HISTOLOGY The Study of Tissues EPITHELIAL TISSUE FACTS

HISTOLOGY The Study of Tissues

EPITHELIAL TISSUE FACTS Free surface – open to its surroundings Basal surface – attached to underlying tissue Basement membrane – “glue” that attaches epithelial tissue to other tissue – is avascular Has ability to repair itself through mitosis Classified by # of layers and shape of cells that make up those layers

SIMPLE EPITHELIUM One cell thick Named based on shape of cell: squamous cuboidal columnar Found in linings of stomach, in blood vessels, and air sacs of lungs

SQUAMOUS

CUBOIDAL

COLUMNAR

STRATIFIED EPITHELIAL More than one layer thick Named for cells at surface Found in areas where protection is needed

STRATIFIED

PSEUDOSTRATIFIED EPITHELIUM

GLANDULAR EPITHELIUM Forms the secreting surface of a gland Glands are either exocrine or endocrine

EXOCRINE Merocrine § Glands secrete without losing cellular material § Examples include: § Enzyme secreting glands

EXOCRINE Apocrine § Gland has cytoplasm in secretions § Examples include: § Mammary glands

EXOCRINE Holocrine § Glands have secretions made of disintegrated cells § Examples include: § Sebaceous glands

ENDOCRINE Glands are ductless Secrete hormones directly into bloodstream Discussed further in ch 10

CONNECTIVE TISSUE

EXTRACELLULAR MATRIX

CT PROPER Loose connective Not very strong Very flexible Ex: attaches skin to underlying tissues

CT PROPER Dense irregular Part of skin = dermis Collagen fibers oriented in all directions Ex: also encapsulates your organs

CT PROPER Dense regular Collagen fibers line up in same direction Strong binding Ex: tendons & ligaments

CT PROPER Adipose tissue Cells fill with oil, enlarge, & get pushed close together Support, protection and insulation Also stores nutrients for future energy

CARTILAGE

HYALINE CARTILAGE Both firm and resilient. Collagen there, but hard to see “hard plastic” Found in bridge of nose, costal cart. of ribs, ends of bones

FIBROCARTILAGE Tough binding and resilient support Packed with collagen that runs parallel to one another Found between vertebra

ELASTIC CARTILAGE Highly flexible support Not as much collagen = elastic fibers instead Stretchy – “soft plastic” Found in tips of nose & outer ear

BONE AND BLOOD Bone AKA Osseous tissue Secrete ground substance, fibers, collagen, & fluid Ground substance hardens thru calcification Blood AKA Vascular tissue Has cells (WBC, RBC) Has ground substance (proteins in blood) Has fluid (plasma) Has fibers that can join together to form clots

MEMBRANES

Membranes are both epithelial and connective tissues 3 categories: • Mucous • Synovial • Serous

MUCOUS Notice spelling Line digestive, urinary, and reproductive tracts

SYNOVIAL Found around moveable joints Secretes synovial fluid

SEROUS Lines and protects internal organs Form thin double layers

TISSUE REPAIR WOW!!!

STROMAL “Supporting” cells that provide structure/support for parenchymal cells Structural cells – form infrastructure Repair – scar tissue

PARENCHYMAL “Performance” cells that provide the actual function of the tissue Do the work the tissue is designed to do

QUESTION: In order for function to be fully restored, which of these would need to be repaired after damage?

QUESTION: In order for function to be fully restored, which of these would need to be repaired after damage? PARENCHYMAL

Labile cells – cells that undergo mitosis regularly & quickly • Ex – epithelial (skin) cells REGENERATION TERMS

Labile cells – cells that undergo mitosis regularly & quickly • Ex – epithelial (skin) cells Stable cells – cells that do not usually undergo mitosis, but can if needed • Ex – undamaged bone tissue REGENERATION TERMS

Labile cells – cells that undergo mitosis regularly & quickly • Ex – epithelial (skin) cells Stable cells – cells that do not usually undergo mitosis, but can if needed • Ex – undamaged bone tissue Permanent cells – cells that do not undergo mitosis • Ex – nervous tissue REGENERATION TERMS

Labile cells – cells that undergo mitosis regularly & quickly • Ex – epithelial (skin) cells Stable cells – cells that do not usually undergo mitosis, but can if needed • Ex – undamaged bone tissue Permanent cells – cells that do not undergo mitosis • Ex – nervous tissue Other factors to consider: • Circulation • Nutrition • Age REGENERATION TERMS