Tissues: The living Fabric Histology! Tissues: The living Fabric Definition: groups of cells that are similar in structure and function

Target: Describe the 4 main tissues and give an example of each.

4 Types of Tissues : each has many subclasses and varieties

And this one! 

Body Tissues Four primary types (functional categories) Epithelium protection /secretion /absorption/ filtration Connective support & structure Nervous communication & control Muscle movement (internal & external)

Epithelial Functions Protection Sensory Secretion Absorption Excretion

Special Characteristics 1. Cellularity- close-packed cells with very little cellular fluid between them. 2. Specialized contacts- adjacent cells are bound together 3. Polarity- all cells have two surfaces Apical surface- exposed to outer body or internal organ cavity Basal surface- attached to base or lower side of structure 5. Avascular but innervated- no blood vessels but are supplied by nerve fibers. Receives nutrients from underlying connective tissue 4. Supported by connective tissue- all epithelial sheets rest on connective tissue. Basal and reticular lamina reinforce the epithelial sheet to resist tearing and stretching along with filtering what will be allowed to pass through to the epithelial 6. Regeneration- replace lost cells rapidly by cell division

Classification of Epithelium Combination of shape & # of cells is used to name tissues Shape of cells Squamous – flattened Cuboidal – cube-shaped Columnar – column-like

Classification of Epithelium Number of cell layers Simple one layer found in areas of transport Stratified more than one layer High abrasion areas for protection Secretory membranes

Classification of Epithelium Pseudostratified “False” layers Ciliated (respiratory tract) Non-ciliated (male urethra) Transitional multiple layers of epithelial cells, “hodge-podge” Found in urinary tract can look cuboidal until bladder stretches, then looks squamos

Location and Function Overview Epithelial Membranes – line body cavity and are open to exterior , helps waterproof and protect body and lines all closed body systems. 3 types Mucous membranes Line body cavities OPEN to the exterior Example: digestive, respiratory, urogenital Cutaneous Membranes Skin Helps waterproof & protect body First line of defense in immune system Serous Membranes Lines all CLOSED body cavities Serous fluid located between layers to reduce friction due to organ motion Glandular epithelium- secrete products into tissues, ducts, or blood. More on these when we study skin!

Connective Tissue Found everywhere in the body! However, the amount in organs varies, skin is mostly connective tissue but brain has very little. Main classes: Fat and fibrous tissue Cartilage Bone Blood Does much more than connect body parts! Functions: Binding and support Protection Insulation Transportation of substances

Nervous Tissue Main component of nervous system (brain, spinal cord, nerves) Neurons are highly specialized cells that generate and conduct nerve impulses.

Muscle Tissue Highly cellular and well vascularized that are responsible for movement! Three Types Skeletal Cardiac Smooth