Term
| Molecules Active vs Passive Diffusion |
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Definition
Passive diffusion: hydrophobic and uncharged molecules (small)
Turned Away- Uncharged molecules (large), Ions
Remember- lipid soluble passively diffuses, non-lipid soluble diffuse through pores |
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Term
| Rate of diffusion depends on: |
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Definition
| permeability and concentration gradient |
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Term
| Simple Diffusion Includes |
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Definition
Pores (non-gated channels) or
Channels (gated channels)
-these are integral proteins--size, hydration energy and charge impact diffusion |
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Term
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Definition
| Molecules of H2O bind to the solute which changes the size, making it to large to fit through the pores. |
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Term
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Definition
| Pore or channel may be lined with anion molecules which block other molecules from passing through. |
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Term
| Carrier Assisted Diffusion |
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Definition
-aka Passive Mediated Diffusion
The Carrier is a conduit that is gated by two 'doors' that are never open at the same time.
Steps:
1. Carrier is open to the outside
2. When a molecule enters, it binds to a binding site inside of the carrier
3. The outer door closes and then the inner door opens
4. the molecule exits the carrier and enters the inside of the cell
5. The inner gate closes and the outer gate opens again
- This process flows from high concentration to low concentration
-Molecules that bind to the extracellular side may have an affinity for it
-No energy used |
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Term
| Carrier mediated Diffusion can be affected by: |
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Definition
Concentration Gradient
Prevalence of the carriers
Competitive and non-competitive diffusion |
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Term
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Definition
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Term
| Active Mediated Transport |
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Definition
Works against the concentration gradient
Relies on use of ATP and ATPase
1. ATP is bound to the NA-K Pump
2. 3 Na+ molecules approach and enter the pump
3. They are bound to binding sites inside of the pump
4. ATP is hydrolyzed, which phosphorylates the alpha subunit on the pump
5. This phosphorylation of the pump results in a confirmational change that closes the cytosolic side of the pump and opens the extracellular space, which allows Na+ to exit the pump
6.Ouabain bind to the pump and changes the confirmation of the pump, which can now accept K+
7. K+ ions approach and bind to the sites
8. The phosphate leaves, which changes the confirmation of the pump
9. new ATP binds, opening the cytosolic end of the pump, and K can leave |
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Term
| Active Mediated Transport facts |
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Definition
Indirect or secondary active transport
Moves uphill, against the concentration gradient
Can use ATP in a secondary process by pushing Na+ with another molecule such as glucose. Then the Na+ is pumped back out of the cell by the ATPase pump, which directly uses ATP |
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Term
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Definition
-Force of diffusion acting on water
-Water moves towards salt
-Hydrostatic force opposes osmosis
-Two fluids with different osmotic concentrations and separted by a water permeable membrane cause diffusion of water toward the higher osmotic concentration |
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Term
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Definition
-gradient or diffusion
-acts to equalize the concentration of each type of particle
-can be imbalance by other forces such as hydrostatic |
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Term
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Definition
-Acts to balance number of positive and negative charges
-Imbalance exists if balanced by a concentration force--represented by the Nernst Equation |
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Term
| Equilibrium Concentration for Na+ |
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Definition
| More when Na+ is OUTSIDE the cell membrance |
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Term
| Equilibrium concentration for K+ |
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Definition
| More when K+ is INSIDE the cell membrane |
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Term
| Equilibrium concentration for Cl- |
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Definition
| More when Cl- is OUTSIDE the cell membrance |
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Term
| Equilibrium concentration for Ca2+ |
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Definition
| More when Ca2+ is OUTSIDE the cell membrance |
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Term
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Definition
V=-60 x log(Ci/Co)--however make it +60 when working with anions like Cl-
-The nernst equation represents balance of charges and concentration of a particular molecule.
-In other words it calculates what the potential is of a molecule when it is at equilibrium |
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Term
| Why is the resting membrane potential so close to the nernst potential for K+? |
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Definition
| K is the most permeable to K+ so the resting potential is highly effected by potassium |
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Term
| What has large effects on membrane potential? |
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Definition
-Negatively charged things--most proteins
-sodium/potassium pump which distributes these two molecules
-high permeability to K, less so for Na |
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Term
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Definition
| Small increase (more positive) in the membrane potential, but not up to -55mv, so not enough to start an action potential. However a graded potential may reach -55mv which will then turn into an action potential |
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Term
| Propagation of an action potential |
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Definition
| Reaching -55mv causes voltage gated sodium channels to open and sodium floods into the axon. Inactivation gates begin to close, but not before the charge on the inside of the cell is so positive that it triggers the next set of sodium gates down the axon. This process also causes K+ to leave the cell through potassium channels which makes the cell less positive, and going into a repolarization state |
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Term
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Definition
| Autoimmune disease that attacks myelin sheaths. As a result K+ gets pushed out of the membrane and action potentials dissipate, unable to propagate down the membrane |
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Term
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Definition
| Damage is caused to the myelin sheath, and stops or slows down action potentials. Nerve damage is caused by inflammation . |
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Term
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Definition
1. Action potential (AP) moves into the presynaptic terminal
2. AP causes a depolarization of the pre-synaptic terminal which results in Ca2+ gates to open and allow Ca2+ into the presynaptic terminal
3. The Ca2+ causes vesicles (that hold neurotransmitter in them) to fuse with the membrane of the pre-synaptic terminal
4. The NT's are released into the synaptic cleft, and move across the cleft to bind with receptors
5. These receptors cause a confirmational change in post-synaptic cell channels which open up and allow ions to flow through. Could be excitatory channels that allow Na+ which could begin another action potential or could be inhibitory channels letting K+ out and making the potential of the cell more negative, preventing an action potential |
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Term
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Definition
1. ATP binds to the Myosin Head (actually an ATPase)
2. The myosin detaches from the actin due to ATP attaching
3. ATP hydrolyzes (ATPase on myosin head pulls a phosphate off of the ATP, which releases energy. Phosphate bonds hold large amounts of energy so when the bond is broken, energy is released)
ATP Hydrolysis= ATP--> ADP+ Pi (inorganic phosphate and Adenosine Diphosphate)
4.The hydrolysis gives the energy to 'cock' the myosin head back, changing the confirmation of it. ("Spring loaded")
5. Phosphate releases from the myosin, and the energy from that causes the myosin to contract (called the power stroke) and pushes on the actin filament
6. ADP released and there is an opening for more ATP to bind and start process over |
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Term
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Definition
1. ATP binds to the Myosin Head (actually an ATPase)
2. The myosin detaches from the actin due to ATP attaching
3. ATP hydrolyzes (ATPase on myosin head pulls a phosphate off of the ATP, which releases energy. Phosphate bonds hold large amounts of energy so when the bond is broken, energy is released)
ATP Hydrolysis= ATP--> ADP+ Pi (inorganic phosphate and Adenosine Diphosphate)
4.The hydrolysis gives the energy to 'cock' the myosin head back, changing the confirmation of it. ("Spring loaded")
5. Phosphate releases from the myosin, and the energy from that causes the myosin to contract (called the power stroke) and pushes on the actin filament
6. ADP released and there is an opening for more ATP to bind and start process over |
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Term
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Definition
| Tropomyosin is a 'string' that surrounds the acting filaments. Ontop of the tropomyosin are small proteins called troponin. If you have a high calcium ion concentration will bind to the troponin, which changes the confirmation of the troponin which moves the tropomyosin, exposing binding sites for myosin heads to attach to the actin. If there is low Calcium concentration the troponin will go back to standard confirmation which recovers the binding sites with tropomyosin. |
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Term
| Difference between ionotropic and metabotropic postsynaptic receptors |
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Definition
Ionotropic- fast and direct--when a neurotransmitter binds to it, a confirmational changes happens and opens an ion channel
Metabotropic- slower and indirect--NT binds to the receptor, causing a confrontational change. G-Protein (on the inside of the cell) binds to the receptor. Once it is bound, the GDP that was already inside of the G-protein is exchanged for GTP, releasing the G-protein. The G-protein separates into its sub-componenets, the alpha components splitting from the beta and gamma component. The now active components bind to adenylyl cyclase, which in turn produces lots of cyclic-AMP. This process is amplification--> one molecule binding causes the creation of several |
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Term
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Definition
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Term
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Definition
Primary Excitatory NT of CNS
doesnt cross blood brain barrier
Stroke can leave a large concentration of glutamate in the synaptic cleft that can result in cell death due to excitation |
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Term
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Definition
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Term
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Definition
| Compression of the nerve. May block conduction. Loss of function, but no structural damage occurs |
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Term
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Definition
| Axon is interrupted, but the myelin sheath is maintained. Distal degeneration occurs. Could be caused from pressure or ischaemia |
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Term
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Definition
| Loss of continuity of axon, sheath and funiculus. Distal nerve degeneration. Need surgery to repair. |
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