#6 Flashcards
How does myelin accelerate the propagation of signals?
Think of the cell membrane as. a conductor that stores charges. Myelin sheath reduces the neuron’s electrical capacity and hence enables the signal to travel faster.
Effects and mechanisms of metabotropic receptors
Effects of metabotropic receptors are slower than ionotropic receptors. However, the effects can last a lot longer (e.g. making new proteins that can function for a long time in the cell). Moreover, this mechanism can do a bunch of things (e.g. the binding of norepinephrine in G-protein coupled receptors can stop smooth muscle in digestion as well as raise blood pressure and increase heart beat).
2nd messangers activate a range of cellular proteins, including ion channels, protein kinases and transcription factors.
Metabotropic receptors at inhibitory synapses called GABAB receptors. When activated, 2’ messengers generated, causing a lot of changes inside the cell.
what other substances does the brain release and what changes do they cause?
Some synapses inside the brain don’t release glutamate or GABA, they release other neurotransmitters like dopamine, serotonin, and norepinephrine. These substances interact mainly with meatbotropic receptors.
also these substances only cause slow changes inside the neurons. They are not directly involved in the fast flow of neural information but modulate gloval neural states, influencing alertness, attention and mood
What is norepinephrine involved in ?
Norepinephrine neurons involved in sleep-awake cycle and in alertness and attention. There are only a few thousands of norepinephrine neurons clustered inside the brain stem.
What is dopamine involved in?
dopamine is involved in pleasure and learning
How many synaptic connections can a single norepinephrine make?
A single norepinephrine neuron can make synaptic connections with thousands of other neurons in the brain. They have branches and branches of axons.
What do norepinephrine neurons modulate?
Norepinephrine neurons modulate the amount of norepinephrine inside our brains. This is the same for serotonin and dopamine neurons.
What are endorphins and serotinin invloved in?
endorphine is involved in pleasure and pain - Serotonin neurons regulate moods.
By increasing the amount of serotonin in the brain, it may be beneficial for people in depression.
Neuromodulator systems exmaples
Neuromodulator systems are important targets for a wide range of drugs. For example, antidepressants, such as Prozac, affect serotonergic transmission, whereas amphetamines, cocaine and other stimulants typically affect dopamine and norepinephrine transmission - Nearly all drugs of abuse/addiction involves dopamine.
How does a smoking addiction work?
Smoking involves nicotine that acts on nicotinic receptors. This increase the release of dopamine and our brain learn to associate nicotine with pleasure -smoking addiction
What are endorphins related to ?
Endorphins are related to Morphine, giving a feeling of euphoria and pleasure, inhibiting pain.
neuromodulators often originate in ?
Neurons that release neuromodulators often originate in small brainstem or midbrain nuclei. Their axons project diffusely throughout the brain.
Can neuromodulators innervate the entire brain?
All neuromodulators are released by a small number of neurons released in the brain stem which have axons going all over the brain, so they can innervate the entire brain
