1st Lec of Connective Tissue for 1st Year Mbbs by Dr Roomi

8/3/2019 1st Lec of Connective Tissue for 1st Year Mbbs by Dr Roomi

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Connective Tissue Histology

By

Dr. Mudassar Ali Roomi (MBBS, M. Phil)


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Connective Tissue or

supporting tissue

It is one ofthe basic tissues in our body.

Consist

s oftw

o basic element

s: Cells (relatively fewer)

Extra-cellular matrix or intercellular

substance (more abundant)


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Epithelium Vs connec

tive

tissue


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True Connective Tissue Cells


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True Connective Tissue Cells

Fibroblasts: Secrete both fibers and ground substance ofthe

matrix (wandering cells)

Macrophages: Phagocytes that develop from Monocytes

(wandering or fixed)

Plasma Cells: Antibody secreting cells that develop from BLymphocytes (wandering)

Mast Cells: Produce histamine that help dilate small blood

vessels in reaction to injury (wandering)

Adipocytes: Fat cells that store triglycerides, support, protect andinsulate (fixed)

Only loose areolar connective tissue contains all ofthe

aforementioned cells.


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Fibroblasts:

Are active cells that synthesize all collagen,

reticular, and elastic connective tissue fibers Synthesize glycosaminoglycans (GAGs),

proteoglycans, and glycoproteins of ground

substance.

Fibrocytes:

Smallerthan fibroblasts

Inactive or resting connective tissue cells


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Macrophages

Most numerous in loose connective tissue

Ingest bacteria, dead cells, cell debris, and foreign matter Are antigen-presenting cells (APCs) to lymphocytes for

immunologic response

Derived from circulating blood monocytes

Called Kupfer cells in liver, osteoclasts in bone, histiocytesin the skin, and microglia in central nervous system


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Lymphocytes

Most numerous in loose connective tissue of respiratory and

gastrointestinal tracts

Produce antibodies and kill virus-infected cells


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Plasma Cells

Characterized by chromatin distributed in radial

pattern in the nucleus (cart-wheel appearance)

Derived from lymphocytes exposed to antigens

Produce antibodies to destroy specific antigens


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Mast Cells

Closely associated with blood vessel

Found in skin, respiratory, and digestive systemconnective tissue

Spherical cells with fine, regular basophilic

granules

Release histamine when exposed to allergens,causing allergic reactions


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Extracellular ma

trix

Also called as intercellular substance

Extracellular matrix = fibers + ground

substance


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Matrix Fibers

Collagen Fibers: Large fibers made ofthe protein

collagen and are typically the most abundant

fibers. Promote tissue flexibility.

Elastic Fibers: Intermediate fibers made ofthe

protein elastin. Branching fibers that allow for

stretch and recoil

Reticular Fibers: Small delicate, branched fibers thathave same chemical composition of collagen. Forms

structural framework for organs such as spleen and

lymph nodes.


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Collagen Fibers

Type I: found in skin, tendons, ligaments,

fibrocartilage, and bone

Type II: found in hyaline and elastic cartilage

Type III: forms meshwork in liver, lymph node,

spleen, and hemopoietic organs

Type IV: found in basal lamina of basementmembrane


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Matrix Ground Substance

Hyaluronic Acid: heteropolysaccharides

(GAGs) found in true or proper connective

tissue.

Chondroitin sulfate: Jellylike ground

substance of cartilage, bone, skin an blood

vessels.

Other ground Substances:

Dermatin sulfate, keratin sulfate, and adhesion

proteins

1st Lec of Connective Tissue for 1st Year Mbbs by Dr Roomi

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1st Lec of Connective Tissue for 1st Year Mbbs by Dr Roomi