Connective Tissue (exam 1) Flashcards
What is the main example in embryonic tissue
Wharton’s jelly
What are the major types of adult CT
Elastic , reticular, loose, and dense
what type of fibers does loose CT have
both collagen and elastic fibers are present and arranged in a very, loose random fracture
What types of fibers make up dense CT
Collagen fibers ppredominate
two types
- regular and irregular
What type of fibers make up reticular CT
Reticular fibers
What type of fibers make up elastic CT
Elastic fibers
where is embryonic CT found and what is it called
Umblical cord and in the pulp of developing teeth
wharton’s jelly
What is Wharton’s jelly composed of
some collagen and elastic fibers but mostly ECM
Describe the structure of loose CT
high ratio of fibroblasts to fibrous components
Type I collagen fibers and elastic fibers
usually found beneath epithelial tissues of most organs, including the tunica adventitia of blood vessels
Contains fibroblasts, mast cells, macrophages, and capillaries
what is the structure of dense regular CT
fibroblast nuclei are very elongated and thin
high ratio of bibrous components to fibroblasts
thicker bundles of collagen than in loose CT
highly ordered bundles of collagen separated in single row fibroblasts
found in tendons and ligaments
what is the structure of Dense irregular CT
high ratio of fibrous component to fibroblasts
thicker bundles of collagen than in loose CT
has no specific orientation of collagen bundles
found in fascia, subucosa of GI tract, and in dermis of integument
What is the structure of reticular CT
A type of dense irregular CT with a predominance of reticular fibers (which like to branch)
Associated primarily with lymphatic tissue
what is the structure of elastic CT
A type of dense irregular CT with an abundance of elastic fibers which form discontinuous lamellae
associated with blood vessel
Where are elastic fibers in the blood vessels produced
produced by smooth muscle cells rather than fibroblasts
What are the types of special CT
Adipose, Cartilage, Bone, and hematopoietic
what are adipocytes
Adipocytes are derived from undifferentiated mesenchymal cells and are distinguished by their unique appearance
most are about 150micrometers in diameter
Two types
- white fat
-brown fat
What is white fat reffered to as
Unilocular (means that there is a single droplet of oil/fat in the cell)
why are special CT tissues categorized as CT
Embryonic development
what are the most common cell types in ECM
Fibrocytes and fibroblasts
what are the most abundant fibers of the ECM
Collagen fibers
Type I collagen
General CT and Bone
fxn: tensile strength
Type II collagen
found in hyalin and elastic cartilage
Fxn: tensile strength
Type III collagen
Parenchyma of organs and walls of blood vessels
Fxn: reticular framework
Type IV collagen
location: basement membrane
FXN: Meshwork, and scaffolding
What is Type I collagen synthesized as
Prepropeptide
Describe the synthesis of Type I collagen
The (pre) sequence of the Prepropetide is cleaved after translocation into the ER lumen of the fibroblast
after the signal sequence is cleaved, the property (pro collagen) molecule is secreted by the fibroblast into the ECM
-procollagen molecule has a non-helical ends that prevent polymerization to occur
- these ends are cleaved by peptidases in order to allow polymerization
- after the terminal ends are cleaved, the molecule is referred to as tropocollagen
The procollagen molecule has terminal non-helical ends that prevent what
Polymerization
what is tropocollagen
what is left after peptidases have clipped off the helical terminal ends of procollagen
List the functions of the CT
Physically supports other tissues, binds other tissues together , provides structural framework and opposes gravity, create body contours, houses specialized tissues (blood forming tissue, and lymphoid tissues)
Cleaving of the non-helical terminal ends of pro-collagen converting it into tropocollagen occurs when
Immediately after secretion
What is ground substance mostly composed of
Glycosaminoglycans and glycoproteins
What composes the CT matrix
Scattered cells (mostly fibrocytes and fibroblasts) protein fibers (most abundant collagen, less abundant reticular and elastic fibers) Ground substance (which is mostly glycosaminoglycans and glycoproteins)
Tropocollagen monomers spontaneously assemble into staggered arrays to form collagen fibers with a characteristic ___ nm banded pattern
64 nm
What is the assembled polymer of tropocollagen monomers called
Collagen
Describe elastic fiber synthesis
Elastin is synthesized as prepropeptide (like collagen)
- The prepropeptide is secreted as propeptide
- propeptide is converted to tropoelastin by extracellular enzymes, also secreted by the fibroblast
- Tropoelastin monomers are assembled into amorphous fibers or sheets with the aid of several types of fibrillins
(Fibrillin-1 and Fibrillin-2)
Marfan syndrome
Autosomal dominant disorder
patients are tall, with long arms, legs, fingers, and toes
(arachnodactyly).
Increased risk of mitral valve prolapse, dilation of the root of the aorta, and aortic dissection
Etiology: Defect in genne encoding the protein fibrillin-1
What are GAGs
Large, negatively charged linear polymers (polysaccharides) consisting of repeated disaccharide units
What where GAGs originally referred to as
acid mucopolysaccharides
Glycoproteins and GAGs form most of what
Ground substance (amorphous substances of CT)
What is the only GAGs to not covalently link to protein and form proteoglycans
Hyaluronic acid
what is the largest of the GAGs
Hyaluronic acid
Where is Hyaluronic acid found
Cartilage, skin, synovial fluid, most general CT, in vitreous body of eye, and Wharton’s jelly
What is the only GAG, which lacks sulfate groups
Hyaluronic acid
Hyaluronic acid consists of repeating carbohydrate chains of ________ and ________
N-acetylglucosamine, D-glucuronic acid
What is the function of hyaluronic acid in synovial fluids
binds readily with water and serves as a lubricant
Where is Heparin and Heparan sulfate found
basement membrane, skin, lung, liver, blood vessels, mast cell granules
Heparin and Heparan sulfate repeating units are ____________ and ___________
N-Acetylglucosamine, D-Glucuronic acid
Chondroitin sulfate and dermatan sulfate are found where
Cartilage, bone, skin, blood vessels, heart valves, and cornea
What is the most abundant group of the sulphate GAGs
Chondroitin sulfate and dermatan sulphate
What is the repeating unit in Chondroitin Sulphate
N-acetylglucosamin and D-glucuronic acid
What GAGs have repeating units of N-acetylglucosamin and D-glucuronic acid
Heparin, Heparan sulphate, Chondroitin sulfate, Hyaluronic acid
What is the most abundant of the GAGs
Hyaluronic acid
What is the repeating unit in dermatan sulphate
N-acetylglucosamine and iduronic acid
Where is Type I keratan sulfate found
only in the cornea
Where is Type II Keratan sulfate found
in cartilage and nucleus pulpous of intervertebral disks
What is the repeating units in Keratan sulphate
N-acetylglucosamine and galactose
Name the 4 groups of GAGs
Hyaluronic acid, Chondroitin sulphate and dermatan, Heparin and Heparan sulfate, Keratan sulphate
Name the GAGs that are found in cartilage
Hyaluronic acid, Chondroitin sulfate and dermatan sulfate, Type II Keratan sulphate
What are extracellular protein complexes of glycosaminoglycans (GAGs) called
Proteoglycans
How are Proteoglycan aggregates formed
Axial hyaluronan molecule, core proteins attach to the hyaluronan molecule (hyaluronic acid) by a linker protein, glycosaminoglycans attach to a core protein
- serval chains of GAGs bound to the core protein form a proteoglycan
what cells secrete proteoglycans
Fibroblasts, chondroblasts, osteoblasts, synovial cells, smooth muscle cells (all derived form the primitive mesenchyme)
What causes Proteoglycans to stain with conventional disease such as hematoxylin
Its sulphate groups
Toluidin blue and crystal violet are cationic dyes that are metachromatic when reacting with what groups of the proteoglycan
Anionic groups
Are proteoglycans polyanions
yes
What are glycoproteins
proteins with one or more heterosaccharide chains containing hexosamine, galactose, and other sugars
Are glycoproteins PAS +
Yes
What are the main characteristics of glycoproteins
High protein content and branched carbohydrate moieties
What are 3 examples of glycoproteins
Fibronectin, Laminin, Chondronectin
Fibronectin is a major surface protein of what kind of cells
Fibroblasts
what are a major surface protein of fibroblasts
Fibronectin
What synthesizes fibronectin
Fibroblasts, epithelia, and endothelia
What is the function of fibronectin
links cells, collagen, and glycosaminoglycans (GAGs)
What is plasma fibronectin called
cold -insoluble globulin or plasma fibronectin
Fibronectin occurs in _____ of platelets
Alpha granules
What is the function of chondronectin
Promotes adhesion of mature chondrocytes to collagenous substrates
Where is chondronectin found
It is found isolated from cartilage
Where is laminin found
in basal laminae (component of lamina rara)
what is the function of laminin in the basal laminae
Involved in the attachment of epithelial cells to the lamina propria
Is Laminin a non-collagenous glycoprotein
Yes
What are the principle cell types in CT
Fibroblasts and Fibrocytes
What are the function of fibroblasts and fibrocytes
secretion and maintenance of CT matrix
secretion of precursor fibrous molecules
secretion of the amorphous components of the matrix including the glycosaminoglycans (GAGs)
List some common types of cells that are found in CT other than fibroblast/fibrocytes
Macrophages, Mast Cells, Plasma Cells
What is the structural difference of macrophages
Wandering macrophages are somewhat oval in shape
fixed macrophages are more irregular in shape with long processes
What is the structure of a macrophages nucleus
Ovoid or indented heterochromatic
what is the size of a macrophage
10-30nm
what is the type of movement that macrophages are capable of using
Amoeboid
What cells are part of the mononuclear phagocytic system (originally called the reticular activating system -RAS)
Macrophages
what are giant cells in terms of macrophages
macrophages that have fused together to from a large multinucleate phagocyte
Discuss the organelle structures of macrophages
Extensive Golgi, rER, SER , Mitochondria , secretory vesicles, and lysosomes
where are macrophages found
wandering in blood (monocytes)
CT (histiocytes)
Liver sinusoids (Kupffer Cells)
Sinusoids of Spleen, Lymph nodes, bone marrow (perialveolar macrophages),
Alveoli of lungs (dust cells)
CNS (microglia)
Associated with bone reabsorption (osteoclasts)
Monocytes
undifferentiated macrophages, are not phagocytic
Histiocytes
Macrophages found in CT
Kupffer Cells
Macrophages in Liver Sinusoids
Perialveolar macrophages
Macrophages in Sinusoids of spleen, lymph nodes, and bone marrow
Dust cells
Macrophages in the Alveoli of lungs
Microglia
Macrophages of CNS
Osteoclasts
Macrophages associated with bone reabsorption
Structure of Mast cells
Irregularly Oval in outline
Small spherical/ovoid nuclei often masked by membrane bound granules
Stain with toluidine blue
large metachromatic granules with histamine, ECF-A, SRS-A, and Heparin
What is ECF-A
Eosinophil chemotactic factor
in large metachromatic granules of Mast Cells
fxn: attracts eosinophils and neutrophils
What is SRS-A
Slow reacting substance of anaphylaxis
found in in large metachromatic granules of Mast Cells
fxn: similar to histamine but has more sustained effect
What is Heparin in mast cells
Heparin form mast cells is a poor anticoagulant and is probably involved in helping clear plasma lipids
found in in large metachromatic granules of Mast Cells
How are mast cells involved in hypersensitivities to allergens
lead to Edema shock pain hyper-coagulation fever
What do the membranes of Mast cells release
Leukotrienes
Where are mast cells found
in all mucosal surfaces and in CT
found near small blood vessels, which are a target of histamine and SRS-A
Where are mast cells absent
The spleen
What is the target for histamine and SRS-A
Blood vessels
What are activated B lymphocytes called
Plasma Cells
Are plasma cells bigger or smaller than B lymphocytes
Bigger
Describe the appearance of plasma cells
Large pale nuclei with “clock-face”distribution of heterochromatin
- spherical and typically offset
Describe some organelle characteristics of plasma cells
Prominent Golgi and extensive RER
Where are plasma cells rarely found
in CT
Where are plasma cells frequently found
serous membranes, lymphoid tissue, and lamina propria of gut tract
What is the typical diameter of a lymphocyte
6-8 micrometers
Where are lymphocytes numerous in numbers
in lamina propria of respiratory and GI tract
What is the characterizing structure of lymphocytes
Relatively large, heterochromatic nucleus surrounded by thin rim of cytoplasm
