Tissues: Living Communities

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Tissues Living Communities

• Chapter 4

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• 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 _________

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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 _____________.

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• 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

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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.

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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.

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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.

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Simple Squamous Epithelium

• Flat and smooth reduce friction
• Often found lining surfaces involved
• in the passage of either _____ or ________
• ENDOTHELIUM, KIDNEYS, ALVEOLI OF LUNGS

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Simple Cuboidal Epithelium

• Round, dark-staining nuclei
• aligned in a single row
• GLANDS (endocrine and exocrine) salivary glands,
  ovaries, liver, kidneys, pancreas

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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

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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)

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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

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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

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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

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• 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

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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

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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

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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

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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.

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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

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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.

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