Tissues Tissue Basics What is a tissue Groups

Tissues

Tissue Basics • What is a tissue? Groups of cells working together to perform a function • Four Basic Types of Tissues 1. Epithelial – Covers surfaces, lines cavities, forms glands 2. Connective – Protect/support, stores energy, provides immunity 3. Muscle – Causes movement 4. Nervous – Detects changes, sends/receives impulses

Epithelial Tissue Characteristics 1. Arranged in closely packed sheets 2. 3. 4. 5. – Singular or multiple layers Layered – Apical surface (most superficial) – Exposed to outer most layer of body cavities – Lines organs or exterior of body – Lateral surface (cells facing cells) – Basal Layer (deepest layer of cells) – Basement membrane fibers that bind and support Avascular: Lacking blood vessels – Materials are exchanged by diffusion from connective tissue Contain a nerve supply High capacity for renewal

Epithelial Tissue • Called: Epithelium = singular, Epithelia = plural • Two Types: 1. Covering and Lining – Outer covering of the skin and internal organs – Lines body cavities and interiors of some systems, blood vessels 2. Glandular – Makes up the secreting portions of glands – Ex: Sweat glands

Basic Epithelia Shapes • Categorized as either: • Simple cells organized in a SINGLE layer – Found where diffusion, osmosis, filtration, secretion, and absorption occur • Stratified cells organized in 2 or more layers – Found where protection is needed and there is often wear and tear

Simple Epithelium • Squamous= flat cells – Important for filtration (kidneys) or diffusion (lungs & capillaries) • Cuboidal= cube shaped cells – Important for secretion and absorption • Columnar= column shaped cells – Important in absorption and secretion of mucus