The study of the tissues of the body Lab 3 – Histology The study of the tissues of the body

There are four tissue categories: Epithelial Tissue Connective Tissue Nerve Tissue Muscle Tissue Histology is the study of tissues.

REVIEW

Epithelial tissue is composed of closely packed cells Connective tissue is composed of a few cells surrounded by lots of extracellular matrix (fibers, fluid, minerals, etc.) Epithelial Tissue Connective Tissue

Questions to ask for identifying tissues Epithelial tissue Connective tissue

Objective 2: Connective Tissues

CONNECTIVE TISSUES – Locations Most abundant tissue Found everywhere except for body surfaces Why not?

CONNECTIVE TISSUES – Functions Bind Support Protect Insulate Transport

Connective tissue has: Cells Fibers Ground substance Areolar connective tissue The prototype of connective tissues: Other connective tissues contain variations in the amount or type of cells, ground substance &/or fibers as found in areolar connective tissue

Connective tissue is relatively cell poor Contains many different cell types Fibroblast Adipocytes Mast cells Macrophage

Cell types Fibroblasts (cytes)*- secret /maintain ground substance (connective tissue proper) Chondroblasts (cytes)*- secret /maintain ground substance (cartilage) Mast cells – secret histamine, heparin Macrophages – phagocytes Adipocytes – fat storage Blasts secrete ground substance Cytes maintain ground substance

Ground substance Fibers Interstitial fluid Proteoglycans – viscosity Collagen fibers Elastic fibers Reticular fibers

Classes of Connective Tissue

Mesenchyme embryologic connective tissue Note star-shaped cells ground substance cells fibers

Connective Tissues Proper Loose Connective Dense Connective Areolar Dense Regular Adipose Dense Irregular Reticular

Loose Connective Tissue Reticular Areolar Adipose elastic fibers collagen fibers adipocyte nucleus adipocytes (vacuoles) reticular cell reticular fibers ground substance extracellular matrix Note: Reticular tissue also contains mast cells Note: Reticular fibers not seen

Dense Connective Tissue Dense Regular Dense Irregular Collagen fibers Collagen fibers Fibroblast nuclei Fibroblast nuclei

Cartilage

Cartilage Hyaline Elastic Fibrocartilage matrix elastic fibers collagen fibers Chondrocytes inside Lacunae Lacunae = “little lakes”

Tissue Comparisons Adipose Elastic Carilage Reticular

Objective 3: Membranes

Serous Membrane Parietal peritoneum Parietal pleura Visceral pericardium Visceral pericardium

Mucous Membrane Mucosa of nasal cavity Esophagus lining Trachea lung bronchi Mucosa of digestive tract

Membranes are simple organs composed of 2 tissues: Epithelium tissue Connective tissue Serous Membrane simple squamous epithelium areolar connective tissue Mucous Membrane stratified squamous, pseudostratified columnar, or simple columnar epithelium areolar connective tissue (lamina propria)

More in-depth information E-Reserves More in-depth information & Practice for identifying the tissues