PT 505 Neurons and Synapses

rapid

Neurons are specialized for __________ communication at distinct structural/functional regions

Excitability

Universal property of neurons describing their ability to respond to stimuli by generating electrical signals

dendrites

Where does excitability TYPICALLY occur in neurons?

Conductivity

Universal property of neurons describing their ability to spread electrical signals throughout the cell

Secretion

Universal property of neurons describing the ability of electrical signals within neurons stimulating the release of chemical signals

soma (cell body), dendrites, axon

What are the 3 structural divisions of a neuron?

nucleus, Nissl substance

What protein creating structures are found in the soma of a neuron?

dendrites

What are the input sites of neurons?

Axon

Division of the neuron where information exits the soma and carries signals away

False

All dendrites exit the soma. True or False

Multipolar

Most common type of neurons

Bipolar

Neuron more common in the periphery with only 1 primary dendrite

unipolar

What kind of neurons do we NOT have?

bipolar

What kind of neurons can end up becoming pseudounipolar neurons?

pseudounipolar

What kind of neurons would respond to things like pressure on the skin? (AKA somatosensory neurons)

axon

Where do the dendrites emerge from the neuron on pseudounipolar neurons?

Anaxonic

Neurons without axons, operating without firing APs

dendrites

Where do anaxonic neurons release their neurotransmitters?

protein synthesis, integration

What are the two main functions of the soma?

nucleus, transcription

What specific part if the soma does protein synthesis begin in? What is this process called?

Nissl substance

Protein synthesis machinery in the soma responsible for translation through ribosomes, ER, and Golgi Apparatus

cell body, dendrites

The nissl substance (ribosomes, ER, Golgi) is more concentrated in what areas of the neuron?

None (axons DON'T make proteins)

what structures in the axon make proteins?

dendrites

In integration, where are the stimuli creating electrical potentials?

cell body

In integration, where do the dendritic potentials converge?

conduction, secretion

What are the two jobs of the axons?

axon hillock

What is the site of axon origin?

myelinated

What type of axons have fast signal transuctions?

action potential

electrical signal that travels down an axon and allows neurotransmitters to be released

proteins

______________ do nearly everything in life

True

Proteins travel along the axon in order to create activity. true ot false?

Axonal transport

What characteristic is required due to axon's inability to make proteins?

anterograde

describe axonal transport of proteins away from the cell body

retrograde

describe axonal transport of proteins toward the cell body

anterograde

What type of axonal transport travels in the same direction as the AP

kinesin

motor proteins in anterograde transport

rapid, slow

two types of anterograde axonal transport

rapid

Insoluble things (mitochondria, integral proteins/lipids, neurotransmitter precursors, synaptic vesicles) undergo what type of anterograde transport?

slow

soluble things (soluble proteins, cytoskeleton components) undergo what type of anterograde transport?

slow

When nerves are damaged, regrowth would happen at what rate?

damaged organelles and proteins

What kind of things undergo retrograde axonal transport back to the cell body?

lysosomes

What cleans up the substances taken back to the soma?

signalling endosomes

surface receptors internalized at a synapse which affect gene expression to keep neurons alive by undergoing retrograde axonal transport back to the soma

retrograde axonal transports

What type of transport unfortunately can create avenues for infections or toxins to gain access to the CNS?

sensory, motor, interneurons

What are the 3 general types of neurons

sensory

Neurons with receptors that detect environmental stimuli

motor

Neurons with receptors that detect neuronal input and have axons that project to a motor or gland?

sensory, toward

Which neurons are termed "afferents"? Would these bring information toward or away from the CNS?

motor, away

Which neurons are termed "efferents"? Would these bring information toward or away from the CNS?

interneurons

Neurons between neurons, with receptors that detect neuronal input.

90%

% of neurons that are interneurons

excitable

Neurons are __________ cells that exhibit rapid changes in membrane potential

membrane potential

electrical charge at a membrane

ionic imbalance, selective permeability

membrane potentials are created by what two things?

resting membrane potential

membrane potential when neurons are not receiving input or firing action potentials

-70mV

What is the typical resting membrane potential

K+

What ion is always permeable to the membrane (therefore always leaving), and creates the resting membrane potential?

Na+/K+ pump, ATPase

what two things help maintain the ionic imbalance of the resting membrane potential?

3 Na+

What is transported out via the sodium potassium pump, and how many?

2 K+

What is imported via the sodium potassium pump, and how many?

20

sodium potassium pump uses about _____% of a neurons ATP

local potential

an external input alters/changes membrane potential thru excitability

ion channels

What opens at the local potential site to change the membrane potential

dynein

motor proteins in retrograde transport

mechanically gated channels

neurons sensitive to pressure require what kind of ion channels to change membrane potential?

ligand gated channels

neurons sensitive to neurotransmitters require what kind of ion channels to change membrane potential?

postsynaptic potentials PSPs

Opening of ligand gated ion channels created _________________ __________________

excitatory, inhibitory

Two types of PSPs

EPSP

PSPs responsible for depolarizing the membrane potential

IPSP

PSPs responsible for hyperpolarizing the membrane potential

cation

What kind of channels do EPSPs open?

Cl-

What kind of channels do IPSPs open?

sum

PSPs eventually reach the initial segment of an axon and ___________ with other PSPs

trigger zone, axon hillock

where does synaptic potential summation typically occur?

False

Synapses in the brain are strong. True or false?

temporal summation

Summation by a postsynaptic cell of input (EPSPs or IPSPs) from a single source over time.

spatial summation

The sum of multiple synapses firing at different locations at one time to create a net effect.

EPSP

What type of PSP increases the likelihood of an AP

IPSP

What type of PSP decreases the likelihood of an AP

depolarization repolarization afterhyperpolarization

name the phases of action potential in neurons after firing, in order?

depolarization

Bringing in sodium, going from -70 mV to +30mV in 1ms

repolarization

occurs after membrane potential peak, going from +30 back to -70 mV in 1ms

afterhyperpolarization

decrease in membrane potential in neurons at the end of the action potential due to opened voltage-gated K+ channels

open

Once membrane potential is greater than the threshold potential, then voltage gated channels _________

close

Once membrane potential is less than the threshold potential, then voltage gated channels _________

VGNCs

Quickly open up once we hit threshold potential and cause a brief depolarization

blocking

Once a sodium channel OPENS, what happens to the sodium channel to keep sodium from coming across the membrane and slow down the action potentials

VGKCs

opens and closes slowly that fixes the membrane potential once we reach the AP peak

ligand gated, mechanically gated

channels that produce local potentials

voltage gated

channels that produce APs

local potentials

Which potential may cause either depolarization or hyperpolarization (meaning this potential does not always follow a distinct order)

Action potentials

Which kind of potential is all-or-none, meaning the peak voltage is relatively uniform (Goes from -70 to +30 always)

local potential

Which kind of potential is graded, meaning it is proportional to the stimulus or synapse strength

Local potentials

Between local potentials and action potentials, one is spread passively and amplitude decreases with distance. The other is active and amplitude does not change with distance. Which one is the passive one?

refractory period

Period when neuron is less excitable because sodium channel is blocked

VGNCs blocked

During absolute refractory periods, why can't action potentials be triggered?

VGKCs re still open

During relative refractory periods, why are APs harder to trigger?

False

sodium channels in the backward direction of an axon are responsive and open up to shift APs down to the next segment of the axon. True or False

frequency

Stimulus strength determines the ________________ of APs

neurotransmitters released

The more APs, the more: