Connective Tissue Flashcards
What are the components of connective tissue?
-Cells(transient and permanent)
- Extracellular matrix (ECM)
a. Fiber
b. Ground substance
Connective tissue is directly supplied by blood, lymphatic vessels and nerves
Exception: Cartilage (avascular connective tissue )
Why is connective tissue important?
Functions:
- support-forms the stroma of organs
- Repair
- Defense
- Nutrition (storage & transport)
What is the stroma of connective tissue?
-Supporting structures
What is the parenchyma of connective tissue?
(Epithelium, nerve, muscle)
-Functional unit
What are the classifications of connective tissue?
- Embryonic connective tissue
- Connective tissue proper
- Specialized connective tissue
What are the types of embryonic connective tissue?
- Mesenchyme
- Mucous connective tissue
What are the types of connective tissue proper?
-Loose connective tissue (sometimes called aerolar tissue)
- Dense connective tissue
- Regular
- Irregular
What are the specialized connective tissue?
- Elastic tissue
- Reticular tissue
- Adipose tissue
- Bone & Hemopoeitic
- Blood
- Cartilage
Discuss the components of mesenchymal connective tissue components
Mesenchymal cells
- Stem cells
- Tapered spindle appearance
- Sparsely arranged reticular fibers
- Abundant ground substance
Discuss the components of mucous connective tissue
- Mesenchymal cells
- Ground substance: Hyaluronan—> imparts gelatinous consistency to the matrix
- Umbilical cord (Whaarton’s jelly)
Summarize mucous connective tissue
- Few cells or fibers
- Mainly ground substance (jelly-like)
- umbilical cord (Wharton’s jelly)
Other examples- cardiac jelly,vitreous humor in eye)
What are the features of the loose (aerolar) connective tissue?
- Large number of cells compared to fibers
- Rich blood supply
- Enables exchange of O2, CO2, and nutrients
- Diffusion of hormones and growth factors
Where are loose (aerolar ) connective tissue?
- Beneath most epithelial linings
- **Lamina propria of most mucous membranes such as those of the respiratory, urinary and digestive systems
Summarize Dense Irregular Connective Tissue
- Fewer cells, more fibers than loose (aereolar) tissue
- No orientation of collagen fibers - resistance to stress in all directions
- Organ capsules, periosteum, dermis
Summarize Dense Regular Connective Tissue
- Specific (regular) orientation of collagen fibers
- Imparts tensile strength
Examples:
- Tendons/aponeuroses
- ligaments
What are the components of dense regular connective tissue?
Fibroblasts
-Tendon: tendinocytes
Collagen fibers: type 1
Summarize the structure of the tendon
Covering an entire tendon:
-Epitendineum
Covering around a group of fascicles:
-Peritendineum
Connective tissue covering around a group of fibers:
-endotendineum
What are the components of reticular connective tissue?
Reticular fibers- type III collagen fibers
Fibroblasts (secrete reticular fibers in most locations)
Nb: Reticular fibers also secreted by reticular, Schwannabd smooth muscle cells
What are the functions of reticular connective tissue?
Forms a framework for the cellular constituents of various tissues and organs including
- Hemopoietic and lymphatic tissue—> bone marrow, lymph nodes, spleen (* not Thymus)
- Liver
- Endocrine tissue
- Nerve tissue
Discuss elastic fibers as a component elastic connective tissue
Composed of cross-linked elastin molecules and a network of fibrillin microfibrils and associated proteins (EMILIN-1, MAGP-1) - The microfibrils are formed first; elastin molecules are then deposited on the surface of the microfibrils
Describe the elastic property of the elastin molecule
This is related to unusual polypeptide backbone of elastin molecules (abundant hydrophobic regions), which causes random coiling
- Elastin molecules are connected by desmosine and isodesmosine (aa)
- Special staining required- Orcein, Resorcin or Verhoeff’s
Example: Ligamentum flavum, vocal ligament, suspensory ligament of the penis
Examples: Ligamentum flavum, vocal ligament, suspensory ligament of the penis
What is trichrome stain used for?
Differentiates between nucleus, cytoplasm and connective tissue
What is silver stain used for?
Used to stain reticular fibers, stains them black
What are elast8c stains used for?
E.g. Orcein, Verhoeff’s—> stain elastic fibers
What is the most common stain?
H & E
Describe white adipose tissue
Large cells
Peripheral nucleus
Uniocular/ one lipid droplet
Used for fat storage
Describe brown adipose tissue
Cells are smaller than white adipose
Central nucleus
Multiovular (multiple lipid droplet)
Function: high energy production (thermogenesis)
What are the specialized connective tissue?
- Cartilage
- Bone
- Blood
Describe Marfan’s syndrome
Decreased elastic fibers (fibrilin gene)
- Autosomal dominant disorder involving the deficiency of the protein fibrillin-1 and TGF-B
- This results in tall stature, long limbs, fingers and toes
- Cardiovascular manifestations can includeaortic aneurysm and mitral valve prolapse
What is a hypertrophic scar?
Scar when more raised than normal, but within original wound boundary
What is a keloid scar?
Scar extending into surrounding tissue (beyond original wound boundary )
What is scurvy?
- Ascorbate (Vit. C) is essential for the hydroxylation of the amino acid proline which forms hydroxyproline- a major component of collagen
- Collagen is an essential structural protein in the body accounting for around a quarter of all of the protein in our body and is critical to the structural integrity of our body
- Patients usually develop gum disease and poor wound healing
What is anaphylactic shock?
Increased mast cell release of histamine
What is edema?
Swelling due to increased tissue fluid
Favored by:
- Increased intravascular (capillary) hydrostatic pressure
- Decreased intravascular oncotic pressure
- Increased vascular permeability
What leads to fibrosis, keloids?
Increased collagen
