Neurotransmitters and Neural Integration (2)

Question 1

Neurotransmitters Definition

Answer 1

molecules that are released when a signal reaches a synaptic nob (or varicosity)

Question 2

How do synapses vary?

Answer 2

Excitatory or Inhibitory- differ based on type of receptor on postsynaptic cell

(some receptors are ligand-gated ion channels; others act though second messengers)

Question 3

What are three examples of synapses with different modes of action?

Answer 3

• excitatory cholinergic synapse
• inhibitory GABA-ergic synapse
• excitatory adrenergic synapse

Question 4

What are the six steps of excitatory cholinergic synapse?

Answer 4

1. Nerve signals at axon terminal and opens voltage-gated calcium channels
2. calcium enters knob and triggers exocytosis of ACh
3. ACh diffuses across cleft- binds to postsynaptic receptors (ligands)
4. Receptors are ion channels-open and allow sodium and potassium to diffuse
5. Entery of sodium causes local depolarizing voltage shift- postsynaptic potential
6. If depolarization is strong (persistent) enough, it will cause an action potential at the trigger zone

Question 5

A nerve signal triggers the release of ____ into synaptic cleft

Answer 5

GABA

Question 6

GABA receptors open?

Answer 6

chloride channels

Question 7

Chloride enters the cell and makes the inside more negative than RMP. What is this called?

Answer 7

hyperpolarization

Question 8

Norepinephrine and other neurotransmitters act through ___ ____ ___ ___

Answer 8

second messenger systems (cAMP)

Question 9

A receptor is not an ion gate. What is it?

Answer 9

it is a transmembrane protein associated with a G-protein

it is slower to respond, bit has an advantage of signal amplification

Question 10

What are the steps to excitatory adrenergic synapse?

Answer 10

• NE bind to receptor G-protein and dissociates
• binds to adenylate cyclase
• converts ATP to cAMP

Question 11

What are the various responses to this process: NE bind to receptor G-protein and dissociates, binds to adenylate cyclase, converts ATP to cAMP

Answer 11

1. binds to ligand gated channel- depolarize cell
2. activate preexisting enzymes within the cell
3. introduce genetic transcription leading to creation of new enzymes or proteins

Question 12

What are the two way cessation of signals occur?

Answer 12

1. Presynaptic cell stops

2. Eliminate neurotransmitters already there

Question 13

What happens in Degradation?

Answer 13

acetylcholine is broken down by acetylcholinesterase (AChE) in the synaptic cleft

Question 14

What happens in reuptake?

Answer 14

axon terminal reabsorbs (transport proteins) neurotransmitter/parts by endocytosis

Question 15

What happens in when they diffuse?

Answer 15

neurotransmitter diffuses into neary ECF (acetate)

Question 16

Synaptic delay does what?

Answer 16

slows that signal

Question 17

Chemical Synapses =

Answer 17

processing; decision making

Question 18

More synapses =

Answer 18

greater amount of information processing

Question 19

What is trade- off?

Answer 19

chemical transmission involved a synaptic delay that makes information travel slower than it would be if there was no synapse

Question 20

What is Neural Integration?

Answer 20

ability to process, store, and recall information and use it to make decisions

Question 21

For a cell to fire an AP it must reach ____

Answer 21

threshold

Question 22

Some chemical messengers ___ the postsynaptic cells

Answer 22

Inhibit

Question 23

Different neurotransmitters cause different types of postsynaptic potential in the cells they blind to. One neurotransmitter might ___ some cells and ___ others

Answer 23

excite

inhibit

Question 24

What is summation

Answer 24

process of adding up postsynaptic potentials and responding to their net effect (occurs in trigger zone/axon hillock)

(one neuron can receive input from thousands of other neurons)

Question 25

In summation, response depends on whether the ___ ____ is excitatory or inhibitory

Answer 25

net input

Question 26

Balance between EPSPs and IPSPs enables the nervous system to make ___

Answer 26

decisions

Question 27

Temporal Summation definiton

Answer 27

single synapse generates EPSPs so quickly that each is generated before the previous one fades (only need signal form one)

Question 28

Spatial Summation definition

Answer 28

EPSPs from several different synapses add up to threshold at axon hillock (stimulation from all different places)

Question 29

Presynaptic Facilitation definition

Answer 29

one presynaptic neuron enhances another one | increases necessary synaptic transmission

Question 30

Presynaptic Inhibition definition

Answer 30

one presynaptic neuron surpasses another | reduces or halts unwanted synaptic transmission

Question 31

Neural (sensory) Coding definition

Answer 31

how the nervous system converts information into a meaningful pattern of action potentials

Question 32

What does qualitative information depend on?

Answer 32

which neurons fire

Question 33

What is a labeled line code?

Answer 33

each sensory nerve fiber to the brain leads from a receptor that recognizes a specific stimulus type (each nerve fiber is "tagged" or "labeled" for a specific stimulus)

Question 34

Quantitative Information defintion

Answer 34

information about the intensity of a stimulus is encoded (two ways)

Question 35

What are the two ways a stimulus is encoded with quantitative information?

Answer 35

1. Different neurons -> different thresholds of excitation 2. Weak stimuli cause neurons to fire at slower rates; strong stimuli cause a higher firing frequency (more action potentials per second)

Question 36

True or False: Neurons don't work together

Answer 36

False Neurons work together (thousands)

Question 37

Neural Pool is a....

Answer 37

localized cluster of neurons that collaborate to perform specific functions

Question 38

How are neural pools connected?

Answer 38

Connected via neural circuits

Question 39

Information arrives at a ___ ___ through one or more ___ ____

Answer 39

neural pool | input neurons

Question 40

Input neurons branch ___ and synapse with many target cells

Answer 40

repeatedly

Question 41

Some form ___ synapses with a single postsynaptic cell

Answer 41

multiple

Question 42

Discharge Zone definition

Answer 42

neuron can act alone to make postsynaptic cells fire

Question 43

Facilitate Zones defintion

Answer 43

inout neurons makes fewer, less powerful synapses | can only stimulate targets with the assistance of other input neurons

Question 44

Systems give neural pools ___ in integrating input from several sources; ____ on appropriate output

Answer 44

flexibility deciding

Question 45

Neural Circuit definitions

Answer 45

Function of neural pool depends on how the neurons are connected

Question 46

Diverging Circuit definition

Answer 46

- one or few neurons produce output | - ultimately branches to multiple destinations

Question 47

Converging Circuits definition

Answer 47

Multiple input neurons | converge on fewer and fewer neurons (reach one or a few output neurons)

Question 48

Reverberating Circuits definition

Answer 48

Neurons stimulate each other in linear sequence | one or more of the later cells restimulates the first cell [axon collateral] to start the process all over

Question 49

Parallel After Discharge Circuits definition

Answer 49

input neurons diverges to stimulate several chains of neurons (each chain has a different number of synapses---eventually they all reconvert on on for a few output neurons but with varying delays)

Question 50

What is an example of a Diverging Circuit?

Answer 50

a small group of neurons in brain sends signals to thousands of muscle fibers

Question 51

What is an example of a Converging Circuit?

Answer 51

Balance Respiratory Center

Question 52

What is an example of a Reverberating Circuit?

Answer 52

Diaphragm and intercostal muscles

Question 53

What is an example of a Parallel After Discharge Circuit?

Answer 53

Pain (withdrawal reflex)