Connective Tissue Flashcards
Connective Tissue
supporting tissue
primarily structural
often the stroma of organs
includes cushioning CT found almost everywhere
cells organized in specialized ECM
classified based on ECM, not cells
Types of Embryonic Connective Tissue
Mesenchymal
Mucous
Types of Adult Connective Tissue
- CT Proper (Collagenous/Elastic)
- loose
- Dense Irregular
- Dense Regular
- Reticular (not elastic)
- Specialized
- Supporting (Bone/Cartilage)
- Adipose
- Blood
Ground Substance
in all CT except Blood
water and salts (primary cation is sodium)
complex carbohydrates (water retention)
proteoglycans (water retention)
Connective Tissue Cells
mostly fibroblasts and immune cells
other specialized cells for specific functions (adipose tissue → adipocytes)
arrangement gives terminology
What makes up collagen?
Fibroblasts
it is a triple helix structural protein
collagen fibril → collagen fiber → proteoglycan
What are the types of collagen?
Type I
Type II
Type III
Type IV
Type V
dif types of collagen do different things
What cell types make up collagen?
Fibroblasts
Reticular cell
epithelia cells (IV)
Equivalents
Making Collagen: Fibroblasts
inactive fibrocytes
Making Collagen: Reticular Cell
make reticular fibers (III)
Making Collagen: Smooth Muscle Cells
in particular places
type I and III
Making Collagen: Equivalents
bone - osteoblasts
Cartilage - chondroblast
Teeth - ondotoblast
Elastic Fibers
elastin with microfibrillar proteins (fibrillins)
What makes elastic fibers detectable?
orcein (black or dark purple)
How are elastic fibers elastic?
Modification of two lysine residues in elastin protein (Lysyl oxidase, extracellular)
Form new amino acid: desmosine
ring structure linkes tropoelastin proteins
allows stretching and recoil
Other cells found in CT
Resident immune cells (macrophages, mast cells, plasma cells)
Non-resident immune cells (neutrophils/eosinophils, transit into CT upon stimulation, produced in bone marrow, travel through blood)
What is the function of macrophages?
phagocytosis of complement-bound particles
turnover of fibers and ECM
antigen presenting cells (lymphocytes)
produce cytokines (include chemokines to bring in other immune cells)
How do macrophages get to the CT?
enter blood as monocytes
not called macrophages until mature (resident)
What is the structure of macrophages?
kidney shaped nucleus
large
indent of one side
Macrophage histology
What is the function of mast cells?
release proteases, proteoglycans, leukotrienes
respond to chemical signals (cytokines, chemokines)
vasoactive mediators - leukotrienes, heparin
produce histamine, chemotactic
Where are mast cells produced?
Travel through blood
activate immune (response to allergies)
What is the structure of mast cells?
many granules
Mast cell histology
What is the function of plasma cells?
make/release antibodies
respond to immune challenge
produce IgAs (and other immunoglobulins)
Where are plasma cells produced?
travel through blood
Mature B lymphocyte
What is the structure of plasma cells?
clockface or wagon wheel nucleus
(clumped chromatid around edge)
basophilic
alot of rough ER
off center nucleus
alot of golgi
comet like appearance
Plasma Cell Histology
Embryonic CT: Mucous
found in umbilical cord and teeth pulp
larger spaces between fibers
jelly is thicker
rich in proteoglycans
Embryonic CT
Mucous CT Histology
where is Mesenchymal CT found?
In embryo → cells give rise to all cells found in CT
in adult → dental pulp, pluripotent pericytes (can act like stem cells)
mesenchymal cells
reticular fiber
Mesenchymal CT (Mouse) Histology
What is the function of CT proper: Loose CT?
supports epithelial function
information
nutrients/waste transport
barrier (including surveillance)
bring nutrients to avascular epithelium
mesentery that holds organs in place
Where is CT Proper: Loose CT found?
often found under epithelium
What does CT proper: Loose CT contain?
fibroblasts and resident immune cells
nerve bundles
blood vessels
fibers: collagen ± elastic (loose elastic CT)
Loose CT Histology
Loose CT Histology
What is the function of CT Proper: Dense Irregular CT?
supports tissue function
information
nutrients/waste
physical support
Where is CT Proper: Dense Irregular CT found?
often found under loose CT
What does CT Proper: Dense Irregular CT contain?
fibroblasts and resident immune cells (fewer than Loose CT)
nerve bundles (larger)
blood vessels (larger)
more fibrocytes and fewer plasma cells
fibers: collagen ± elastic
What is Dense Irregular CT often associated with?
adipose
Dense Irregular CT Histology
Dense Irregular vs. Loose CT
loose → fewer fibers (nuclei) → darker
dense → more fibers, fewer nuclei → lighter
What is the function of CT Proper: Dense Regular CT
supports tissue function
physical support
connection between tissues
What does CT Proper: Dense Regular CT contain?
fibroblasts
thick collagen bundles in regular array (same direction)
usually contains elastic fibers
typically no immune cells unless sick
Where is CT Proper: Dense Regular CT found?
mostly tendons or ligaments
Dense Regular CT Organization
Dense Regular CT Histology
CT Proper: Elastic CT
Subcategory of Loose, Dense Irregular, or Dense Regular CT
contains: above/elastic fibers
supporting tissue function → stretching
special stains typically required
Elastic CT Organization
Elastic CT Histology
Elastic CT Histology: Silver Stain
What is the function of CT Proper: Reticular CT?
supports tissue function → cells in a fibrous matrix
What stains are required to see reticular fibers?
silver staining
reticulin (uses silver and other heavy metals)
What does Reticular CT contain?
specialized fibroblasts (reticulocytes)
reticular fibers (stroma)
hepatocytes - perinchyma
only reticular fibers and ground substance
Reticular CT Organization
Reticular CT Histology
Reticular CT Histology: Silver Stain
What does Adipose CT contain?
adipose cells (adipocyte)
very little ground substance
What is the function of adipose CT?
supports tissue function → cushioning, energy storage (in form of lipids)
What stain is required to see lipids?
fixation with osmium
Adipose CT Organization
Adipose CT Histology
How does ground substance contribute to the function of CT?
