Chapter 4 Tissues

Tissue Groups of cells that are similar in structure and perform a common or related function

Four Tissue Types Epithelial-covering Connective-support Muscle-movement Nervous-control

Epithelia Cellularity Specialized contacts-tight junctions/desmosomes sheets Polarity- apical (top) with microvilli or cillia basal (bottom/connective tissue connection) Connective Tissue support – reticular lamina Basement membrane=basal lamina and reticular lamina

Epithelial Characteristics Avascular-no blood vessels Innervated- has nerve fibers Regenerative- high capacity

Classification- I- cell layers Simple-single layer cells Stratified-2 or more layers of cells

Classification- II- Cell Type Squamous- thin, flat Cuboidal- length, width, height same (box) Columnar- height ~ 3 X length or width

Simple Epithelia Major Function-absorption, secretion, filtration; NOT PROTECTION

Stratified Epithelia Regenerate from the basal layer Major Function-PROTECTION Always named by the top layer of cells

Glands One or more cells that make or secrete a product Product- secretion Endocrine Gland-product into bloodstream Exocrine Gland- product into duct; more numerous

Modes of Secretion Holocrine-cell products explode from cell Sebaceous glands-acne due to sebum Merocrine- secrete by exocytosis Most sweat glands, pancreas, salivary glands

Connective Tissue Common Characteristics Degrees of Vascularity Extracellular Matrix

Functions of Connective Tissue Binding and support Insulation Protection Transportation

Structural Elements Ground substance- fills space between cells Interstitial fluid, proteins, proteoglycans Fibers-collagen, elastic, reticular Cells-type is tissue dependent Fibroblast, chondroblast, osteoblast, hematopoietic stem cell Others cells: Mast, Plasma, White cells

Connective Tissue Found everywhere in body

Four Main Classes Connective Tissue Proper- loose/dense Cartilage Bone Blood

Connective Tissue Proper

Cartilage CT-Three Types Hyaline-ends long bones, nose, respiratory tract, fetal skeleton, epiphyseal plates Fibrocartilage-discs of knee, vertebrae, symphysis pubis Elastic-ear, epiglottis

Elastic cartilage Areolar CT Simple Cuboidal (Glands) fibrocartilage What is this organ sample from?

Bone Hard, rigid matrix good for support mineral reserve blood production levers for muscle (similar to cartilage)

Blood Only CT with a liquid matrix Major Function- transportation on the cardiovascular highway

Membranes Made of both epithelia and CT Cutaneous- keratinized stratified squamous epithelium attached to dense irregular tissue Mucous-line cavities open to exterior; digestive, respiratory, and urogenital tracts Serous- line closed cavities of ventral body cavity

Homeostatic Imbalance Pleurisy, Pericarditis and Peritonitis Inflammation of serous membranes

Muscle Tissue Responsible for most types of body movement highly vascular highly innervated

Three Muscle Types Skeletal-attached to skeleton Striated Voluntary multi-nucleate cylindrical

Three Muscle Types Cont’ Cardiac- heart only Striated intercalated discs single nucleus involuntary

Three Muscle Types Cont’ Smooth- lines hollow organs/vessels single nucleus no striations spindle shaped involuntary

Nervous Tissue Main component of nervous system Regulates and controls body activities through electrical signals

Tissue Repair/Regeneration Inflammation-chemicals released during trauma call in cells; vasodilation/ increased permeability; clot formation Organization- clot replaced by granulation tissue; capillaries, fibroblasts, macrophages Regeneration/Fibrosis- surface epithelium regenerates; fibrous tissue matures/contracts; scab detaches; scar formation