Connective Tissue Flashcards
Connective Tissue
found throughout the body, although never exposed to external environment & most is highly vascular
basic components:
1. specialized cells
2. extracellular fibers
3. ground substance
2+3 = ECM
ECM dominates tissue and determines characteristics, consistency varies
Function of CT
all CT derive from embryonic mesenchyme
- supports, surrounds, & interconnects tissue
- provides structural framework for the body
- transports fluids
- provides protection
- stores energy
- defends body from invasion by microorganisms
Connective Tissue Proper
composed of specialized cells & ECM
Fixed cells:
- differentiate from mesenchymal cells
- formed and reside in CT
- involved with local maintenence, repair, & energy storage
Wandering Cells:
- arise from hematopoietic stem cells & differentiate in bone marrow
- migrate into CT
- increase in number with tissue damage or infections
Fibroblasts
abundant and always present
spindle shaped cells
fn - produce all CT fibers & ground substance
fixed
Adipocytes
lipid storing cells
fixed
Plasma Cells
derive from B lymphocytes, egg shaped, eccentric, small nucleus
fn - antibody producing cells
halo around nucleus
wandering
clockface
Macrophages
derive from monocytes, mature in tissue spaces
relatively small & inconspicuous unless they have been active in phagocytosis
irregular cell surface
highly phagocytic cells; function in ECM turnover, phagocytosis of dead cells, & antigen presentation
wandering
Mast Cells
oval, irregular shaped cells with central nucleus, filled with basophilic granules
numerous near small blood vessels in skin, mesenteries, & tissue lining digestive, & respiratory tract
fn - localized release of bioactive substances important in local inflammatory response, innate immunity, & tissue repair
become sensitized to specific antigens when antibodies made against that antigen become bound to receptors on the mast cell membrane
- work with plasma cells
wandering
Leukocytes
derived from circulating blood cells, but migrate into CT when functional
increase in number in CT is indicative of inflammation
neutrophil
eosinophil
basophil
wandering
Extracellular Fibers
Collagen fibers - resist tension, most predominant
Elastic fibers - stretch and recoil
Collagen
strong protein, resistant to shearing forces
formed by 3 𝛼 chain subunits
type I: most common; skin, tendon, bone
type II: cartilage
type III: blood vessels & reticular fibers
type IV: forms meshwork in basement membrane
Type I Collagen
striated
thick wavy
Type III Collagen (Reticular Fibers)
forms the stroma of highly cellular organs on which they arrange their parenchyma
silver stain
Elastic Fibers
sparse networks interspersed with collagen bundles
composed of elastin embedded in microfibrils composed of fibrilin
Ground Substance
fn - resists compression allows passage of molecules between plasma & interstitial fluid, & anchors cells within tissues
composed of interstitial fluid + GAGs + proteoglycans + adhesive glycoproteins
Glycosaminoglycans (GAGs)
unbranched carbohydrate chains, most linked to a core protein
hydrophilic
Hyaluronic Acid (GAG)
unbranched, long, & large linear carbohydrate chain; negatively charged & hydrophilic
Proteoglycan
composed of GAGs attached to a core protein; responsible for gelatinous consistency of ECM
Adhesive glycoproteins
small proteins; stabilize & link ECM to cell surfaces
Interstitial Fluid Derived from Blood Plasma
Ph pushes fluid out of blood vessels (hydrostatic pressure)
Po pulls fluid into blood vessels (oncotic pressure)
Ph > Po = fluid moves into CT
Po > Ph = fluid moves into blood vessel
exces interstitial fluid enters lymphatic vessels and becomes lymph
Loose (Areolar) CT
fn - provides support but allows independent movement of cells; most cells are wandering cells that migrate from blood vessels in response to specific stimuli
several types of cells, few fibers arranged randomly & embedded in semifluid ground substance
Dense Regular
Consists mainly of type I collagen arranged in parallel arrayes with fibroblasts squished between
location - tendons and ligaments
fn - strong attachment between structures; withstands tension along the long axis of fibers
Dense Irregular CT
tightly packed, woven collagen type I fibers irregularly arrange
location - fasciae, dermis of skin, pericardium of heart, joint capsules, membrane capsules of various organs
fn - tensive strength in many directions
Elastic CT
predominately elastic fibers with fibroblasts in spaces between
location - lung tissue, walls of elastic arteries, trachea, some ligaments between vertebrae
fn - provides support & allows for stretching, accomodates pressure changes on the walls of arteries closest to heart
Reticular Tissue
fine interlacing network of reticular fibers (type III) & reticular cells
location - stroma of liver, spleen, lymph nodes, red bone marrow, pancrease
fn - forms stroma or organs; binds together smooth muscle tissue cells & removes blood cells in spleen & microbes in lymph nodes
Adipose Tissue
consists of specialized fat storing cells called adipocytes
location - found with loose CT
fn - reduces heat loss through skin, serves as an energy reserve, support, and protects
