Connective Tissue Flashcards
Histology
The study of the
microscopic structure of tissues
Bright-field (normal) microscopy
light passed through or reflected off a
specimen.
* Limitations:
- Low contrast for weakly absorbing
samples
- Low resolution
Cellular Pathology
diagnostic service that looks
at cells of the body from either tissues or fluids. By looking at
the way that the cells are arranged, how they have developed
and how they are functioning, it is possible to determine if a
patient has a disease, inflammation, a cancer or a non-
cancerous growth.
Tissue
A collection of cells performing a similar function
four basic tissue types
-Connective Tissue
-Epithelial Tissue
-Muscle Tissue
-Nervous Tissue
What are connective tissues?
- Adipose tissue (Fat)
and other soft tissue - Tendons &
Ligaments - Bones
- Blood & Lymph
What is connective tissue made of?
- Dispersed CELLS embedded in EXTRACELLULAR MATRIX.
- Connective tissue cells secrete extracellular matrix.
- Highly vascular (exc cartilage and tendons).
- Does not usually occur on body surfaces.
- Rich nerve supply
Embryonic connective tissue
Mesenchyme:
- First connective tissue to appear
- Abundance of Mesenchymal stem
cells
- Gives rise to all connective tissue
Mucous connective tissue:
- Wharton’s Jelly!
- Found in parts, including umbillical
cord
* Both lost in adults – but scattered mesenchymal stem
cells remain
Classification of adult connective tissue
CT proper-
* Many types of cells
and ECM
* Broad group
Fluid CT
. Distinct cells in watery
matrix and proteins
Supporting CT
* Particularly dense
matrix
* Less diversity of cells
CT Function
Structural framework
Energy stores
Transport And Communication
INSULATION & PROTECTION
IMMUNE RESPONSE
Connective tissue cells- Fibroblasts
- Most common
Secrete fibres and ‘ground
substance’ thus maintain
extracellular matrix - Ground substance is a gel of
GAGs - Migrate to sites of damage
Connective tissue cells -
Macrophages
- Derived from monocytes
- Phage- eaters
- Engulf bacteria/debris by
phagocytosis - Fixed and wandering
- Also other immune cells
(Lymphocytes, neutrophils and
eosinophils) - These coordinate the immune
response
Connective tissue
cells - Adipocytes
- Contains single enormous lipid
droplet - Triglyceride store
- Surround organs (heart, kidney)
- Protection
Connective tissue cells - Mesenchymal cells
- These are stem cells
- Respond to injury
- Divide and make the
daughter cells needed
Connective tissue cells - Mast cells
- Produce histamine
(vasodilator) - Important in inflammation
- Ingest and kill bacteria
ECM
- Secreted by connective tissue cells
- Determines characteristics
1) Ground substance
-Semi-fluid gel (GAG, glycoproteins and
proteoglycans)
2) Protein fibres - Collagen (structural strength)
- Elastin (stretch and recoil)
- Reticulin (support and strength)
Extracellular matrix- ground
substance
- Between cells & fibres
- Various consistencies (fluid, semi-fluid, gelatinous,
calcified) - Allows exchange between blood & cells
- Role in cell development, proliferation, migration &
structural integrity
Ground substance GAGs
1) Hyaluronic Acid GAG
small amount of GAG absorbs a lot of water; useful space-filler.
Ground substance GAGs
CS/DS
Chondroitin sulphate and dermatan sulphate
- Chondroitin sulphate and dermatan sulphate
- Heparan sulphate
- Protein core
These are smaller; Always found attached to a protein, forming a proteoglycan.
Three types of fibre occur in
connective tissue
1) Collagen
* Long, straight and unbranched
* Strong but flexible triple helix
* Tendons and ligaments
2) Elastic
* Elastin fibres and fibrillin, branched and wavy
* Snap back to shape
* Interconnecting vertebrae
3) Reticular
* Same subunits as collagen; thin and branched
* Tough yet flexible
* Stabilises positions of cells
Loose connective tissue
- “Packing material” – fill gaps and
spaces. - Support, cushion and protect.
Includes: - Areolar connective tissue.
- Reticular connective tissue.
- Adipose connective tissue.
Loose connective tissue - Areolar
- Least specialised
- All 3 fibre types (C, R, E)
- All cell types
- Ground substance
- Absorbs shock
- Surrounds blood vessels
and nerves - Skin – separated from
muscle; blood supply - Abundant
Loose connective tissue - Reticular
- “Fibrous framework”
- Fibres create 3D
stroma - Stroma support
parenchyma - Examples: Liver; lymph
nodes
Loose connective tissue - Adipose
- Adipocytes
- Packing; shock absorber
- Prevents heat loss
- Subcutaneous layer
- Surrounding heart, kidneys, major
cavities and eye socket - Rapid heat generation infants – why
not in adults? - Research shows fat cell number
determined before adolescence; do
not die but shrink! - Areolar → adipose
2) Dense connective tissue
- Collagenous
- Dense regular and irregular
- Regular – collagen fibres parallel; packed tightly; force
aligned - Irregular – Interwoven meshwork; inconsistent pattern
2) Dense regular connective tissue
- Tendons and ligaments
- Fibers run along longitudinal axis – transfer pull of muscle to
bone - Many fibroblasts
2) Dense irregular connective tissue
- Stress from many directions
- Gives skin its strength
- Sheath around cartilage and bone
- Capsule around organs
- Deeper dermis
2) Dense connective tissue contains
elastic
- Variable amounts present
- Stretch and recoil up to 150%
- Example - walls of large blood vessels and airways;
- Elastic ligaments (vertebrae column)– almost completely dominated by
EF
Disorders of Connective Tissue
- Scurvy
- Dietary Vitamin C
deficiency - Vitamin C important in
collagen production. - Lethargy, bleeding
gums, muscle/bone pain,
teeth loosening, skin
changes, impaired wound
healing. - Marfan Syndrome
- Genetic (fibrillin-1
mutation) - Affects elastic fibre
production - Excessive height, long &
slender limbs,
dislocated lens,
cardiovascular issues,
stretch marks
Ehlers-Danlos syndrome
- Genetic (mutation of
numerous genes involved
in collagen production.
- Weakened collagen so
increased elasticity
- Increased skin elasticity,
hypermobile joints
