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ElectricalSignaling
| Question | Answer |
|---|---|
| What are ions? | Just atoms with a charge |
| How are membrane potentials established? | By ionic charges (electrical gradients) |
| What do changes in charge affect? | Affect membrane proteins such as channels |
| What do other membrane channels allow ions to do? | Allow for ions to flow down concentration gradients, creating a change that can affect other membrane potentials |
| What do excitable tissues have? | Na+ and K+ channels that operate at a threshold level |
| Describe electrical signals | 1. fast 2. specific/localized 3. shocking 4. SOMETIMES used as conveyers of chemical signals 5. SOMETIMES used for coordination among cells 6. SOMETIMES used for integration |
| Describe the characteristics of a traveling electrical charge | 1. non decremental over time & distance 2. All or None 3. Unidirectional 4. occur only on tissues w/ voltage gated Na+ channels 5. Sends signal in 3 diff ways 6. may travel in a 'domino effect' style or in a 'jumping' style |
| A traveling electrical charge sends a signal along in what 3 different ways? | Along... 1. axon & associated axon collaterals of neurons 2. sarcolemma & transverse tubules of muscle cells 3. some glandular cell membranes |
| What exactly is the 'domino style' of a traveling electrical charge? | Local current flow - slower |
| What exactly is the 'jumping style' of a traveling electrical charge? | Saltatory conduction - faster |
| What is the basic process of action potentials? | 1. stimulus cause mem. pot. 2 reach thresh. lvl 2. memb depolarize quickly as Na+ volt gated chans open en masse once thresh. reached 3. memb repolarize as slow reacting K+ volt gated chans open en masse milimoments later 4. resting mem. pot. restore |
| Describe in details what happens at the process action potential formation (PART 1)? | 1. membrane is at rest @ -70mV 2. Excitatory stimulus (mechanical, electrical, chemical) applied & activates corresponding Na+ gated channel 3. Na+ enters in causing slight depolarization (possibly to threshold) |
| Describe in details what happens at the process action potential formation (PART 2)? | 4. If threshold reached, all of voltage gated Na+ chans will open, increasing membrane permeability by 6000 fold 5. The rising phase (after Step 5) - case further depolarization of the membrane to +30mV |
| Describe in details what happens at the process action potential formation (PART 3)? | 6. The falling phase a. slow voltage gated K+ chans open b. K+ flows down its concentration gradient - mem potential falls 7. In meantime, voltage gated Na+ channels have closed (both gates), mem pot. contin to fall as K+ continues its outward flow |
| Describe in details what happens at the process action potential formation (PART 4)? | 8. Slow voltage gated K+ channels start to close, additional K+ diffuse thru during closing, causing membrane potential to hyperpolarize slightly 9. Na+/K+ ATPase restore resting membrane potential |
| According to the action potential graph, what happens at -70mV? | Stimulus applied |
| According to the action potential graph, what happens at -55mV? | Threshold reached |
| What is the peak voltage of action potential? | +30mV |
| When hyperpolarization occurs, what is the voltage? | -80mV |
| What is voltage at RMP (resting membrane potential)? | -70mV |
| T/F - The process of action potentials will occur along the entire length of the excitable cell membrane | True - as long as it has local influx of Na+ which will cause the next adjacent voltage gated chans to open, cascading to the end of the membrane |
| What happens when action potential gets to end of membrane? | 1. Signal tranduced & chemical signal is generated 2. Prior sections of membrane finishes up, getting back to resting membrane potential as K+ effluxes |
| Why are potentials all or none? | 1. Can't increase beyond ALL open 2. If threshold isn't reached, no channels open |
| What is absolute refractory period? | 1. Na+ channels open in the beginning 2. Na+ channels close and K+ channels open |
| What is relative refractory period? | 1. Na+ channels reset to orignal position 2. K+ channels remain open |
| What is the excitability level at absolute refractory period? | ZERO |
| What is the excitability level at relative refractory period? | INCREASING |
| Why are action potentials unidirectional? | 1. voltage gated chans when closed just after depolarization enter into state of inactivity (closed and unable to open) 2. prevents ions from infuluxing into cell from regions that were just affected |
| What are the channel states? | 1. closed and unresponsive - both activation & inactivation gates CLOSED 2. closed and responsive - activation gate CLOSED, inactivation gate OPENED 3. open state - BOTH GATES OPENED |
| The speed of transmission depends on: | 1. membrane/cell characteristics (THICKER = FASTER) 2. presence of insulation around cell a. myelin around axon portion of neuron b. insulation = FASTER (conduction of depolarization jumps to nodes of exposed memb. btw insulation) |
| What do the Nodes of Rainier have? | Na+ voltage-gated channels |
| What is electrical signaling good for? | Coordination - GAP JUNCTIONS btw cells |
| What kind of potential does Integration deal with? | Graded potential. The way neurons figure stuff out. Switches ON & OFF |
| An action potential is described as non-decremental, what does that mean? | Doesn't decay/breakdown/non-diminishing |
| T/F No matter how long/far the action potential travels, it should NEVER get any smaller | TRUE |
| Axons deal strictly with what system? | Nervous system |
| What does the word "sarco" related to? | Muscles |
| What does saltatory mean? | Insulation wrapped around axon |
| What does depolarizing mean? | getting rid of difference in charges |
| What does myelin do for axons? | Myelin acts as insulation, and makes axon thicker |
| T/F The bigger/thicker the axon, the faster it travels | TRUE |
Created by:
lophung
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