3. 2-The connective tissues
The connective tissue ,connects ,holds and supports body tissues and organs together.
Connective Tissue is mesodermal in origin .
It is characterized by the presence of several types of cells separated and immersed in an abundant intercellular formed by these cells.
Function:
Structural function ( tendon) .
Defensive function (phagocytic cells-plasma cells).
Neutritional functions due to its rich content of blood vessels and abundant matrix and tissue fluid .

4. Connective tissue composed of 3- Cells
1- Matrix
(may be solid (as in bone), soft (as in loose connective tissue), or liquid (as in blood).
2- Fibers:
A- Collagenous fibers (white) (protein=collagen) (flexible-bundles- unbranched )
B- elastic fibers (protein=elastin) ( elastic single-branched)
C- reticular fibers. (protein =reticulin)
3- Cells
fibroblast and fibrocytes- plasma cell –adipocytes-mast cell

5. Types of connective tissues:
1--Connective tissue proper:
A-Loose connective tissue .
B-Adipose connective tissue .
C-Dense fibrous connective tissue .
2-Specialized connective tissue:
A-cartilage (perichondrium- chondroblast and chondrocytes- matrix)
B-bone (periosteum-osteoblasts-osteocytes)-ossien(calcium phosphates –calcium carbonate)
C-Blood (red blood cells-white blood cell-plateletes )and lymph

6. 1- Connective tissue proper
A-Loose Connective tissue
- Loose connective tissue has all three fiber types(collagen-elastic –reticular).
Flexible-richly vascular -support epithelial T.
It composes of different cell types:
1-fibroblast (secretes matrix & fibers)
2-Macrophage (defense by phagocytosis)
3- adipocyte (storage fat as a source of energy)

7. B-Adipose connective tissue
It is a type of connective tissues that store fat in adipose cell distributed throughout the matrix
Function:
1-Store energy .
2-Subcutaneous adipose tissue shapes the body.
3-Act as a fixative to vital organ as kidney and uterus.

8. C-Dense fibrous connective tissue
dense collagen fibers-little amount of ground substance –less flexible and more resistant than loose CT.
example :tendon

9. 2-Specialized connective tissue A- cartilage
We have cartilage in nose, ears, and vertebral disks (Support )

10. B- Bone The skeleton supporting most vertebrates is made of bone.
The bone contain osteoblasts
that deposit a matrix and collagen
fibers .
Hard mammalian bones consists of repeating units called
osteon (Haversian system).
Each osteon has a central canal containing blood vessels
and nerves that service the bone.

11. C-Blood
The matrix is a liquid called plasma, consisting of water, salts, and a variety of dissolved proteins.
Types of blood cells are:
Erythrocytes (red blood cells),
Leukocytes (white blood cells)
Platelets.
Functions of cells:
Red cells carry oxygen.
White cells function in defense against microbes.
Platelets help in blood clotting.

12. 4-Nervous Tissue It consists of two types of cells :
(b) Neuroglia
It consists of two types of cells :
(a)-Neurons (nerve cells) It consists of cell body and extensions, called dendrites and axon.
The neurons(receive information and conduct it)
(b)-Neuroglia (supporting cell )

13. Dendrites transmit nerve impulses from their tips toward the rest of the neuron.
Axons transmit impulses toward another neuron or toward an effector, such as a muscle cell.