Fibrous Connective Tissue Flashcards
What are the functions of connective tissue?
Structural framework of the body (bones) Protection Supports and interconnect other tissues Energy storage (adipose) Transport fluids, cells, and dissolved chemicals (blood) Defense against invasion
What are the 3 types of cells that makeup the fibrous component of the ECM?
Collagens= resist tension
Elastin= stretchable fiber
Reticular Fibers= supportive meshwork
What is the most common type of collagen? What is its role in the ECM?
Type-1, see banding in electron micrographs
When cross-linked increase tensile strength
- alpha 1 and 2 trimers released as procollagen on the surface and crosslinked
What makes up the Amorphous Ground Substance of the ECM?
Proteoglycans= protein + sugar covalently linked, neg charge so suck up water
- chondroitin sulfates
- heparan sulfates
- keratan sulfates
Hyaluronan= linke proteoglycans
Glycoproteins= cytokines, growth factors, structural proteins
Extracellular Proenzymes
What are integrin receptors role in the ECM?
Bind specific ECM components and initiate intracellular signaling for Cell-ECM interactions
Co-receptor examples: Syndecans, CD44 (bind hylauronan), selectins, GF receptors, cytokine receptors
What are structural features of embryonic connective tissue?
Rich in ECM= a lot of proteoglycans, well hydrated, not as many collagen or reticular fibers
Rich in mesenchymal stem cells
What is embryonic connective tissue in the umbilical cord often referred to as?
Warton’s jelly
What do adult mesenchymal stem cells differentiate into?
Fibrobalsts Muscle cells Osteoblasts Chondroblasts Adipocytes
What are the 3 types of loose connective tissue? What are their defining characteristics?
Lots of proteoglycans
Areolar= low density with fixed and wandering cells, widespread
Adipose= fat
Reticular= mesh for holding free cells
What are the 3 types of dense connective tissue? What are their defining characteristics?
Big bundles of collagen
Irregular= deposited in random pattern, dermis of skin
Regular= highly regular, tendons connecting skeletal muscle to bone
Elastic= rich in elastin fibers
What cells are fixed cells in loose areolar connective tissue?
Fibroblasts
Adipocytes
Mesenchymal Cells
What type of cells are wandering cells in loose areolar connective tissue?
Macrophages
Mast Cells
Leukocytes/Lymphocytes
Plasma Cells
Go in and out of CT through circulation
What is the function of Loose Connective Tissue? Where are they found?
Support and bind tissues, hold body fluids, defend against infection
Found immediately beneath membranous epithelia and around blood vessels, muscles, and nerves
Where is loose areolar connective tissue found?
SI villis
not very strong
What is the role of adipose CT? Where is it found?
Abundant in adipocytes and sparse ECM, very well vascularized
Provides reserve energy source, insulates against heat loss
Supports and protects organs
Under skin and around organs
- kidney, eyeballs, abdomen, breast, buttocks
What is the difference between white and brown fat?
White= energy storage, insulation, cushioning vital organs, hormone secretion
Brown= thermogenic tissue, abundant in newborns greatly reduced in adults
What is the role of Reticular CT? Where is it found?
Forms open framework to create a labyrinth for holding free cells
Bone marrow, lymph nodes and spleen
- meshwork houses blood cells and immune cells outside the blood and lymphatic vessels
What characterizes Dense Irregular CT? What is its principle cell type? Where is it found?
Tightly packed, interwoven collagen fibers running in a random pattern
Fibroblasts
Dermis of skin, capsules that surround internal organs, perichondrium (collagen) and periosteum (bone), fascia
What characterizes Dense Irregular CT? What is its principle cell type? Where is it found?
Tightly packed regularly arranged collagen fibers
- resists pulling forces
- poorly vascularized
Fibroblasts
Tendons, ligaments, aponeuroses, dense fascia, joint capsules (places with lots of tension)
What characterizes Dense Irregular CT? Where is it found?
High proportion of elastic fibers that allows the recoil of tissue following stretching
Found in blood vessel walls, bronchiole tubes, and special ligaments (ligamentum nuchae)
What is Marfan’s Syndrome?
Autosomal dominant, mutation in fibrilin-1 gene
Targets ocular, skeletal, and cardiovascular systems
- life threatening cardio anomalies (dissecting aneurysms)
Tall with long arms and legs
What is the role of a fibroblast?
With the BM functions to produce the collagen, elastin, reticular fibers, proteoglycans, and glycoproteins in the ECM
What is the role of adipocytes?
Remove lipids from blood, store them, and then release them again when needed (energy reserve)
Very well vascularized
Closely packed with nuclei pushed to side because of fat droplet
What is the role of macrophages?
Phagocytosis
What is the role of mast cells?
secrete chemicals that mediate the allergic response and anti-coagulation, serine proteases chemoattractants
- normally around blood vessels
- filled with granules
Key feature= lobulated nuclei
What is the role of Plasma Cells?
Differentiate from B-lymphocytes
Produce antibodies to mediate immunity
