Ch 4 Book notes.docx - 1 Chapter 4 The Tissue Level of Organization 4-1 Identify the body’s four basic types of tissues and describe their roles Four

Ch 4 Book notes.docx - 1 Chapter 4 The Tissue Level of...

This preview shows page 1 - 3 out of 16 pages.

1 Chapter 4 : The Tissue Level of Organization 4-1 Identify the body’s four basic types of tissues and describe their roles. Four types of tissues are epithelial, connective, muscle, and neural Tissues are specialized cells and cell products that perform a limited number of functions Histology is the study of tissues. 4-2 Describe the characteristics and functions of epithelial cells. Epithelial tissue includes epithelia and glands 1. Epithelia are layers of cells that cover internal or external surfaces the cells are bound closely together a free (apical) surface exposed to the environment or to an internal chamber or passageway attachment to underlying connective tissue by a basement membrane the absence of blood vessels. They are avascular, so epithelial cells must obtain nutrients across their attached surface from deeper tissue or across their exposed surfaces they continue to replace/regenerate epithelial cells that are damaged or lost at the exposed surface epithelia cover both external and internal body surfaces (in addition to covering skin) ex. Digestive, respiratory, reproductive and urinary tracts epithelia line internal cavities surrounding lungs and heart, etc. they help to prevent friction, regulate fluid of internal cavities, and restrict communication between the blood and tissue fluids 2. Glands are composed of fluid-secreting cells derived from epithelia Functions of Epithelia 1. Provide physical protection Protect against abrasion, dehydration, and destruction by chemical and biological agents Ex. Epithelium of skin restricts water loss, and prevents bacteria from invading structures 2. Control permeability Any substance that enters or leaves the body must cross an epithelium
Image of page 1

Subscribe to view the full document.

2 Chapter 4 : The Tissue Level of Organization Some are impermeable, others can be crossed easily by large compounds e.g. proteins 3. Provide sensation Can detect changes in environment and send information to nervous system Ex. Touch receptors in deepest layers of epithelium of skin respond to touch by stimulating neighboring sensory nerves 4. Produce specialized secretions Exocrine – secretions are discharged onto the surface of the epithelium Ex. Enzymes entering digestive tract, perspiration on skin, and milk produced by mammary glands Endocrine – secretions are released into the surrounding tissue fluid and blood. Also known as hormones, act as chemical messengers and regulate or coordinate activities of other tissues, organs, and organ systems o Endocrine secretions are produced in organs like pancreas, and thyroid and pituitary glands Intercellular Connections o To be effective in protecting other tissues, epithelial cells must remain firmly attached to the basement membrane and to one another to form a complete cover or lining. If an epithelium is damaged or the connections are broken, it is no longer an effective barrier.
Image of page 2
Image of page 3
  • Winter '08
  • Spranger

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

Ask Expert Tutors You can ask bonus questions You can ask questions ( expire soon) You can ask questions (will expire )
Answers in as fast as 15 minutes