Histology number 6 CONNECTIVE TISSUE.pptx

Histology connective tissue

1. CONNECTIVE TISSUE

2. It’s the supporting tissue. It fills the intersticium , capsulate organs, connect organ parts and maintain them in a relative position.

3. Structure connective tissue is formed by three classes of components: Cells. Fibers. Ground substance. The major constituent of connective tissue is the extracellular matrix .

4. Cells of connective tissue Fibroblasts: Secrete both fibers and ground substance of the matrix. Macrophages: Phagocytosis(defense) Plasma Cells: Antibody secreting cells that develop from B Lymphocytes. Mast Cells: Produce histamine that help dilate small blood vessels in reaction to injury . Adipocytes: Fat cells that store triglycerides, support, protect and insulate . Others esinophils , lymphocytes,

5. Extracellular Substance

6. Connective tissue fibers Collagen fibers the dominant fiber type. The primary function of collagen fibers is to add strength to the connective tissue.

7. Reticular fibers very delicate branched fibers and form fine networks instead of thick bundles. Only seen when using special stains e.g. silver stain. constitute a network around the parenchymal cells of organs especially the hematopoietic(blood forming) organs ( eg , spleen, lymph nodes, red bone marrow.

8. Elastic fibers Thinner than collagen fibers and made of protein elastin Branched fibers. allow stretch and recoil.

9. Ground substance is a highly hydrated, transparent, complex mixture of macromolecules. It fills the space between cells and fibers of connective tissue and acts as a lubricant and a barrier to the penetration of invaders. e.g. Hyaluronic Acid, Chondroitin sulfate, Dermatin sulfate, keratin sulfate, and adhesion proteins

10. Types of connective tissue

11. Loose connective tissue(Areolar) consists of all 3 types of fibers, several types of cells, and semi-fluid ground substance found in subcutaneous layer and mucous membranes, and around blood vessels, nerves and organs It supports organs under low pressure and friction.

12. Dense C.T. contains more numerous and thicker fibers and far fewer cells than loose CT Of 2 types, regular and irregular

13. dense regular Connective Tissue consists of bundles of collagen fibers and fibroblasts. The fibers are arranged in regular bundles. forms tendons, ligaments and Aponeuroses Function = provides strong attachment between various structures.

14. Dense Irregular CT consists of randomly-arranged collagen fibers and a few fibroblasts Found in fasciae, dermis of skin, joint capsules, periostium . Function = provide strength

15. Reticular CT Consists of fine interlacing reticular fibers and reticular cells It forms the structural framework( stroma ) in which the cells of the organ are suspended Found in liver, spleen and lymph nodes

16. Elastic connective tissue Contains elastic fibers. The elastic fibers usually branch , anastomose, and don’t form bundles unlike the collagen fibers. Provide resilience e.g. ligamentum nuchae .

17. Adipose tissue consists of adipocytes; "signet ring" appearing fat cells found separately or within loose connective tissue . it represents 15–20% of the body weight and 20–25%in women. found in subcutaneous layer, around organs and in the yellow marrow of long bones function = supports, protects and insulates, heating and serves as an energy reserve. .

18. There are 2 types of adipose tissue Unilocular Adipose Tissue Multilocular Adipose Tissue

19. Unilocular Adipose Tissue It is color varies from white to dark yellow (carotenoids dissolved in fat droplets. represents all adipose tissue in adults is of this type. Its distribution is regulated by sex hormones and adrenocortical hormones.

20. cells are spherical and closely packed in adipose tissue. cell measures 50 and 150µm in diameter . cell appears as a thin ring of cytoplasm surrounding the vacuole left by the dissolved lipid droplet and eccentric and flattened nuclei (signet ring). The cytoplasm surrounds the nucleus contains a Golgi complex, mitochondria, poorly developed cisternae of the rough endoplasmic reticulum

21. Unilocular adipose tissue is subdivided into incomplete lobules by highly vascular connective tissue . Adipose tissue can synthsize and secrete leptin which participates in the regulation of the amount of adipose tissue in the body and in food ingestion .

22. Multilocular Adipose Tissue A lso called brown fat ( due to both the large number of blood capillaries and the numerous mitochondria). In humans it is important mainly in the first months of postnatal life as heat producer and protects the newborn against cold.

23. cells are polygonal and smaller than cells of unilocular adipose tissue and chatacterized by :. The cytoplasm contains a great number of lipid droplets of various sizes spherical and central nucleus numerous mitochondria with abundant long cristae .