1. Cell Connections
Chapter 4

2. 4 major types of tissues
Epithelial tissue- Covers surface of body, lines hollow organs and body cavities. Ex: Skin and stomach tissue
Connective tissue- Holds organs in place, protects and supports body. Ex: Tendons and ligaments
Muscular tissue- Generates physical force and movements. Ex: Biceps, quadriceps
Nervous tissue- Helps control and coordinate body movement by detecting changes and responding with nerve impulses. Ex: Brain and spinal cord

3. To function in a coordinated way as part of a tissue, cells must have cell junctions.
Cell junction- points of contact between neighboring plasma membranes.
Imagine trying to build a house with nothing to hold the lumbar, roof, and walls together.

4. Plant cells
Plasmodesmata- Channels between adjacent plant cells. They form a circulatory and communication system connecting the cells in plant tissues.
*Helps water and small molecules pass easily from cell to cell.

5. Animal cells
Adjacent cells in animal tissues also connect by cell junctions; there are three types:
Tight junctions
Anchoring junctions
(desmosomes)
Gap junctions

7. Tight junctions Bind cells very tightly together
Forms a leakproof sheet
Prevents passage of materials
Lines digestive tract, preventing
contents from leaking into surrounding tissues.

8. Anchoring junctions
Strongly link cells together with cytoskeletal fibers
Forms strong sheets
Common in tissues that have to stretch, such as skin and heart muscle.
Helps keep skin cells from separating
Ex: Desmosomes

9. Gap junctions Channels similar to plasmodesmata in plant cells
Allows small molecules to flow between neighboring cells.
Important for chemical communication.