Transcript Tissues: Living Communities

Tissues: Living Communities
Chapter 4
 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 _________
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 _____________.
 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
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.
 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
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.
Simple Squamous Epithelium
 Flat and smooth; reduce friction
 Often found lining surfaces involved
in the passage of either _____ or
________
 ENDOTHELIUM, KIDNEYS, ALVEOLI
OF LUNGS
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 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
 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
Glandular
Epithelia
 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
 NO DUCTS (cells die)
 Produce and secrete _____________.
 Blood stream delivers secretions to entire
body
 ___________ within the gland bring
secretions to the circulatory system
Endocrine 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
 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
Unicellular Exocrine Gland:
Goblet Cell
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 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.