

Dense regular connective tissue

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5
Q

Dense collagen fibers, closely packed, but running in all directions
Few cells
(dermis)

A

Dense irregular connective tissue

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6
Q

Fewer and thinner collagen fivers, more space (watery gel) between
More cells
(hypodermis, lamina propria)

A

Loose (areolar) connective tissue

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7
Q

Special term for loose CT beneath a mucous (moist) epithelium - GI tract, respiratory, etc.

A

Lamina propria

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8
Q

Collage fibers are made of densely packed bundles of collagen ________ that cannot be resolved with a light microscope

A

Fibrils

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9
Q

Form 67nm banding pattern
About 50-150 nm in diameter
About 100 make bundles that are fibers

A

Collagen fibrils

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10
Q

In a collage triple helix, three collagen _______ chains are wrapped around each other, and support each other in a near maximally extended form.

A

alpha

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11
Q

Describe a collagen molecule

A

trimer
very long, thin
very limited stretch
rigidity of plexiglass

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12
Q

Characteristic signature of collagen chain

A

Every third aa is glycine
Gly needs to be in the center when three alpha chains come together
Closely packed center

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13
Q

Protein-protein bonds are _____________ and reversible (hydrophobic bonds)

A

non-covalent

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14
Q

The strength of the bond is roughly proportional to the ____________ of the contact interface.

A

surface area

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15
Q

Why is collagen made with a 67nm staggered overlap?

A

Increase surface area and strength

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16
Q

What is the hierarchy of collagen substructures from molecules to tendon?

A 
Alpha chain 
Collagen molecule
Fibril (staggered overlap) 
Fiber
Tendon
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17
Q

How are fibrils and fibers stalinized once non-covalently self-assembled?

A

Intermolecular covalent crosslinks

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18
Q

How is triple helix assembly lined up and fibril formation prevented until properly distributed in ECM?

A

Propeptides

allow for assembly, but block fibril formation due to bulkiness

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19
Q

List the steps for collagen processing and assembly that occur in the RER and golgi before secretion.

A
  1. Synthesis and translocation of pro alpha chain into RER
  2. Hydroxylation of selected pro and lys
  3. Assembly of C-propeptides of three alpha chains **aligns the alpha chains
  4. Folding of the triple helix, from C to N term. (only begins are C-propeptide fold)
  5. Formation of N-term propeptide finishes the procollagen molecule
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20
Q

List the steps in fibril assembly following secretion.

A
  1. The N and C term pro peptides block assembly of the secreted procollagen molecules.
  2. Two enzymes, procollagen N and C-peptidase cleave the pro peptides.
  3. Once the propetides are released, the collagen molecules are active for assembly. They spontaneously self assemble into long, 50 nm diameter fibrils. (staggered)
  4. The fibrils aggregate side to side to form fibers.
  5. Covalent crosslinks are added to stabilize fibrils and fibers.
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21
Q

Why are blood vessels affected before tendons during vitamin c deficiency (scurvy)?

A

Tendons turn over more slowly

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22
Q

Align three alpha chains prior to folding triple helix
Block assembly of fibrils until molecules are properly deposited in ECM
In non-fibrillar collagens (Type IV), used for assembly

A

Pro-collagen peptides

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23
Q

Possible combinations for three alpha chains in molecule

A 
three different (3 genes)
three identical (one gene) - Type 1 
two identical, one different (2 genes) - Type II, IV
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24
Q

Type of collagen found in skin, tendon, bond ligaments, cornea, internal organs (most of body’s collagen)

A

Type I

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25
Q

Type of collagen found in cartilage, intervertebral disc, notochord, vitreous body of eye

A

Type II

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26
Q

Type of collagen found in basement membrane, and specialized basement membrane of kidney (glomerular BM)

A

Type IV

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27
Q

Found between epithelium and CT, surrounding muscle cells, and between two cell layers in the kidney (filtration barrier)

A

Basement membrane (basal lamina)

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28
Q

3 components of basement membranes

A

Collagen type IV
Laminin
Proteoglycans

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29
Q

Froms a 2-D net (not fibrils)
A major structural component of basement membranes
Cell adhesion
**Binds integrin receptors

A

Collagen type IV

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30
Q

Second major structural component of basement membranes
Also functions for cell adhesion of overlying epithelium
**Binds integrin receptors

A

Laminin

31
Q

Proteins with positively charged carbohydrate chains

Regulate filtration, passage of growth factors, and proteins in basement membrane

A

Proteoglycans

32
Q

Functions:
Attachment of epithelial cells (integrins, col IV)
Barrier to cell migration (for metastasis cells must cross)
Barrier to large molecules (filtration barrier in kidney)
Cell signaling (define pathway for cell growth, migration - nerve regeneration)
Cell signaling (induce endothelial cells to form capillaries, great epithelial cells to form secretory follicles)

A

Basement membranes (basal lamina)

33
Q

Disorder with mutations in a type IV collagen with three minor alpha chains (found in kidney BM)
Kidney degernation and hearing loss

A

Alport’s syndrome

34
Q

Complex molecule with multiple cell adhesion and interaction sites (globular domains)
3 chains makes triple coiled-coil helix
Associates with itself and Col Type IV in BM

A

Laminin

35
Q

Mediate cell-matrix adhesion
TM cell surface receptors (bind ECM on extracellular side and cytoskeleton on the inside)
Integrate matrix and cytoskeleton
Alpha and beta subunits
Different ones can bind fibronectin, laminin, or fibrinogen on platelets etc.

A

Integrins

36
Q

Integrins connect platelets through fibrinogen (cross-linked) to form the ________, which is the primary factor for hemostasis

A

Platelet plug

37
Q

Bleeding disorder due to lack of platelet aggregation and clotting
Caused by genetic defects in an integrin

A

Glanzmann’s thrombasthenia

38
Q

2 protein components of elastic fibers and sheets

A

Elastin

Fibrillin

39
Q

Found in blood vessels, lungs, dermis, GI tract (wherever stretching is needed)
Can stretch 2x and contract fully

A

Elastic fibers and fenestrated sheets

Fenestrated = holes to permit diffusion of nutrients

40
Q

70kDa protein extensively cross linked to to make a fiber

cross-linked subunits can stretch

A

Elastin

41
Q

350 kDa protein makes one microfibrils
may define orientation of elastin deposition
dominant (-) mutations cause Marfan’s syndrome (aortic aneurism likely)

A

Fibrillin

42
Q

OMIM

A

Online Mendelian Inheritance in Man

43
Q

All large arteries have _____. The amount deposited in arterial walls is highly regulated.

A

elastin

44
Q

Cells that make collagen and organize the assembly of collagens fibrils in grooves and tunnels on their surface
Define directionality of fibers
Maintain attachments to collagen through integrins - have contractile activity that can pull fibers together

A

Fibroblasts

45
Q

Unilocular fat cells
Large fat droplet surrounded by a thin halo of cytoplasm
Most don’t show a cytoplasm

A

Adipocytes

46
Q

Many small fat droplets in each cell
Many mitochondria
Uncouples oxidative phosphorylation (UCP1)
Heat producing (more efficient than shivering)
Prominent in hibernating animals, rodents, human infants
Adults - cold response (less is associated with obesity)

A

Brown adipose tissue

47
Q

Reside in CT near blood vessels
Release granules containing histamine, heparin, and cytokines including platelet activating factor, eosinophil chemotactic factor
Clock face nucleus

A

Mast cells

48
Q

Glycosaminoglycan that prevents clotting of leaked plasma

Binds and regulates many proteins

A

Heparin

49
Q

Causes blood vessels to dilate, leak plasma

Edema produces symptoms of hay fever

A

Histamine

50
Q

Activated B - secretes Ab
Abundant RER
Pale Golgi
Clock-face nucleus

A

Plasma cell

51
Q

Phagocytes that kill parasites
Granulocyte
Bi-lobed nucleus

A

Eosinophil

52
Q

Two mechanisms for dominant negative mutations

A

Haplo-insufficiency

Assembly poison

53
Q

defective protein is dead
other gene produces half the normal amount of good protein
half is not enough

A

Haplo-insufficiency

54
Q

if half of the protein molecules are defective, they poison the rest
(pro collagen suicide and murder, bent collagen poisons the fibrils)

A

Assembly poison

55
Q

defective collage alpha chain starts to make triple helix, but folding is blocked
unfolded protein is destroyed - two associated good chains are also destroyed

A

Pro-collagen suicide and double murder

56
Q

collagen triple helix folds, but with a kink
during fibril assembly, causes fibril to branch
a few bad molecules can poison the good

A

Bent collagen

57
Q

Collagen that keeps globular pro-peptides to aid in assembly
End to end
Doesn’t make fribrils

A

Collagen Type IV

58
Q

RBC x MCV

Percent of blood that is RBCs (45%)

A

Hematocrit (HCT)

59
Q

Noncellular component of blood, plus fibrinogen

A

Plasma

60
Q

Noncellular component of blood, sans fibrinogen (without)

A

Serum

61
Q

Structural protein largely responsible for biconcave shape of erythrocytes

A

Spectrin

62
Q

Blood groups are due to

A

Post translational modifications - addition of sugar groups

Genetic difference is whether you have the transferase enzymes

63
Q

Hemoglobinopathy
Alpha or beta mutations
Like, Sickle cell, is protective against malaria

A

Thalessemia

64
Q

Why does hemoglobin need to be packaged into RBCs?

A

Kidney filtration

Sequester iron

65
Q

Causes hemoglobinuria, tubular necrosis, death

Requires dialysis treatment

A

Hemolysis

66
Q

Organ where RBCs have open circulation

A

Spleen

67
Q

Found on endothelial surface to initiate leukocyte rolling

A

selectins

68
Q

Found on endothelial surface to trigger tight binding (arrest) of leukocytes

A

ICAM

69
Q

Found on leukocytes, interact with ICAM for tight binding

A

Integrins (LFA-1)

70
Q

Diapedesis in between two cell or uses pseudopod to poke through

A

Paracellular diapedesis

71
Q

Diapedesis through the cell as a form of phagocytosis

A

Transcellular diapedesis

72
Q

Adult hematopoiesis is made in the bone marrow, but fetal is made in:

A

Liver, spleen

73
Q

What is yellow marrow?

A

Found more as you get older, more fatty

74
Q

Platelet precursor

A

Megakaryocyte

MCT (13 decks)

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