Shared Flashcard Set

Details

Psych 345 Lecture 2
Neurons
71
Psychology
Undergraduate 3
02/10/2009

Additional Psychology Flashcards

 


 

Cards

Term
2 main classes of brain cells are
Definition

1) neurons

 

2) glial cells AKA glia

Term

Number and fxn of neurons?

 

" " of glia?

Definition

100 billion neurons; fxn: communication

 

1 trillion glia (10x more than neurons); fxn: support system

Term
The 4 specific types of glia are:
Definition

Astrocytes

Oligodendrocytes

Schwann Cells

Microglia

Term

Myelin in the CNS is provided by?

 

in the PNS?

Definition

CNS myelin - Oligodendrocytes

PNS myelin - Schwann Cells

Term
Function of astrocytes?
Definition

Astrocytes form tight junctions with the endothelial cells that line capillaries and venules

 

Note:  this is somehow related to the blood-brain barrier. Possible relation: they ARE basically the blood-brain barrier.

 

Term
Function of Oligodendrocytes?
Definition

Insulate axons with myelin in the CNS

 

*** Note: you should review the diagram on slide 4; it's very clear and provides a perspective that will help your mental image of myelination.

Term
Function of Schwann Cells?
Definition
Myelinate axons in the PNS
Term
Function of microglia?
Definition
Microglia remove the debris that follows injury or cell death
Term
3 roles of glia not specifically attributed to a certain type of glia:
Definition

1) structural & metabolic support

 

2) Help clean up extracellular ions and neurotransmitterrs

 

3) Guide the migration of neurons during development

 

Term
What did 19th century scientists examine that allowed them to infer to much about the function of neurons?
Definition

They examined the shapes of neurons under the microscope  (examined 'neuronal morphology')

 

Term
What did Camillo Golgi's stain allow? When did he invent it?
Definition
Golgi stain made it possible to see individual neurons (1873)
Term
What did Golgi believe about the brain?
Definition
He thought it was a continuous mass of tissue with a common cytoplasm.
Term

Santiago Ramon y Cajal:

 

- The _________ Doctrine (year: ____)

 

- Using the Golgi stain they discovered that: ____________ .

Definition

The Neuron Doctrine (1889)

 

they discovered that the brain is a bunch of individual nerve cells linked by long extensions

(so NOT Golgi's  continuous mass model)

Term

Neurons receive inputs from ________, pass info down the ______ toward the ______  ________ .

 

*Note: lots of variety in ___________ .

Definition

Neurons receive inputs from dendrites, pass info down the axon toward the nerve terminals

 

Lots of variety in MORPHOLOGY

Term
The firing properties of neurons vary by...
Definition
brain region
Term

What approximate range is the # of synapses cortical neurons make?

 

Is the upper limit of that range higher or lower for subcortical neurons?  (Name an example and give its approximate upper limit)

 

Definition

cortical: 1000-5000 synapses

 

 subcortical: many more

ex: cerebellar Purkinje cells make 200,000 synapses

 

Term
Do neurons ever exhibit a 1:1 connection?
Definition
No
Term
What is one important result of the interconnectivity of neurons?
Definition
Each neuron is only a few synapses away from other neurons
Term
Explain divergent and convergent neuronal connections.
Definition

Divergent: one neuron branches out to connect to many other neurons

 

Convergent: a neuron has inputs coming in from many other neurons

Term

"Connections are many to many."

 

"Observed at all levels: molecular, cellular, operational, systems levels"

 

 

The above to statements are explaining the property of neurons known as ____________.

Definition
Parallelism
Term
Learning is related to which property of neurons?
Definition
Plasticity
Term
T or F:  each neuron can produce several NTs
Definition
True
Term
The chemical messengers of the nervous system are called:
Definition
Neurotransmitters
Term

Where are NTs synthesized?

Where are they released from?

Where do they bind the post-synaptic neuron?

Definition

synth'd: in the cell body OR synaptic terminals

released: from synaptic vesicles by the presynaptic neuron

post-release: bind receptors on post-syn. neuron

 

Term
2 excitatory NTs (and their abbreviations) are:
Definition

glutamate (Glu)

acetylcholine (Ach)

Term
2 inhibitory NTs (plus abbreviations) are:
Definition

Gamma-aminobutyric acid (GABA)

glycine (Gly)

Term
What is the function of neuromodulators?
Definition
They modulate activity in entire regions/circuits rather than exciting or inhibiting one specific postsynaptic neuron.
Term
3 Neuromodulators (with abbreviations)
Definition

Dopamine (DA)

Norepinephrine (NE)

Serotonin (5-HT)

 

Term
The widespread effects that neuromodulators have on neurotransmission are known as:
Definition

Volume transmission

 

Term

Acetylcholine facilitates _________ & _________

and is affected in this illness/disease/disorder: 

Definition

Ach facilitates learning and memory

and is affected in Alzheimer's Disease

 

Term
2 things NE enhances
Definition

vigilance

&

preparation for action

Term

3 functions of dopamine (as a neuromodulator):

 

Definition

1) facilitates movement

2) reinforces behaviors

3) keeps info in short-term (working) mem.

 

Term

low DA levels in:

 

high DA levels in:

Definition

low DA = Parkinson's Disease

 

high DA = schizophrenia

 

Term
Serotonin does this (besides lots of other effects) and its levels are affected in:
Definition

serotonin inhibits some behaviors

and is affected in depression

Term

When elec. impulses carry signal within a neuron:

inputs from other neurons elicit _____s (aka _______ _______s) that travel down the neuron _________ly and decay __________ly.

Definition

When elec. impulses carry signal within a neuron:

inputs from other neurons elicit currents (aka synaptic potentials) that travel down the neuron passively and decay exponentially.
Term
Passive currents through the neuron add up at the:
Definition
axon hillock
Term
if membrane voltage reaches critical threshold, this is generated
Definition
action potential (AKA "spike")
Term
process by which action potentials travel down the neuron and regenerate themselves
Definition
by opening voltage-gated ion channels at the nodes of Ranvier
Term
signal potentiation between neurons:
Definition
NT-filled vesicles released at synapse
Term

Neuron Anatomy

 

Place where inputs received:

Cell body / basic cell functions carried out:

Where passive currents are summed:

Place where APs are transmitted:

Where NT-filled vesicles released into synapse:

Fatty substance insulating the axon to facilitate conduction:

Definition

Place where inputs received: dendrites

Cell body / basic cell functions carried out: soma

Where passive currents are summed: axon hillock

Place where APs are transmitted: axon

Where NT-filled vesicles released into synapse: nerve terminals

Fatty substance insulating the axon to facilitate conduction: myelin sheath
Term
Before passive currents can be summed at the axon hillock, how do these passive currents start?
Definition
A NT binds to a receptor causing ion channels to open (known as the 'receptor potential') which leads to the change in electric potential that is the 'passive current' or 'synaptic potential'
Term
Where on the neuron's anatomy do the EPSPs and IPSPs that get summed at the hillock come from?
Definition
the dendritic tree and the cell body (soma)
Term
EPSP stands for:
Definition
excitatory post-synaptic potential
Term
IPSP stands for:
Definition
inhibitory post-synaptic potential
Term

What is the first, most immediate next step that occurs after an AP travels down the axon?

 

 And after that?

Definition

1) voltage-gated calcium channels open

 

2) calcium triggers 'cascade of events' causing vesicles to fuse to membrane and release NT into synapse

Term
Being VERY specific, what is the name of the anatomical part on the post-synaptic neuron that a synapse is 'connected' to?
Definition
a dendritic SPINE
Term
Signal transduction via ionotropic receptors (AKA ligand-gated ion channels) is known as __________  ____________ and involves a _____________ change in the receptor protein.
Definition
it's known as 'direct coupling' for ionotropic receptors and involves a conformational change in the receptor protein
Term
Signal transduction via metabotropic receptors (AKA G-protein-coupled receptors) is known as ____  _____.
Definition
indirect coupling
Term
Signaling via metabotropic receptors / indirect coupling can involve very complicated pathways. Briefly run through the simplified version given in the lecture slides (diagram on slide 24 if needed).
Definition

The NT binding to the receptor leads to a second messenger signaling cascade (involving second messengers and G-proteins) that results in an ion channel opening.

 

Unnecessary note: the simplification here is that a metabotropic pathway is NOT always just another way to get an ion channel to open. The 2nd messenger/G-protein pathway can have many steps and lead to many other things.

Term
Are nicotinic Ach receptors ionotropic (directly coupled) or metabotropic (indirectly coupled) ?
Definition
ionotropic / directly coupled
Term
Drugs that treat neurological disorders often work by affecting:
Definition
synaptic transmission
Term
Drugs that act by affecting synaptic transmission can intervene at many different stages of transmission. Name a couple examples.
Definition

- The drug is a precursor to the NT being synthesized

- Drug prevents packing of NT into vesicles

- Drug [in]activates enzyme that synths NT

- Drug blocks NT reuptake

- Drug inactivates acetylcholinesterase

- Drug stimulates/blocks post-synaptic receptors

- Drug blocks/stimulates autoreceptors

 

Term
What is the (neurological) problem in depression, anxiety & OCD & which class of drugs is used to treat the problem?
Definition

problem = low serotonin levels

 

treatment = SSRIs

(selective serotonin reuptake inhibitors)

Term
What does an SSRI do and give an example
Definition

SSRIs block the reuptake of 5-HT into the presynaptic cell

 

Example: Fluoxetine (aka Prozac)

 

Term
When a neuron is at rest (resting membrane potential) it is ___________ly polarized which means:
Definition
it has a negative electric potential relative to the outside of the membrane
Term

Describe the concentrations and locations of Na+ and K+ at resting membrane potential.

 

How is this polarization maintained?

Definition

high Na+ outside and high K+ inside

 

maintained by Na+/K+ ion pumps (in the cell membrane)

 

[obviously Na is pumped out and K is pumped in]

Term
How much of each ion does the Na+/K+ pump move in/out? (ie, what is the ratio)
Definition
3 Na+ out for 2 K+ in
Term
Besides Na+ and K+ what other charged particles are involved in the resting membrane potential? (what are their charges and where are they mainly concentrated)
Definition

Cl- concentration is higher outside the cell.

 

Negative charges from proteins are inside the cell.

 

Term
How can membrane voltage be manipulated experimentally?
Definition
Input of electrical current to the cell
Term

Know where the following are: resting membrane potential, EPSP, AP, hyperpolarization, return to resting potential

 [image]

Definition
Just know it
Term
The Hodgkin-Huxley cycle represents what part of the action potential?
Definition
the depolarizing phase
Term
4 steps of the Hodgkin-Huxley cycle?
Definition

Synaptic potential or receptor potential -->

 

1) Depolarization of membrane -->

 

2) Opening of voltage-gated Na+ channels -->

 

3) Na+ flows into neuron --> BACK TO STEP 1

Term
Identify the 2 types of ion channels in the membrane of a neuron
Definition

1) Passive (nongated) - are open ALL THE TIME

 

2) Gated (their opening is triggered by something, for example, a voltage change)

Term

Which ion channels are open to the outside and inside of the membrane and which ions are flowing in or out at each of the following phases of the AP:

- resting

- depolarization

- repolarization

- hyperpolarization (refractory period)

[next phase is resting again]

Definition

**Note: the pic this is based on (slide 35) shows the K+ channel with no 'gate' on the interior side of the channel (so it would always be open to the inside of the cell)

Resting: Na & K closed to outside, Na open to inside, no ion flow

Depolarization: K closed to outside, Na open to in & out, Na flowing in

Repolarization: Na closed to inside, K open to outside, K flowing out

Hyperpolarization: Na closed to outside, Na open to inside, K open to outside, K still flowing out

Term
A Node of Ranvier on an axon is known as an _____ _____ while the myelinated portion is known as __________, where ______ ______ flows (rather than actual AP propagation)
Definition
A Node of Ranvier on an axon is known as an active region while the myelinated portion is known as internode, where passive current flows (rather than actual AP propagation)
Term
Ion channels are clustered at these parts of an axon
Definition
Nodes of Ranvier
Term
APs 'jumping' from node to node on the axon is known as:
Definition
saltatory conduction
Term

Myelin on axons increases ____ ____ and has what effect on signal speed and signal decay?

 

What is the transmission speed of the signal in saltatory conduction?

Definition

electrical insulation

 

speed = maximized

signal decay = minimized

 

 

speed = 120 m/s (meters/sec)

Term
What is the approximate distance between Nodes of Ranvier on an axon?
Definition
about 1 mm
Term

What disease results in demyelination of nerve fibers?

 

What effect does this have on nerve conduction?

Definition

multiple sclerosis (MS)

 

demyelination slows OR COMPLETELY DISRUPTS nerve conduction

(Note: symptoms of MS depend on the site of nerve damage, ie, which part of brain, which part of PNS, whether sensory or motor neurons are damaged...)

Term
3 causes of schizophrenia
Definition

1) genetic AND environmental factors

2) abnormal neural development

3) abnormally high DA levels

Supporting users have an ad free experience!