Neurons Flashcards
How many neurons in the nervous system?
10-100 billion
How many neurons does each neuron communicate with?
1000 neurons
What other cell is the brain comprised of and what do they do?
Glial cell - provide nutrients to neurons and structural support to nervous system
3 neuron functional levels are:
Motor
Sensory
Interneurons
Sensory neurons
Transmit sensory
Info from sensory receptor to brain for processing
Motor neurons
Transmits info from brain to muscles, organs with instructions on how to function.
Describe and sensory and motor neuron:
Very long - toe all the way to brain
Interneuron
Make up most of neurons in brain. Transmit info from one neuron to another
Neuron parts
Dendrite, cell body, nucleus
Which parts of the neuron receive information from other neurons?
Dendrites and cell body
Cell body function
Where all important processing of neurons take place
Can receive information from other neurons in the body
Nucleus function
Inside cell body
Contains DNA
Control house for how the neuron is structured and functions
Dendrites function
Received information from other neurons
Axon
Extends like an arm from cell body
Transmits electrical signal from cell body to terminal buttons
Terminal
Buttons
Where information is converted to other neurons
Myelin
Axon interspersed with myelin (white matter)
Unmyelinated parts of axon are caked?
Node of ranvier
Axon hillock
(Shoulder to axon)
Connects cell body to axon
Which areas carry out the function action potential
Nodes of ranvier and axon hillock
Action potential
Propagates electrical signal from axon hillock to allow information to be transmitted to the dendrites of next cell
Gap between terminal buttons of the neuron and dendrites of next neuron is:
Synapse
Unipolar neuron
One projection from cell body. Dendrites or axon
Neuron structures
Unipolar neuron
Bipolar neuron
Prototypical neuron
Pseudo-unipolar neuron
Bi polar neuron describe and fiction
Two projections
Function: visual system
Prototypical neuron
Multipolar neuron (many projections)
Most common type of neuron
Pseudo unipolar neuron
Only one projection but has both dendrite and axon (T shape)
Function: long sensory and motor neurons travelling the length of the body
Grey matter
Cell bodies and dendrites
What is an example of white matter in the brain?
Corpus callosum
Communication between hemispheres of the brain - comprised entirely of axons spanning from one part of the brain to the other, thus white matter
How does communication occur
A
B
C
A - all info from dendrites culminate in cell body to determine whether or not to transmit (electrical signal)
B - info from axon hillock to terminal buttons (electrical signal)
C - electrical signal in thermal buttons becomes chemical allowing communication across synapse
Ion
Molecule or chemical with a positive or negative charge
Cation
Positively charged ion
Anion
Negatively charged ion
Diffusion
Movement of substance from high concentration to low concentration
Electrostatic pressure
Passive attraction of oppositely charged ions and repulsion of similarly charged ions
Intercellular space
Inside of neuron
Extra cellular space
Outside of neuron
What makes the cell membrane semi-permeable ?
Opening and closing of ion channels that allow certain ions to go in and out
How are ion channels open or closed?
Electrical signals
Membrane potential is?
Charge inside neuron relative to outside
Restating membrane potential
Intercellular space - negative charge
Extracellular space has positive charge
-70mV
What is depolarising and how does it occur?
Charge becomes more positive due to excitatory signal
What is hyperpolarise?
Inside of membrane becomes more negative and less positive
What is received by dendrites and cell body?
Excitatory and inhibitory potential
Cell body and dendrites send signals that cause what to happen happen?
Cell membrane manipulated and causes inhibitory or excitatory potential
Graded potential
Dependent on inhibitory or excitatory signal
Where are graded potential located?
Axons hillock - waiting for electrical signal and to have the net effect
What causes a neuron to fire?
Net effect of excitatory and inhibitory graded potentials that converge at axon hillock
Threshold of excitation (when the excitatory effect reaches a certain mV)
-55 to -65mV
What triggers action potential?
Overall net effect of graded potential is excitatory and has a large enough magnitude to cause membrane to depolarise to -55 to -65
Synaptic cleft
Another name for synapse
Presynaptic neuron
Neuron sending chemical signal
Post synaptic neuron
Neuron receiving chemical signal
List the steps of neuron firing:
Electrical signal from presynaptic neuron propogates down axon —> through terminal buttons of presynaptic cell —> presynaptic cell releases chemicals into synapse —-> chemical traverse synapse and bind to post synaptic neuron—> post synaptic neuron either hyperpolarises or depolarises —-> post synaptic neuron causes excitatory or inhibitory potential
ESPS and IPSP
Excitatory postsynaptic potential
Inhibitory postsynaptic potential
Neurotransmitters
Chemicals that are released by presynaptic neuron into synapse and bind to postsynaptic neuron
What stores neurotransmitters?
Vesicles
What triggers vesicles to move towards cell membrane, bind to membrane and release neurotransmitter into the synapse?
Terminal buttons
What is it called when specific neurotransmitters bind to specific receptors?
Lock and key principle
What happens when the neurotransmitter bonds to receptor in postsynaptic membrane?
It causes EPSP or IPSP by indirectly or directly opening up ion channels in membrane that changes concentration of positive and negative ions in cell
How does the neutron know to stop releasing neurotransmitters?
Neurotransmitters can also bind to pre-synaptic neutrons to act as a feedback loop
What happens to excess neurotransmitters?
Degrade by enzymes in the synapse to be recycled
Effects of drugs 1.
- Increase or decrease synthesis of neurotransmitter in cell
Effects of drugs 2
Could alter how much neurotransmitter is released by cell
Effects of drugs 3
Influence amount of neurotransmitter in synapse by manipulating reuptake of neurotransmitter or the enzyme that breaks down the neurotransmitters
Effects of drugs 4
Could increase or decrease amount of neurotransmitter receptors in post synaptic neuron
Effects of drugs 5
Chemical could pretend to be a neurotransmitter and increase the number of receptors in the post synaptic neuron that are activated
Glutamate
Function: often produce EPSPs
Implicates: epilepsy and seizures
Learning and memory
GABA (gamma amino buteric acid)
IPSPs
Function: behaviour
Example: alcohol effects the GABA as it inhibits the frontal lobe of your brain which were suppose to control behaviour. Alcohol increases GABA functioning and increases inhibition by activating GABAergic neurotransmitters
Which receptor site do drugs that put you to sleep or reduce anxiety target?
GABA
Dopamine function
Activates reward pathway
Controls: emotions, motivations, Arousal, movement
What can high level of dopamine be linked to?
Schizophrenia
What can low levels of dopamine be linked to?
Parkinson’s
Serotonin function
Regulation of sleep, mood, arousal, emotions and empathy
What is low level of serotonin linked to?
Depression
What is one way of increasing serotonin in synapse?
Drugs that block reuptake sites in presynaptic neuron thus increasing amount of serotonin that can bind to postsynaptic neuron
Acetylcholine
Function: learning, memory, movement, muscle coordination
What is acetylcholine linked to?
Alzheimer’s disease
Endorphins
Reduce pain and influence mood
