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Epithelial Tissue

Epithelial Tissue. Histology: the study of tissues. Tissues: Simply groups of similar cells that work together performing the same task Greatest form of teamwork in the body. Where are epithelial tissues found?. With few exceptions, organs are composed of four basic tissue types:

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Epithelial Tissue

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  1. Epithelial Tissue • Histology: • the study of tissues. • Tissues: • Simply groups of similar cells that work together performing the same task • Greatest form of teamwork in the body

  2. Where are epithelial tissues found? With few exceptions, organs are composed of four basic tissue types: – Epithelial Tissue – Connective Tissue – Muscular Tissue – Nervous Tissue

  3. Why Study Histology? Knowing the difference between normal and abnormal tissue is the first step in diagnosis and treatment of patients.

  4. Skin, our largest and heaviest organ Epithelial Tissue Muscular Tissue Nervous Tissue Connective Tissue made of all four tissue types

  5. Epithelial Tissue • Makes up 3% of your body weight • Cells don’t move • They don’t send messages • Their cells are all touching one another • Of all tissues, they are the most widely varied in structure and function

  6. Locations of Epithelial Tissues • Covers the body • Found on the inside of hollow organs and the outside of all organs • Found above a connective tissue layer • Lines the cavities, tubes, ducts, and blood vessels inside the body

  7. Epithelial Anatomy • Apical surface – upper surface that is free or exposed to the “exterior” • Basal surface – attached surface (below) • Microvilli – small fingerlike extensions that increase the surface area allowing for more work to be done

  8. Functions of Epithelial Tissue • Protects from physical & chemical injury • Protects against microbial infection • Contains nerve endings which respond to stimuli • Filters, secretes & reabsorbs materials • Secretes fluids to lubricate joints

  9. Three Basic Shapes • Squamous – like scales, or pancakes (“being squashed like a pancake”) • Cuboidal – looks like cubes • Columnar – longer and look like columns

  10. Cell Organization • Simple – single layer of cells; typically found where absorption and filtration occur simple squamous simple cuboidal simple columnar • Stratified – layers of cells; common in areas where protection is needed like the skin stratified squamous

  11. Two Types of Stratified Columnar • Ciliated • Unciliated cilia No cilia

  12. Squamous Epithelium • Simple Squamous Forms solid, single layer of cells lines blood vessels, body cavities and covers organs • Stratified Squamous Forms epidermis and is mostly for protection Found in areas of high friction

  13. Cuboidal Epithelium • Simple Cuboidal • Roughly cube shaped • Line ducts in kidneys where absorption and secretion activities take place. • Very, very rare to have stratified cuboidal

  14. Columnar Epithelium • Simple columnar– one cell thick • rectangular shaped (long and narrow) • Lines digestive tract where absorption & secretion occurs. • White spots are goblet cells which secrete mucous • No stratified columnar

  15. Confusing Epithelial Tissue • Transitional Epithelium – Numerous layers of cells of varying and often irregular shape • Shape of cells depends upon the amount of stretching (ex: bladder)

  16. Confusing Epithelial Tissue Continued… • “Pseudostratified Columnar Epithelium” • Tall rectangular cells, with multiple irregular rows of nuclei. Nuclei are positioned at differing levels • Cells narrow in the area without the nucleus • Located in the trachea; secrete & move mucous Goblet cells secret mucous to aid cilia in moving substances across the cells’ surface

  17. Epithelial Tissue in Review… Epithelial tissues can be found in three types of membranes: Cutaneous, Serous, and mucous membranes.

  18. Mucosa Membranes • Mucus-secreting membranes line tubes; moistens and protects from enzymes and acid (i.e., stomach, trachea, mouth, and vagina) • Membranes are involved in absorption and secretion.

  19. Serous Membranes • Serous membranes line body cavities that do not open directly to the outside • They cover the organs located in those cavities. • Fluid lubricates the membrane and reduces friction and abrasion when organs move against each other.

  20. Cutaneous Membranes • Cutaneous membranes cover the surface of the body. • Consists of stratified squamous epithelium • Cutaneous membranes are thick, relatively waterproof, and dry. • Function = protection

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