8- Nervous System Flashcards
What is the CNS?
Central nervous system
What are the 2 components of the CNS?
brain and spinal cord
What is the PNS?
Peripheral nervous system
What are the components of the PNS?
all the nerves travelling between the CNS and the visceral sites
What are the 2 branches of the PNS?
Autonomic nervous system (ANS), and sensory/somatic nervous system
Is the ANS provide voluntary motions or involuntary changes?
Involuntary
What are the 2 divisions of the ANS?
Sympathetic and parasympathetic
What does “ANS” sound like?
Anus
What is the responses carried out by the sympathetic autonomic nervous system (SANS)?
Fight/flight responses
What is the responses carried out by the parasympathetic autonomic nervous system (PANS)?
Rest/digest/DSP responses
How many neurons do ANS fibers use to get to their target organ?
2
What is the first ANS neuron that originates in the brainstem or spinal cord called?
Preganglionic neuron
The preganglionic neuron synapses outside the spinal cord in an autonomic ganglion onto what neuron?
Postganglionic neuron
What is the size of the parasympathetic preganglionic neuron?
Long
What is the size of the parasympathetic postganglionic neuron?
Short.
What is the size of the sympathetic postganglionic neuron?
Long
What is the size of the sympathetic preganglionic neuron?
Short
Which neurotransmitter (NT) does the PANS use exclusively?
Acetylcholine (Ach)
Which NT is released from the preganglionic SANS neuron?
Ach
Which NT is released from the postganglionic SANS neuron?
Norepinephrine (NE)
What is the exception to the 2-neuron ANS system? (think SANS)
the 1 neuron use for the adrenal medulla, where 1 sympathetic neuron synapses directly on the adrenal medulla to release epinephrine using acetylcholine as the neurotransmitter
What are long-tract neurons?
these act as tracts between the periphery and higher sites in the CNS
What is divergent signaling?
when there is 1 preganglionic neuron that makes synaptic connections with up to several thousand postganglionic neurons
What is convergent signaling?
when there are multiple stimuli onto 1 neuron
What are local circuits?
these are layered neurons that contain excitatory and inhibitory neurons to process information in your brain
What are single-sourced divergent neurons?
They’re neurons that originates in the brainstem and innervates in the cerebrum of the brain
What structural motif does the PNS exclusively have?
Long tract neurons
Which structural motifs does the CNS have?
all 3 types
What are neurotransmitters, anyway?
small endogenous molecules that transmit signals from a neuron to target cells
What are metabotropic receptors?
ones that act through second messengers (G proteins)
What are ionotropic receptors?
Ligand-gated ion channels
What type of response does GABA give? (inhibitory or stimulatory)
inhibitory
What are the 2 receptors for GABA?
GABA(A) and GABA(B)
How does GABA(A) receptors inhibit cells?
Increase Cl and K conductance (makes the cell more negative inside)
How does GABA(B) receptors inhibit cells?
they decrease cAMP.
What are the 4 receptors that Glutamate acts on?
AMPA, Kainate, NMDA and mGlu
What type of response does glutamate give? (inhibitory or stimulatory)
Stimulatory
How does AMPA, Kainate, and NMDA receptors excite cells?
Increasing Na and K conductance (and Ca in NMDA)
How does mGlu receptors excite cells?
decreasing cAMP and increasing IP3/DAG/Ca
What type of response does dopamine give? (inhibitory or stimulatory)
Mostly excitatory
What types of receptors does dopamine use?
D1-5
How does D1 cells excite cells?
increasing cAMP
What type of response does NE give? (inhibitory or stimulatory)
either excitatory or inhibitory
What types of receptors does NE bind to?
alpha 1 and 2, beta1-3
How does alpha1 receptors work?
Gq stimulation (increasing IP3/DAG/Ca)
How does alpha2 receptors work?
Gi stimulation (decreasing cAMP and increasing K conductance)
How does beta1-3 receptors work?
Gs stimulation (increasing cAMP)
What type of response does serotonin give? (inhibitory or stimulatory)
Generally inhibitory
What types of receptors does serotonin bind to?
5-HT(1-7)
How does the 5-HT1 serotonin receptor inhibit cells?
Gi stimulation (decreasing cAMP and increasing K conductance)
How does the 5-HT2 serotonin receptor inhibit cells?
Gq stimulation (increasing IP3/DAG/Ca)
What type of response does histamine give? (inhibitory or stimulatory)
Stimulatory
What types of receptors does histamine bind to?
H1-3
How does the H1 histamine receptor work?
Gq stimulation (increasing IP3/DAG/Ca)
How does the H2 histamine receptor work?
Gs stimulation (increasing cAMP)
What type of response does Ach give? (inhibitory or stimulatory)
Excitatory to SkM. Excitatory or inhbitory to other parts.
How does the Nicotonic Ach receptor excite cells?
Ligand-gated opening of channels that allow Na, K and Ca through into SkM cells
How does the Muscarinic Ach receptor excite cells?
Gq stimulation (increasing IP3/DAG/Ca)
What are biogenic amines?
they are the primary modulatory neurotransmitters in the CNS
Which AA are dopamine, epinephrine and NE all synthesized from?
Tyrosine
Give the general synthesis of epinephrine from Tyr
Tyrosine –> L-DOPA –> Dopamine –> NE –> Epinephrine
Which AA is serotonin (5-hydroxytryptamine) synthesized from?
Tryptophan
Which AA is histamine synthesized from?
Histidine
What is the role of Ach in the periphery?
to excite SkM at the NMJ
What is the role of Ach in the ANS?
it is used by all preganglionic neurons and parasympathetic postganglionic neurons as its neurotransmitter
What is the role of Ach in the CNS?
Thought to regulate sleep and wakefulness
What are fenestrae?
small gaps between the endothelial cells in the microvasculature
What do fenestrae allow to pass through them?
water and small molecules to diffuse across the lining without resistance but don’t allow large proteins and cells to cross
Where are fenestrae found?
only exist in the vasculature of the periphery, because in the CNS they have tight junctions and astroglia covering all the vasculature. This is the blood-brain barrier (BBB)
What is facilitated diffusion?
specialized transporters that move the molecule down its concentration gradient
What is the function of MDR’s?
pump hydrophobic compounds out of the brain cells and back into blood vessel lumen
