True or false?

The nerve impulse is vastly oversimplified

Membrane of a neuron not stimulated = polarized

* this means there is an electrical difference between the outside of the membrane and the inside

*outside of cell contains more sodium ions (ions:atom w/ + or - charge)

Complete the sentence:

When a neuron is inactive and polarized, it is said to be at its .....

resting potential = when a neuron is inactive and polarized

*will remain at a resting potential until there is a stimulus*

Neurons need to reach a threshold level to completely depolarize

*In this state the neuron continues to open Na⁺ channels all along the membrane*

True or false?

A neuron may respond to any incoming stimuli during its refractory period.

False

Neurons do not repond to any incoming stimuli during the refractory period.

*refractory period: Time when neuron is busy returning everything to normal resting state*

Myelin covers all axon EXCEPT nodes of Ranvier

*myelin: composed of lipids (fat) and functions like rubber insulation around an electrical wire*

Speed conduction depends on:

1) diameter

2) if axon is myelinated

True or false?

Saltatory conduction requires more Σ than continuous conduction.

False

Saltatory conduction requires way less Σ than continuous conduction

*Saltatory conduction ↑ nerve conduction speed without need to ↑ axon diameter = less Σ used*

Complete the sentence:

Multiple Sclerosis is an example of .... disease

True or false?

In unmyelinated fibers, the impulse is propagated as a continuous wave of depolarization spreading along the axon.

True or false?

In myelinated fibres, the impulse is propagated as a continuous wave of depolarization.

False

In myelinated fibers, the impulse jumps from node to node

*results in a faster, Σ saving process aka saltatory conduction*

Most common synapse = axodendritic synapse

*axon of one goes to dendrite of another cell*

fastest synapse = axosomatic synapse

*axon of one cell skips the dendrite and straight to the cell body*

most efficient synapse = axoaxonic synapse

*key synapse for pain*

* by-passes the dendrite and cell body and goes straight to the synapse*

synapse = region of approximation between 2 neurons

*typical synapse = 1 presynaptic neuron + 2 synaptic cleft + 3 postsynaptic neuron*

A NT/neurotransmitter crosses the synaptic cleft to ..... the postsynaptic neuron.

a) inhibit

b) stimulate

c) inhibit and stimulate

axodendritic synapse

*common*

axosomatic synapse

*common*

axoaxonal synapse

*not so common*

*relates to pain*

Calcium ion is necessary for NT and neuron membrane to fuse together.

*cause vesicles to fuse with cell membrane*

*NT are released into synapses*

1) inactivaction by enzymes (e.g.: ACh)

2) Re-uptake: NT actively pumped back into axon terminal

3) Diffusion out of synaptic cleft

Complete the sentence:

An excitatory postsynaptic potential/facilitation/hypopolarization makes it 1).... likely that an AP will continue in the postsynatptic neuron

1) more likely that an AP will continue the postsynaptic neuron

*make it more likely that the threshold/firing point/ of postsynaptic neuron is reached = EPSP makes you closer to threshold*

Complete the sentence:

An inhibitory postsynaptic potential makes it 1)... likely that an AP will continue on the postsynaptic neuron

Temporal summation : frequent excitatory signals from small number of sources

*summation determines whether the next neuron will continue sending an AP and transmit the info to other parts of the NS and effectors*

*neuron does not reach threshold level = AP does not occur (none)*

*neuron reaches threshold level, fires = AP goes all the way to the end of the axon (all)*

Complete the sentence:

A change in the 1).... of AP usually indicates a change in the 2)... of a stimulus.

Its synaptic action will release neurotransmitter/NT

*NT we speak of are endorphins*

Neurotransmitters are released by the presynaptic neuron.

* there are over 50 kinds of NT identified*

True or false?

A single neuron can only produce one neurotransmitter.

False

A single neuron can produce several different neurotransmitters.

What do you call a molecule that has the same effect on the postsynaptic neuron as the neurotransmitter itself does?

Glutamate, dopamine, serotonin, adrenalin, Gamma Aminobutyric Acid (GABA)

*emotional disorders i.e.: anxiety, depression, mood disorder caused from excess or shortage of NTs*

GABA/ Gamma Aminobutyric Acid

*inihibits/depresses the neurons receiving the GABA NT and makes it less likely to fire an AP*

GABA neurotransmitter

*meds used to alleviate anxiety: valium, librium (bind the same neuronal receptors as GABA)*

classified as Benzodia zepiness

*enhance the natural effect of GABA and are referred to as agonists*

*help reduce neural activity even further*

most excitatory NT = Glutamate

*neurons receiving/binding to glutamate become more likely to fire an AP*

Complete the sentence:

A serotonin deficit is linked to...

Prozac

*SSRI increase the length of time that serotonin stays in the synapse = more likely to bind to postsynaptic receptors*

True or false?

Massage has been shown to ↑ serotonin levels associated with mood enhancement.

Dopamine

*shortage causes lack of controlled movements i.e.: Parkinson*

What is the consequence of excess dopamine in the limbic system and a decrease in dopamine in the cortex?

Oxytocin

*released in large amounts after distension of the cervix and vagina during labor as well as after stimulation of the nipples*

Oxytocin

*involved in social recognition and bonding, and may be involved in the formation of trust between people and generosity*

How can drugs modify synapse function?

a) mimic the NT

b) block re-uptake of NT

c) decrease SympNS

d) block enzyme pathways that degrade NT

e) all of the above

f) A, B, D

Drugs modify synapse function by:

> mimic the NT

> block re-uptake of NT

> block enzyme pathways degrading NT

Cocaine: blocks reuptake of dopamine

Prozac: serotonin reuptake inhibitor

Beta-blockers/ beta/adrenergic blocking agent

*anti-anxiety drugs*

Which beta-adrenergic blocking agent has been used to erase, at least in short-term, the fear response induced by a laborator-induced painful memory in humans?

Complete the sentence

Anorexia is said to be associated with a low level of.... in women.