Histology: The Study of Tissues

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Histology The Study of Tissues

• Mrs. Hartley
• Anatomy and Physiology

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Types of Tissues

• Epithelial Tissue Covering and Lining
• Connective Tissue Support and Manufacture
• Muscle Tissue Movement
• Nerve Tissue Signaling and Support

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Epithelial Tissue

• Cells closely joined together with little or no
  intercellular material between cells
• Blood vessels cannot penetrate between them
  therefore they are avascular
• Covers body surfaces, lines body cavities and
  organs and forms glands
• May perform secretion, absorption, and serve as
  protection in certain areas

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Covering Lining Epithelium

• Cover external body surfaces and lines inner
  walls of cavities and organs
• Cells are stationary and anchored by their basal
  surfaces
• 3 general shapes can are recognized
• Squamous flat
• Cuboidal cube-shaped ( in height width)
• Columnar cylindrical (greater in height)
• Two cell arrangements
• simple single layer
• stratified multiple layers

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Simple Squamous

• Simple one layer
• Squamous flat
• Flattened cells arranged in a single layer
• Centrally located nucleus
• Found where layers must be thin to permit
  diffusion of materials
• Lines the walls of blood vessels, forms walls of
  capillaries, forms walls of air sacs in lungs,
  linings of the body cavities
• Outermost section of frog skin viewed from the
  top

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Simple Cuboidal

• Single layer of cube-shaped cells
• Centrally located nucleus
• Often contain cilia and/or microvilli along their
  free border
• Forms the walls of small tubes, or ducts, that
  carry secretions from one part of the body to
  another
• i.e. kidneys, liver, and many glands

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Simple Columnar Epithelium

• Single layer of elongated, cylindrical cells
• Nuclei lie near basement membrane
• Frequently secrete a product (abundance of ER and
  Golgi)
• Lining the walls of the uterus and digestive
  organs such as the stomach and small intestine
• Small intestine microvilli

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Pseudostratified Columnar

• Appears multi-layered but is not
• Uniformity among cell shapes and locations of
  nuclei
• Long cilia that create currents for the movement
  of mucus
• Lines parts of the respiratory tract such as the
  trachea and bronchi

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Transitional Epithelium

• Multiple-layered arrangement of cells of cubelike
  or irregular shape
• Have the capacity to expand in size and recoil
  giving the tissue the ability to stretch
  (elasticity)
• Lines the insides of organs that require
  elasticity and extensibility for normal function
• Urinary bladder and the ureters (tubes that
  travel from the kidneys to the bladder)

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Left Empty BladderRight Full Bladder
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Glandular Epithelium

• Closely packed cells highly specialized to
  manufacture and secrete products
• Particular type gland
• Exocrine glands empty their products into ducts
  which transport the product onto the body surface
  or into a cavity where it will provide some
  benefit (sweat, oil, salivary)
• Endocrine glands secrete their products into the
  extracellular space and into the bloodstream
  where it is distributed throughout the body
  (pituitary, thyroid, adrenal, the endocrine
  system)

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Exocrine GlandsLeft Salivary GlandsRight
Sweat Glands
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Endocrine GlandsLeft PituitaryRight Bottom
Adrenal Glands
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Stratified Squamous

• Multi-layered arrangement of flat cells
• Covers areas of the body that take constant wear
  and tear and must resist that wear and tear
• Surface layer is squamous, deepest layers may
  have cuboidal or columnar cells that have become
  flattened
• Outer layer of skin to protect from abrasions

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Your Assignment

• Create a picture atlas of tissues.
• You will be able to use this atlas on the test!
  So make it good!
• Each page will have the tissue name, the
  function, location, and a picture.
• You may use the text or this slideshow which is
  found on my website.
• You will be graded by test and by completion of
  the atlasdo not get behind!