General Features of Epithelial Tissue•Cells are closely packed with littleextracellular material (between cells)•Are in continuous sheets•Single or multiple layered
General Features of Epithelial Tissue•Epithelia is avascular meaning“without blood vessels”.•Nutrients and wastes are exchangedby diffusion with the adjacentconnective tissue.
General Features of Epithelial Tissue•have a free surface which isexposed to a body cavity, lining of aninternal organ, or the exterior of thebody, and• a basal surface which isattached to the basementmembrane.
General Features of Epithelial Tissue•Subject to wear, tear and injury, sohas a high capacity for renewal (highmitotic rate).•Functions include protection,filtration, lubrication, secretion,digestion, absorption, transportation,excretion, sensory reception, andreproduction.
General Features of Epithelial Tissue•Epithelial tissue sits on a basementmembrane located between it andthe tissue underneath. Epithelial tissue Connective tissuehttp://www.ouhsc.edu/histology/Glass%20slides/13_04.jpg
Epithelial Tissue con’tThere are two kinds epithelial tissuebased on function: (1) lining or covering epithelium –covers the skin and outside of someinternal organs, forms the innerlining of body cavities, blood vessels,and internal organs.
Epithelial Tissue con’tThere are two kinds epithelial tissue (function): (2) glandular epithelium -consists of cells that secretesubstances. (ex. Thyroid/sweat/oilglands)
Epithelial tissue can be dividedinto categories based on……>the shape of the cells and> the number of layers of cells.
SHAPES of epithelium:1. Squamous-flat cells-thin which allows substances to passthrough (diffuse) them.-have limited cell structures due to size
2. Cuboidalcube shapedImportant in secretion andabsorptionHave more cell structures thansquamousUses active transport to secrete andabsorb substances
3. Columnar cells are tall and cylindrical Have the most cell structures Most complex Most secretion ability
4. Transitional•cells can readily change shapefrom squamous to columnar•change shape due to stretching, ofbody parts. (ex. Found in bladder)
Arrangement of Layers1. Simple epitheliuma single layer of cellsfound in areas where diffusion,osmosis, filtration, secretionand absorption occur.Can be squamous, columnar,or cuboidalEx. lungs
Arrangement of Layers2. Stratified epithelium contains two or more layers of cells protects underlying tissues found where there is wear and tearEx. Skin Named by the free surface.
Arrangement of Layers3. Pseudostratified epitheliumcontains a single layer of a mixtureof cell typeshas a stratified appearancebut is a single layerAll cells touch basementmembrane
Glandular EpitheliumColumnar epithelium that containsspecial cells capable of synthesizing andsecreting certain substances such asenzymes, hormones, milk, mucus, sweat,wax and saliva
Glandular EpitheliumGoblet cells :Special columnar cells that theirfunction is to secret mucin whichmixes with water to form mucous -intestines
Exocrine glands come in manyarrangements/types:
Glandular EpitheliumThere are two types of glands:1. Exocrine glandsTypes of exocrine glands based on how they secrete:a. Merocrine glands – by exocytosis (without losing cellular material) into the duct. Example sweat glands.
Merocrine gland directly secretes into duct. http://www.med.umich.edu/histology/fieldTrip/sweatGland.jpg
Glandular EpitheliumThere are two types of glands:1. Exocrine glandsTypes of exocrine glands based on how they secrete: a. Merocrine glandsb. Apocrine glands - a portionof the plasma membrane containingthe secretion and some cytoplasmbuds off the cell and enters the duct. Ex. Mammary glands
There are two types of glands:1. Exocrine glandsTypes of exocrine glands based on how they secrete: a. Merocrine glands b. Apocrine glands c.holocrine gland - the entire cell containing its secretion disintegrates in the duct.Ex. Oil glands
Glandular EpitheliumThere are two types of glands:1. Exocrine glands2. Endocrine glandno ductssecrete hormones by exocytosis intointerstitial fluids that surround cellsand blood stream picks them up.Ex. Thyroid gland
Why does skin flake off? Cells attop of skin are so far from nutrients thatthey are dead.Keratin – protein that fills deadepidermal cells at top layerKeratinized membrane – top layerof skin cells that are dead and filled withkeratin.
CONNECTIVE TISSUE continuedCHARACTERISTICS:Greater space between cells(extracellular space) compared toepithelial tissuecells secrete extracellularmaterial or MATRIX which fillsspace between cells
CONNECTIVE TISSUE continuedCHARACTERISTICS:Matrix is thematerial between thecell which containsground substance(non-collagenous partof matrix) andcollagen protein
CONNECTIVE TISSUE continuedCHARACTERISTICS:Connective Tissue isclassified according to thetype of extracellularmatrix it produces
TYPE 1: Connective Tissue ProperGuess how many kinds ofconnective tissue proper there are? 4
TYPE 1: Connective Tissue ProperFour types of Connective TissueProper:A. Loose connective tissue Extracellular matrix is not strong Is used for light binding and flexibility Also called areolar connective tissue
TYPE 1: Connective Tissue ProperFour types of Connective Tissue Proper:A. Loose connective tissue Found between the skin and the muscles holding the skin to muscles Has fibroblasts which make tissue’s ground substance, protein fibers, collagen fibers Mature fibroblast are called fibrocytes
Four types of Connective Tissue Proper: A. Loose connective tissue B. Dense irregular connective tissueC. Dense regular connectivetissue proper Collagen fibers run in one direction giving more strength called tensile strength Found in tendons which hold muscle to bones and ligaments that hold bone to
c. Dense regular connective tissue properTendons andligaments take a longtime to heal wheninjured because ofdense amount of
Four types of Connective Tissue Proper: A. Loose connective tissue B. Dense irregular connective tissue C. Dense regular connective tissue proper D. Adipose tissue Fatty tissue it has fat cells in it as well as connective tissue cells
D. Adipose tissue Function is to store energy, insulate, and to hold organs in place Example – kidneys are protected and held in place by adipose tissue
CONNECTIVE TISSUETYPES:1. connective tissue proper2. Cartilage Supporting connective tissue with tensile strength and supporting fibers of collagen in the ground substance
CONNECTIVE TISSUETYPES:1. connective tissue proper2. Cartilage• Firmer than connective tissue proper• Has no blood supply• Thin matrix• Found in nose, ear, larynx• Often replaced by bone
CONNECTIVE TISSUETYPES:1. connective tissue proper2. CartilageChondrocytes – maturechondroblast that becometrapped in matrix and livein hollow spaces calledlacuna in the cartilagetissue.
Lacuna (histology),a small spacecontaining anosteocyte in boneor chondrocyte incartilage
CONNECTIVE TISSUETYPES:1. connective tissue proper2. Cartilage3 types of cartilage:A. Hyaline cartilage occurs at end of bones, external ear, fetal skeleton, nose, ribs and vertebrae Weakest and most common
CONNECTIVE TISSUETYPES:1. connective tissue proper2. Cartilage3 types of cartilage:B. Elastic cartilage found in epiglottis and external ear contains elastic fibers great flexibility and is able to withstand repeated bending
CONNECTIVE TISSUETYPES:1. connective tissue proper2. Cartilage3 types of cartilage:C. Fibrous cartilage Strongest Dense collagen fibers with limited ground substance Found in disk between vertebrae and skull Where bears great amount of weight Has fibrous appearance
New Topic: MembranesMembrane = layers oftissueThere are three categories ofmembranes:
New Topic: MembranesThere are three categories of membranes:1. Mucous found in linings of organsystems that open to the outside
New Topic: MembranesThere are three categories of membranes:1. MucousEx. Respiratory system,reproductive system, digestivesystemTraps foreign material
New Topic: MembranesThere are three categories of membranes:2. Serous line the body cavities that do notopen directly to the outsidethey cover the organs located inthose cavities
New Topic: MembranesThere are three categories of membranes:2. Serous are covered by a thin layer ofserous fluid that lubricates and issecreted by the epithelium
New Topic: MembranesThere are three categories of membranes:2. SerousSerous fluid lubricates themembrane and reduces frictionand abrasion when organs moveagainst each other or the cavitywall.
New Topic: MembranesThere are three categories of membranes:3. Synovial membranes connective tissue membranes thatline the cavities of the freelymovable joints such as the shoulder,elbow, and knee.
New Topic: MembranesThere are three categories of membranes:3. Synovial membranessecrete synovial fluid into the jointcavity, and this lubricates cartilageon the ends of the bones so thatthey can move freely and withoutfriction.
New Topic: tissue repairRemember: Tissues are made up ofcells.Two types of cells that make up tissuebased on function:1. Stromal cells – provide structure andsupport to tissue; usually connectivetissue
New Topic: tissue repairRemember: Tissues are made up of cells.Two types of cells that make up tissue based on function:1. Stromal cells – provide structure and support to tissue2.Parenchymal cells – cells that actually perform the function of the tissue
Organ Parenchymakidney nephron alveoli, respiratory bronchiole, alveolarlungs duct and terminal bronchiole white pulp and redspleen pulpbrain neuronliver hepatocyte
New Topic: tissue repairCategories of cells based on ability toreproduce or regenerate:1. Labile cells cells that multiply constantly throughout life Most of cells in body ex. Parenchymal epithelial cells replace themselves quickly
New Topic: tissue repairCategories of cells based on ability to reproduce or regenerate:2. Stable cells only multiply when receive external stimulus to do so ex. Bone parenchymal cells when a bone is broken can reproduce and repair the broken bone
New Topic: tissue repairCategories of cells based on ability to reproduce or regenerate:3. Permanent cells do not have the ability to multiply Nervous system parenchymal cells (neurons) are permanent; can’t be replaced.
New Topic: tissue repairSo, if cells are parenchymal permanentand die they will be replaced by labilestromal cells..This is why brain damage or heartdamage is said to be irreversible.