• includes things like , fat, & blood.

All connective tissues include:

1. specialized cells

2.extracellular protein fibers } matrix that surrounds cells. 3. a fluid known as ground substance

Functions include: Connective tissues come in 3 major types •Establish a structural framework 1. Connective tissue proper •Transporting fluids from one part of the body to another 2. Fluid Connective Tissue •Protecting delicate organs

•Supporting, surrounding and interconnecting 3. Supporting Connective Tissue other tissue types

• Other CTP cells are involved in defense and Connective Tissue Proper large repair jobs (these roam from site to site as • Connective tissue with many cell types and needed) extracellular fibers in a syrupy ground substance. A.

• Some cells of CTP are involved w/repair, B. Mast cells maintenance, and energy storage. C. Lymphocytes

a. D. plasma cells E. Microphages b. • The number of cells and cell types within a tissue at c. Mesenchymal cells any given moment varies depending on local conditions.

1 The Cell Population C. Adipocytes A. Fibroblasts • Fat cells • Most abundant cells in CTP • Typically contain a single enormous lipid droplet • Permanent resident of CTP (always present) • Other organelles squeezed to side of cell wall • Produce proteins to make the ground substance (resemble a class ring) very viscous • Also secret e prot ei ns th at mak e th e fib ers DMD. Mesenc hyma l cell s • Stem cells B. Macrophages • Large amoeboid cells • Respond to injury by dividing into daughter cells which differentiate into connective tissue cells • Engulf & digest pathogens or damaged cells that enter the tissue • Release chemicals that activate the bodies immune system

E. Melanocytes G. Mast Cells • Synthesize and store the brown pigment melanin • Small mobile connective tissue cells • Found near blood vessels F. Lymphocytes • Filled with histamine & heparin • Migrate through the body *released after tissue damage to promote • Some mayypp develop into plasma cells (produce inflammation antibodies) • Congregate where tissue damage occurs H. Microphages • Neutrophils & eosinophils • Phagocytic blood cells

2 B. Reticular Fibers Connective Tissue Fibers • Thinner than and branched

A. Collagen • From interwoven network (tough but flexible) • Long, straight, unbranched • Can resist forces from many different directions • Most common fiber in CTP • Generallyygpyp used for stabilizing the position of body part • Flexible, but greater tensile strength than steel C. Elastic Fibers • are almost entirely composed of collagen • Contain (protein) fibers (connect muscle to bone) • Fibers are branched and wavy

• Rare but important (connect vertebrae, etc.)

Ground Substance

•Fills the spaces between cells CTP comes in two basic varieties •Surrounds connective tissue fibers 1. •In CTP it’s clear , viscous, and colorless (normally) 2. dense connective tissue •The viscosity makes it difficult for pathogens to move through the tissue

A. Loose Connective Tissue

• Also called areolar tissue Two Specialized commonly found types of loose • “packing noodles” of the body CT

• Fills spaces between organs, providing 1. cushioning • Surrounds & supports blood vessels and 2. Reticular Tissue: found in liver & spleen making a nerves, and stores lipids 3D network which supports the functional cells. • Least specialized CT in the body • Most of the volume is filled by ground substance • Forms a layer that separates the skin from deeper structures

3 1. Dense regular (white fibrous) CT • Collagen fibers parallel to each other Dense Connective Tissue • Packed tightly • Most of the volume filled by collagen fibers i.e.- tendons (muscle to bone) • Known as collagenous tissue (bone to bone) elastic fibers (underlay transitional epithelium, Come in two types: can with stand lots of stretching, also located in walls of blood vessels)

4 2. Dense irregular CT • Form interwoven meshwork • No consistent pattern • Provide strength/support to areas where stress is received from many directions. i.e.- *gives skin its strength *forms sheath around & ↓ ↓ Periosteum Perichondrium *forms a layer around organs called a capsule

Fluid CT Blood •Blood & lymph contain a distinctive set of cells in a •The cells and cell pieces are collectively known as liquid matrix formed elements

•These contain many cells, but normally do not •The watery ground substance is called plasma. generate or contain insoluble fibers •Tiny membrane covered packets of cytoplasm in the •Plasma, Interstitial Fluid, & Lymph blood called platelets contain enzymes and special proteins that function in clotting.

A. RBC’s or erythrocytes • Almost ½ volume of the blood

• Responsible for transport of O2 (and CO2) in the blood

BWBCB. WBC’ s or leukocytes • Include microphages (neutrophils, eosinophils, basophils, lymphocytes) • Monocyte (macrophages)

5