Neural control of the heart and vessels:
The parasympathetic control of the heart rate, medulla oblongata to a ganglion, through acetylcholine
transduction, nicotinic receptor. Post-ganglionic nerve transduce Ach onto S.A. node cells, muscarinic
receptor. Atropine will collect at the clefts between S.A. nodes and post-ganglionic nerve cells, will
speed up heart rate as parasympathetic system control is removed.
Sympathetic control of the heart rate is controlled by acetylcholine and then norepinephrine at the
beta-adrenergic receptor. Beta-agonist would speed up the heart rate by making it more sensitive, an
antagonist would competitively bind. If norepinephrine is dumped on the ventricular muscle would
increase calcium inflow like on the S.A. nodes and increase contraction force. Sympathetic contractions
do not follow the normal EDV/SV ratios, they have their own curves.
Most of the vessels in the bodies (all the way down to venules and arterioles), are controlled by the
sympathetic vessels, using an alpha-adrenergic receptor. Activation would lead to constrictions of the
Adrenal Glands: cells of the adrenal glands are ganglion cells that lost their axon, and symthesize
norepinephrine and epinephrine. 2/3 epi and 1/3 norepi, epi to the SV nodes and norepi to the smooth
muscles of vessels to constrict.
Blood Pressure Control:
Baroreceptors ensure that when postures change, one does not faint, functions in 1-2seconds. The
kidneys, on the other hand, takes hours to days to change. Maximum feedback gain is an indicator of
how strong the reflex is. When BP drops, different pathways have different effects, e.g. baroreceptors
cannot function any better at 40 than at 50, and h