Lecture 3 - connective tissue Flashcards
Types of connective tissue proper
Loose and dense.
Types of dense CT
regular (ligaments and tendons) and irregular (dermis)
Two origins of CT
hematopoietic stem cells and undifferentiated mesenchymal cells
Fibroblast, chondroblast, osteoblast, and odontoblast
Production of fibers and ground substance
Lymphocyte
Production of immunocompetent cells (T cells)
Eosinophilic leukocyte
participation in allergic and vasoactive reactions, modulation of mast cell activities and the inflammation response
Neutrophilic leukocyte
phagocytosis of foreign substances
Macrophage
secretion of cytokines, phagocytosisof foreign substances, antigen processing and presentation to other cells. Derived from monocytes
Mast cell and basophilic leukocyte
inflammatory response. Driven by IgE, antigens, and calcium.
adipose cell
storage of neutral fats
Components of CT
Cellular and extracellular matrix
Extracellular matrix components
Amorphorus (ground substance) and fibrous (has a distinct structure)
Cellular components
fibroblasts, adipose cells, macrophages, mast cells, leukocytes, and plasma cells
Fibroblasts
excrete a lot of extracellular material. structural role in sticking things together
Unilocular vs Multilocular adipose cells
Unilocular - only one lipid droplet
Multilocular - multiple lipids droplets within a cell. Known as brown fat. Lots of mitochondria
Plasma cells
derived from B lymphocytes. Off center nucleus and cartwheel arrangement of heterochromatin. Abundant RER for production of antibodies
What do Mast cells release?
Heparin, Histamine, ECF-A, and proteoglycans
Amorphous components
glycosaminoglycans, proteoglycans, and glycoproteins
Glycosaminoglycans
disaccharide linked in a linear long chair, unbranched. Consists of only sugars. Hyaluronic acid is an example
Proteoglycans
Proteins and glycans attached.
Glycoproteins
proteins with some disaccharides that are branched. Mostly proteins with little sugar.
Integrins
protein dimers that pass through the cell membrane and are linked to intracellular matrix components.
Types of Fibrous material
collagen fibers, reticular fibers (type III collagen), and elastic fibers
4 main functions of collagen
adhesion, skeletal, protective, and messenger
Collagen synthesis’ cofactor
Vitamin C
Scurvy
lack of vitamin C leads to defective collagen synthesis and weakened CT
Most common stain for elastic fibers
Orcein
Reticular fibers
Type III collagen. Found in lymphoid organs and tissues (spleen and thymus). Stain with silver. Much smaller than collagen fibers
Cartilage characteristics
More amorphous than fibrous. Rich in proteoglycans. Presence declines from fetus to adult
Cellular components of Cartilage
periochondrial fibroblasts, chondroblasts, chondrocytes, and chondroclasts (osteoblasts)
Extracellular matrix of cartilage
Most amorphous (GAGs, proteoglycans, and glycoproteins) and less prominent fibrous
Type II collagen
hyaline cartilage, elastic cartilage
Type I collagen
fibrocartilage
Chondrocytes
mature cartilage that has a territorial matrix around it.
Chondroclasts
reabsorb calcium and very rare. Related to osteoclasts. Derived from monocytes.
Papain
hydrolyzes proteoglycans (bunny ear example)
Is cartilage vascular?
No. There is no blood supply, diffusion takes place and is rate limiting, thus it is difficult to regenerate.
Periochondrium
essential for appositional growth, provides nutrients, and sox transcription factors induce differentiation into chrondroblasts
3 areas with no periochondrium
epiphyseal growth plate, fibrocartilage (invertebrate discs), and articular cartilage (joints)
Types of cartilage growth
appositional growth and interstitial growth
Appositional growth
occurs by differentiation of perichondrial fibroblasts into chondroblasts and chondrocytes
Interstitial growth
occurs by mitosis of existing chrondroblasts and chondrocytes (restricted to areas with no periochondrium)
Isogenic groups
multiplication of chondrocytes which are surrounded by a condensation of territorial matrix (interstitial growth)
Staining for articular cartilage and epiphyseal growth plate
Safranin O which stains for proteoglycans
Osteoarthritis
damage of cartilage coming off of the bone (covering articular surfaces)
Rheumatoid arthritis
swelling of membranes which puts pressure on the joints
Hyaline Cartilage
Type II collagen. Perichondrium present in most places (except articular cartilage). articular ends of long bones, nose, larynx, trachae, bronchi, ventral ends of ribs. Avascular
Elastic cartilage
Type II collegen, but with elastic fibers. Perichondrium present. Ear - lots of vibration or movement. Avascular
Fibrocartilage
Type I collagen. seen in parallel rows. Interstitial growth and no perichondrium. Intervertebral discs. Generally avascular.
