Lecture 7 - Neurotransmitters, Neuromodulators, and the Autonomic Nervous System Flashcards
Neuromodulators are involved in direct synaptic transmission, in which a presynaptic neuron directly influences a postsynaptic partner. T/F?
FALSE. Neurotransmitters are involve din direct synaptic transmission. RAPID COMMUNICATION is involved in NTs.
What is the difference between neurotransmitters and neuromodulators?
Neurotransmitter
-quick, fast, localized
Neuromodulator
-slower, does not have to be localized
• And some can act as bothWhat are cholinergic neurons?
Neurons that use ACh as the primary NT
What produces ACh in presynaptic axon?
the enzyme choline acetyl transferase
Degradation of ACh is caused by what enzyme?
acetylcholinesterase (AChE)
ACh can act on what two receptors?
muscarinic (G protein coupled) or nicotinic (ion channels)
What are muscarinic receptors?
acetylcholine receptors that form G protein-receptor complexes in the cell membranes of certain neurons and other cells. They play several roles, including acting as the main end-receptor stimulated by acetylcholine released from postganglionic fibers in the parasympathetic nervous system.
What are nicitinic receptors?
cholinergic receptors that form ligand-gated ion channels in the plasma membranes of certain neurons and on the presynaptic and postsynaptic sides of the neuromuscular junction.
What does the nerve gas, Sarin, do?
inhibit acetylcholinesterase, causing a buildup of ACh in the synaptic cleft; overstimulation of postsynaptic ACh receptors causes uncontrolled muscle contractions, ultimately leading to receptor desensitization and paralysis.
What does atropine do?
antagonist of muscarinic receptor (when an anatagonist binds to receptor, it prevents activity of NT) receptors. It also relaxes the muscles of the iris.
How is Alzheimer’s disease caused?
By the degeneration of cholinergic neurons. Associated w/ decreased amts of ACh in certain areas of the brain and loss of postsynaptic neurons that would have responded to it.
What catecholamines are made from tyrosine?
dopamine, norepinephrine, epinephrine
What catecholamines are made from tyrptophan?
serotonin
What catecholamines are made from histidine?
histamine
What are the enzymes that degrade biogenic amine NTs?
monoamine oxidase (MAO) catechol-o-methyltransferase (COMT)
What does dopamine do?
contribute to brain processes that control locomotion, emotional response, pleasure, and pain
Parkinson’s disease is caused by?
loss of dopamine-transmitting neurons. Treated w/ L-Dopa, a precursor of dopamine.
norepinephrine and epinephrine use what type of receptors?
adrenergic
Where is norepinephrine amd epinephrine found?
NE is in both CNS and PNS; Epi is found mainly in PNS.
Paticular organs can contain alpha and beta adrenergic receptors. T/F?
True
What AA NT’s are excitatory synapses?
aspartate, glutamate
what AA NT’s are inhibitory synapses?
glycine, GABA
__________ is estimated to be the primary NT at 50% of excitatory synapses in CNS?
glutamate
What are the 2 types of receptors for glutamate?
-metabotropic glutamate receptors (mGluR)
G-protein coupled receptor
- ionotropic glutamate receptors
AMPA receptors (bind to a-amino-3 hydroxy-5 methyl-4 isoxazole proprionic acid)
NMDA receptors (bind to N-methyl-D-aspartate)
What is the major inhibitory NT in the brain?
GABA; may bind to ionotropic or metabotropic receptors.
What happens GABA binds to ionotropic receptor?
increases Cl- flux into cell; resulting in hyperpolarization
How do benzodiazepine drugs work?
reduce anxiety, guard against seizures, and induce sleep by icnreasing Cl- flux through GABA receptor. (dampens excitation of neurons)
Ethanol ____ GABA synapses and simultaneousy ____ excitatory synapses. (choose between stimulates and inhibits)
Ethanol STIMULATES GABA synapses and simultaneousy INHIBITS excitatory synapses
What are examples of neuropeptides?
- Endogenous opiods: enkaphalins, endorphins
- Substance P - released by afferent neurons that relay sensory info to CNS (involved in pain sensation)
- neuropeptides coreleased w/ other neurotransmitters and act as neuromodulators
- neuropeptides typically have slow onset and long duration
How are gases released as NTs?
produced by enzymes in axon terminals and simply diffuse from sites of origin in one cell into intracellular fluid of other neurons or effector cells
Examples of gases as NTs?
nitric oxide (produced by nitric oxide synthase)
carbon monoxide
hydrogen sulfide
Tell me about neuroeffector communication.
NT released from efferent neuron, diffuses to the surf. of the effector cell, where it binds to receptors on that cell’s PM
Efferent division of PNS is subdivided into _________ an _______.
somatic nervous system and autonomic nervous system (ANS)
Tell me the number of neurons betw CNS and effector cell, the targets, and the activity of the somatic nervous system and the autonomic system.
Somatic nervous system:
- number of neurons betw CNS and effector cell: 1
- targets: skeletal muscle
- activity: excitatory
Autonomic nervous system:
- number of neurons betw CNS and effector cell: 2
- targets: smooth/cardiac muscles, glands, GI neurons
- activity: excitatory or inhibitory
ANS is subdivided intoo what?
parasympathetic and sympathetic
Where do we get sympathetic fibers from?
thoracic and lumbar regions
Where do we get parasympathetic fibers from?
brainstem and sacral portion
Sympathetic system?
short pre-ganglionic and long post-ganglionic synapses; major NT are ACh ar preganglionic synapse and NE and Epi at post-ganglionic (“fight or flight”)
Parasympathetic system?
long preganglionic and short post-ganglionic synapses; major NT is ACh at both pre- and post-ganglionic synapses (“rest and digest”)
Most of the ACh receptors in autonomic ganglia are __________ receptors. In contrast, the ACh receptors on smooth muscle, cardiac muscle, and gland cells are __________ receptors.
Most of the ACh receptors in autonomic ganglia are NICOTINIC receptors. In contrast, the ACh receptors on smooth muscle, cardiac muscle, and gland cells are MUSCARINIC receptors.
What forms the adrenal medulla?
postganglionic neurons in the sympathetic division that never develop axons
MEMORIZE THE TABLE 6-10 ON LECTURE NOTES
:D
