Neurons, Neural Communication & Synaptic Transmission Flashcards
what is the brain simply a mass of?
The brain is simply a mass of billions of neurons.
how much metabolic energy is from the brain
20%
what are neuron’s?
Neurons are specialised cells that receive and transmit information throughout the central nervous system.
how many neurons does the average brain contain?
80-100 billion neurons.
what does the soma of a neuron contain?
the cell nucleus
what is inside the cell nucleus
Chromosones and DNA
what is the cytoplasm
The bulk of the cell is made of cytoplasm
Cytoplasm is all the organelles (except the nucleus), structures and fluid within the cell.
houses the mitochondria, endoplasmic reticulum, Golgi apparatus and plasma membrane
what does the mitochondria do
Extract energy from the breakdown of nutrients to provide energy in the form of adenosine triphosphate (ATP)- uses nutrients (predominantly glucose and oxygen)
what are the 2 types of Endoplasmic reticulum
Rough ER: contains ribosomes, involved in protein synthesis
Smooth ER: involved in lipid metabolism - It’s also involved in regulating calcium ions and processing toxins.
what is the Golgi apparatus
an organelle that processes and packages proteins and lipids for use inside and outside of a cell
what is the all or nothing law
The size and the strength of an action potential is independent of the intensity of the stimulus that generates it. Any stimulus that is sufficient to cause depolarisation to the threshold can stimulate an action potentia
can action potentials occur anywhere in the neuron?
no
what does the sodium-potassium pump use to transport relevant ions
Active transport
what is the resting potential of a neuron
-70mv
what is a refractory period
The refractory period is a state of recovery that occurs after a neuron has fired an action potential. During this period, another action potential cannot be easily produced.
during a refractory period can a action potential be sent
It depends on whether the neuron is in its absolute or relative refractory period.
where does an action potential begin in a neuron
axon hillock
How many sodium (Na+) and potassium (K+) are transported by the sodium-potassium pump and to where?
2 K+ ions into the cell with 3 Na+ ions out of the cell.
4 major structures of the neuron
- axon
- dendrite
-soma - terminal button
how strong is an action potential at the end of the fire compared to the start?
The same
what are antagonists
Antagonist neurons are neurons that are affected by antagonist compounds, which reduce the effect of neurotransmitters
how do antagonists work
Bind to synaptic receptors
Block neurotransmitters from binding to receptors
Reduce the amount of time neurotransmitters are in the synaptic cleft
Prevent the activation of a synaptic receptor
what are agonists
agonists mimic or increase
the action of neurotransmitters.
what is the function of nitric oxide in neural activity?
to augment blood flow to the neuron’s (increasing delivery neural fuel resources)
what is the purpose of Monoamine Oxidase A (MOA A)
an enzyme that breaks down serotonin before re uptake into the pre-synaptic neuron
what is neuroplasticity
the capacity of the brain to adapt and modify neural connections in response to experience
what is exocytosis
This is the process of the fusing of the vesicles with the cell membrane and the release of
neurotransmitters in the synapse
what is inside the cytoplasm
mitochondria, endoplasmic reticulum, Golgi apparatus and plasma membrane
what does the Golgi apparatus produce?
Produces Lysosomes to break down unwanted substances out of the cytoplasm & produces small packages used to transport chemicals (neurotransmitters).
what is the plasma membrane
The layer that separates the in and outside of the cell. Selectively permeable ( some substances are able to pass through the membrane, while other substances are not able to pass through.) Holds everything together
where is information in a neuron sent along
the axon
how is information sent along an axon
electrical impulse called an action potential
what is the myelin sheath
a fatty layer that wraps around nerve cells, protecting them and allowing electrical impulses to travel quickly.
what are nodes of ranvier
there are breaks in the myelin called Nodes of Ranvier – Important!
which 2 ways to neurons communicate
Electrical communication- within neuron
Chemical communication- between 2 neurons
where is info in a neuron received from
dendrites
where do synapses line
dendrites
how is info received from other neurons and where
information is received from other neurons (via their terminal button) across a tiny gap called the synapse.
when an action potential reaches the terminal buttons what chemical substance do they release
neurotransmitter
what is a presynaptic neuron
a neuron that sends a message
what is a postsynaptic neuron
a neuron that receives a message
what is a catabolic reaction
breaks things down
what is a anabolic reaction
builds things up
neurotransmitters either ___ (stimulate) or _____ (blocks) the __ synaptic receptors on the dendrites of another neuron
- excite
-inhibit
-post synaptic
what is an action potential
how neurons communicate with one another
what happens if a neurotransmitter excites the post synaptic neuron
the neuron is more likely to send a signal
what happens if a neurotransmitter inhibits the post synaptic neuroon
the neuron is less likely to send a signal
where does the action potential start
axon hillock- between cell body and axon
how does an action potential move- what does it move by
saltatory conduction- action potential jumps down the axon rather than passing- jumping between unmyelinated areas (nodes of rangier). This saves energy and is much faster
what is a nociceptor
a pain receptor
what is the difference between A alpha nociceptor and C fibre nociceptor
A Alpha= myelinated- fast conduction, very quick and sharp pain
C fibre= unmyelinated so messages send slower, slow conduction, dull pain sensation,
what is the membrane resting potential
electrical charge difference across. neurons membrane when it is not actively sending a signal
where is a neuron more negatively charged
inside
what is a neurons resting potential
-70mv
when is a resting potential disrupted
voltage change
what provides the energy for a action potential
unequal distribution of charged potassium and sodium ions in the membrane
what is the starting point for an action potential
the membrane resting potential
how many sodium ions and potassium ions are in a neuron and how many are pumped in and out
3 sodium ions pumped out and 2 potassium ions pumped in- maintains the negative charge in neurons
what is an electrostatic gradient
positively charged ions attracted to negatively charged ions and vice versa
why does sodium (NA+) try to get into the cell and why does potassium (K+) try to leave
na trying to get in as less na inside
potassium tries to leave as less potassium outside
what is the diffusion gradient
high concentrations of ions are attracted to areas of low concentrations of ions
if the voltage in a neuron becomes more positive then what is it called
it is called an excitatory postsynaptic potential (EPSP).
what is a Inhibitory postsynaptic potential (IPSP).
when the voltage in a neuron becomes more negative
how is it decided wether a neuron becomes IPSP OR EPSP
depends on the flow of potassium and sodium ions in and out of the membrane.
And the flow of the ions is dependent on stimulation of the neuron by neurotransmitters
what electrical pattern is seen in a action potential
0- resting potential
1- depolarisation
2- repolarisation
3- hyperpolarisation
how does resting potential become more positive in EPSP
depolarisation
describe action potential EPSP
EPSP depolarises postsynaptic neuron making it more likely to send a action potential
- resting potential- wants to be kept at -70mv. More sodium outside axon than inside - maintained by ion pumps
- depolarisation- when stimulated past the threshold (-55mv)- sodium channels open and sodium rushes into axon causing a region of positive charge - change of threshold makes inside less negative than outside
- repolarisation- sodium channels shut anf potassium channels open and potassium exits the axon. Cell returns to its resting state after depolarisation- occurs after cell reaches highest voltage after depolarisation
3.hyperpolarisation- potassium continues to exit after repolsaritaion causing brief undershoot in charge (too negative) - ion pumps restore balance - allows for refractory period- sodium out- potassium in.
describe action potential IPSP
Makes resting membrane more negative
decreases likelihood of a action potential
when inhibiting neurotransmitters like GABA or Glycine kind to receptors on a post synaptic neuron causing hyperpolarisation
don’t involve NA+ influx
chloride ions enter and potassium exit- making inside more negtaive
membrane potential moves away from threshold (-55mv)
membrane may become -75mv or lower making it harder fr a neuron to fire
inhibitory neurotransmitters open CL- or K+ channels
