Resting, Action Potential, Synaptic Transmission X Flashcards Preview

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Flashcards in Resting, Action Potential, Synaptic Transmission X Deck (19):
1

Absolute Refractory Period

All Na+ channels inactivated until after membrane potential back to resting

2

Relative REfractory Period

During hyperpolarization when still closing K+ cells make I difficult but not impossible to have action potential

3

Depolarizing after-potential - what, why

B/C K+ slowly diffusing out of T-Tubles in skeletal muscle

4

Factors the modify threshold potential

K & Cl permeability - inhibitory
# Na+ Channels i.e. local anesthetics
Rate of depolarization ( if too slow, inactivation gates have time to close before AP fired)

Charge movement
Current
See other slide

5

Factors that increase rate of action potential propagation

inc. Cell diameter (most significant)
inc. Resisting membrane resistance
inc. # of Na+ channels present
presence of myelin
dec. Capacitance
inc. length constant

6

Saltatory Conduction

Discontunous - jumping from on node to another

7

Ability of tissues in the heart to allows actiona potentials to propagate in wrong direction can cause...

cardiac arrhytmias

8

Effect of Charge movement and Current on action potential

charge movement - positive into cell & current - negative/inward = positive or less negative threshold
OPPOSITE TRUE TOO
charge movement positive into cell & current - positive/outward = negative of less positive threshold
OPPOSITE TRUE TOO

9

EPP larger than ESPS b/c

EPP can reach voltage that exceeds amount to produce action potential in muscle while ESPS are small and need many to have effect. THEREFORE you can have an action as soon as you want it.

10

Neuropeptides - a.k.a, fxn

Neuromodulators
From dense core visicles.
Act pre or post synaptically
longlastin, complex effects

11

Temporal v Spatial summation

S - Many inputs at same time in different locations, meet up elsewhere and combine or cancel out
T - many inputs fired in rapid succesion - larger postsynaptic response

12

End plate potential - def

membrane potential developed in post-synaptic muscle fiber

13

Structure of gap junction

One synapse per fiiner, although a single motoneuron may innervate up to 2000 muschle fibers

14

Events leading to transmission at chemical synapse

AP reaches
Ca2= enters. Synap[tic vesicles fuse to presynaptic membrane.
Contents(transmitters) released.
Transmitters bind to post synaptic membrane receptors
directly coupled channels open, causing AP or Inhibition on muscle

15

Desensitization - explain

If ACh remains bound to ACh receptors for prolonged time, those channels will close (desensitize). This is prevented by use of enzyme, acetylcholine-esterase.

16

Receptors in Muscle v CNS / Organs

Nicotinic v Musarinic ACh receptors

17

Excitatory v inhibitoyr receptors

Glutamate
Glycine/GABA

18

NMDA glutamate receptors

Require relatively prolonged membrane depolarization
Also binding glutamate, Ca2 & Na+ and K+ permeability
(Non-NMDA = only bind glutamate, Na+ & K+ permeable)

19

Presynaptic facillitation

increases presynaptic transmitter released