Connective Tissue Flashcards Preview

Anatomy 6511 > Connective Tissue > Flashcards

Flashcards in Connective Tissue Deck (67)
1

Embryonic connective tissue

Mesenchyme 2. Mucous

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Adult Connective Tissue

1. Connective Tissue Proper a. Loose (Areolar) b. Reticular c. Dense Regular d. Dense Irregular
e. Adipose 2. Specialized a. Blood
b. Supporting Connective Tissue
1) Cartilage 2) Bone

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Functions of connective tissue

Binds, supports, strengthens -- incredibly abundant. Protection, insulation, compartmentalization, transport, storage of energy reserves, immune responses.

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Protection

Bone tissue protects brain for example, adipose protects organs, etc.

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Compartmentalization

Sections organs and body

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Storage of Energy Reserves

Adipose tissue

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Immune responses

Blood - white blood cells in particular.

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Common characteristics of connective tissue

Incredibly diverse tissue - share the presence of cells in an extracellular matrix, common origin, varying degrees of vascularity.

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General Composition of Connective Tissue

Cells (make ground substance) and ECM

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ECM

Protein Fibers a. Collagen b. Reticular c. Elastic 2. Ground Substance
a. Glycosaminoglycans (GAGs) (ex. hyaluronic acid and chondroitin sulfate) b. Proteoglycans c. Multiadhesive Glycoproteins (ex. laminin and fibronectin)

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Fibroblast, chondroblast, osteoblast, odontoblast

Production of fibers and ground substance-Structural

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Mesenchyme

Loosely organized embryonic connective tissue. Has undifferentiated elongated mesenchymal (stem) cells. These cells have an oval nucleus usually, fine chromatin. Have cytoplasmic processes. Brown substances between cells is very viscous. Source of all connective tissues.

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Plasma cell

Production of antibodies - Immunologic

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Lymphocyte

Production of immunocompetentcells - Immunologic

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Eosinophil

Participation in allergic and vasoactive reactions, modulation of mast cell activities and the inflammatory process - Immunologic

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Neutrophil

Phagocytosis of foreign substances, bacteria - defense

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Macrophage

Secretion of cytokines and other molecules, phagocytosis of foreign substances and bacteria, antigen processing and presentation to other cells - defense

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Mesenchymal stem cells

Can also differentiate into muscle and epithelial tissue.

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Mast cell, Basophil

Liberation of pharmacologically active molecules (e.g., histamine) - defense

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Adipose cell - adipocytes

Storage of neutral fats and thermogenesis - Energy reservoir, heat production. From mesenchymal cells. One of the largest cells in body, fat droplet is directly exposed to cytoplasm.

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Three Types of Fibers

Collagen – collagen protein 2. Reticular – collagen protein 3. Elastic – elastin protein

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EC Matrix

Protein fibers + ground substance. These are secreted by some of the cells.

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Collagen

Most abundant protein in human body - 30% of dry body weight. Polymerize into fibers/fibrils. Over 20 types of collagen proteins. Resistant to pulling forces, still flexible (see dermis of skin). In bone, cartilage, tendons, ligaments.

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Elastic

Create networks. These are very strong and can be stretchted to 150% of their original length w/o breaking (and can return to shape). Found in skin, blood vessels, lungs, etc.

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Reticular

Similar to other collagen fibers, but much thinner, found in networks 0.5-2 microm in width. Provide a lot of framework and structure for other cells. Problem, as these don't stain with others. Use silver stain to stain them black. Main connective tissue associated with lymphatic system. Lymphocytes hang off of it.

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Ground substance

Provides medium through which nutrients, proteins and other substances may diffuse. Can be fluid, semifluid, gelatinous or calcified (no diffusion). Very hydrophilic, binds water and is thus able to be easily compressed (can withstand forces).

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Glycoaminoglcans

GAGs

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Adult Connective Tissue

Connective Tissue Proper a. Loose (Areolar) b. Reticular c. Dense Regular d. Dense Irregular
e. Adipose 2. Specialized a. Blood
b. Supporting Connective Tissue
1) Cartilage 2) Bone

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Wharton's Jelly

Embryonic connective tissue. Mucous tissue - only present in umbilical cord. Something similar in the pulp cavity in young teeth, but not exactly the same. Gelatinous ECM, a few collagen occasionally in the matrix.

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White Adipose Tissue

Predominant type in adults
Adipocytes: unilocular, spherical, flattened nucleus, rim of cytoplasm, larger diameter
(15-150 μm)
Location: subcutaneous layer, mammary gland, greater omentum, mesenteries, orbits, bone marrow cavity
Function: energy storage, insulation, cushioning of vital organs, and secretion of hormones

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Brown Adipose Tissue

Predominant type in fetus and newborn
Adipocytes: multilocular, spherical, round,
eccentric nucleus, smaller diameter (10-15 μm)
Location in Newborns: 5% of total body mass; back, along upper half of spine and toward shoulders
Location in Adults: retroperitoneal space, around aorta, neck, back, mediastinum
Function: heat production (i.e., thermogenesis)

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Fibroblasts

Produce, secrete, maintain ECM. Synthesize fibers, carbohydrates. Have larger nucleus, eosinophilic cytoplasm (if active, they will be producing a lot of protein and thus there will be a lot of ribosomes). Spindle shaped, and two forms: quiet and active (exactly how they sound).

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Fibroblasts- quiet and active

Active produce a lot of fibers and ground substance. Quaiescent fibrocyte (fibroblast) are a little smaller than active fibroblast, and the nucleus is coiled tightly.

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Myofibroblasts

Somewhat looks like smooth muscle and fibroblast. Elongated cell - characterized by bundles of actin filaments, associated with actin motor protein (some movement that ties into cytoplasm and ECM). This can "pull" on ECM for movement. Produces ECM as well.

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Mast cell

Progenitor cell in bone marrow/somewhere else, circulates and gets to connective tissue where it develops. Large, oval/rounded, about 20-30microm in diameter, small spherical (central) nucleus, cytoplasm filled with very basophilic secretory granules. 0.3 to 2 microm in diameter (granules). Granules contain substances to aid immunity, immune response, tissue repair.

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Plasma cells

Some in connective tissue - 10-20 day life span. Rise from B lymphocytes. These cells are responsible for antibody production. Have huge amount of rough ER. Basophilic cytoplasm from rough ER. Has a small dark rounded nucleus with chromatin in large blocks near periphery**. Golgi complex right near nucleus (clear spot).

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Macrophages

From monocytes (white blood cells). Monocytes migrate from bloodstream into connective tissue where they differentiate. Lots of lysosomes in cytoplasm, golgi, rough and smooth ER, these cells produce proteins involved in phagocytosis and digestive functions. 15-25 microm in diameter. Heavy staining cells. Cytoplasm has an almost foamy view due to vacuoules. Indistinct cell border. Nucleus is small and darker, chromatin rich in color. Lots of these monocytes create specifically named macrophages (osteoclast is a macrophage for example).

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Longer Han cells

Macrophages

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Koufer cells

Liver macrophages

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Collagen fiber structure

Molecules assemble into several fibril structures. Basic unit is a trimer of 1 or more alpha chains. Depending on what alpha chain is used, different collagen molecules can be made. Fibrils can be formed and then bundled to fibers. Chemical differences in alpha chains that are responsible for structural differences.

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Endothelium

Simple squamous associated with blood vessels and heart.

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Lumellae

Sheets of elastic fibers in the wall (gives heavy elasticity to structures like aorta).

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SEM photo

Top is collagen, middle "fuzzy" rod is elastic

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Glycosaminoglycans

Hyaluronic acid is the largest and most common GAG. Binds water, and are thus important for diffusion. Important for giving pressure withstanding properties to tissue.

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Proteoglycans

Create protein core to which GAGs actually attach.

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Multiadhesive glycoproteins

Globular proteins to which branches or chains of monosaccharides are covalently attached.

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Multiadhesive glycoproteins

Globular proteins to which branches or chains of monosaccharides are covalently attached. Serve as a glue, helps cells attach to ECM (lymphocytes hanging on to Reticular fibers in lymphatic system).

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Mesenchyme

Loosely organized embryonic connective tissue. All cells are mesenchymal stem cells. Undifferentiated that could be elongated, fusiform, prominant nucleus and fine chromatin. High ratio of nuclear cytoplasmic volume (mostly nucleus), viscous round substance outside of cells. Occasionally reticular fibers show up. Mainly ground substance and cells.

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Fusiform

Cells - wide at center, thin at edges

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Umbilical cord

2 umbilical arteries (deoxygenated blood), 1 umbilical vein (oxygenated blood), everything filling in the space between arteries is wharton's jelly.

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Areolar connective tissue

Adult connective tissue type. Connective tissue proper. Most widely distributed connective tissue in body. Lots of fibroblasts, fibers loosely oriented. All 3 fibers present, in random arrangement (reticular needs silver stain). Amount of ground substance = fibers = cells. Supports body structures under a bit of pressure and friction (but not a whole lot). Well vascularized and flexible. Universal packing material of the body.

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Lamina propria

Loose connective tissue associated with mucous membranes

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Loose connective tissue collagen

Type 1

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Reticular connective tissue

Made up of reticular fibers (type 3 collagen fibers). These cells produce a stroma (network/lattice) that other cells can attach to. In lymph, bone marrow, spleen. Looks like a cherry blossom tree.

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Stroma

Network of reticular connective tissue.

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Dense connective tissue

Less flexible more resiliant than loose connective tissue. Offers resistance and protection. Far fewer cells, predominately collagen fibers (type 1 mostly). Regular and irregular.

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Dense regular connective tissue

Fibers run in same direction, run parallel to direction of force on tissue. Cells sit in rows. When no tension is present, it is a little wavy. When tension is present, waves disappear. Poorly vascularized, long time to heal.

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Dense Irregular connective tissue

Collagen fibers mostly, fibers run in odd directions - irregularly arranged. Important in locations where pulling forces are coming in from all directions (dermis of skin, fibrous capsules of organs/joints, etc.)

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Fascia

Act to hold in muscle, dense regular connective tissue.

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Ligaments

Bone to bone - dense regular. Ligaments have a bit more elastic fibers than tendons.

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Unilocular

Fat tissue - one large fat droplet within each cell. During processing, organic solvents will break (mostly) triglyceride (not-membrane bound) droplet out. Special fixation required to maintain lipid droplet in cell.

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Adipose cell size

15-150 microm in diameter.

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Hypertrophy

Gain of weight, cells increase in size.

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Yellow bone marrow

Adipose tissue - as you age, red bone marrow is replaced with this.

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Fat tissue have a lot of -------- for energy transfer

Blood vessels. Lot of different things cause this.

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Multilocular

Fat stored in many droplets, not just one. Brown fat is like this. Nucleus is now rounded, not flat up against the side. Usually in center of cell, cells are much smaller. 10-15 microm in diameter. Droplets are membrane bound.

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Brown fat locations

Infant/child until age 10. In hibernating animals, occasionally in adults. Needed for kids because there is a high surface to mass ratio. This gives us a lot of surface area and thus a lot of heat loss. This fat is for thermogenesis (heat production). When lipids are mobilized/broken down by adipocytes, heat is generated which warms nearby blood. Have a special uncoupling mitochondria protein that makes mito release energy as heat, not produce ATP. Release under control of sympathetic nervous system.