Chapter 4

Tissues: Living Communities

Cells of similar ____________ and _____________ cluster together to form tissues.

Epithelial tissueCovers and lines

Connective tissueProvides support

Muscle tissueEnables movement

Nervous tissueControls work

The study of microscopic structures of tissues and organs is called _________

Characteristics of EpitheliaSheets of cells that cover and line other tissues.

Covers the surface of organs and also lines the lumen of hollow organs.

Lines bladder, blood vessels, thorax, etc.

Can be composed of single layer or multiple layers depending on location.

________ - Each epithelial cell has an apical surface and a basal surface

Apical surface faces the lumen or environmentBasal surface faces the underlying connective tissue

All epithelial cells are ______________.Rely on underlying connective tissue for oxygen and nutrients

Most epithelial cells are _____________.

Junctional Complexes – specialized attachments between epithelial cells on their lateral surfaces. They connect via plasma membranes.

Tight junctionsPrevent ____________Ex: Bladder

DesmosomesTough, resist __________ and stretching (like Velcro). Consist of

intermediate fibers Ex: Uterus

Gap junctionsCytoplasm continuous between cellsLinked by tubular channel proteins called _______________.

Allow exchange of ions, nutrients, and transport signalsEx: Cardiac muscle

Epithelial Cells: Basement Membrane

Foundation of epithelial cellsMeshwork of fibers that cements epithelial cell to

underlying ___________________ tissue (CT)Helps to prevent the epithelial cell from being torn

awayAlso called basal _________

Oxygen and nutrients diffuse up to epithelium through the basement membrane from the connective tissue. Absorbed substances and waste products produced by epithelium diffuse down through basement membrane to the connective tissue.

Surface Specialization

Surfaces vary depending on location in body and function

May be smooth or contain _____________ or _______

Cilia found in respiratory and reproductive tracts.

Microvilli in intestines and urinary tract.

If the cell contains microvilli, it is said to have a __________ border.

Brush border helps to increase _____________ area, which aids in absorption. (can add up to 20 times the surface area).

Epithelial cells of the skin are filled with a

waterproof protein called __________.

Accumulates as cell matures.

Classifications of Epithelia

Number of cell layers.

Single layer is called __________

More than one layer is called __________

Shape of cellsBased on shape that is on exposed or _________

surfaceSquamous, cuboidal, and columnar

Presence of surface specializationsKeratinized, ciliated, etc.

Flat and smooth; reduce friction

Often found lining surfaces involved

in the passage of either _____ or ________

ENDOTHELIUM, KIDNEYS, ALVEOLI OF LUNGS

Simple Squamous Epithelium

Simple Cuboidal Epithelium

Round, dark-staining nuclei aligned in a single row

GLANDS (endocrine and exocrine): salivary glands, ovaries, liver, kidneys, pancreas

Simple Columnar Epithelium

Elongated cells with elongated nuclei aligned in a row at the base of the cell

Line DIGESTIVE TRACT from stomach to rectum

____________ cell- apical surface is blanketed by microvilli that maximize absorption by increasing surface contact with nutrient-filled lumen.

__________ cell- manufacture and store mucin (component of mucus) for lubrication

Stratified Squamous Epithelium

Multilayered

Continually worn away or sloughed off

Cuboidal 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.

MOUTH, VAGINA, RECTUM, SKIN (keratinized)

Areas of the body that encounter mechanical stresses)

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

Transitional EpitheliumStratified epithelium

Basal layer of cuboidal or columnar cells

Superficial layer of cuboidal cells (domelike)

Ability to _______ URINARY TRACTleak-proof

As epithelia stretches, layers often thin depending on how much volume is present

Glandular Epithelia

Gland- cells that have the ability to manufacture and discharge a secretion.

_____________- specialized protein molecules that are produced in the RER, packaged by the golgi and discharged from the cell.

Glandular epithelial cells have prominent ER, Golgi

Secretions may be sent far away in the body for use.

Multicellular glands form in uteroA layer of epithelial cells folds

inward (___________).Form __________ that lead to the

epithelial surfaceSome glands (__________) lose the duct

and become separated from the original epithelium

Glands can be classified by the following factors:

Presence or absence of ductsEndocrine vs. Exocrine

Number of cells that compose themUnicellular vs multicellular

Shape of secreting ductsSimple or compound

Complexity of glandular structureTubular, acinar, tubuloacinar

Type of secretion madeMucoid or serous

Manner in which secretion is stored and dischargedMerocrine, apocrine, or holocrine

Endocrine Endocrine GlandsGlandsNO DUCTS (cells die)

Produce and secrete _____________.

Blood stream delivers secretions to entire body

___________ within the gland bring secretions to the circulatory system

Exocrine Exocrine GlandsGlands

Contain ducts (except for ________ cells)

Have local effect. Discharge secretions via ducts directly into nearby areas. Secretions act locally and do not

enter into the circulatory system

Examples of secretions:SalivaBilePancreatic and liver digestive

enzymesSweatEgg/Sperm

Unicellular Exocrine Unicellular Exocrine Gland:Gland:

Goblet Cell Goblet CellOnly unicellular exocrine gland

_____less

Composed of a modified ___________ epithelial cell.Found interspersed among the

columnar cells of the respiratory and digestive tracts and conjunctiva of eye

Secretes _______: (polysaccharides, proteins, and glycoproteins) when mixed with water →

mucusMucus functions to protect and

lubricate the apical surface of the epithelial cell and traps microorganisms and foreign particles

Multicellular Exocrine Glands

Contain 2 distinct components:

1) ___________ Unit Secretory cells usually surrounded by connective tissue rich in

blood vessels and nerve fibers that provides nourishment and structural support to the unit.

2) ________carries secretion to its deposit site

_____epithelial cells may be present that assist with the discharge of secretions into the glandular duct.

Rate of secretion production is controlled by hormonal and nervous influences.

Classification of Multicellular Exocrine Glands: Shape

Based on shape and number of tubes

If main duct is unbranched, the gland is ________

If main duct is branched, gland is __________

If secretory cells form a long channel of even width, gland is _________

If cells form a rounded sac, it is _________ or acinar

Glands with both tubular and alveolar qualities are tubuloalveolar or tubuloacinar

Classification of Exocrine Glands: Manner of secretion How much of a cell is sacrificed in the act of

secretion determines its classification:

_______________Glands package their secretions and release them

via exocytosis as they are manufactured Secretory cells remain intactMajority of glands

_______________Glands store their secretions in the apex of the

secretory cell after they are manufactured. When apex is full, it is pinched off and released with the secretions into the duct system. Cell is repaired and process is repeated.

________________Glands store their secretions until they are

needed. The cell lyses, releasing its contents. Cell dies and is replaced via mitosis.