Quiz 2 Exam 2 Flashcards
Neuro
What chemical was used in the first experiments that blocked the muscle response to nerve stimulation?
Curare (it was later found that curare blocked the Ach receptors so Ach could not bind)
What is retrograde neurotransmission?
This is when transmission goes in the opposite direction. NTs are released from the postsynaptic site and activate the presynaptic site.
What are the two broad categories of receptors located on the postsynaptic site?
Ionotropic (fast and ions) and Metabotropic (slow and G proteins 2nd messengers)
An action potential stimulates the release of ____________ into the cell which activates _______ channels. This then allows the secretory vesicles to bind to the presynaptic site and release the NTs into the cleft.
Na+
Ca2+
What is the neuromuscular junction?
These are the skeletal muscle neurons that are not apart of the ANS. They are activated by Acetylcholine (Ach) binding to nicotinic acetylcholine receptors and stimulate the release of Na+ which is part of muscle contraction.
Where is epinephrine made?
Adrenal glands
What are the 3 main groups of neurotransmitters?
- Biogenic Amines/ Catecholamines- dopamine, EPI, and NE
- Amino acids- glutamate and GABA
- Acetylcholine (Ach)
What is the amino acid precursor for catecholamines synthesis?
Tyrosine
What are the steps in converting tyrosine to dopamine, NE, and Epi?
Tyrosine ——-> DOPA via Tyrosine Hydroxylase
DOPA——–> Dopamine via Aromatic Amino Acid Decarboxylase (AADC)
Dopamine ——> NE via dopamine beta-hydroxylase (DBH)
NE travels in systemic circulation and reaches adrenals
NE ——-> Epi via PNMT
What is the rate limiting enzyme of catecholamine synthesis?
Tyrosine hydroxylase
What are two enzymes that metabolism catecholamines to their inactive versions?
Monoamine oxidase (MAO) and Catechol-O-methyltransferase (COMT)
What is the primary mechanism of inactivating catecholamines in the cleft?
Reuptake transporters. They remove catecholamines from the synapse and suck them back up into the presynaptic neuron.
What is the MOA of cocaine?
Cocaine blocks the reuptake of NE in the peripheral and dopamine in the reward pathway.
What is the MOA of amphetamines?
Amphetamines reverse the direction of the reuptake transporter therefore spitting more catecholamines out and not taking an back up. Overall, it increases the release of dopamine and NE.
What are presynaptic autoreceptors?
These are typically alpha2 and dopamine2 autoreceptors. There are feedback inhibitory receptors that sense how much NE or dopamine has been released and when it senses the limit, it tells the neuron to slow down and stop the release of the NTs.
What are the steps in the creation and breakdown of acetylcholine (Ach)?
Acetyl CoA + Choline ——-> Acetylcholine (Ach) via Choline Acetyltransferase (ChAT)
Acetylcholine (Ach)——–> Acetic acid + Choline via acetylcholinesterase (Ache)
What happens to choline after Ach is metabolizied?
It is taken back up into the presynaptic neuron.
What is myasthenia gravis?
Myasthenia gravis is an autoimmune disorder that results in the destruction of Nicotinic Acetylcholine Receptors in the neuromuscular junction. It is characterized by muscle weakness.
Curare (plant alkaloid) and a-bungarotoxin (snake venom) have what MOA?
These compounds block Ach receptors.
What is the MOA of botox/ botulinum toxins?
Botox destroys the presynaptic vesicles that hold Ach which leads to the inhibition of Ach release.
What is the MOA of black widow toxin?
Black widow toxin stimulates the release of Ach
What is the MOA of insecticides?
Insecticides inhibit Acetylcholinesterase leading to massive increases in Ach levels.
What is a disease state that uses acetylcholinesterase inhibitors to slow the progression of the disease?
Alzheimer’s
The effect of an alpha2 agonist would be to?
A. Inhibit release of NE
B. Inhibit reuptake of NE
C. Inhibit metabolism of NE
D. Increase the release of NE
A. Inhibit the release of NE
Alpha2 receptors are the autoreceptors that are the natural breaks for the release of NTs. Stimulating that receptor would inhibit the release of more NE.
Cocaine acts to?
A. Increase the synthesis of NE
B. Inhibit NE metabolism
C. Inhibit NE reuptake
D. Indirectly activate NE receptors
E. C and D
E. Inhibits NE reuptake and indirectly activates NE receptors
Cocaine’s MOA is to inhibit the reuptake of NE. Therefore it also indirectly allow more NE to activate its receptors.
What is the neurochemical pathology of Myasthenia gravis?
A. Loss of Ach neurons
B. Loss of acetylcholinesterase
C. Loss of nicotinic acetylcholine receptors
D. Impaired uptake of choline
C. Loss of nicotinic acetylcholine receptors
What would be the RX for myasthenia gravis?
Increase Ach transmission by inhibiting acetylcholinesterase enzyme.
What are the two parts of the peripheral nervous system?
Somatic and Autonomic
What does the somatic nervous system control?
Skeletal muscle (voluntary movements)
What does the autonomic nervous system include?
Sympathetic and parasympathetic
What does the autonomic nervous system innervate?
Cardiac muscle, smooth muscle throughout the body, and glands
What are the general lengths (short vs long) of the parasympathetic innervation to the ganglion and organs?
Long preganglionic neuron and short postganglionic neuron
What is the NTs used at the ganglion and at the organs in the parasympathetic system?
Acetylcholine for both!
What type of receptor does Acetylcholine bind to in the parasympathetic nervous system at the organs?
Muscarinic
Where in the spinal cord do the parasympathetic fibers originate from?
Cranial and sacral portions of the spine
Where in the spinal cord do the sympathetic fibers originate from?
Thoracic and lumbar portions of the spine
For sympathetic innervation, what is the general length (long vs short) of the ganglionic neurons?
The preganglionic are very short while the postganglionic are long.
What NTs is released at the ganglion in sympathetic innervation?
Acetylcholine
At the site of the organs, excluding the adrenal medulla and sweat glands, what NT is released with sympathetic innervation?
Norepinephrine and it binds to a/B adrenergic receptors
T or F: Almost all visceral organs are served by both the sympathetic and parasympathetic divisions, but always cause the opposite effects.
False. The first portion is correct but it is not every single time they cause the opposite effect. They mostly cause the opposite effects but not every time.
Know this chart
Does sympathetic or parasympathetic have control over the vagus nerve (X)?
Parasympathetic
In the sympathetic division, what innervation arises from the paravertebral ganglia?
Innervation of organs above the diaphragm.
In the sympathetic division, what innervation arises from the prevertebral ganglia?
Innervation of organs below to diaphragm.
How are sympathetic responses described?
Sympathetic responses are the ‘E’ situations like exercise, emergency, excitement, and embarrassment
How are the parasympathetic responses described?
Parasympathetic responses are described with SLUDD + 3 Ds
Salivation, lacrimation, urination, digestion, and defecation with decreased heart rate, decreased airway diameter, and decreased diameter of the pupils.
What NT is used in all ganglions regardless that it is sympathetic or parasympathetic?
Acetylcholine binding to nicotinic receptors
Why are sweat glands and SOME blood vessels in skeletal muscle the outliers in sympathetic innervation?
In general, the sympathetic nervous system used NE at organs but at sweat glands, acetylcholine is used and it binds to muscarinic receptors. This is similar to parasympathetic but it is innervated by the sympathetic system.
What is unique about the adrenal medulla and how it is innervated?
It is known that the adrenal medulla secretes epinephrine. It is innervated by the sympathetic nervous system but this innervation has no ganglion intermediate. Ach is released from the spinal cord portion and it binds to nicotinic receptors are the adrenal medulla. This stimulates the adrenal medulla to release Epi and NE into the blood stream.
Where are M2 (muscarinic 2) receptors located?
The heart (and some nerve endings but really the heart)