Neurons And Neurotransmitters (3.1) Flashcards
What are the parts of a neuron?
Dendrites Cell body Axon Myelin sheath Axon terminal
What is the purpose of the myelin sheath?
Increases speed of transmission of impulses along an axon
Insulation
What does it mean when a neuron excites a cell? (What needs to happen?)
To excite a cell, threshold must be met. Axon then opens gates to let Na and K ions flow, triggering a new neuron.
Importance of inhibitory response
When in pain, the brain has mechanisms which inhibit the sensation of pain.
Generally, what is the order in which an impulse will travel through a neuron?
Dendrites Cell body Axon Myelin sheath Axon terminal
What is resting potential and when does it occur?
1) an electrical polarization across the membrane
2) whenever an axon is not stimulated
How is an axon get its negative charge?
From negatively charged proteins inside the acon
Na+ is always being pushed out by pump, so there is more K ions inside cell and more Na outside at rest.
How does action potential start? (2 ways)
Many axons produce spontaneous activity
Input from other neurons excite cell membrane
What does the influx of Na+ translate to?
Action potential
T or F - Sodium gates close before potassium gates after a neurotransmitter is delivered.
True
Sodium enters the cell and causes ….
Excitation
Potassium leaves the cell and causes….
The return to resting potential
Where is synapse located in relation to two neurons?
At the end of axon terminal of one neuron and before dendrites of another
What structure is located at the end of each axon terminal branch? What does it do?
Terminal bouton
Releases a neurotransmitter
Neurotransmitter molecules diffuse across a gap called to receptors called…
A postsynaptic neuron
Endocrine vs Nervous - which is faster?
Nervous system
________ transmitters diffuse to a wider brain area and produce effects that last many minutes.
Peptide
In what imstances are slow/long messages more useful?
Hunger, thirst, sex drive
When does a message end?
When neurotransmitter separates from receptor
What specificslly releases a neurotransmitter?
Synaptic vesicles
If the binding of a transmitter to receptor cells opens gates for Na+ to enter the cell, this is a ______ _________.
Excitatory synapse
If binding of transmitter to receptor cell opens gates for charged potassium ions to leave the cell or negatively charged chlorine to enter cell, the cell has a ______ _______.
Inhibitory synapse
Glutamate: Functions and comment.
Main excitatory transmitter present at most synapses. Essential for all brain activities including learning
Strokes kill neurons by excess release of glutamate
GABA: Functions and comment.
Brain’s main inhibitory transmitter
Antianxiety drugs and antiepileptic druhs increase activity of GABA
Acetylcholine: Functions and comment.
Increases brain arousal
Released by motor neurons to stimulate muscle cells.
Dopamine: Functions and comment.
One path is important for movement, the other is important for memory and cognition.
Antipsychotic drugs decrease activity at dopamine synapses. L-dopa is used for Parkinson’s disease.
Serotonin: Functions and comment.
Modifies many types of motivated and emotional behavior
Many antidepressant drugs prolong activity ar serotonin synapses
Norepinephrine: Functions and comment.
Enhances storage of memory of meaningful events.
All or nearly all axons releasing thi come ftom a small brain area called locus coerulus.
Histamine: Functions and comment.
Increases arousal and alertness
Antihistimines block histamines and prevent allergies, but also cause drowsiness.
Endorphins: Functions and comment.
Decrease pain and increase pleasure
Morphine and heroin stimulate the same receptors as endorphins
Nitric oxide: Functions and comment.
Dilates bloof vessels in most active brain areas
The only known transmitter that is a GAS
Anadamide, 2AG, and others: Functions and comment.
Sent by postsynaptic neuron back to presynaptic neuron to decrese further release of transmitters
