2. Cells & Tissues

Cell materials can be located in 2 locations parts of the cell. What are these 2 different locations?

Intracellular & extracellular

What are intracellular materials?

Cell materials found inside of the cell membrane (ex. cytoplasm, organelles & inclusions, like fat, hemoglobin, glycogen, keratin, etc)

What are extracellular (INTERcellular) materials?

Materials outside of the cell’s membrane or in between cells in a tissue. Can also be found in body cavities

What are the 5 components of extracellular material?

1. Fluid

2. Matrix

3. Proteoglycans

4. Fibers

5. Attachment proteins

A component of extracellular material is fluid. What can be found in this fluid?

Water, other stuff (inorganic materials) dissolved in those fluids, & small organic molecules (ex. glucose, amino acids, etc.)

A component of extracellular material is the matrix. What is the matrix?

Stuff (proteins & polysaccharides) that is secreted by the cells of a tissuehaW

What are the 6 functions of the matrix?

1. Determines physical properties of a tissue

2. Stabilizes physical structure of tissue

3. Regulates cell division

4. Regulates cell migration

5. Regulates cell proliferation (growth & division)

6. Keeps cell shape for their specific functions

A component of extracellular material is proteoglycans. What are 2 examples of these proteoglycans?

Hyaluronic acid, glycosaminoglycans (GAGs)

The structure of a proteoglycan looks very similar to what?

Fuzzy caterpillars

1. Where are proteoglycans found?

2. What is their function?

1. Between cells & in other connective tissues

2. Lubricate joints & cushion bone contact points

A component of extracellular material are fibers. What are the 3 different types of fibers that could be in extracellular material?

1. Collagen fibers

2. Elastic fibers

3. Reticular fibers

A component of extracellular material are attachment proteins. What are attachment proteins?

Non-collagen proteins that organize the matrix & help cells attach to the matrix

1. What is cell adhesion?

2. What is cell-cell adhesion?

3. What is cell-matrix adhesion?

1. Cells being able to stick to each other or molecules in their environment

2. Cells sticking to cells

3. Cells sticking to the matrix

What allows cells to adhere to each other & to the extracellular matrix?

Cell adhesion molecules (CAMs)

What are the 4 functions of cell adhesion molecules (CAMs)?

1. Guiding the movement of cells during embryonic development

2. Guiding the movement of cells during wound repair

3. Attach cells to each other & to the matrix

4. Help to control cell shape

What are the 3 types of cell-to-cell adhesion?

1. Tight junctions

2. Desmosomes

3. Gap junctions

What are tight junctions?

Type of adhesion where 2 cells are held so tightly together that it forms an impermeable barrier, so that fluids can’t between them

What is the function of tight junctions?

Forming an impermeable barrier so fluids can’t pass between 2 cells

1. Generally, when would you find a tight junction?

2. What 3 structures would you find tight junctions?

1. Found in areas where diffusion between cells is unwanted (where you WANT to keep things separate)

2. Intestine, kidney, urinary bladder

What are desmosomes?

Type of adhesion that hols cells tightly together, but does not form an impermeable barrier

What is the structure of desmosomes?

Interlinker proteins are attaches to thickenings (thick parts) in the plasma membrane called plaques (like ropes attached to the cell)

What is the function of desmosomes?

Helps 2 cells stay in place when they are being pulled apart

What 3 structures would you find desmosomes in?

1. Between cells in the skin

2. Muscle

3. Cervix of the uterus

What are gap junctions?

Type of adhesion that allows for a small opening from 1 cell to another to allow them to communicate by passing materials through

What is the function of gap junctions?

To hold cells together, but also allow ions to pass directly from cell to cell

What are 3 places you can find gap junctions in the body?

1. Between embryonic cells for nutrient transfer

2. In muscle cells for rapid transfer of electrical signals

3. In nerve cells for rapid transfer of electrical signals

Why would heart muscle cells (cardiomyocytes) be connected by gap junctions and desmosomes?

• Gap junctions have a small gap to allow ions to pass through. In cardiomyocytes, having a gap junction allows electrical signals—the signals that allows the heart to contract—to pass from one cell to another. The heart pumps as one unit rather than individual cells

• Desmosomes keep the cell together despite pulling. In cardiomyoctes, desmosomes hold adjacent cells together to resist pulling apart during contraction