Post on 24-Dec-2015
IntroductionDEFINITION
It is one of the four general classes of animal tissues- as well as epithelial, muscle and nervous tissues.
Is a kind of animal tissue that connects, supports, binds, or separates other tissues or organs of the body.
It is the most diverse tissue and is found throughout the body
Unlike epithelial tissue, connective tissue has relatively little intimate contact between the cells that make up part of its structure
Function:
1. Storage of energy
2. Protection of organs
3. Provision of structural framework for the
body
4. Connection of body tissues
5. Connection of epithelial tissues to muscle
fiber.
6. Transportation of fluids and dissolved
substances
7. Defend the body against microorganisms
8. Repair of body tissue
Structurally, connective tissue is made up of cells and extracellular matrix. The extracellular matrix is made up of protein fibers in and polysaccharide matrix, secreted and organized by cells in the extracellular matrix. Variations in the composition of the extracellular matrix, determines the properties of the connective tissue. For example, if the matrix is calcified, it can form bone or teeth.
Structure of Connective tissue
Cells are spread through an extracellular fluid.Ground substance - A clear, colorless, and viscous fluid containing glycosaminoglycans and proteoglycans to fix the body water and the collagen fibers in the intercellular spaces, fills the space between the cells and contains the fibers.Ground substance slows the spread of pathogens.Fibers. Not all types of CT are fibrous. Examples of non-fibrous CT include adipose tissue and blood.
Characteristics of Connective tissue
CELLS OF CONNECTIVE TISSUE
A variety of cells with different origins
and functions are present in connective
tissue
1) Fibroblasts
2) mast cells
3) macrophages
4) plasma cells
5) Adiposities cells
Macrophage
Fibroblast
Lymphocyte
Fat cell
Mast cell
Neutrophil
Capillary
Cell types Extracellularmatrix
Fibers• Collagen fiber• Elastic fiber• Reticular fiber
Ground substance
CELLS OF CONNECTIVE TISSUEOrigin of cells :
Fibroblasts originate from : undifferentiated mesenchymal cells spend all their life in connective tissuemast cells, macrophages, and plasma cells
originate from: hematopoietic stem cells in bone marrow These are all types of Immune cell. circulate in the blood, and then move into
connective tissue where they remain and execute their functions.
1.Fibroblasts They are mainly responsible for secreting the
non-rigid extracellular matrix including the fibers collagen, elastin or fibronectin.
Two stages of activity:o active fibroblastso inactive fibroblasts.
Cells with synthetic activity are morphologically distinct from inactive fibroblasts that are scattered within the matrix they have already synthesized.
CELLS OF CONNECTIVE TISSUE
Active fibroblast Large, euchromatic, oval nucleus
Cytoplasm not usually visible but contains
abundant rough endoplasmic reticulum and
Golgi apparatus
Elongated, spindle-shaped cells
High synthetic activity
CELLS OF CONNECTIVE TISSUE
Inactive fibroblast
Small, heterochromatic, flattened
nucleus.
Reduced cytoplasm and organelles.
Low synthetic activity.
CELLS OF CONNECTIVE TISSUE
2.Macrophages Derived from blood monocytes Are large cells with more cytoplasm than
lymphocytes or plasma cells. They have no granules and function to ingest
other cells and bacteria by phagocytosis, antigen processing, and cytokine secretion.
Enter connective tissue from the bloodstream and rapidly transform into macrophages
CELLS OF CONNECTIVE TISSUE
3.Mast cells releasing immune modulators from
cytoplasmic granules, in response to
antigen binding with cell surface antibodies.
Mast cells secrete histamine, heparin and
other factors.
They are important in the uptake of fatty
acids from the blood into fat cells.
CELLS OF CONNECTIVE TISSUE
4.Plasma cellsSecrete antibodies to provide humeral
immunity
Derived from B-lymphocytes take up
residence in lymph nodes, bone marrow, and
loose connective tissue where they synthesize
and secrete specific antibodies.
CELLS OF CONNECTIVE TISSUE
5. Adipose cells
Adipocytes are connective tissue cells that
have become specialized for storage of neutral
fats or for the production of heat.
CELLS OF CONNECTIVE TISSUE
Collagen is the most common protein found in the human body. It is found in almost all organs and body parts. In general, collagen winds itself into a fiber mesh that adds structural stability to that specific body part.It is commonly associated with skin integrity, but is critical for proper function of many other body parts, too.At least 12 types of collagen exist, four of which are commonly found in different body parts. Type I collagen is the most abundant type
collagen fiber
composed of type III collagen secreted by reticular cells.Reticular fibers crosslink to form a fine meshwork (reticulin). This network acts as a supporting mesh in soft tissues such as liver, bone marrow, and the tissues and organs of the lymphatic system.
Reticular fiber
Elastic fiber
are bundles of proteins (elastin) found in extracellular matrix of connective tissue produced by fibroblasts and smooth muscle cells in arteries. These fibers can stretch up to 1.5 times their length, and snap back to their original length when relaxed.Elastic fibers include elastin, elaunin and oxytalan.
EXTRACELLULAR MATRIX
3. Ground substances
It is a jelly like substance having proteins and
sugars, in bone the ground substance
include minerals and in blood the ground
substance is the plasma