Connective Tissue Flashcards
What is connective tissue?
Diverse group of cell within ECM
What are the different types of connective tissues?
Embryonic
Specialized( cartilage, bone, lymph, adipose, blood)
CT porper: Loose and dense
What are the functions of connective tissues?
Support and connections- tendons and ligaments
Defense- site of inflammation and immune reaction. Physical barrier.
Nutrients - blood supply, fat storage, diffusion of nutrients and waste.
reservoir for water and electrolytes.
What is loose connective tissue?
is Lots of cells, lots of ground space and few fibers loosely arranged right.
Functions of loose connective tissue?
what is an example of loose CT?
1-Support epithelium cell.
2-Surrounds blood vessels.
3-Fills in spaces between muscles.
4-Site of inflammatory and immune response bc it surrounds blood vessels.
5-Diffusion of nutrients and waste (o2 and co2) bc it surrounds blood vessel.
6-provide structural support.
Lamina propria is a loose CT
What is Dense CT?
Densely packed tissue composed of lots of fibers and very few cells and gound substances
it is divided into regular and irregular dense CT
Function of Dense CT ?
Protection.
Tensile strength
Transmission force of muscle contractility.
Attaches muscles to bone.
tendons, ligaments, cornea.
What is Regular dense CT ?
where is it found?
Function?
Orderly parallel bundles of collagen
Tendons, ligaments, cornea
Attaches muscles to bone,
Transmit force of muscle contraction
Protection
What is irregular dense CT?
Where is it found?
Function?
Fibers arranged in random order.
Found in skin and Gi tract.
Provides tensile strength and protection.
What are the different fibers in CT ?
Collagen system fibers: Collagen fibers
Reticular fibers (type 3 collagen)
Elastic fibers which are elastic system fibers
Collagen Fibers
how common?
stain what color?how do they appear?
histologic structure?
Property and function?
synthesized by what?
Most abundant
Stain red in H and E stain
Stain blue in trichrome stain.
Thick bands
Wavy structure
Flexible yet high tensile strength. Variable width
Structural support, tissue healing, cartilage, bone.
Synthesized by fibroblasts, chondrocytes, bone cells
How is collagen synthesized?
intracellular and extracellular.
1) we have an active transcription in the nucleus of fibroblast.
2) Post translation modification of procollagen in the RER; hydroxylation of proline and lysine residue which is Vit C dependent.
3) Goes to Golgi for modification then it is released to the outside of the cell.
4) outside the cell the pro collagen overlap and bind to form a collagen fibril.
a bundle of fibril forms a collagen fiber..
collagen fiber can also exist in bundle of collagen fiber.
Scurvy
It’s a vitamin deficiency disease that is caused by not eating enough fruits and vegetables. Left untreated, scurvy can lead to bleeding gums, loosened teeth and bleeding under your skin
characterized by bone disease in children and hemorrhage and healing defects in both children and adult.
What are reticular fibers?
Synthesized by?
Structure?
Function?
Where are they found?
Histologic features? what are they stained by ?
They are part of the collagen system fibers. They are collagen 3 fiber.
Synthesized by reticular cells
Form 3d network instead of bundles.
Structural support of cells. Support hematopoietic cells (bone marrow) and lymphoid organs (except thyroid)
appear as black cracks in silver stain.
Types of collagen and where are they found.
Type 1- Bone
Type 2- Hayine Cartilage
Type 3- Reticular Fibers
Type 4- Basil lamina
Elastic Fibers
Composed of ?
Synthesized by?
Function ?
Found in ?
Histological structure and staining?
Elastic fiber system
Elastin
Fibroblasts (skin and tendons), chondroblasts ( elastic cartilage), smooth muscles ( in large blood vessels)
Allow tissues to respond to stretch and dissension.
Skin, tendons, aorta, cartilage
black and purple in h and e. thin lines. thinner than collagen
Osteogenesis Imperfecta
Disease that causes brittle, and blue sclera.
Bones break and fracture easily due to defective synthesis of collagen 1 fibers.
Ehlers -Danlos Syndromes
Defect in collagen synthesis or assembly.
Leads to hypermobility of joints, hyperextensible skin that is vulnerable to trauma and poor wound healing.
Marfan syndrome
Mutation ion the FBN1 gene than codes for fibrillar which results in lack of resistant in tissues rich in elastic fibers.
Clinical features include aortic aneurysm and aortic dissection( rupture of walls bc no elastic fibers) , long fingers,
hyper mobility of joints bc some collagen fibers are also affected.
Ground substance
what is it ?
Functions?
Components of ECM
colorless Gell like substance that fills space between cells and fibers. High water content (water storage)
1)Provides lubrication for movement of collagen.
2)Path for cell migration
3)Allows diffusion for water soluble molecules
4)Binds and retains growth factors
5)Anchors cell to ECM (integral and fibronectin)
6)Via cell adhesion molecules information is transmitted across the plasma membrane.
Ground substance molecules
1)Glycosaminglycans (GAGs) - unbranched polysaccharide chains.
Hyaluronic acid is a special type of GAGs
2) Proteoglycan- GAGs + protein core. Indirectly binds to HA with linker protein. Combines with lots of water.
3) Glycoprotein- stabilize the ECM and link it to cell surface
-integrin- binds ECM to cell
-fibronectin- binds many ECM components and attach to integrins.
-laminin- attaches cell to basement membrane.
Hyaluronic Acid
How does it present?
What does it bind?
Where is it found ?
Function?
Present as a free carbohydrate chain
Not covalently bound to protein
Proteoglycan indirectly binds to HA via linker protein; More than proteoglycan can bind one HA forming proteoglycan aggregates.
Found in cartilage
-Important in immobilizing molecules like growth factors.
-Effective insulator , preventing diffusion through dense network
Enzymes that degrade ECM
Hyaluronidases
Matrix Metalloproteinases(MMPs)
Hyaluronidases
Enzymes that degrade hyaluronic acid.
which lowers the viscosity of connective tissue and increases permeability.
It is important in drug delivery
Bacterias secrets it to get into deep tissue.
Metastatic potential of tumors- to spread
Matrix metalloporteinases (MMPs)
Tissue remodeling and degradation of the ECM
Increased expression of MMPS for tumor invasion, and metastasis and tumor angiogenesis.
Resident cells
Fibroblasts
Mast cells
Macrophages
Adipocytes
Stem cells
Wandering Cells
Lymphocytes
plasma cells
Neutrophils
Eosinophils, basophils , monocytes
Fibroblast
Shape? Nucleus?
Function ?
Activity?
Most common cell type of connective tissue
Spindle shaped cell
flat elliptic nucleus
thin cytoplasm
Synthesizes procures of ground substance, collagen and elastin fibers.
Rarely divide but capable in response to injury, inflammation example Myofibroblasts are a differentiated cell type essential for wound healing
Active fibroblasts have large euchromatic nuclei while inactive fibroblasts are smaller with heterochromatic nuclei.
Most common cell in connective tissue?
Most common fiber in connective tissue?
Fibroblast
Collagen
Macrophages
What is it? Structure?
Precursor ?
Function?
Histologic structure?
A phagocytes: contains lysosome and residual bodies. Contains lots of phagocytic vesicles for transient storage of ingested material;
Originates in the bone marrow as monocytes that travels in blood. When activated it becomes a microphage.
Initiate immune response; release cytokines, present antigens to lymphocytes
secretes hydrolytic enzymes like collagenase to move into the tissues .
Hard to identify with Hand E staining. It’s injected with black dye.
Oval or kidney shaped nucleus
Mast cells
What does it arise from ?
Shape of cell?
Nucleus? Cytoplasm?
Arise from multipotent hematopoietic stem sells in the bone marrow
Oval round cell shape with microvilli
Nucleus is centered in the cell.
Cell express Ig E receptors
Cytoplasm filled with secretory granules containing heparin, histamine and other vasoactive mediators and chemotactic factors.
Adipose tissue
Function
Specialized CT
Main energy storage.
Insulation
Fat stores as triglycerides
Fills space in between tissues: provide cushion for certain parts as shock absorbers like kidney, around eyes and soles of feet.
Hormone production substances, secretes leptin.
Adipocytes types and function
resident in ct
white/uniocular adipocytes: energy storage, insulation, cushion, hormone production
multi ocular/brown:
heat production and thermogenesis
Uniocuar/White adipocytes
structure
Nucleus
What does it secret?
One large lipd droplet surrounded by a ring of cytoplasm
nucleus is flattened and located on the periphery.
Secrets reticular fibers that surround the adipocyte
Multiocular (Brown) adipocyte
Structure, nucleus, etc
what does it look like in staining
Fetal life and first decade after birth
multiple lipid droplets.
eccentric nucleus ( to the side)
Numerous mitochondria
in h and e it looks red bc of mitochondria.
Plasma cell
Wondering cells of CT
Driver from B lymphocytes.
Oval cell
eccentric nucleus
wheel or clock face nucleus
ghost of Golgi bc it doesn’t stain in h and e.
Diapedesis
WBC moves from blood capillaries to CT
increases during inflammation.
