neurotransmittorer Flashcards
Type 1 and 2 synapses
Type 1 synapse: excitatory. Typically located on the shafts or spines of dendrites. Has round vesicles. Wider synaptic cleft. The material making up presynaptic and postsynaptic membranes is denser. Larger activation zone
Type 2 synapse: inhibitory. Typically located on a cell body. Has flattened synapses.
Glutamatsystemets funktioner
- Important for memory, cognition and mood regulation
- main neurotransmitter responsible for plasticity(on neuronal level?)
Renshaw loop
All motor-neuron axons leaving the spinal cord are cholinergic, and each has an axon collateral within the spinal cord that synapses on a nearby CNS interneuron. The interneuron, in turn, synapses on the motor neuron’s cell body. In a renshaw loop, the main motor neuron projects to a muscle, and its axon collateral remains in the spinal cord synapse with an inhibitory Renshaw interneuron that contains the inhibitory transmitter glycerine. Both main motor axon and its collateral terminals contain ACh. When the motor neuron is highly excited, it modulates its activity level through the renshaw loop - this enables the motor neuron to inhibit itself and not become overexcited in response to excitatory inputs it receives from other parts of the CNS. If the neurotransmitter(amino acid) in the renshaw cell, glycine(gly), is blocked by the toxin strychnine, motor neurons do become overactive - this leads to convulsions that interfere with breathing and thus causing death.
Serotonergic system
- Originating in raphe nuclei(one in the upper brain stem, one in the middle and one in the lower)
- travels throughout the brain(gissar att dom menar överallt iom att dom inte specificerar?)
Functions:
- Mood regulation
- Regulates sleep cycle
- Contrasts impulsive behavior
- Promotes well-being
- Regulates sexual drive
- Social cognition(makes you more empathetic, make you seek out company of others, make you relate to others more)
- active in maintaining the waking EEG pattern(in the forebrain?)
- plays a role in learning
Serotonin imbalance
Low levels:
* Poor memory and forgetfulness
* Anxiety
* Difficulty falling asleep
* Impulsive behavior
* Craving sweets and starches
* Headaches
* Exhaustion
* Social avoidance
* related to depression
High levels:
* Tremor
* Hyperthermia
* Sweating
* Agitation
* Confusion
* Hallucinations
* related to OCD and schizophrenia
IDK om höga eller låga nivåer:
* Abnormalities in brain stem 5HT neurons are linked to disorders such as sleep apnea and SIDS
* relaterat till tics
Dopamine imbalance symptoms(high levels and low levels)
Both motor symptoms, cognitive symptoms, behavioral symptoms.
Low levels:
* muscle spasms
* Tremor
* Trouble keeping balance
* Lack of focus or concentration
* Low energy
* Lack of motivation
* Fatigue
* Low mode
High levels:
* Repetitive tics
* psychosis
* Hypersexuality
* Gambling
* Impulsive behavior
* Aggressive tendencies
* Nausea
Mesolimbic pathways
- originating in ventral tegmentum
- axons travel down the brain stem, to the cerebellum, to the frontal cortex and to nucleus accumbens in the basal ganglia
- dopamine release causes feelings of reward and pleasure
- through to be the system most affected by addictive drugs and behavioral addiction
- increases in DA activity might be related to schizophrenia
- decreases in DA activity might be related to attention deficits
Vilka 3 pathways finns i det dopaminerga systemet(och vad är deras primära funktioner)?
Mesolimbic - belöning, njutning
Mesocortical - Kognition, minne, uppmärksamhet, känslomässiga beteenden och inlärning
Nigrostriatal - Rörelse och sensorisk stimuli
Nigrostriatal pathways
- originating in nuclei in substantia nigra
- axons go to caudate nucleus(a part of the striatum, the largest structure in the basal ganglia)
*active in maintaining normal motor behavior - loss in DA related to muscle rigidity and akinesia in parkinsons
GABA SYSTEMET
Functions:
* Reduce neuronal excitability by inhibiting nerve transmission
* Relaxing effect in brain and peripheral nervous system
* Affects mood, Mental health.
Main purpose: relax after stress.
Low levels:
* Anxiety
* Depression
* Insomnia
* Mood disorders
* Risk for convulsions and seizures(bc the brain is more excitable)
High levels:
* Sleep apnea(bc inhibitory effect on respiratory system)
* Drowsiness
* Daytime sleepiness
Which neurotransmitter is the main excitatory neurotransmitter in the CNS and which one is the main inhibitory one?
Excitatory - glutamate
Inhibitory - GABA
Noradrenerga systemet
*originating from locus coeruleus(upper part of brain stem)
* axons travel down the brain stem, into the cerebellum up around the corpus callosum to the rest of the brain, and to the thalamus.
Function - Mobilize brain and body for action:
* fight or flight
* Stress response in general
* Arousal
* Alertness
* Vigilance
* Attention
* Memory formation(u need to learn and retain information from dangerous situations)
* may also facilitate normal brain development and play a role in organizing movements and learning, by stimulating neuronal plasticity
* active in maintaining emotional tone.
Noradrenaline imbalance
Low levels:
* Lack of focus/energy/motivation
* Decreased mood
* Decreases in NE activity thought to be related to depression
* Decreases in NE activity thought to be related to ADHD
High level:
* stress and anxiousness
* hyperactivity
* headache
* increased blood pressure
* Hot flashes
* Anger
* Weight management issue(both underweight and overweight)
* Increased NA activity thought to be related to mania
Vilka två neurotransmittorer är starkast kopplade till de två autonoma systemen?
Sympatiska: NE
Parasympatiska: ACh
Both ANS divisions(sympathetic and parasympathetic) are controlled by cholinergic neurons that emanate from the CNS at two levels of the spinal cord. The CNS neurons synapse with parasympathetic neurons that contain ACh and with sympathetic neurons that contain NE.
Whether ACh synapses or NE synapses are excitatory or inhibitory on a particular body organ depends on that organs receptors:
- NE receptors on heart are excitatory(turns up heart rate)
- NE receptors on gut are inhibitory(turns down digestion)
- Opposite true for ACh receptors
Vad är de experimentella kriterierna för en neurotransmittor?
- The chemical must be synthesized in the neuron or must otherwise be present in it
- When the neuron is active, the chemical must be released and produce a response in some target cell
- The same response(receptor action) must be obtained when the chemical is experimentally placed on target
- A mechanism must exist for deactivating or removing a chemical from its site of action after its work is done
In which 2 ways can metabotropic receptors inhibit the firing of an action potential?
- metabotropic receptors are usually inhibitory
Works in 2 different ways.
A (metabotropic receptor coupled to an ion channel)
1. Transmitter binds to binding site
2. This triggers the activation of a G protein
3. The alpha subunit of the G protein binds to a channel, causing a structural change in the channel that allows ions to pass through it
B (metabotropic receptor coupled to an enzyme)
1. Transmitter binds to binding site
2. This triggers the activation of a G protein
3. The alpha-subunit binds to an enzyme, which activates a second messenger
4. The second messenger can activate other cell processes
3 exempel på vad en second messenger kan göra
*bind to membrane channels causing the channel to change its structure and thus alter ion flow
* initiate reaction that incorporates protein molecules within the cell into the cell membrane, for example, resulting in formation of new ion channels
* influence cell’s DNA to initiate or cease gene expression and thus regulate protein formation
