chapter 4 tissues: living communities. cells of similar ____________ and _____________ cluster...
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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.
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