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Exam 2 > Connective Tissue And Components > Flashcards

Connective Tissue And Components Flashcards

1
Q

what are the structural function of ECM?

A

maintains the three-dimensional structure of the body, forms the sheet of the basement membrane (basal lamina), and holds cells and tissues together

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2
Q

What are the regulatory functions of the ECM?

A

Regulates processes like proliferation, differentiation, migration, and cell-cell recognition. It can prevent of limit the movement of cancer cells and microorganisms…

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3
Q

Matrix Metallo-proteinases

A

MMP-group of enzymes that constantly remodel the ECM, includes the collagenases

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4
Q

What does the dysregulation of MMPs lead to?

A

The spread of cancer-due to the fact that the ECM can limit cancer cells from moving, so if it’s not being maintained then the cells could move

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5
Q

What are the insoluble proteins of the extracellular matrix?

A

Collagen and elastin

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6
Q

Collagen

A

Most abundant fibrous protein (25-30% of total body protein mass).

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7
Q

What is the structure of a typical collagen molecule?

A

A triple helix of three alpha chains which are tightly wound around each other and form a rope like structure

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8
Q

Glycine in Collagen

A

Glycine is found in each third position of the alpha chain, which allows a tight-winding of the triple helix.

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9
Q

Proline in Collagen

A

Abundant and lead to “kinks” (due to their ring structure) in the protein chain that allow for tight winding

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10
Q

Hydroxyproline and Collagen

A

Hydroxyproline residues stabilize the triple helix via MANY hydrogen bonds between the alpha chains

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11
Q

Lysine and collagen

A

Form covalent bonds and cross-link tropocollagen

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12
Q

Hydroxylysine

A

Hydroxylysine residues allow for the additions of sugars

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13
Q

What are the 3 general types of collagen fibers?

A

Fibril forming, network forming, and fibril associated.

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14
Q

Collagen Type 1

A

Most common type. Fibril Forming. Makes up the skin, bone, tendon, blood vessels, and cornea

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15
Q

Collagen Type2

A

Cartilage, intervertebral disk, and vitreous body. Fibril forming.

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16
Q

Collagen Type III

A

Fibril forming. Makes up blood vessels and fetal skin

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17
Q

Collagen Type IV

A

Network forming. Makes up the basement membrane.

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18
Q

Collagen Type VII

A

Network Forming. Found beneath stratified squamous epithelia.

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19
Q

Collagen Type IX

A

Fibril Associated. Found in cartilage

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20
Q

Collagen Type XII

A

Fibril Associated. Found in tissue, ligaments, and some other issues.

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21
Q

Collagen in the bones

A

Arranged to resist mechanical shear

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22
Q

Collagen in tendons

A

Bundles in tight, parallel fibers and provides great strength

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23
Q

Collagen Biosynthesis

A

Collagen is created at the level of a soluble procollagen (still has pro-peptides)

The 3 pro-alpha-chains are modified by specific hydroxylation or glycosylation and a triple helix is formed.

Molecule is released into the ECM and the propeptides are cleaved forming an insoluble collagen.

Collagen molecules associate to form a collagen fibril.

Extracellular cross linking with lysine or modified lysine results in mature collagen fibers.

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24
Q

Where is procollagen synthesized?

A

Fibroblasts, osteoblasts, and chondroblasts

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25
What do COL1A1 and COL1A2 lead to?
Two a1 chains and one a2 chain for the triple helix.
26
What is the cofactor for prolyl hydroxylase and lysyl hydroxylase?
Vitamin C (ascorbic acid)
27
Hydroxyproline
A hydroxylated proline molecule that allows hydrogen bonds between the three alpha chains (stabilizes the triple helix)
28
Hydroxylysine
Hydroxylated lysine that can be further glycosylated by glucose or galactose
29
What are the three functions of propeptides?
1) needed in cytosol for the linkage of the correct three pro-alpha-chains to each other by disulfide bonds 2) Allow efficient winding during triple helix formation 3) Keep the procollagen soluble
30
Procollagen Peptidases
Enzymes that cleave the propeptides from the procollagen.
31
Tropocollagen
Collagen after the propeptides have been cleaved. Tropocollagen molecules spontaneously associate to form a collagen fibril (each overlaps its neighbor) leading to a striated appearance.
32
What does scurvy cause?
Decreased stability and tensile strength of collagen, which leads to bleeding gums, hemorrhages, and poor wound healing.
33
Is is extracellular cross-linking performed?
The EC enzyme lysyl oxidase (require copper) oxidatively deaminates lysine residues in collagen. This results in a free ammonia and an aldehyde residue known as allysine (or hydroxyallysine). The reactive aldehyde forms a covalent bond with other lysine or modified lysine residues.
34
What happens if there is a copper deficiency?
reduced collagen cross-linking
35
What can cause Ehlers-Danlos Syndrome?
Connective tissue disorder. Can result from a mutation of a gene for the pro-alpha chains of collagen or result from a hereditary defect related to one of the enzymes that are needed for correct collagen synthesis/
36
What types of collagen are usually affected by Ehlers-Danlos Syndrome?
Type I, III, and V
37
What are the symptoms of classic (Type V) Ehlers-Danlos syndrome?
Hypermobility of joints and hyperextensibility of the skin
38
Vascular Ehlers-Danlos Sndrome
Caused by defects of type III collagen and leads to fragility of skin and vascular walls. It is most serious as arteries can rupture.
39
Osteogenesis Impefecta
Due to defective collagen synthesis either by less than normal collagen or abnormal collagen of type 1 (displacement of glycine) resulting in bone fractures and bending.
40
OI Type 1
Mildest form leads to early childhood long bone fractures after minor trauma (goes away in adulthood). Blue sclera due to it being thin and revealing the appearance of the uveal tissue (pigmented layer)
41
OI Type II
Most severe form . OI congenita. Leads to death in utero or neonatal due to respiratory problems. Small rib cage and underdeveloped lungs.
42
OI Type III
Severe
43
OI Type IV
Deforming with normal sclerae
44
Elastin
Highly cross-linked insoluble structure. It is the major protein in elastic fibers which allow the flexibility in blood vessels, lungs, and ligament, and skin.
45
Elastin Synthesis
Tropoelastin is secreted from fibroblasts into the ECM as a highly soluble liner at polypeptide (about 700 amino acids). The protein fibrillin-1 acts as a scaffold for the EC tropoelastin which needs to be cross linked in order to become insulble. Lysyl oxidase forms extracellular allysine residues which are needed for cross linking. The aldehydes form covalent binds with other lysine or allysine residues of elastin.
46
Desmosine and Isodesmosine
Characteristic for elastic and allow it to stretch and bend in any direction.
47
What is linked to form desmosine?
3 allysine and 1 lysine
48
Hydrophobic Affect
Force that allows the stretched structure of elastin to reform to its original form.
49
Hydrophilic Sequence
Found in elastin. Sequence that is rich in lysine (charged) and alanine (uncharged). Contributes to the hydrophobic effect
50
Hydrophobic Sequence
Found in elastin. Rich in glycine, valine, and proline. Contributes to the hydrophobic effect.
51
Marfan Syndrome
Autosomal dominant defect in the gene that encoded fibrillin-1 (connective tissue disorder)
52
What are the three major components of connective tissue?
Cells, fibers, and ground substance
53
What are the main functions of connective tissues?
Support, repair, defense (immune system), nutrition
54
What are the permanent residents of connective tissue?
Fibroblasts, adipose cells, macrophages/monocytes, mast cells, mesenchymal stem cells.
55
What is the transient cell population?
Lymphocytes, plasma cells, eosinophils, basophils, and neutrophils
56
Fibroblasts
Most common cell in connective tissue, synthesize fibers and ground substance, spindle shaped, may be active (fibroblasts) or inactive (fibrocytes)
57
Myofibroblasts
Involved in wound healing, has contractile filaments. Less ordered appearance in EM.
58
Fibroblasts in embryo
Cells are plump and separated by early collagen
59
Adult Fibroblasts
Large oval nucleus, spindle shaped basophilic cytoplasm, active protein synthesis
60
Fibrocytes
Collagen synthesis stops, loose basophilic cytoplasm, nucleus shrinks. Flat nuclei.
61
Adipocytes
Found in CT. Store energy and have good blood supply.
62
Unilocular Adipocyte
One large fat droplet. Have a signet ring appearance, with nucleus pushed to periphery of the cell. Large fat vacuole. Major energy source (TAGs)
63
Multilocular Adipocytes
Brown fat. Many lipid droplets. Central nucleus. Rich in mitochondria. Highly vascular. Mainly functions in heat production. specialized locations in the body and neck of neonates.
64
Macrophages
Moved in marrow and moved to tissue. Derived from monocytes. they have an irregular cell membrane with cytoplasmic extensions. they are phagocytic (produce cytokines)..
65
Kupffer Cells
Liver macrophages
66
Microglia
Brain macrophages
67
Osteoclasts
Bone macrophages
68
Dust Cells
Lung macrophages
69
Electron Micrograph Features of Macrophages
RER, prominent Golgi, lots of lysosomes, and irregular nucleus outline
70
Mast Cells
Originate in bone marrow from precursor cells lacking cytoplasmic granules. Gain cytoplasmic granules when they migrate to CT.
71
Leukotrienes
Vasoactive products of mast cells. They are released from the cell membrane of the mast cells as metabolites of arachnidonic acid
72
Mast Cell Granules
Contain histamine, heparin, chemotactic activators that attract monocytes, neutrophils, and eosinophils to site of mast cell activation
73
Metachromasia
Coloring observed in mast cells due to a change in structure of the dye after binding.
74
Lymphocytes
Small, spherical (little cytoplasm), condensed basophilic nucleus, immune cells (B and T cells), B-lymphocytes develop into plasma cells
75
Plasma Cells
Synthesizes and secretes single class of immunoglobulin (glycoprotein). Basophilic cytoplasm with a soccer ball, "clock face" distribution of chromatin.
76
Eosinophils
Granules in the cytoplasm. Condensed, bilobed nucleus. Helps with phagocytosis of antibody-antigen complexes and kills parasitic worms.
77
Type V Collagen
Amnion and chorion in the fetus, makes up muscle and tendon sheaths. Doesn't form banded fibrils.
78
Reticular Fibers
Type III collagen (primarily). Short, thin, and branching. Found I organs with large volume changes (blood vessels, arteries, spleen, testes). Silver staying and PAS positive. First type of collagen synthesized during wound healing.
79
What are the three developmental stages of elastic fibers?
Oxytalan-->elaunin-->elastic
80
What makes up elastin?
Glycine, proline, desmosine, and isodesmosine
81
what are the two components of elastic fibers?
Fibrillin and elastin
82
What are the core proteins that make up proteoglycans?
Aggrecan, decorin, versican, and syndecan
83
which glycoprotein can be commonly found in the basement membrane?
Laminin
84
What stain do you use for glycoproteins and proteoglycans?
Periodic Acid Schiff
85
Mucous Connective Tissue
Few cells or fibers, mainly ground substance (jelly-like). Umbilical cord or vitreous humor in eye
86
Mesenchyme
Embryonic connective tissue
87
Loose Areolar CT
Fills the space between other tissues (large number of cells), flexible and rich in blood supply, not resistant to stress
88
Dense Irregular CT
Fewer cells, more cells than Areolar tissue. there is no orientation of collagen fibers, which means there is resistance to stress in all directions. Makes up organs, periosteum, dermis
89
Dense Regular Connective Tissue
Specific orientation of collagen fibers. Makes up tendons and ligaments. Imparts tensile strength.
90
Endotendineum
Innermost layer. CT covering each cell. Dense regular CT
91
Peritendineum
CT covers a group of cells. Dense regular CT.
92
Epitendineum
CT covers the entire tendon (outermost layer). Dense regular CT
93
Reticular CT
Shorter than elastic fibers, branched, and thin
94
Elastic CT
Made of elastic fibers (yellow colored). Found in the arteries, penis, vocal cords.
95
Hypertrophic Scar
Scar is raised more than normal, but within the normal boundary
96
Keloid Scar
Scar exceeds boundary, extending into surrounding tissue. Commonly seen in people of African descent.
97
Anaphylactic Shock
Caused when there is an increased mast cell release of histamine.

Exam 2 (10 decks)

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