Exam 2 Flashcards
Ionotropic (Ligand-Gated) receptors (Neurotransmitter systems)
-Nicotine Acetylcholine Receptors
-GABA-A Receptors- Shunting Inhibition
-Ionotropic Glutamate Receptors
Metabotropic ( G-coupled) Receptors (neurotransmitter system)
Gs, Gi, GQ alpha subunit
Shortcut pathway (beta, gamma subunits)
What are the types of neurotransmitters?
Amino acids
Monoamines
Acetylcholine
Unconventional
What are the amino acids?
Glutamate
aspArtate
Glycine
Gamma-aminobytytic acid (GABA)
What are the monoamines?
Dopamine (catecholamines) synthesized in the midbrain
Epinephrine
Norepinephrine synthesized in the pons
Serotonin ( indolamines)
How does catecholamine synthesize the monoamines?
It synthesizes phenylalanine into tyrosine to L-Dopa to Dopamine to norepinephrine to epinephrine
Where serotonin synthesis from?
Tryptophan
What are the unconventional neurotransmitters?
Nitric oxide
Carbon monoxide
What stimulate the production of second messenger membrane?
The unconventional neurotransmitters
What is involved in retrograde transmission? And what is it?
The unconventional neurotransmitters
Retrograde transmission is when neurotransmitters go from the post synaptic cell to the presynaptic
What are the neuropeptides?
Pituitary peptides in the pituitary gland
Hypothalamic peptides in the hypothalamus
Brain gut peptides in the gut
Opioid peptides in the resemble opium
Miscellaneous
What can neurotransmitters cause? And are direct actions as neurotransmitters?
Excitation
Inhibition
What are excitatory responses? ( glutamate)
They results in depolarization, the cell became more positive of the post synaptic neuron
What are inhibitory responses cause? (Glycine and GABA)
They cause hyper-polarization of the post synaptic neuron, making it more negative
Is acetylcholine excitatory or inhibitory?
Excitatory for skeletal muscles
Inhibitory for cardiac muscle
Explain direct action?
Neurotransmitters binding causes receptors to open up so that ions can pass through
What can be involved in direct action?
Acetylcholine and amino acids
Explain indirect action
When the action is promoted through second messenger molecules
What initiated indirected action? What else work that way?
It is initiated by metabotropic receptors and hormones work that way
What are amino acids?
They are small molecules containing amine( NH2) and carboxyl (-COOH)
What are the most abundant type of neurotransmitters? ( 70% of all neurons in CNS utilize AANTs)
Act as both Ionotropic and metabotropic?
Have a fastest effects due to change in resting membrane potential?
GABA
GLUTAMATE
What is synthesized from glutamine? The enzyme being glutaminase
Glutamate
What happens if GABA-A receptors are blocked?
Convulsions and Death can result
What synthesized GABA?
GABA is synthesized only by GABAergic neurons
Where does GABA from and what catalyzed it?
GABA is made from glutamate, synthesized by glutamic acid decarboxylase (GAD)
The catecholamine Systems
Dopamine and movement
Dopamine and reward
Dopamine and cognition
Dopamine and movement
Nigrostriatal tract: axons in the substantia nigra extend to the basal ganglia
Dopamine and reward
Mesolimbic dopamine pathway: from the ventral tegmental area to various structure of the limbic system
What are mesolimbic dopamine pathway and mesocortical dopamine pathway
though of as? Explain it.
It is though of as the primary reward pathway
It is though to contribute to the development of addiction
Dopamine and cognition
Mesocortical dopamine pathway from the VTA to the prefrontal cortex, cognition of reward
What is the catecholamine systems?
Dopamine to norepinephrine to epinephrine
How is amino acid converted to L-dopa?
It is converted by the enzyme tyrosine hydrolase ( addition of an hydroxyl group to tyrosine, considered as the rate limiting enzyme)
How is dopa converted into dopamine?
By the enzyme aromatic amino acid decarboxylase ( removal of carboxyl group from dopa)
How is dopamine converted to norepinephrine?
By the enzyme dopamine beta hydroxylase ( addition of OH group to dopamine)
How is epinephrine is converted to norepinephrine?
By the enzyme phenyl-ethanonolamine-N-methyltransferase ( addition of a methyl group to norepinephrine)
Where is acetylcholine found at?
Neuromuscular junction
Autonomic nervous systems
Isolated within the brain (fibers originate and stay in brain )
What are the 3 primary areas where the ACh is found?
Projecting ACh cell bodies: basal forebrain and brainstem
ACh interneurons: Striatum
Where is ACh synthesized?
In two discrete brain regions: basal forebrain and medulla
The main neurotransmitter at the muscular junction
How is ACh formed?
It is formed from choline and acetyl coenzyme A
Most choline comes from the consumed foods with natural fats( meats, eggs, vegetables…)
Actively transported across BBB
Acetylcholine CoA is produced during metabolism of sugars
What catalyze the synthesis of ACh and where is it found?
Choline Acetyltransferase catalyzes the synthesis of ACh and is found in neurons that use ACh as their transmitter
What is the role of CHAT?
It transferse the acetyl group from acetyl CoA to choline
What inactivate acetylcholine? And How does it breaks it down?
ACh is inactivated by acetylcholinesterase, which breaks it down to choline and acetyl acid
Where can we find ACHE?
We can find it in the presynaptic and post synaptic cell
Explanation
Most choline in the cleft after ACh breakdown by ACHE is taken back into the cholinergic nerve terminal by a choline transporter.
Where is Serotonin synthesized?
In several nuclei in the midbrain and brainstem
The clusters project to broadly and are mostly inhibitory
What are the Rostral raphe group?
Dorsal
Linear
Median
What are the caudal raphe group?
Magnus
Obscurus
Pallidus
What is Serotonin?
Known as indoleamine, it is a neurotransmitter that has a wide range of behavioral and physiological functions including regulation of mood, sleep, hunger,anxiety, pain, and learning and memory
Formation of serotonin?
L-Tryptophan to L-5-Hydroxytryptophan by trytophydrolase
L-5-Hydroxytryptophan to serotonin by aromatic L-amino acid decarboxylase (COOH is gone)
How do we call neurotransmitters that bind to more than one type of receptors?
Receptors subtypes
What results in fewer side effects?
When drugs are designed to affect specific subtypes.
What are the major categories of transmitters receptors ?
Ionotropic and metabotropic
What can be qualified as Ionotropic receptor?
Ligand gated ion channel
Transmitter gated ion gated
How does Ionotropic neurotransmitter receptors work?
Ion influx changes the membrane potential into excitatory or inhibitory
What is an important second messenger for many developmental and environmental responses?
Calcium
How does metabotropic receptors work?
Act more slowly but responses last longer
Consists with one subunit with seven transmembrane domains
Work by activating G proteins ( G proteins coupled receptors)
How does G proteins act?
Inhibit or activate ion channels ( potassium moves out of the cell and hyperpolarization results)
Stimulate or inhibit effector enzymes in the cell membrane, that synthesize or breakdown second messenger molecules
Good summary ( seven steps in neurotransmitters action)
1-Synthesis
2- Storage of vesicles
3- Breakdown of any neurotransmitters leaking from the vesicle
4- Exocytosis
5- Inhibitory feedback via auto receptors
6- Activation of post synaptic receptors
7- Deactivation
Step of sensory input
Receptors
Thalamic Relay Nuclei
Primary Motor Cortex
Secondary Motor Cortex
Association Cortex
Step of motor output
Association Motor Cortex
Secondary Motor Cortex
Primary Motor Cortex
Brain Stem Motor Cortex
Muscles
Sensorimotor Association Cortex
Posterior Parietal Association Cortex
Dorsolateral Prefrontal Association Cortex
The Posterior Parietal Association cortex
Receive messages from the visual, auditory, somatosensory system
The dorsolateral prefrontal association cortex
Receives information from the posterior parietal cortex and send information to the primary and secondary motor cortex and the frontal eye field
Secondary Motor cortex
Receives information from the posterior parietal association cortex and the dorsolateral prefrontal association cortex. It send information largely to the primary motor cortex.
What does the primary motor cortex consist of?
The supplementary motor area
The premotor Cortex
The role of the secondary motor cortex
It involves the programs patterned movement
Where can we find the primary motor cortex?
In the precentral gurus of the frontal lobe
What are important sensorimotor structures?
The cerebellum
Basal Ganglia