histo lab 3

CONNECTIVE TISSUE

Generally provides a matrix that supports and physically connects other tissues and cells together

• Forms organs

• Gives metabolic support to cells (diffusion of nutrients and wastes)

Functions of connective tissue

• Cells, protein fibers, ground substance

• Variety of connective tissues reflects the difference in composition of components

• Responsible for structure and functions

Primary components of the extracellular matrix

GROUND SUBSTANCE

Highly hydrated, transparent, complex mixture of macromolecules

• Glycosaminoglycans (GAGs), proteoglycans, glycoproteins

Ground substance

• Allows diffusion of small molecules and acts as a lubricant and barrier from penetration of foreign material

• Influences cellular activities

Collagen
Elastic
Reticular

CONNECTIVE TISSUE FIBERS

Collagen

• Key component of connective tissues, epithelial basement membranes and external laminae of muscle and nerve cells

• Most abundant protein in the human body

• Functions for structure and support

Structure and support

Function of collagen

Reticular

• Contains mainly of collagen type III, forms a network (reticulum) of fibers

• Provides support structure

Collagen III

Reticular fiber consist of what type of collagen

Elastic

• Primarily composed of elastin

• Possess rubberlike properties allowing tissues to stretch, expand and return to their original shape

AREOLAR TISSUE

• Consists of all 3 types of fibers, several cell types and semifluid ground substance

• Found beneath the epidermis of the skin, mucous membranes, and around blood vessels

• Provides nutrition to cells and acts as cushion to protect organs from external forces; keeps skin flexible and elastic

RETICULAR TISSUE

• Network of collagen III (reticulin) fibers with attached fibroblasts

• Consists of fine interlacing reticular fibers and reticular cells • Supports blood-forming cells, secretory cells, and lymphocytes in lymph organs; forms the framework (stroma) of organs

• Found in the bone marrow, liver, pancreas, lymphoid organs

bone marrow, liver, pancreas, lymphoid organs

Reticular tissue can be found in

WHITE ADIPOSE TISSUE

• Contains typically large adipocytes containing one large lipid droplet

• Cytoplasm and nucleus are pushed to the sides • Primary source of fats during metabolism; Provides long-term energy storage

• Found in subcutaneous layer beneath skin, surrounding organs and in the marrow

BROWN ADIPOSE TISSUE

• Contains typically smaller adipocytes with small lipid droplets

• Functions primarily in heat production

• Found around the neck, kidneys, heart, and chest

DENSE REGULAR CONNECTIVE TISSUE

• Consists mostly of thick type I collagen and fibroblasts showing parallel alignment

• Provides resistance to prolonged or repeated stresses from the same direction

• Found in ligaments, tendons, aponeuroses, deep fasciae

Type I

Dense regular connective tissue consists of what type of collagen

DENSE IRREGULAR CONNECTIVE TISSUE

• Collagen fibers are arranged randomly with little ground substance and few cells (mostly fibroblasts)

• The collagen network provides resistance to stress and tearing from all directions

• Found on the dermis of the skin, hollow organs, joints