Ch. 4-4 Connective Tissue Flashcards
What three components does all connective tissue share?
- Specialized cells
- extracellular protein fibers
- Ground substance
What is ground substance?
A fluid that fills the space between cells and surrounds connective tissue fibers.
In CTP, it is clear, colorless, and viscous
Classification of Connective Tissues (3)
- Connective tissue proper 2. Fluid connective tissue 3. Supporting connective tissue
Connective tissue proper
Broad category: divided into ‘loose’ and ‘dense’ connective tissue based on # of cell types present, proportion of fibers and ground substance Ex: Loose connective: adipose Dense connective: tendons
Fluid Connective Tissue
Distinctive populations of cells suspended in a watery matrix that contains dissolved proteins
Two types: Blood and lymph
Supporting connective tissue
Less diverse cell population and a matrix of more densely packed fibers. Types: cartilage and bone
Fibroblasts
- Secrete hyaluronan & proteins 2. Secrete protein subunits that assemble to form large extracellular fibers 3. Contribute to ground substance to make it viscous 4. One of two most abundant cells in connective tissue proper; only cells always present.
Three components of connective tissue
- Specialized cells 2. Extra cellular protein fibers 3. Ground substance 2+3 = matrix surrounding cells; accounts for most of the volume of connective tissue
Fibrocytes
Second most abundant fixed cell in CT Proper. Differentiate from fibroblasts. Maintain the connective tissue fibers of CTP.
Mesenchymal cells
Stem cells that respond to local injury or infection by dividing into daughter cells that differentiate as needed
Mast cells
Cytoplasm filled with histamine and heparin
Microphages
Neutrophils and eosinophils. Phagocytic blood cells, present in CTP in small numbers
Melanocytes
Synthesize and store melanin. Present in connective tissue of eye & dermis of skin
Connective tissue fibers (3)
- Collagen fibers 2. Reticular fibers 3. Elastic fibers
Collagen fibers
Long, straight, and unbranched. Most common fiber in CTP. Flexible, but stronger than steel when pulled from either end. Ex: Tendons (skeletal muscle to bone) Ligaments (connect bone to bone)
Reticular fibers
‘reticulum’ = network 1. Form a branching, interwoven network (STROMA) that is tough and flexible. 2. Composed of same protein subunits as collagen fibers, but arranged differently. Thinner than collagen fibers. 3. The stroma stabilizes A.) the relative positions of parenchyma cells in organs and B.) positions of organ blood vessels, nerves, etc.
Elastic Fibers
Contains the protein elastin. Branched and wavy; return to original length after stretching. Elastic ligaments: rare, dominates by elastic fibers. Ex: interconnecting vertebrae.
Ground Substance
Fills space between cells and surrounds connective tissue fibers. Viscous due to proteogylcans and glycoproteins
Embryonic Connective Tissue (Mesenchyme)
- Mesenchymal cells 2. Mucous connective tissue (Wharton’s Jelly)
Loose Connective Tissues
- Areolar 2. Adipose 3. Reticular 4. Mesenchyme (embryos)
Areolar tissue
A loose connective tissue. Least specialized connective tissue in adults. Open framework with loose structure. Absorbs shocks, distort without damage. Elastic fibers makes it resilient. Separate skin from deeper structures; has extensive blood supply that diffuses oxygen, etc. to epithelial layer. Proportion of adipocytes distinguishes from adipose tissue.
Reticular tissue
Composed of reticular fibers to form a stroma complex. Fibrous framework in organs, lymph nodes, and bone marrow.
Dense Connective Tissue (collagenous tissues)
A type of connective tissue proper distinguished by cell types present and relative proportion/properties of fibers.
Most of the volume is fibrous; collagen fibers are dominant.
What are the two types of dense connective tissue?
- Dense regular connective tissue
- Dense irregular connective tissue
Characteristics and examples of dense irregular connective tissue
Fibers form an interwoven network with no consistent pattern. Strengthen and support areas that resist stress from many directions,
Ex:
- Layer in skin to provide strength (leather)
- sheaths around bone, i.e perichondrium, periosteum.
- ‘Capsule’ around internal organs
- Encloses cavities of joints
Characteristics and examples of dense regular connective tissue
Collagen fibers are parallel and packed tightly to align with forces applied to the tissue.
Ex: Ligaments, Tendons
Tendons
Cords of dense regular connective tissue that attach skeletal muscle to bone. Collagen fibers run along longitudinal axis to transfer pull of contracting muscle to bone
Ligaments
Connect bone to bone and stabilze the positions of internal organs.
aponeurosis
a tendonous sheet that attaches a broad flat muscle to another muscle or to several bones of the skeleton. Can also stabilize positions of tendons and ligaments.
Associated with large msucles of the skull, lower back, and abdomen; with palmar and tendons/ligaments
perichondrium
dense irregular connective tissue; forms a sheath around cartilage
periosteum
dense irregular connective tissue; froms a sheath around bone
capsule
dense irregular connective tissue; a thick fibrous layer that surrounds internal organs like hte liver, kidneys, spleen, and encloses the cavities of joints
Elastic Fibers
When elastic FIBERS outnumber collagen FIBERS, tissue has spring, resilient nature that allows it to tolerate cycles of extension and recoil. Elastic FIBERS are present in connective tissue that supports transitional epithelia, large blood vessels (aorta), and respiratory passageways.
Elastic TISSUE
dense regular connective TISSUE dominated by elastic FIBERS. Elastic ligaments help stabilize vertebrae.
Formed elements
Components of plasma, the watery matrix in blood. More specifically, blood cells and fragments of cells.
Three types:
- Red Blood Cells
- White Blood Cells
- Platelets
What are the major subdivisions of extracellular fluid?
- Plasma
- Interstitial fluid
- Lymph
Lymph
Forms as interstital fluid enters lymphatic vessels. Composition similar to blood, but contains more lymphocytes
Recirculation of body fluid
From cardovascular system, throguh interstitial fluid, to the lymph, back to cardivascular system
