Lecture 10 Learning Objectives Flashcards
characteristics of connective tissues and compare with epithelial tissues
Relatively few cells when compared to epithelial tissue
Abundant matrix containing various amounts of protein fibers
Physically supports other tissues
Binds other tissues together
Provides structural framework and opposes gravity
Helps create body contours
Houses specialized tissues (hematopoietic and lymphoid tissues)
Loose (areolar)
High ratio of fibroblasts to fibrous components
Type 1 collagen fibers and elastic fibers
Usually found beneath epithelial tissues of most organs
Contains fibroblasts, mast cells, macrophages, and capillaries
Dense Regular
High ratio of fibrous components to fibroblasts
Thicker bundles of collagen than in loose CT
Highly ordered bundles of collagen separated by a single row of fibroblasts
Found in tendons and ligaments
Dense irregular CT
High ratio of Fibrous components: fibroblasts
Thicker bundles of collagen than loose CT
No specific orientation of collagen bundles
Found in fascia, submucosa of GI tract, and in dermis of integument
Reticular
Type of dense irregular CT with predominance of reticular fibers
Primarily associated with lymphatic tissue
Elastic
Type of dense irregular connective tissue with an abundance of elastic fibers which form discontinuous lamellae
Walls of blood vessels
Characterize embryonic connective tissue and tell where it is located
Composed of some collagen and elastic fibers but mostly an abundance of ECM
Found in umbilical cord (wharton’s jelly) and in pulp of developing teeth
White fat
distributed throughout the body (unilocular)
Brown fat
Multilocular
Slightly more cytoplasm
Abundant mitochondria, which give them brown color
adipogenesis
Mesenchymal cells differentiate into adipose cells when insulin binds to insulin-like growth factor 1 (IGF1) and stimulates lipoprotein lipase blood-to-cell fat transfer
Ehlers-Danlos
A group of disorders resulting from defects in synthesis and/or structure of collagen
Collagen defects are devoid of tensile strength and skin is hyperextensible and vulnerable to trauma
Collagen defects extends to blood vessels and the internal organs resulting in tissue rupture or detachment (retina)
Marfans syndrome
Inherited defect in gene encoding fibrillin-1 – a component of tropoelastin (predominant in aorta, skin, ligaments, lens) increase in proteoglycans between elastic lamellae weakens walls of aorta
Patients are tall, long arms, legs, fingers, and toes. Mitral valve prolapsed, dilation of root of aorta, and aortic dissection typically manifest
Synthesis of collagen
Synthesis of precollagen occurs in Rough ER and packaged in golgi
Signal (pre-) sequence is cleaved
Secreted into ECM (still has nonhelical ends that prevent polymerization)
Terminal ends are cleaved by peptidases Tropocollagen
Tropocollagen monomers spontaneously assemble into staggered arrays collagen
Elastic Fibers
Elastin begins as prepropeptide in RER packaged and secreted from Golgi
Propeptide converted to tropoelastin by EC enzymes, also secreted by fibroblast
Coassembly of fibulin 1, fibrillins and tropoblastin produce elastic fibers
(tropoelastin monomers are assembled into amorphous fibers or sheets with the aid of several types of fibrillins)
four groups of glycosaminoglycans
Hyaluronic acid
Heparin and heparan sulfate
Chondroitin sulfate and dermatan sulfate
Keratan Sulfate
