Neural structure and function Flashcards
William, a philosophy student, asked Ian the psychology student what type of cell contributes the most to Ian’s thoughts, feelings, and actions. Without hesitation, Ian replied ______.
neurons
What is the fundamental concept of the Neuron Hypothesis?
Individual neurons represent the fundamental building blocks of the nervous system.
What are neurons specialized for?
communcation
What electrical property do all cells, including neurons, have?
Charged ions moving in and out.
What is the difference in voltage inside/outside the cell known as?
Membrane potential (MP).
What is the typical resting potential of a neuron?
-70mV.
What maintains the negative charge inside a neuron?
A balance of positive and negative ions.
What ions are more concentrated outside and inside the neuron, respectively?
Sodium (Na+) outside; Potassium (K+) inside.
What is the process called when a neuron receives signals from other neurons?
Summation.
What is an action potential?
A nerve impulse characterized by a rise and fall in electrical membrane potential.
What happens during depolarization in an action potential?
Na+ ions flood into the cell, increasing the membrane potential.
What triggers the action potential?
If the threshold of -55mV is reached.
What occurs during repolarization of an action potential?
K+ ions flood out, reducing the membrane potential.
What is the ‘all or nothing principle’ in relation to action potentials?
An action potential is a fixed size and either occurs fully or not at all.
Who first worked out how action potentials are generated?
Hodgkin and Huxley.
What is a synapse?
A chemical junction between neurons.
What types of neurotransmitters are classified as excitatory and inhibitory?
- Glutamate → Excitatory
- GABA → Inhibitory
What role do microglia play in the nervous system?
Immune function.
What is the role of astrocytes?
Control NT levels, modulate neuron function and synapses.
What neurotransmitter is associated with muscle control and memory regulation?
Acetylcholine.
What is the primary function of dopamine?
Produces feelings of pleasure and is involved in motivation and addiction.
What effect does alcohol have on neurotransmission?
Acts as a depressant, enhancing GABA transmission and inhibiting glutamate.
What is the role of cocaine in neurotransmission?
Prevents dopamine reuptake.
What is neurodegeneration?
Progressive loss of neurons due to underlying disease conditions.
What characterizes Parkinson’s disease?
Loss of dopaminergic neurons in the substantia nigra.
What does the autonomic nervous system regulate?
Functions such as heart rate, respiratory rate, and digestion.
What is the role of the pituitary gland in the endocrine system?
It is the ‘master gland’ that controls other glands.
How do the nervous system and endocrine system generally differ in speed?
Nervous system = fast; Endocrine system = slow.
Fill in the blank: The inside of a neuron is more _______ charged compared to the outside.
negatively
True or False: Neurotransmitters can only excite neighboring neurons.
False.
What are the two divisions of the autonomic nervous system?
- Sympathetic: ‘fight or flight’
- Parasympathetic: ‘rest and digest’
What type of receptors does nicotine bind to?
Acetylcholine receptors (nicotinic receptors).
What is the effect of psychedelics like LSD on the brain?
They distort perception, cognition, and mood.
What happens when we lose neurons?
Loss of function.
what is the typical resting potential of neuron
-70mV
example of a molecule that can diffuse in and out
h2o
what is a semi permeable membrane
thin sheets that allow some molecules to pass through easier than others
what triggers action potential
depolarisation reaching threshold 9~55mV), causing Na+ to flood in
what is repolarisation
K+ ions flow out of the neuron, restoring negative internal change
what is the refractory period
a short time after an action potential when a neuron can’t fire again
how fast do signals travel
myelinated: ~100m/s unmyelinated: ~1m/s
what is a synapse
a chemical junction where neurotransmitters transfer signals between neurons
most common excitatory neurotransmitter
glutamate
most common inhibitory neurotransmitter
GABA
what does acetylcholine do
controls muscles and supports memory
is acetylcholine excitatory or inhibitory
usually excitatory
what does dopamine do
pleasure, motivation, reward
is dopamine excitatory or inhibitory
can be both
what does serotonin regulate
mood, appetite, sleep
what is an agonist
a compound that mimics or increases a neurotransmitters effects
what is an antagonist
a compound that blocks or reduces a neurotransmitters effects
how does cocaine work
blocks dopamine reuptake (which also affects serotonin and norepinephrine)
how does nicotine work
binds to acetylcholine receptors (nicotinic)
how does caffiene work
antagonist for adenosine receptors (keeps you alert)
how do psychedelics affect the brain
act mostly on serotonin receptors, altering perception and mood
what are glial cells
non-neuronal cells that support neurons
name three types of glial cells
- microglia
- astrocytes
- oligodendrocytes
role of microglia
immune response
role of astrocytes
regulate neurotransmitters
role of oligodendrocytes
produce myelin in the CNS (Schwann cells in PNS)
what is the function of autonomic nervous system
regulates involuntary functions (e,g. heart rate and digestion)
what is neurodegeneration
progressive loss of neurons leading to functional decline
what happens in Parkinson’s disease
loss of dopaminergic neurons in the substantial nigra (basal ganglia), leading to motor and cognitive issues
The ______ potential is the neuron’s means of transmitting information over long distances.
action
The ______ is the difference in electrical potential between the inside and outside of an inactive neuron.
resting
The gaps in the myelin sheaths on axons are known as:
nodes of ranvier
Which of the following concepts does the all-or-nothing law describe?
The size of an action potential does not depend on the amplitude of the stimulus that started it.
what is synaptic cleft
microscopic area between presynaptic and postsynaptic neurons
how wide is synaptic cleft
around 40nm
what is the presynaptic neuron
neuron where signal is initiated
what is the postsynaptic neuron
neuron that receives the signal
what are vesicles
found in presynaptic neuron, contain thousands of NTs
what happens after a presynaptic neuron is excited by an action potential
vesicles fuse fuse with presynaptic membrane and release contents into the synaptic cleft, then onto the receptors of the postsynaptic neuron
what is diffusion
when NT molecules drift out from the synaptic cleft
what is reuptake
where NT molecules are taken back to the presynaptic neuron to be reused
