Is this true of neurotransmitters?

Question

A)they are stored in the vesicles in the axon

B) most are produced in the cytoplam of the dendrite and migrate to the axon

C)teh effect of acetylcholine on the heart muscles is excitatory

D)the peripheral nervous system has a wider variety of nerotrasmitters than the central nervous system

Answer 1

Some neurotransmitters are stored in vesicles within the axon all the way down to the terminal buttons, it depends on the neurotransmitter though. Nitric oxide, for example, is indeed a neurotransmitter but is unique in its own way and is not kept in vesicles, it actually wouldn't be possible to contain it within. However, with the neurotransmitters your likely to be discussing it is a fair bet to say they are housed within vesicles.

As far as most being produced in the cell body, not so much dendrite but body, and migrating through the axon to the axon terminals that is correct. An outstanding feat when you consider the length of some nerve cells and the distance the vesicle has to travel.

Acetylcholine is not excitatory on cardiac tissue. It is used by the parasympathetic nervous system to decrease heart rate actually. This is in contrast to Acetylcholine's actions on skeletal muscle compared to smooth, on skeletal muscle it is excitatory. The reasoning for the difference is rather complicated to get in to, briefly though the reason for this is the difference in acetylcholine receptors between skeletal muscle and cardiac tissue. Skeletal muscle has a normal acetylcholine ligand gated sodium channel. Cardiac has what is called a muscarinic acetylcholine receptor. You can try looking up this receptor on wikipedia which provides rather decent information on the receptor, but if you have a limited knowledge of cellular biology and neurophysiology then I wish you luck in trying to understand it.

As far as the peripheral NS having a greater variety of neurotransmitters that seems questionable. In fact I would likely say that the word variety may not be what you are looking for, as for variety both the central and peripheral NS likely share the same variety of neurotransmitter types: peptides, gaseous, small molecule are the three that come to mind and would be used in both. As for number last I heard there was upwards of mid thirties to maybe 40 neurotransmitters thought to be in use within the central nervous system, though I don't have  a source for this information and can not back it up. As far as the peripheral nervous system goes I would have a hard time believing that it uses that many different neurotransmitters, I wouldn't be surprised if the number it is restricted to is more like 5 or so. Again no direct evidence to back this one up.