chapter 4 tissues: living communities. introduction since cells are differentiated, they have lost...
TRANSCRIPT
Introduction
Since cells are differentiated, they have lost ability to perform all metabolic functions required to sustain life as an isolated entity.
Cells exist in cooperative communities in multicellular organisms
Cells of similar type and function cluster together to form _____________.Tissues cluster to form
organs.
Classification of Tissues
Epithelial tissueCovers and lines
Connective tissueProvides support
Muscle tissueEnables movement
Nervous tissueControls work
Most organs contain all 4 tissue types.
The study of microscopic structures of tissues and organs is called _________
Epithelial TissueComposed of sheets of cells that cover and line other
tissues.Lines bladder, mouth, blood vessels, thorax, etc.
Have an exposed surface that affords access to the surrounding environment or to the inner openings of chambers and ducts.
Functions:____________, covers, lines____________ of biochemical substancesMay be _____________May play an important role in ____________ input____________ and ____________ of biochemical substances
Glandular epitheliaIndividual glandular epithelial cells are goblet cells, groups
are referred to as glands.
Characteristics of Epithelia
Organized into tightly packed groups that form _________ of tissue.
Can be composed of single layer or multiple layers depending on _________.
Epithelial cells share the following characteristics:________ - Each epithelial cell has an apical surface and a
basal surfaceApical surface faces the lumen or body cavityBasal surface faces the underlying connective tissue
Lateral surfaces are connected to neighboring cells by ________________ complexes
Epithelial cells are avascularRely on underlying connective tissue for oxygen and
nutrients
Most epithelial cells are innervated
Between the cell membranes of adjacent epithelial cells are channels that carry nutrients to the cells and wastes away from them.
Junctional Complexes – specialized attachments between epithelial cells at their plasma membranes. Give epithelial tissue strength.
Tight junctionsNothing can penetratePrevent ____________Bladder, GI tract
DesmosomesWelded plaqueTough, resist __________ and stretching (like Velcro). Consist of
intermediate fibers (tonofilaments)Skin, heart, uterus
Gap junctionsCytoplasm continuousLinked by tubular channel proteins called _______________.
Allow exchange of ions, nutrients, and transport signalsCardiac, smooth muscles
Epithelial Cells: Basement Membrane
Foundation of epithelial cells and made by epithelial cells
Meshwork of fibers that cements epithelial cell to underlying _____________________ tissue (CT)
Its strength and elasticity help to prevent the epithelial cell from being torn away
Also called basal _________Varies in thickness
Oxygen and nutrients diffuse through the basement membrane from the connective tissue. Absorbed substances and waste products produced by epithelium diffuse through basement membrane to the connective tissue.
Surface Specialization
Surfaces vary depending on location in body and function May be smooth or contain ___________(fingerlike projections)
or _______(hairs)Cilia found in respiratory and reproductive tractsMicrovilli in intestines and urinary tractIf the cell contains microvilli, it is said to have a __________
border.Brush border helps to increase surface area, which aids
in absorption. (can add up to 20 times of surface area).
Epithelial cells of the skin are filled with a
waterproof called __________.Accumulate as cell matures
Classifications of Epithelia
Classified according to 3 characteristics:
Number of cell layers.Single layer is called __________
Found in protected parts of body where they provide minimal protection to underlying structures
More than one layer is called __________Thicker and stronger and are on parts of body that
are subjected to mechanical or chemical stress.
Shape of cellsBased on shape that is on exposed or _________
surfaceSquamous, cuboidal, and columnar
Presence of surface specializationsKeratinized, ciliated, etc.
Simple Squamous Epithelium
Fragile and thin
Flat and smooth; reduce friction
Found lining surfaces involved in the passage of either _____ or ________lining of lungs, kidneys
______thelium – lining of chest (pleura), abdomen (peritoneum), and pericardium
______thelium – lining of blood vessels
Simple Cuboidal EpitheliumSingle layer of cubical
cells
Round, dark-staining nuclei aligned in a single ______
Occurs in areas of the body where ___________ and ______________ take place
Surface of ovaries, glands, lining of ducts of liver, kidneys, pancreasFound throughout the
____________ system
Simple Columnar
EpitheliumElongated and closely packed
together – thick and protectiveNuclei aligned in a row (not
central) at the base of the cell near the basement membrane
Also found in areas of absorption and secretion
Line the _____ tract from stomach to rectum____________ cell- apical surface
is blanketed by dense microvilli that maximize absorption by increasing surface contact with nutrient-filled lumen.
__________ cell- manufacture and store mucus for lubrication
Also found in many excretory ducts
________ in respiratory tract and uterus
Stratified Squamous Epithelium
Multilayered Continually being _____ away
or __________ offReplaced by cells from deeper
layers_________ cells are attached to
the basement membrane. As they mature, they are pushed to the surface away from nutrients. Lose their cytoplasm and
nuclei and become squamous
Occur in areas of the body subject to __________ and ___________ stressesMouth, esophagus, vagina,
rectumSkin (keratinized)
Stratified Cuboidal Epithelium
Usually ______ layers of cuboidal cells
Provides protection to deeper, delicate tissues
Found primarily along large excretory ductsSalivary glands,
mammary glands, sweat glands
Rare
Basal cells are _________
Function in secretion and protection
Found only in select parts of the respiratory, digestive, reproductive systems and along some excretory ducts
Stratified Columnar Epithelium
Pseudostratified Columnar Epithelium
“_______” stratified – truly simple epithelium
Cell nuclei are found at different levels across the length of the tissue
Some cells do not reach luminal surface, but all attach to basement membrane.
Usually ________ and often associated with ______ cells.
Found in respiratory tract and in portions of male reproductive tract
Transitional Epithelium
Stratified epithelium Basal layer of cuboidal or
columnar cells Superficial layer of
cuboidal or squamous cells
Ability to _______ - found in areaswhere changes in volume occur__________ tract
As epithelia stretches, layers often thin depending on how much volume is present
Forms a _____-proof barrier