10-16c Connective Tissue Histology

Question 1

What does connective tissue do?

Answer 1

Maintains/supports structures and communicates

Mediates exchange (Things can travel within, throughout it, and through it

Plays a role in immune response, inflammation and tissue repair

Question 2

What are the different CT classifications?

Answer 2

CT proper (loose CT, Dense CT( irregular CT and regular CT)

Specialized CT: (adipose: modified loose CT), cartilage, bone, hematopoietic tissue

Question 3

What is the general structure of CT proper?

Answer 3

ECM (fibers)

Cells (resident vs. visiting)

Question 4

What are the two components of the ECM?

Answer 4

ground substance: (largely proteoglycans that attract water) and fibrous proteins (embedded throughout ground substance)

Question 5

What composes the ground substance? What does its wateriness depend on?

Answer 5

GAGs: long-chained polysaccharides that are highly negatively charged and attract water

ECM function (more water in loose CT less in tendons)

Structural glycoproteins (fibronectin, fibrillin, and binding proteins

Question 6

What are the two most common fibers of the ECM?

Answer 6

elastin and collagen

Question 7

What is type I collagen? What is its function? How does it do this well? Arrangement? What is an example of their arrangement in the dermis?

Answer 7

most common type
found in bone, ligament, tendon, fascia, joint capsules, etc.

function: helps resist/relay tensile stresses (does this via high degree of organization/bundled and cross linked structure)
arrangement: fettuccini-like (solid and rigid), parallel, grouped in bundles of fibrils and cross linked by glycoproteins (fibronectin)
dermis: form in directions skin gets pulled on; Wolf’s Law

Question 8

What does the ECM dictate?

Answer 8

the amount of water within the type of CT

Dictates the types of fibers produced (depends on function of CT)

Dictates the amounts of fibers produced (depends on type)

Question 9

Type II Collagen:

Arrangement, appearance, function? What does it have more of? Where is it found?

Answer 9

arrangement: not in bundles, no highly regular appearance

More deformable: easier shape change and elasticity

More ground substance/cellular

Hyaline and elastic cartilage

Question 10

Type III Collagen also called? organization and structure? Where is it found?

Answer 10

Reticular Fibers
mesh-like
lymph tissue, bone marrow, blood vessels, immature wound beds

stuff supported is in between mesh

Question 11

Type IV Collagen: where does it occur?

Answer 11

basal laminae (epithelial cell basement membrane)
support of tissue layer and filter

Question 12

What are elastic fibers made of? Where is it found? Structure? Function?

Answer 12

elastin and fibrillin (binding protein found within elastic fibers that keeps them together)

Loost CT, bv, lungs, alveoli, skin, ligaments,
found in places for high degree of shape change and elasticity

Not bundled (somewhat in parallel depending on tissue); wavy in relaxed state and straight when tense

Function: allows for elastic recoil; allows tissue to stretch and revert to original state

Question 13

What are the resident cells of CT proper?

Answer 13

fibrocytes
or fibroblasts (if active): produce ground substance, fibers, everything within CT (workhorse)

mesenchymal cells (stem cells that are an immature precursor fibroblast): ramp up protein production within CT

Question 14

Visiting Cells of CT Proper: where produced? three types? functions?

Answer 14

all involved in immune response within CT

produced in bone marrow and travel to CT

macrophage: (phagocytic, antigen presenting and cytokines) cleans up and calls for inflammatory response,

mast cell (inflammatory mediators, heparin, histamines,etc.) secrete vasoactive substances that call for capillaries to be leaky to cause influx into tissue

plasma: and plasma cells (B lymphocytes, antibody production):

Question 15

What is the second type of CT proper? Characteristics? functions?

Answer 15

Loose CT
most abundant CT proper, sparse fibers, increased cells and ground substance

function: vehicle by which bvs, nerves, inflammatory mediators, etc. get to where they’re going: allows for space for travel (how epidermal layer gets nutrients)
space occupying material where b/w organs to help protect and absorb forces: shock absorbers

all different types of fibers (mostly gel ground substance)

Question 16

Dense Irregular CT Proper: functions, characteristics, where found

Answer 16

either dense regular or

dense irregular (dermal layer of skin): withstands tension from diff directions; flexible, presence of elastic fibers)

characteristics of dense irregular: densely packed with Collagen (irregularly arranged) in sheaths and some elastic fibers

found in dermal layer, sheaths around tendons, bursa, and n.

Question 17

Dense regular CT proper: arrangement, function, where found?

Answer 17

arrangement: collagen bundled and parallel in arrangement/same direction

resist tension in one direction/maximum tensile strength

function: provide ability to relay and respond to tensile stress in ligaments, musculotendinous units, and aponeuroses (b/w radius and ulna, etc.)
communication: fibroblasts linked

Question 18

What are disorders of elastic fibers? (fibrillin)

Answer 18

Can be damaged by UV light (affects skin elasticity); dermis degraded

Loss of elastin in respiratory system causes emphysema (large spaces and no elastic recoil)

Question 19

What is Ehlers-Danlos syndrome? what is it a disorder of?

Answer 19

A disorder of collagen
Autosomal dominalt, recessive, x-linked recessive collagen defect where it lacks tensile strength

most common clinical sx’s: joint hypermobility, large joint dislocation, and skin hyperelasticity

Question 20

What is osteogenesis imperfecta?

Answer 20

disorder of collagen

defect in type I where there is a high fracture incidence