Lecture 2 T1 CNS structure and function Flashcards
What is the function of acetylcholine?
usually excitatory
What secretes acetylcholine?
- pyramidal cells of cerebral cortex,
- some neurons in the basal nuclei,
- alpha motor neurons,
- preganglionic neurons of ANS,
- postganglionic neurons of the parasympathetic system,
- some postganglionic neurons of the sympathetic system
What targets ACh?
nicotine, chantix, sarin, aricept (alzheimers), botox, tensolin (myasthenia gravis), biperiden (parkinsons).
What is the function of norepinephrine?
can be excitatory or inhibitory
What secretes norepinephrine?
- many neurons located in the brainstem and hypothalamus,
- some neurons located in the pons (locus ceruleus),
- most postganglionic neurons of the sympathetic system
What is the function of dopamine?
usually inhibitory
What secretes dopamine?
Most neurons originating the in the substantia nigra
What is norepinephrine targeted by?
amphetamines, cocaine, cymbalta, propranolol.
What is dopamine targeted by?
amphetamines, cocaine, levadopa (parkinsons), haldol (antipsychotic).
What is the function of glycine?
always inhibitory
What secretes glycine?
synapses in the spinal cord
What is the function of GABA?
always inhibitory
What secretes GABA?
many areas in the spinal cord and cerebral cortex
What is the function of glutamate?
always excitatory
What secretes glutamate?
- many sensory pathways entering the CNS,
- many areas of cerebral cortex
What are the targets of Glycine?
not a drug target
What are the targets of GABA?
alcohol, barbituates, valium, bacloden
What are the targets of Glutamate?
ketamine, namenda, robitussin
What type of conduction occurs in dendrites?
decremental conduction
What is decremental conduction?
The signal becomes weaker the further it is from the site of initiation. This is opposite to action potentials, which are constantly renewed along the length of the axon and do not decrease in strength.
What is electrotonic conduction?
direct spread of electrical current by ion conduction in the dendritic fluids without generating an action potential
What are the dendritic characteristic that result in electrotonic conduction?
few voltage-gated sodium channels in dendritic membranes, and thresholds too high for action potentials to occur.
Explain the firing rate of dendrites.
As long as the excitatory rate of a neuron remains above the threshold for excitation, the neuron will fire repeatedly. The firing rate depends on the normal excitatory rate and on the changes in the excitatory rate due to superimposition of additional excitatory or inhibition signals.
In reference to dendrites, what is synaptic delay? and what is the synaptic delay?
Synaptic delay refers to the time it takes to transmit a signal from a presynaptic neuron to a postsynaptic neuron. The minimal synaptic delay of a dendrite is 0.5 second.
