Term
| About how many different cells are there in the human body? |
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Definition
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Term
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Definition
| Collections of cells and their products working together to perform certain specialized functions. |
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Term
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Definition
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Term
| What are the two broad categories of epithelial tissue? |
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Definition
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Term
| What are the two categories of glands and their general characteristics? |
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Definition
Exocrine - Tissues that secrete onto external surfaces/internal passages (ducts) that connect to the exterior. Examples: sweat and salivary glands.
Endocrine - tissues that secrete hormones or their precursors into interstitial fluid, usually for distribution to blood stream. |
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Term
| What are the four essential functions of epithelial tissues? |
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Definition
1. Physical protection
2. Control of permeability
3. Provision of sensation
4. Production of specialized secretions |
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Term
| How does the epithelium provide protection from physical damage? |
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Definition
| It lines all exposed surfaces of the body and body cavities and protects against abrasion, dehydration, and damage from chemical and biological agents. |
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Term
| How does the epithelium control permeability? |
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Definition
| All substances that enter the body must do so through the epithelium. These tissues have selectively permeable membranes which can be altered and controlled to increase/decrease the permeability of a given substance. |
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Term
| How does the epithelium provide sensation? |
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Definition
| Signals from the special senses originate in modified epithelial tissue that sense changes in pressure or heat and produce a signal that is carried by the nerves to the spinal cord and brain. |
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Term
| Describe some of the common characteristics of epithelial tissue: |
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Definition
- Base and apical surfaces. The base surface anchors the cell. The apical surface faces the exterior space, or is the secretory surface.
- Microvilli or cilia are common on the apical surface.
- Nucleus, Mitochondria, ER, and Golgi |
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Term
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Definition
| The interior diameter of a passageway. |
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Term
| What are the basolateral surfaces? |
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Definition
| The non-apical surfaces - sides and base that give support and anchorage to the cell. |
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Term
| What does polarity refer to in regards to cells? |
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Definition
| Having a structural difference between exposed and attached sides. |
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Term
| What are the three shapes of epithelial cells? |
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Definition
Squamous - flat
Cuboidal - squared
Columnar - tall...like columns |
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Term
| What is a simple epithelium layer? |
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Definition
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Term
| What is meant by stratified epithelium? |
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Definition
| Multiple layers of epithelium. |
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Term
| What are occluding junctions and how do they work? |
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Definition
| These seal the spaces between cells, preventing leakage of fluids and molecules around the sides of the cells. They involve the lipid portions of the cell membrane being tightly bound by interlocking proteins. |
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Term
| What is an adhesion belt, and how does it work? |
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Definition
| These provide extra rigidity and support to epithelial cells. A strong belt of fibers anchors the terminal web to the cell wall and to neighboring cells. |
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Term
| What are gap junctions, and how do they work? |
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Definition
| These are groups of connexons that facilitate the movement of small molecules (especially ions) from one cell to another. They are also important in cardiac muscle. |
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Term
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Definition
| These protein channels are imbedded in the plasma membranes of adjacent cells. The lumens of the channels line up, permitting unhindered movement of ions back and forth from one cell to another. |
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Term
| What are desmosomes, and how do they work? |
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Definition
| These secure neighboring cells together. They included Cell Adhesion Molecules. |
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Term
| What are Cell Adhesion Molecules (CAMs)? |
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Definition
| These transmembrane proteins have a head that sticks out into the extracellular space. The heads from the opposing desmosome on the neighboring head bind together, locking fast adjoining cells. |
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Term
| What is intercellular cement? |
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Definition
| A thin layer of proteoglycans that contain polysaccharide derivatives. These glue neighboring plasma membranes together. |
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