Chapter 4

Tissues: Living Communities

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