1. Tissues: Living Communities
Chapter 4

2. Cells of similar ____________ and _____________ cluster together to form tissues.
Epithelial tissue
Covers and lines
Connective tissue
Provides support
Muscle tissue
Enables movement
Nervous tissue
Controls work
The study of microscopic structures of tissues and organs is called _________

3. Characteristics of Epithelia
Sheets 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 environment
Basal surface faces the underlying connective tissue
All epithelial cells are ______________.
Rely on underlying connective tissue for oxygen and nutrients
Most epithelial cells are _____________.

4. Tight junctions Desmosomes Gap junctions
Junctional Complexes – specialized attachments between epithelial cells on their lateral surfaces. They connect via plasma membranes.
Tight junctions
Prevent ____________
Ex: Bladder
Desmosomes
Tough, resist __________ and
stretching (like Velcro). Consist of
intermediate fibers
Ex: Uterus
Gap junctions
Cytoplasm continuous between cells
Linked by tubular channel proteins called _______________.
Allow exchange of ions, nutrients, and transport signals
Ex: Cardiac muscle

5. Epithelial Cells: Basement Membrane
Foundation of epithelial cells
Meshwork of fibers that cements epithelial cell to underlying ___________________ tissue (CT)
Helps to prevent the epithelial cell from being torn away
Also 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.

6. 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.
Surface Specialization

7. Classifications of Epithelia
Number of cell layers.
Single layer is called __________
More than one layer is called __________
Shape of cells
Based on shape that is on exposed or _________ surface
Squamous, cuboidal, and columnar
Presence of surface specializations
Keratinized, ciliated, etc.

9. Simple Squamous Epithelium
Flat and smooth; reduce friction
Often found lining surfaces involved
in the passage of either _____ or ________
ENDOTHELIUM, KIDNEYS, ALVEOLI OF LUNGS

10. Simple Cuboidal Epithelium
Round, dark-staining nuclei
aligned in a single row
GLANDS (endocrine and exocrine): salivary glands, ovaries, liver, kidneys, pancreas
Simple Cuboidal Epithelium

11. 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

12. 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)

13. 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

14. Transitional Epithelium
Stratified epithelium
Basal layer of cuboidal or columnar cells
Superficial layer of cuboidal cells (domelike)
Ability to _______
URINARY TRACT
leak-proof
As epithelia stretches, layers often thin depending on how much volume is present

15. 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 utero
A layer of epithelial cells folds inward (___________).
Form __________ that lead to the epithelial surface
Some glands (__________) lose the duct and become separated from the original epithelium

16. Glands can be classified by the following factors:
Presence or absence of ducts
Endocrine vs. Exocrine
Number of cells that compose them
Unicellular vs multicellular
Shape of secreting ducts
Simple or compound
Complexity of glandular structure
Tubular, acinar, tubuloacinar
Type of secretion made
Mucoid or serous
Manner in which secretion is stored and discharged
Merocrine, apocrine, or holocrine

17. Endocrine Glands NO DUCTS (cells die)
Produce and secrete _____________.
Blood stream delivers secretions to entire body
___________ within the gland bring secretions to the circulatory system

18. Exocrine Glands 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:
Saliva
Bile
Pancreatic and liver digestive enzymes
Sweat
Egg/Sperm
Exocrine Glands

19. Unicellular Exocrine Gland: Goblet Cell
Only 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 → mucus
Mucus functions to protect and lubricate the apical surface of the epithelial cell and traps microorganisms and foreign particles

20. 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.

21. 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

22. 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 intact
Majority 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.