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93 Cards in this Set
- Front
- Back
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What is connective tissue and where is derived from?
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Connect all other cells of different tissue types both mechanically and metabolicaly. They are all derived from the common origin of embryonic mesenchyme.
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Three Groups of connective tissue
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Embryonic - Mesenchymal and mucous
Connective tissue proper - Loose (areolar), Dense, Reticular, Adipose Specialized Connective Tissue- Cartilage, Bone, Blood |
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Seven functions of connective tissue
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1) Mechanical Support- structural support to organs, packing material, rigid structural support (cartilage and bones)
2) Mechanical Protection- Bony protection, cushion 3) Energy storage and temperature regulation- Fat cells store energy and act as insulation 4) Metabolic support- mediates the exchange of all metabolites between the blood and the cells in the tissue 5) Transportation of materials- done by blood and lymphatics 6) Protection against infection- contains immune system cells, mechanical barrier to infection, macrophage system cells also located 7) Repair after injury- Scar formation |
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3 Elements of all types of CT
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Cells, Extracellular fibers, Ground substance
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CT cells (3 types)
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Fixed cells, Wandering cells, Associated cells
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Fixed Cells
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Responsible for the synthesis and maintenance of the extracellular matrix
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Wandering Cells
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Transient cells that migrate into and out of the extracellular matrix (immune cells)
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Associated cells
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Cells associated with blood vessels that are always found surrounded and supported by connective tissue
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Three types of Extracellular fibers and their function
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Collagen fibers for strength
Elastic fibers for stretch and flexibility Reticular fibers for delicate support |
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Ground Substance: What is it and what 3 things does it contain?
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Is an amorphous clear area that contains:
Interstitial Fluid (Water) Proteoglycans (Complex macromolecules consisting of core protein with glycoaminoglycans (GAGs) attached to it) Glycoproteins (Core protein with sugars attached, form adhesion molecules) |
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Extracellular Matrix
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Space between the cells which consits of extracellular fibers and ground substance. Is secreted by fixed cells.
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Fibrocyte
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Fixed Cell
-Most common fixed cell of connective tissue proper -Appearance: Vesicular nucleus with nucleoulus, can't see cytoplasm -Secretory cell -Fibro blasts make new matrix and can differentiate and divide - Fibro cytes can't differentiate and maintain the matrix around them |
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Mesenchymal cell
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Fixed Cell
-Looks like a fibroblast -Found in the embryonic tissue and has the same function as a fibroblast -Pluripotential cell |
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Reticular cell
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Fixed Cell
-Found in Reticular tissue -Cell processes wrap around reticular fibers -Form cell lined fiber network -Secretes reticular fiber (glycoprotein) which sperates cells and prevents clotting |
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Two types of Adipose cells
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White and Brown
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White Adipocyte: Morphology, Location, Function
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Morphology: Large spherical cell with a Unilocar (single large lipid droplet)
May be empty due to extraction of lipid during processing "signet ring" appearance Fat tissue is lacy and very light staning Location: Normal component of areaolar (loose) CT, subcutaneous fascia Function: Lipid storage, leaves blood vessel and broken down by Lipoprotein Lipase Free fatty acids are taken up and complexed with glycerol to form triglycerides Produces Leptin Insulin acts on adipocytes Mobilized by epinephrine or norepinephrine |
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Lipoprotein Lipase
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Protein on endolthelial cells that breaks down white adipocytes into free fatty acids and glycerol
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Hormone sensitive Lipase
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Breaks down triglycerides into free fatty acids that complex with albumin to be transported around the body
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Leptin
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a protein produced by adipocyte that targets the hypothalamus. Decreases food intak and increase energy consumption.
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Insulin w/adipocytes
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Acts on adipocytes to form trigycerides from glucose, increases uptake of glucase and the production of lipoprotein lipase
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Epinepherine and norepinephrine action on adipocytes
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"Flight or flight" response
Stimulate hormone sensitive lipase system to break down lipids and release glycerol and free fatty acids |
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Hypercellular Obesity
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(hyper plastic obesity)
Increased number of fat cells Usually due to overfeeding as infant and is serious |
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Hypertrophic obesity
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Increased size (more lipid) of same number of fat cells, most common
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Brown adipocytes: Morphology, Location, Function
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Fixed Cell
Morphology: Smaller size, numerous mitochondria, are multilocar (numerous small droplets of lipid in cytoplasm) Location: along aorta, mediastintum, axilla and between scapulae Function: Generate heat w/ uncoupled oxidation process and use of Therminigen (unique to brown fat and used in hibernation and newborns) |
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Thermogenin
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A mitochondrial protein permits the back flow of protons instead of using them for ATP production
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Chondrocyte
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Fixed cell of the cartilage
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Osteocyte
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Fixed cell of bone tissue
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Blood Cells
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Fixed cell of blood
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Wandering Cells (3 types)
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Macrophages, mast and plasma cells that migrate into and out of the connective tissue.
Also all leukocytes |
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Macrophages: Function, Origin, Appearance
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Wandering Cell
Phagocytic- ingests particulate material Are antigen presenting Cells part of mononuclear macrophage system Arise from monocytes (Granulocytic Mononuclear Stem Cell) in the circulating blood that once the moncyte leaves the blood vessel it becomes a macrophage Has different dnames based on the organ where it is located Appearance: Oval indented nucleus with vesicular chromatin pattern (more condensed than fibroblast nuclei), lots of lysosomes |
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Histiocytes
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Wandering macrophage found in immune system
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VonKupffer cells
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Wandering macrophage found in the liver
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Microglia
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Wandering macrophage found in the brain
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Alveolar macrophage
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Wandering macrophage found in the lungs
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Foreign body giant cells
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Wandering macrophages found near wounds
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Mast Cells: Morphology, Function, Location
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Wandering Cell
Morphology: granular appearing, oval cells asssociated with small blood vessels, Nucleus is clear and mostly obscured by granules Granule contents: Heparin, Histamine, Eosinophilic Chemotaxic Factor Neutrophilic CHemotaxic Factor, leukotrines, cytokines. (Paracrine secretion - localized action) Location: Along capillaries in mucosal membranes in respiratory, digestive and urinary tracts where Ag's (antigens) can easily enter. |
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Histamine
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-Vasodilator
-Increased vascular permeability -Constriction of Smooth Muscle Cells of bronchioles |
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Cytokines
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Immune system signalling molecule eg; tumor necrosis factor alpha
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Action of Mast Cells
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1) Store mediators of inflammatory response
2) bind IgE to its surface and then interacts with antigens 3) First exposure to Ag (antigen) causes formation of IgE's 4) IgE's bind to receptors on mast cell surface 5) Second exposure Ag binds to IgE on surface and activates adenyl cyclase 6) this causes phosphorylation of proteins that release Ca++ and causes fusion of granules and release of contents on surface. |
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Heparin
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Anticoagulant binds and inactivates histamine
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Plasma cells: Morphology, Location, Function
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Morphology: Diagnostic characteristics are the eccentric nucleus and cartweel chromatin pattern, lots of RER at EM level
Location: normally found only in connective tissue, not in peripheral blood Derived from B-lymphocytes Function: Produce Antibodies |
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Associated Cells (3 Types)
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Endothelial Cells - line blood vessels
Smooth Muscle Cells- surround endothelium and control vessel size Pericytes - Multipotential stem cells for vessel repari and growth |
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Extracellular Fibers (3 Types)
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Collagen, Reticular Fibers, Elastic Fibers
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what is Collagen's function? What percentage of dry weight and total protein does it make up?
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Most abundant protein in the body
Makes up 30% of dry weight and 20% of all protein Has high tensile strength, elastic yet flexible Added to connective tissue where strength is needed. |
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Fasciles
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Bundles of fibers usually found in the connective tissue proper
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Collagen fiber
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Straight unbranched fibrous protein
Has periodicity Made up of collagen fibrils |
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Collagen Fibril
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Smaller than a Fiber
Has periodicity Made up of Tropocollagen molecules |
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Tropocollagen Molecules
What are they? What holds them together? What are they made of? |
Consists of 3 alpha polypeptide chanis
Rich in glycine, proline, hydroxyproline and hodroxylysine. Hydrogen bonding between hydroxyproline molecules of adjacent polypeptide chains hold the chains together. Covalent bonding between the hydroxylysine molecules in adjacent tropocollagen molecules hold the fiber together |
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Type I Collagen (function, location)
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Function: Strength
Location: Dermis, tendon, bone, dentin |
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Type II Collagen (function, location)
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Function: Resists Pressure
Location: Hyaline and eleastic cartilage |
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Type III Collagen (function, location)
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Function: Forms a delicate support meshwork
Location: Cardiovascular system, Lungs, Liver |
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Type IV Collagen (function, location)
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Function: Attachment, Filtration
Location: Basal Lamin |
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Describe the synthesis of collagen
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1) Transcription within nucleus
2) Translation within rER 3) Hydroxylation of proline and lysine occures in rough ER 4) Formation of procollagen in rER 5) Merocrine secretion via Golgin apparatus 6) Procollagen peptidase cleavage of procollagen to form tropocollagen molecules outside the cell membrane 7) Self assemply of tropocollagen molecules to form collagen fibril in extracellular matrix. 8) Lysyl oxidase covallently links hydroxyllysine molecules of adjacent tropocollagen molecules to form insoluble fibrils |
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Scurvy
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Disease casued by lack of Vitamin C
Vitamin C is a cofactor required for hydroxylation of proline |
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Ehlers-Dalos Type VII
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Due to one AA change in procollagen peptidase
Cause hyperflexible joints, dislocations, soft skin |
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What are collagen fibers broken down by?
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Collagenase
Excessive action of this enzyme will present elevavated glycine in urine |
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Reticular Fibers (Morphology and Composition)
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Morphology and composition: Small branched fibers forming branched network (squiggly), Branching fibers intersect at right angles
At EM level fibers composed of thin collagen type III fibrils covered with a sugar coat Reticular fibers wrap each fiber Secreted the same way as collagen fibers Location: Found in regiond with lots of wantering cells, i.e. areolar connective tissue, reticular tissue, lymphatic tissue, liver Function: Where delicate support is needed (holds space open for wandering cells) |
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Ehler-Danlos type IV
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Reticular Fiber disease
Due to dificiency in type III collagen, causes Aneurysms and intestinal rupture common |
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Elastic fibers (Morphology, Function, Location, Formation)
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Morphology: Y-branched fibers which form a continuous network within the tissue by fusing with adjacent fibers
Also be found as sheets or lamella in large blood vessels, intersect at acute angles not right angles Consists of 2 components at EM level (Amorphous and Microfibril) Function: Stretches to 150% of original length without breaking. Springs back to original shape without using muscle energy Location: Found in organs normally subjected to large amounts of stretching and repositioning i.e. blood vessels, aorta, lung, skin, ligamentum nuchae and uterus Formation: Like collagen, proelastin to tropoelastin at cell membrane to elastic fibers outside cell. Lysyl oxidase forms covalent cross links between tropo elastin molecules to form elastin in a mesh of microfibrils. |
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Amorphous component
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Part of elastic fibers, contains elastin, also rich in glycine like collagen but contains unique amino acids desmosine and isodesmosine
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Microfibril Component
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Part of Elastic Fibers
A glycoprotein |
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Elastic fiber system has 3 types of elastic fibers
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Oxytalan fibers consisting primarily of microfibrillar component
Eulanin fibers consisting of microfibrils and some amorphous elastin Elastic fibers |
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Emphysema
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Disease of elastic fibers, causes lung dysfunction
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Elastase
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Breaks down elastic fiber for contiuous turnover
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Marfan's Syndrome
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Casued by poor microfibril formation in elastic fiber, Tendency to rupture aorta and other blood vessels
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Ground Substance (what does it look like, what is it?)
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Has no visible structure, and is what remains after the cells and extracellular fibers have been removed
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3 Components that make up ground substance
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Proteoglycans, interstitial fluid, and glycoproteins
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Proteoglycans
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Part of Ground substance
Holds water Is a protein core with glycosaminoglycans (GAGs) attached "Bottle Brush Appearance) Forms a porous hydrated gel which is slippery and resists compression |
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6 Different GAGs
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Hyaluronic Acid (Non-sulfated), Keratan sulfate, Heparan sulfate, Chondroitin-6-sulfate, Chondroitin-4-sulfate, dermatan sulfate
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Hyaluronic Acid (Appearance, Morpholgy, Function)
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Nonsulfated GAG
Large highly coiled molecule Negatively charged molecule that pulls in Na+ and Ca++ and holds water Is slippery,resilient, lubricating Gel like consistency that resists compression Contains channels through which diffusion of materials is allowed Forms a physical barrier that prevents migration of bacteria through ECM Inhibits cell adhesion and facilitates cell migration. Higher levels of HA during embryogenesis and repair |
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5 Sulfated GAGs and Locations
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Keratan sulfate: Cartilage
Heparan sulfate: Located in basement membrane Chondroitin-6-sulfate: located in cartilage, skin and bone Chondroitin-4-sulfate: located in cartilage, skin and bone Dermatan sulfate: located in dermis |
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Free Proteoglycans
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Present within ground substance
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Aggrecan
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Free Proteoglycan
Free in areolar CT matrix Core protein with chondroitin sulfate and keratin sulfate attached "bottle brush appearance" |
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Aggrecan Aggregate
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Hyaluronic Acid with Hundreds of Aggrecan molecules
Found in cartilage matrix and much more gel-like and compression resistant |
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Perlecan
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A free Proteoglycan that contains primarily heparin sulfate
Found in the basal lamina |
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Transmembrane Proteoglycan
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PGs that extend throug hte cell membrane
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Syndecan
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A transmembrane PG, one end in the cytoplasm and the other end in the EMC
Rich in heparin sulfate and chondroitin sulfate Heparin sulfate binds to other PG's with heparin sulfate and chondroitin sulfate. |
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Fibroglycan
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A transmembrane Proteoglycan that is rich in heparin sulfate, Binds to 3 types of collagen and fibronectin
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Glycoproteins
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Protein core with branched sugars attached
Typically they are all adhesion molecules to help hold cells to the EMC |
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7 Examples of Glycoproteins
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Fibronectin, Laminin, Entactin, Tenascin, Chondronectin, Oseonectin
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Interstitial fluid
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Water found in extracellular space, AKA tissue fluid
Important in the transport of nutrients and wastes between blood vessels and the parenchyma Bound by the proteoglycans and hyaluronic acid |
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Formation of Interstitial Fluid
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Hydrostatic pressure on arterial end forces fluid out of capillary into ECM
Circulated through channels in HA and Proteoglycans towards venous end of capillary Most fluid reenters capilllary due to higher oncotic pressure (due to loss of fluid) and large albumin molecules still in blood Always excess fluid left in ECM this is drained away in lymphatic capillaries Production and resorption of fluid creates continuous circulation through ECM Supplies nutrients and removes wastes from parenchymal cells |
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Edema
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Abnormal build up of interstitial fluid in ECM
Causes Pitting Edema (leaves a dent when pushed on) |
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Causes of Edema
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Blocked lympahtics-surgery, elephantiasis
Blocked venous return- compromised veins in pregnancy Liver disease - insufficent albumin (produced by liver) to pull H2O back in vessel Increase vascular permeability- asthma, hypersensitivity, anaphylactic shock, histamine from mast cells Hypertension- due to increased hydrostatic pressure at arterial end of capillary bed. Starvation - causes lack of plasma proteins that results in H2O remaining and ECM " |
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Myxedema
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due to over production of GAGs during hyperthyroidism
"mucous edema" |
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Basement Membrane
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Light microscope term
Located in extracellular space Functions to connect cells (epithelial, muscle and nerve cells) to connective tissue Surrounds all cells except connective tissue cells (fixed and wanderin) |
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3 Layers of Basement Membrane
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Lamina lucida (light)
Lamina densa Lamina reticularis |
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Lamina lucida (structure/function)
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light layer next to cell membrane
Contains integrins, laminin, entactin |
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Lamina densa
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Dense fuzzy band, contains collagen IV, perlecan (heparan sulfate) and fibronextin
negatively charged acts as a flexible macromolecular filter |
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Lamina reticularis
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containes reticular fibers (collagen III) and also IV and VII of anchoring fibrils
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Basal lamina
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Basal lamina consits of both the lamina lucida and lamina densa (not lamina reticularis) used when looking at the epithelium
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Alternative view of what the basal lamina is
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Just the lamina densa
Appears this way in muscle cells but really only has a reduced amount of lamina lucida |
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Function of Basal lamina (2)
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Holds cells to surrounding connective tissue
Acts as macromolecular filter |
