Connective tissue (Martini Chpt 4 (4-4 to 4-7), Chpt 6 (6-3 to 6-6))
Able to recognize and name different types of connective tissue
Able to explain the relation between shape and function of different types of connective tissue
Able to explain how different types of connective tissue develop and grow
Able to name the characteristics and functions of different types of connective tissue and
extracellular matrix
Connective tissue connects the epithelium to the rest of the body, other connective tissue includes; bone,
fat, and blood.
Connective tissue vary widely in appearance and function, but three basic components:
1. Specialized cells
2. Extracellular protein fibers
3. Fluid; ground substance
Extracellular fibers + ground substance = matrix. The matrix surround the cells. The matrix account for
most of the volume of connective tissue (in epithelial tissue this is not the case, there the cells make up the
bulk of the tissue). So cells are separated by extracellular matrix. The embryonal precursor tissue:
mesenchyme.
Connective tissue types
Loose (fat) and dense (tendons) connective tissue (proper)
Cartilage and bone (supportive connective tissue)
Blood and lymph (fluid connective tissue; distinctive
populations of cells suspended in watery matrix that
contains proteins)
Endothelium and mesothelium
Extracellular matrix of these connective tissues is very different.
Functional classification
- Supportive connective tissue
- Metabolic connective tissue
Supply of oxygen, nutrients; drain of carbon dioxide, metabolites; storage of energy, fat;
immunological defense, immune system.
Cells of the connective tissue =
- Resident cells
Undifferentiated mesenchymal cell (stem cells, present in many connective tissues) ->
Permanent residents of Function in local maintenance, repair, and energy storage
the connective tissue
Chondroblast ->
chondrocytes
Adipocyte Fat cells. Contains a single enormous lipid droplet. Nucleus and other organelles are
squeezed to the site.
Fibroblast Only cells that are always present in connective tissue proper -> loose and dense
connective tissue. Secrete hyaluronan and proteins.
Fibrocytes -> spindle-shaped cells that maintain the connective tissue fibers of dense and
loose connective tissue.
Mesothelial cell
Endothelial cell
Osteoblast -> osteocyte
Mast cells Vasodilating factors (histamines) first circulate in the blood in an immature form before
they migrate to other vascularized tissues and undergo maturation. Cytoplasm is filled
with histamine (stimulates inflammation after injury or infection) and heparin.
macrophages Skin (cells of Langerhans), liver (Kupffer), lung (dust cells), brain (microglia): immune
system. Fixed macrophages, spend long periods in a tissue you also have free ones,
, which migrate through tissues.
- Wandering cells (discuss later)
Loose connective tissue: packing materials of the body. They fill spaces between organs, cushion and
stabilize specialized cells in many organs, and support epithelia. Store lipids, provide a route for diffusion of
materials. Includes mucous connective tissue in embryos, areolar tissue, adipose tissue and reticular
tissue in adults.
Dense connective tissue: fibroblasts, matrix (ground substance and fibers). Ground substance –
glycoproteins; macromolecules interact with each other, with fibers and with cells (of connective tissue,
epithelia, ect.). Ground substance fills the spaces between cells and surrounds connective tissue fibers.
The ground substance is viscous (bacteria have trouble moving through it, this viscosity slows the spread of
pathogens and makes them easier for phagocytes to catch.
Dense connective tissue: collagenous tissues, because collagen fibers are the dominant type of fiber in
them. Dense regular connective tissue, dense irregular and elastic tissue is specialized type of dense
regular tissue.
Three types of fibers
Collagen fibers Most common fibers in connective tissue. Are long, straight
and unbranched. Each collagen fiber consists of a bundle of
fibrous proteins. Fiber if flexible and really strong.
Tendons (connect skeletal muscle to bones, consists entirely
of collagen fibers. Ligaments connect one bone to another
bone. Both can withstand tremendous forces. Glue, need
vitamine C -> scurvy.
15 different types of collagen fibers:
Type I: in tendons, and in bone
Type II: thin fibers in cartilage
Type III: thin fibers in reticular connective tissue
Type IV: basal lamina
Synthesis collagen: in RER and Golgi, secreted via a
constitutive route. Self-assembly of tropocollagen into
collagen fibers in the extracellular matrix.
Collagen composition of tendons
Reticular fibers Meshwork of fibers. Predominantly in basal membranes and around organs. Contain the
same protein subunits as do collagen fibers, but they are arranged differently. Thinner than
Able to recognize and name different types of connective tissue
Able to explain the relation between shape and function of different types of connective tissue
Able to explain how different types of connective tissue develop and grow
Able to name the characteristics and functions of different types of connective tissue and
extracellular matrix
Connective tissue connects the epithelium to the rest of the body, other connective tissue includes; bone,
fat, and blood.
Connective tissue vary widely in appearance and function, but three basic components:
1. Specialized cells
2. Extracellular protein fibers
3. Fluid; ground substance
Extracellular fibers + ground substance = matrix. The matrix surround the cells. The matrix account for
most of the volume of connective tissue (in epithelial tissue this is not the case, there the cells make up the
bulk of the tissue). So cells are separated by extracellular matrix. The embryonal precursor tissue:
mesenchyme.
Connective tissue types
Loose (fat) and dense (tendons) connective tissue (proper)
Cartilage and bone (supportive connective tissue)
Blood and lymph (fluid connective tissue; distinctive
populations of cells suspended in watery matrix that
contains proteins)
Endothelium and mesothelium
Extracellular matrix of these connective tissues is very different.
Functional classification
- Supportive connective tissue
- Metabolic connective tissue
Supply of oxygen, nutrients; drain of carbon dioxide, metabolites; storage of energy, fat;
immunological defense, immune system.
Cells of the connective tissue =
- Resident cells
Undifferentiated mesenchymal cell (stem cells, present in many connective tissues) ->
Permanent residents of Function in local maintenance, repair, and energy storage
the connective tissue
Chondroblast ->
chondrocytes
Adipocyte Fat cells. Contains a single enormous lipid droplet. Nucleus and other organelles are
squeezed to the site.
Fibroblast Only cells that are always present in connective tissue proper -> loose and dense
connective tissue. Secrete hyaluronan and proteins.
Fibrocytes -> spindle-shaped cells that maintain the connective tissue fibers of dense and
loose connective tissue.
Mesothelial cell
Endothelial cell
Osteoblast -> osteocyte
Mast cells Vasodilating factors (histamines) first circulate in the blood in an immature form before
they migrate to other vascularized tissues and undergo maturation. Cytoplasm is filled
with histamine (stimulates inflammation after injury or infection) and heparin.
macrophages Skin (cells of Langerhans), liver (Kupffer), lung (dust cells), brain (microglia): immune
system. Fixed macrophages, spend long periods in a tissue you also have free ones,
, which migrate through tissues.
- Wandering cells (discuss later)
Loose connective tissue: packing materials of the body. They fill spaces between organs, cushion and
stabilize specialized cells in many organs, and support epithelia. Store lipids, provide a route for diffusion of
materials. Includes mucous connective tissue in embryos, areolar tissue, adipose tissue and reticular
tissue in adults.
Dense connective tissue: fibroblasts, matrix (ground substance and fibers). Ground substance –
glycoproteins; macromolecules interact with each other, with fibers and with cells (of connective tissue,
epithelia, ect.). Ground substance fills the spaces between cells and surrounds connective tissue fibers.
The ground substance is viscous (bacteria have trouble moving through it, this viscosity slows the spread of
pathogens and makes them easier for phagocytes to catch.
Dense connective tissue: collagenous tissues, because collagen fibers are the dominant type of fiber in
them. Dense regular connective tissue, dense irregular and elastic tissue is specialized type of dense
regular tissue.
Three types of fibers
Collagen fibers Most common fibers in connective tissue. Are long, straight
and unbranched. Each collagen fiber consists of a bundle of
fibrous proteins. Fiber if flexible and really strong.
Tendons (connect skeletal muscle to bones, consists entirely
of collagen fibers. Ligaments connect one bone to another
bone. Both can withstand tremendous forces. Glue, need
vitamine C -> scurvy.
15 different types of collagen fibers:
Type I: in tendons, and in bone
Type II: thin fibers in cartilage
Type III: thin fibers in reticular connective tissue
Type IV: basal lamina
Synthesis collagen: in RER and Golgi, secreted via a
constitutive route. Self-assembly of tropocollagen into
collagen fibers in the extracellular matrix.
Collagen composition of tendons
Reticular fibers Meshwork of fibers. Predominantly in basal membranes and around organs. Contain the
same protein subunits as do collagen fibers, but they are arranged differently. Thinner than
