HISTOLOGY
Samenvatting college 3 (Connective Tissue) (Chapter 4; 4.4 – 4.7 + Chapter 6;
6.3 – 6.6)
4.4 Connective tissue has varied roles in the body that reflect the physical
properties of its three main types
Connective tissue connects epithelium to the rest of the body.
Reticular lamina layer of basement membrane of all epithelial tissues is made up of
connective tissue components.
Three basic components of connective tissue;
1. Specialized cells
2. Extracellular protein fibers
3. Ground substance; glycoproteins. These interact with each other, with fibers
and with cells (of connective tissue, eptihelia etc.)
Matrix; extracellular protein fibers + ground substance. Matrix around the cells,
accounts for the volume.
Many connective tissues high vascular (many blood vessels) and contain sensory
receptors
Connective tissues functional classification
- Supportive connective tissue
- Metabolic connective tissue
o Supply of oxygen, nutrients
o Drain of carbon dioxide, metabolites
o Storage of energy (fat)
o Immunological defense; immune system
Specific functions of connective tissues;
- Establishing (oprichten) a structural framework for the body
- Transporting fluids and dissolved materials (opgeloste materialen)
- Protecting delicate (gevoelig) organs
- Supporting, surrounding and interconnecting other types of tissue
- Storing energy, especially in the form of triglycerides
- Defending (verdedigen) the body from invading microorganisms
Three categories of connective tissues;
- Connective tissue proper; contains varied cell populations and extracellular
protein fiber types surrounded by a syrupy (stroperig) ground substance. 2
groups, the grouping is based on the number of cell types present and the
relative properties (eigenschappen) and proportions (verhoudingen)of fibers
and ground substance
o Loos (los) connective tissues; adipose tissue (fat)
o Dense (dicht) connective tissues; tendons (pezen)
- Fluid connective tissues; distinctive (kenmerkend) population of cells
suspended in watery matrix contains dissolved (opgeloste) proteins.
o Blood
o Lymph
, - Supporting connective tissues; less diverse cell population and a dense matrix
with closely packed fibers. They protect soft tissues.
o Cartilage (kraakbeen)
o Bone (botten)
4.5 Connective tissue proper includes loose connective tissues that fill internal
spaces and dense connective tissues that contribute to the internal framework
of the body
Structure of connective tissue proper
- Cell population; resident cells
Cells function in local maintenance,
repair and energy storage; fibroblasts,
fibrocytes, adipocytes and
mesenchymal. permanent in tissue
Cells function in defend (verdedigen)
and repair; macrophages, mast cells,
lymphocytes, plasma cells and
microphages not permanent in tissue,
more flexible
--Blast (germ) produce matrix
--Cyte (cell) maintain matrix
--clast (break) break down for
remodeling
o Fibroblasts; are always present in connective tissue (embryo). They
produce fibers and ground substance in matrix.
o Fibrocytes; they maintain the matrix.
o Adipocytes (fat cells); nucleus, organelles and cytoplasm squeezed to
one site.
o Mesenchymal cells; stem cells, respond to local injury or infection.
o Melanocyte; synthesize and store the brown pigment melanin. They are
common in epithelium of the skin. They are also in connective tissues of
the eye and the dermis (lederhuid onder de opperhuid) of the skin
o Macrophage; large white blood cell that move around and ingest
(inslikken) foreign substances in connective tissue
Fixed macrophages; spend long period in a tissue
Free macrophages; migrate rapidly through tissues
o Mast cells; Cytoplasm is filled with granules containing histamine and
heparin. Histamine released after injury or infection, stimulates local
inflammation (onsteking). They are vasodilating (vaatverwijderende)
factors
o Lymphocytes; increase when tissues damage occurs. Lymphocytes
develop into plasma cells which produce antibodies
o Microphages; attracted to infection or injury by chemicals released by
macrophages and mast cells
- Extracellular protein fibers
o Collagen fibers; Most common, long, straight and unbranched
(onvertakt)
Type I; in tendons and in bone
Type II; thin fibers in cartilage