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30 Cards in this Set

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What non-ionic source contributes to the charge within cells? What is this charge?
Proteins, negative
How is an ion gradient maintained within a cell?
Na-K pump
What is the Na-K distribution like in a cell?
More Na on outside, more K on inside
Typical resting potential of a cell?
-70mV
What two forces pull on ions in cells?
Where does Potassium want to go based on these forces? Why?
How about Sodium?
Concentration gradient, charge differences

K:
Conc: Wants to leave
Charge: wants to stay

Na:
Conc: wants to come in
Chrge: wants to come in
What happens when sodium ions are allowed to pass through ion channels? Which direction do they proceed in?
Decreased membrane potential, enters the cell until reaches an equilibrium.
What are the 5 types of channels within a neuronal cell membrane? Describe their mechanism of opening/closing.
Passive (leak): always open
Active (gated): open/close in response to stimuli
Chemical (ligand)
Voltage
Mechanically
Label diag 7.
1. Central canal
2. Epyndymal cells
3. Grey matter
4. Neurons
5. Myelinated axons
6. Microglia
7. Astroglia
8. Oligodendrocyte
9. White matter
Describe the steps of a graded potential.
Membrane is exposed to a chemical that opens sodium ion channels, sodium ions enter cell membrane and produce a local current that depolarizes adjacent portions of he cell membrane.
Would sodium ion leakage result in depolarization or hyperpolarization?
How about K+ ions?
Na: Depolarization
K: Hyperpolarization
What are the general steps of an AP?
Mebrane depolarizes to threshold, sodium channels open, close, potassium channels open, return to normal permeability.
What must a graded potential do in order to generate an AP?
Reach threshold.
How does the amplitude of an AP vary?
It doesn't.
What is a refractory period? What are the two types? When do they occur?
New action potential cannot occur until recovery.
Absolute: NO AP NO MATTER HOW MUCH OF A DEPOL (under peak)

Relative: Possible is stimuli large enough (undershoot)
Place in order of increasing speed:
Type A fibers
Type B fibers
Type C fibers

Why do they differ in speed?
A, B, C

Diameter, myelination
Describe how nonmyelinated axons propagate APs.
Same for myelinated axons.
What are these methods used known as?
nonmy:
Ap develops in initial segment, local current depol adjacent portion of membrane to threshold, AP develops, initial segment enters refractory, repeat.

AP at initial segment, depol at node 1, repol at initial segment, repeat.

Continous Conduction
Saltatory Conduction
Relationship between graded potentials and distance traveled? Action potentials?
Decrease with distance.
No effect.
Effect of Excitatory NTs on AP?
Inh?
Will an NT always be excitatory?
Cause dpol, promote AP
Hyperpol, suppress AP

Nope, can promote or inhibit based on receptor
NT in cholinergic synpases?
Why is there a synaptic delay?
What happens to ACh once it's broken down?
When doe synaptic fatigue occur?
ACh
Ca++ influx and NT release take time
Reabsorbed and recycled by Presyn Neuron
When you run out of ACh
Synapses ACh involved in?
All neruomusc junctions
Neuron-neuron in PNS
Parasymp post-ganglion
Steps of a cholinergic synapse?
AP arrives, depolarizes synaptic knob, extracellular Ca++ enters and triggers release of ACh (exocytosis), ACh binds receptors and depol post syn mem, AChE removes ACh
Why does ACh have a direct effect on receptors?
WHen it binds, it causes a conformational change in the receptor, making it open.
List effects and whether INH/EXC:
Norepi
DA
5HT
GABA
Exc: brain, AutoNS
Exc/Inh, movement, muscle tone
------attention, emotoin, sleep/wake
Inh, reduce anx
Role of neuromodulators? Direct or indirect effect?
Major class? Suffix?
Influence post syn resp to NTs
Both
Opiates, phins, ins
How do neurotransmitters exert effect in indirect fashion? Give examples of such NTs.
G protein system (second messengers)

Epi, NE, DA, GABA, Hist
Give examples of direct NTs.
ACh, glut, asp.
What kind of effect do NO and CO have? Direct or indirect? Describe the pw.
Indirect-->lipid soluble, activate second messengers that effect receptor opening.
What are some ways neuronal signaling can be altered?
Promote depolarization, channel blockers, depress membrane sensitivity, remove myelin, block/promote release, block NT binding, stimiulate receptors, block inactivation of NTs
Classify as hyperpol or depol:
EPSP
IPSP
Depol
Hyperpol
Describe temporal and spatial summation.
Graded potentials timed (release one after the other at the same pre syn term)

Spatial: simultaneous graded potential from two different pre syn neurons.