Anatomy and Physiology – Apical Surface Structure Adaptation of Epithelial Cells For Different Functions – Pseudo Stratified Columnar Epithelium

Cells have adaptions to perform functions…. WHAT?

Get To Know What The Hell I’m Talking About:

  • Epithelial Cells cover EVERYTHING, well not really, but it does cover the body surface and lines the hollow organs as well as forming ducts and some other pretty cool things, it can be put into two types: Covering and Lining Epithelium (skin, lining of the blood vessels, ducts and tracts – GI, Urinary, Reproductive and Respiratory) and Glandular Epithelium – thyroid, adrenal and sweat glands .
  • Epithelial Cells are very closely packed and cell junctions make sure that they are securely attached. There is no blood vessels so everything moves by diffusion. Here there is also a super high mitotic rate.
  • These epithelial cells sit on the basement membrane : the  Apical – free surface (top) and the basal surface against the basement membrane (bottom).
    They are classified by their arrangement: Simple(One cell thick), Stratified (two or more layers thick) or Pseudo Stratified (not all the cells reach apical surface but they are touching the basement membrane – nuclei are located at different levels )
    They are also classified by their shape of the surface cells:
    Squamous – flat, Cuboidal – cube shaped, columnar – like columns, transitional – varied shape.

Now that we are on a flat playing field and we all have the basic basic knowledge we can talk further about the cells adaptation for function. While as interesting as it is to know about cell mutations in the body due to adaption, we better save that for another day and focus on The adaption of cells to perform a designated function.

Let’s look at Pseudo Stratified Epithelium –  Ciliated and Columnar :

Epithelial Cells have adapted their surface shape to meet the requirements to perform their function. Pseudo Stratified Epithelium has the nuclei at different levels and appears multi layered and only have the appearance of multiple layers unlike stratified epithelium – which isa actually layered for two or more. These cells are at varied lengths, so not all cells reach apical surface, and those that do will either secrete mucus – goblet cells or have cilia – to sweep away mucus in the Ciliated Columnar Pseudo Stratified Epithelium.  Columnar Cells – protect underlying tissue and are specialised with secretion and absorption (mainly non ciliated columnar) and often have microvilli or cilia.
Ciliated Columnar Pseudo Stratified Epithelium can be found in the respiratory system as well as the epidermis and male urethra. Due to it’s location in the respiratory tract the epithelial cells are adapted so that they can get rid of the foreign particles that get swept in with inhalation.

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