Lecture three
By Dr. Alaa Al-sahlany
Connective tissue
Is one of the basic tissues which gives structural and metabolic support to other
tissues and organs of the body.
Classification
(1)Connective tissue proper
(a)Loose connective tissue: a cellular (has many cells) with sparse and thin collagen
fibers
(b)Dense connective tissue e.g. tendon, ligaments, dermis : contains mostly
collagen fibers with fewer cells.
(2)Specialized connective tissue
(a)Adipose tissue(we already talked about)
(b)Cartilage
(c)Bone
(d)Hemopoietic tissue
(e)Lymphatic tissue
Connective tissue is made of:
(1)Cells
(2)Extracellular matrix(ECM) which includes:
(a) fibers
(b) ground substance
Cells
(a)Resident cells
1. Fibroblasts and fibrocytes
2. Undifferentiated mesenchymal cells
3. Fat cells (adipocytes)
4.Macrophages
5.Mast cells
(b)Transient cell: consists primarily of cells that have migrated into the tissue from
the blood in response to specific stimuli
1.Lymphocytes
2.Plasma cells
3.Neutrophils
4.Eosinophils Granulocytes
5.Basophils
6.Monocytes.
Extracellular matrix
(a)Fibers: include
1. Collagen: the most abundant
2. Elastic
3. Reticular
(b)Ground substance :occupy the space between cells and fiber. Include:
1.Glycosaminoglycans (most abundant) e.g. hyaluronic acid: are responsible for the
physical properties of ground substance
2.Proteoglycan
3.Glycoproteins
Cells
Fibers
Types of collagen
Type I – found in bones and skin
Type II – found in cartilage
Type III – found in skin
Type IV – found in basement membranes
Ascorbic acid (vitamin C)
Is a required cofactor for the hydroxylation of proline and lysine residues in chains
of collagen
Hydroxylation enhance the stability of collagen
