Chapter #6: Interactions Between Cells and the Extracellular Environment

Extracellular Environment

area surrounding cells that consists of a fluid compartment in which molecules dissolve

Intracellular Compartment

All of the material inside of cells

Extracellular Compartment

All of the material outside of cells, including the extracellular fluid with all of its solutes, insoluble protein fibers, and, in some cases, crystals

Extracellular Matrix

The extracellular material of connective tissue, consisting of varying proportions of extracellular fluid, a gel-like ground substance, and extracellular protein fibers, including collagen

What are the components of the extracellular matrix?

Collagen, elastin, and ground substance

Diffusion

Net movement of molecules from a high to low concetration

Osmosis

Diffusion of water across a selectively permeable membrane

Example of diffusion

O² moving into the cell until there is equal concentration

What are the factors that affect the rate of diffusion?

Magnitude, permeability, temperature, surface area, and size of molecule

Why is the plasma membrane said to be semi-permeable?

Because it only allows certain kinds of molecules to pass into the cell

Non-carrier Mediated Transport

Occurs by diffusion through the membrane (simple diffusion)

Example of simple diffusion

O² moving into the cell

Carrier-mediated transport

helps non-permeable molecules enter the cell by carrying it

Example of facilitated diffusion

Na⁺ needs to be carried since it has a charge

Primary active transport

occurs when the hydrolysis of ATP is directly responsible for the function of the carriers

Secondary active transport

uses the electrochemical gradient of one ion to drive the transport of another ion or molecule against its concentration gradient, without directly using ATP

Active transport pump

Pushes molecules against their gradient

Mole

How is a mole related to Avogadro’s number?

1 mole = Avogadro’s number

How is the mole related to the molecular weight (mw) of a compound in grams?

1 mole = molecular weight of a compound in grams

Molarity (M)

1 mole of solute dissolved in 1L of solution (does not specify exact amount of water)

Molality (m)

1 mole of solute dissolved with 1L of solution (amount of water is specified)

Osmolality (Osm)

Total molality of a solution

What is Osm related to the freezing point of a solution?

(Osm) x (-1.86) = freezing point

What is the Osm of blood?

range around 300 mOsm

Isotonic

Solutions have same osmotic pressure

Hypertonic

Solutions have higher osmotic pressure and are osmotically active

Hypotonic

Solutions have lower osmotic pressure

How does the body regulate blood osmolality?

By increasing water retention and water intake