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45 Cards in this Set
- Front
- Back
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4 major tissues of the body
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epithelial
connective muscle nerve |
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what different types of connective tissue are there?
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connective tissue proper
specialized CT - adipose tissue, bone/cartilage, blood |
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connective tissue proper
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bounded above by basal lamina or external lamina
contains blood vessels , lymphatics , nerves, etc. |
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CT components
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cells - stationary and migratory
ECM - made of fibers and ground substance collagen and elatin fibers reticular fibers are specifically type 3 collagen |
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What is in the ground substance?
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water, GAGs, proteoglycans, structural glycoproteins
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How is Ct proper classified?
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either loose/areolar CT
or dense CT dense CT broken down to either regular or irregular CT |
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How do you describe loose CT?
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contains mainly cells and ground substance
Supports Epithelial tissue, Surrounds blood vessels, Fills spaces between Muscles flexible and well vascularized can have diffusion of CO2, O2 and nutrients/wastes can have inflammatory and immune reaction provides structural support |
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Describe dense CT
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lots of fibers (not as many cells and ground substance)
fiber arrangement determines if it is regular (parallel bundles) or irregular (random) |
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ex. of dense regular CT and irregular dense CT
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regular = tendons, ligaments, cornea
transmits force of muscle contraction/attaches muscle to bone/protects irregular = skin and GI tract protection tensile strength |
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functions of CT
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support
defense - site of inflammatory and immune reactions/ also provides physical barriers nutrition = has water/electrolytes; stores energy in form of TGs; blood vessels for nutrients/gases |
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What makes fibers in CT proper?
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fibroblasts
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What makes fibers in walls of blood vessels?
in cartilage? |
smooth muscle
chondrocytes |
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What are reticular fibers made of?
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Collagen type 3
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What does collagen look like in an image?
What does it do? |
wavy structures with variable width
looks like a railroad track in EM because stain get stuck in spaces between alpha 1 and alpha 2 in helix fibrous and flexible provides tensile strength |
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steps in biosynthesis of collagen type 1
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intracellularly get synthesis of preprocollagen
clip signal peptide to get procollagen hydroxylation of lysine and proline (VITAMIN c DEPENDENT!) assembly of procollagen triple helix molecules transport to Golgi to package into secretory vesicles secretion of procollagen procollagen is processed outside of cell by enzymes assemble into collagen fibers collagen fibrils form covalent bonds between collagen molecules in adjacent rows (strength) |
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structure of reticular fibers
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synthesized by reticular cells of fibroblast
fine type 3 collagen fibers forming a 3D network rather than a thick bundle for support supports hemaotopeirtic and lymphoid organs (except thymus) high content of sugar chains |
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What is type 1 collagen?
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fibril forming collagen
for dermis, tendon, bone, fibrocartilage provides resistance to tension |
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What is type 2 collagen
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fibril forming
hyaline cartilage and intervertebral disc resistance to pressure |
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What is type 3 collagen?
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reticular CT
maintenance of expansible organs |
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type 4 collagen
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basal lamina
support delicate structures and filtration |
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type 7 collagen
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basal lamina
connect collagen fibers to basal lamina |
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What are elastic fibers and their function
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allow tissues to respond to stretch and distension
responsible for elasticity resilience, and shape control in walls of large blood vessels and ligaments main component of elastic tissue |
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What synthesizes elastic fibers
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fibroblasts and smooth muscle cells
PROelastin is synthesized and secreted from cell cleaved to make tropoelastin secreted tropoelastin is synthesized and interacts with FIBRILLIN to organize immature elastic fibers which aggregate into mature elastic fiber |
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What is responsible for cross linking elastic fibers?
function? |
desmosine and isodesmosine
enable stretch and recoil |
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What is the ECM?
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a system that informs cells about the biochemical and mechanical changes in their extracellular environment
consists of ground substance and fibers |
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characteristics of ground substance
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extracellular substance
colorless hydrated (high in water) fills spaces lubricant allows diffusion of water soluble molecules anchors cells through cell-ECM adhesion binds and retains growth factors via cell adhesion molecules - info is transmitted across the plasma membrane |
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molecules of the ground substance
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GAGs
proteoglycans glycoproteins water |
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What are glycosaminoglycans?
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long chain, unbranched polysaccharide (sulfated and hydrophilic)
binds water and ions (causes more water to come in) negatively charged/acidic comprises 10% of ECM mass but 90% of the volume provides compressive strength |
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What is hyaluronic acid?
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a GAG that is sulfated and synthesized on cell surface
major component of ECM - prevents diffusion immobilizes moleucles that regulate cell proliferation and migration important in cartilage (resists compression, promotes flexibility, shock absorber) major component of umbilical cord degradative enzyme = hyaluronidase makes it easier for things to get through CT not covalently bound to protein but can be noncovalently bound by linker proteins |
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What is a proteoglycan?
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core protein with GAGs attached
looks like a bottle brush |
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What is syndecan?
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a transmembrane proteoglycan
links cells (actin cytoskeleton) to ECM heparin sulfate associated with embryonic epithelia, lymphocytes, and plasma cells |
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What is aggrecan?
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a proteoglycan that is non cov bound to hyaluronic acid and covalently bound to chondroitin sulfate and keratin sulfate
cartilage and chondrocytes hydration of ECM |
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What does a glycoprotein do in ECM?
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protein attached to a carbohydrate
multi-adhesive glycoproteins can facilitate cell - CT or CT element -CT element stabilizes ECM |
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What is laminin?
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a glycoprotein (cross shaped made of 3 chains (alpha, beta, gamma)
in basal lamina of all epithelia cells and some external lamina laminin binds to cell surface receptors (integrins) type 4 collagen and other ECM protein and laminin associate with each other to form a mesh like polymer anchors the basal surface of the cells to basal lamina |
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What is fibronectin?
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glycoprotein
2 peptides linked by a disulfide bond 3 domains - cell surface receptors (integrins) type 4 collagen, GAG (heparin) responsible for cell adhesion, mediates cell migration |
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What are fibroblasts?
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cell in CT
synthesizes precursors of ground substance (proteoglycans and glycoproteins), collagen, elastic fibers rarely divide but capable in response to injury or inflammation myofibroblast = specialized fibroblasts spindle in shape with elliptic nucleus |
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What are macrophages?
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come from monocytes in the bone marrow - travel to target organ before fully differentiating
phagocytic cell with other functions recognizes antigens and present them to other immune cells many lysosomes to break down material ingested many phagocytic vesicles with ingested material over or kidney shaped nucleus |
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What are mast cells?
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arise from multipotent hematopoietic stem cells in bone marrow
circulate in undifferentiated state oval to round cells with microvilli nucleus is centrally located surface express IgE receptors - when antigens bind - release these factors see granules containing heparin, histamine, chymase, chemotactic factors |
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What are plasma cells?
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produce antibodies in response to antigen
oval eccentric nucleus (wheel nucleus) Golgi ghost well developed ER and golgi |
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What is a lymphocyte?
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a leukocyte
nucleus occupies most of cell surface markers that classify them as T, B, or natural killer cells |
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What is a eosinophil?
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a leukocyte
nucleus is typically bilobed see cytoplasm has granules functions in allergic response and parasitic response |
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What is a neutrophil?
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a leukocyte
usually segmented ino 3-5 lobes primary granules |
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What is adipose tissue's function?
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store energy - TG
insulates body against heat loss fills spaces - shock absorber ex. around kidney metabolically active - seceretes paracrine and endocrine substances |
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white adipocytes (unilocular)
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large lipid droplet surrounded by ring of cytoplasm
nucleus is flattened and located at the periphery richly supplied with blood vessels secretes reticular fibers that surrounds adipocytes |
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brown adipocyte (multilocular)
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fetal like and first decade after birth
multiple lipid droplets eccentric nucleus numerous mitochondria primary function is to generate heat |
