Chapter 4 - Bio 2870 - CHAPTER 4 There are only 4 general...

Info icon This preview shows pages 1–2. Sign up to view the full content.

CHAPTER 4 - There are only 4 general types of tissue found in the human body: epithelial, connective, muscle, and nervous tissue . Epithelial Tissue – do not have a lot of intercellular matrix and is classified by its cells - can be found in two forms: 1. Epithelial linings (skin, internal lining of digestive system, body cavities) 2. Epithelial Glands which are modified epithelial cells (sweat glands, sebaceous glands which release oil, carotid gland, pituitary gland). Internalized epithelia will form glands. A gland forms when a plasma membrane invaginates inward inside a cell, but never pinches off to form a vesicle. Any gland of your body is derived from epithelial cells. Important characteristics of Epithelial tissue: - Epithelial tissue is cellular - tissue is made up of cells bound together. - Epithelial cells are polar - they look different on one end than they do on another. - Epithelial tissue is avascular - does not have its own blood supply and is far away from capillaries. - Epithelial tissue is very regenerative – there are stem cells located deep down in the interior of the skin that can give rise to new skin cells. Functions of Epithelial Tissue: - They form a physical protective barrier to the environment ( Ex: Skin). It is a selective barrier and allows certain things to pass/not pass through. - Epithelial Tissue is loaded with sensory structures ( Ex: Temperature, Pain, Vibration, etc). - Very common function of epithelial tissue is secretion ( Ex: The serous membrane that line body cavities.) and absorption . ( Ex: Small intestine we have epithelial cells absorbing various nutrients during digestion) Epithelial Tissue Modifications APICAL SURFACE MODIFICATIONS - The upper surface of the cell is the Apical Surface . (Area that faces the lumen or the external environment). Epithelial tissue also contain Apical Surface Modifications which include: 1. Cilia which contain microtubules and are motile . Cilia are considered cytplasmic extensions of the cell. 2. Microvilli contain actin filaments (microfilaments) which increase the surface area of the cell for absorption and secretion. Microvilli also function for structural support, are non- motile, and are considered cytoplasmic extensions of the cell. Many microvilli are especially located in the Gastrointestinal (GI) tract. Stereocillia are NOT a type of cilia. They are a long type of Microvilli (contain microfilaments). - As cells move up towards the surface of the skin, they eventually die, and release a protein called keratin. This leads to Keratinization (cornification) of the skin’s surface of skin. (A layer of protein called keratin on surface of skin). This is not an apical surface modification because it is not a physical extension of the cell. It is just stuff laying on the surface.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern