Lecture Exam 2 (Set 1)
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- Four factors affecting PERMEABILITY:
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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:
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--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:
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-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
- Equilibrium:
- When no net movement-all movement is equal
- Factors that effect DIFFUSION:
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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:
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-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 - Specificity:
- When carriers will only move one kind of thing across membrane
- Co-transport:
- When more than one thing is transported across the membrane at the same time
- Symport:
- Moving in same direction at same time
- Antiport:
- Moving different things in opposite directions at same time
- Primary active transport:
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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:
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-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 - Phagocytosis:
- Moving into cell "cell eating"
- Pinocytosis:
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Moving into cell
Requires ATP - Receptor mediated endocytosis:
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Moving into cell
Requires ATP - Exocytosis:
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Moving out of cell
requires ATP - Osmosis:
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-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
-passive
-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 - Solution:
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Solvent + Solute
Amt of What was added
H2O - Concentrations:
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If more particles of solute= less water
If more water= less particles
H2O concentration differs because solute concentration differ - Osmotic pressure:
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-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 - Osmolarity:
- number of moles of solute particles per liter of solution
- Molarity:
- number of moles of substance per liter of solution
- Isosmotic:
- same--equal number of solute particles in two solutions--no net movement
- Hyperosmotic:
- more--larger number of solute particles than other solution
- Hyposmotic:
- less--fewer number of solute particles, but has more H2O
- Tonicity:
- classified solutions based on what they do to cell size
- Isotonic:
- cells stays same size
- Hypertonic:
- H2O leaves and cell shrinks (crenation)
- Hypotonic
- Cell size increases, water goes into cell
- Lysis:
- 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:
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--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 - Paracrine:
- Chemicals released effects other nearby cells
- Autocrine:
- Chemicals released effects cells that released them
- Can chemicals do both paracrine and autocrine functions?
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Yes, most can with stimulation
ex: mast cells release histamine--effect blood vessels - Cytokines:
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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:
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-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:
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-both electrical and chemical
--electric: graded potential
action potential
--chemical:
neurotransmitters
neuromodulators
neurohormones - Neurotransmitters:
- signal nearby cell
- Neuromodulators:
- nearby cell effects are different
- Neurohormones:
- released by neurons but get into blood and go everywhere
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