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45 Cards in this Set

  • Front
  • Back
Four factors affecting PERMEABILITY:
1. size--bigger=harder
2. soluability in lipid
3. ionic charge of molecule
a. bigger charge=bigger hydration shell
b. proteins--the charge
4. presence or absence of transport protein for that molecule
Passive transport:
Does NOT have to use energy (ATP) to move across membrane
Characteristics of active transport:
--Does use ATP to move across membrane
--can move against concentration gradient
--has to transport proteins
--carriers will be: specific, competitive, saturated
--sometimes more than one thing is transported at same time---co-transport
Characteristics of DIFFUSION:
-does not require a cell
-net movement of molecules from area of high concentration to area of low concentration
-movement is random
-change direction more often on side with more
-more will move from area of high concentration to low concentration
Concentration gradient:
Two adjacent areas and one has higher concentration than the other
When no net movement-all movement is equal
Factors that effect DIFFUSION:
1. permeability of membrane to substance; lipid soluble or water soluble.
2. size of concentration gradient
3. dimensions of pathway (cell membrane)
-microvilli will increase it
-thickness of plasma membrane=harder to get through
-surface area
4. molecular weight/size of molecule
-larger size=less diffusion
- O2, H2O, CO2 all thru easily
Facilitated diffusion:
-diffusion helped--carrier proteins will help molecule get across membrane
-no energy required
-carriers are specific
-competition--other substances will try to compete
-can be saturated
When carriers will only move one kind of thing across membrane
When more than one thing is transported across the membrane at the same time
Moving in same direction at same time
Moving different things in opposite directions at same time
Primary active transport:
When you spend ATP as the first transport occurs

Ex: sodium potassium ions Na+ K+ (Na+ K+ pump)

moves 3 Na+ out of cell
moves 2 K+ into cell

---for every 1 ATP cell uses
Secondary active transport:
-initial movement is coupling diffusion of one molecule to transport of another molecule against its concentration gradient
--use energy in different place to transport diffused item back out
Moving into cell "cell eating"
Moving into cell

Requires ATP
Receptor mediated endocytosis:
Moving into cell

Requires ATP
Moving out of cell

requires ATP
-NET movement of H2O from area of high H2O concentration to area of low H2O concentration
-H2O will move to dilute area that is more concentrated
-does not require energy at all times
-there is chemical disequilibrium between cytoplasm and extracellular
-uses energy to maintain disequilibrium
-H2O can easily move into different body compartments/across plasma membranes
-water moves to restore osmotic equilibrium
Solvent + Solute

Amt of What was added
If more particles of solute= less water

If more water= less particles

H2O concentration differs because solute concentration differ
Osmotic pressure:
-driving force for H2O caused by the difference in H2O concentration between solution and pure H2O
-how much pressure would you have to apply to stop or oppose the movement of H2O down its gradient
number of moles of solute particles per liter of solution
number of moles of substance per liter of solution
same--equal number of solute particles in two solutions--no net movement
more--larger number of solute particles than other solution
less--fewer number of solute particles, but has more H2O
classified solutions based on what they do to cell size
cells stays same size
H2O leaves and cell shrinks (crenation)
Cell size increases, water goes into cell
When cell gets so big it explodes
Osmotically active:
Cannot get across
How much water crosses membrane every second?
100x volume of cell in water
Cellular communication:
--gap junctions-- between cells
-cell junction--have protein that extends across cell membranes of two cells and hole down the center
--size limits what can go through
Chemicals released effects other nearby cells
Chemicals released effects cells that released them
Can chemicals do both paracrine and autocrine functions?
Yes, most can with stimulation

ex: mast cells release histamine--effect blood vessels
chemical communication, big variety, can act as paracrine and autocrine, but also get into blood and can effect cells at distance

ex: immune system--interferons
Endocrine system:
-long distance
-only chemicals, hormones
-hormones travel in blood-can go anywhere
-only cells that will respond are ones with receptor for that hormone
Nervous system:
-both electrical and chemical

--electric: graded potential
action potential
signal nearby cell
nearby cell effects are different
released by neurons but get into blood and go everywhere