physiology of autonomic nervous system Flashcards
nicotininc neuronal receptors are located on the postganglionioc neurons of both the sympathetic and parasympathetic post ganglionic neurons
musacarinc receptors
found on the end organs of the parasympthateic nervous system
found on sweat glands which are part of the sympetjetic nervous sytem
Muscarininc receptors
pre ganglionc neurons of the parasymepthatic system outflow from the craniosacral area to release
acetylcholine on nicotinunc neuronal (Nn) receptors
post ganglionic neurons also release acetylcholine but onto
musacrinic receptors on the end organs
effects of SNS activation on heart
Heart rate increase
conduction through AV node
contractlitity of atria and ventricles
increase acitvity of SA node
sympathetic nerves control ventricular contractility
effects of SNS activation on blood vessels
constriction of all vascular beds
dilation of skeletal muscle blood vessels
dilation of blood vessels to liver
arteries and veins (tonic sympathetic tone)
effects of SNS activation on adrenal medulla
increase release of EPI/NE into circulation
functions as a hormone
effects of SNS activation on sweat glands
increase sweating
when the sympathetic system is full activated
EXPLAIN the role of the adrenal medulla and epinephrine.
The epinephrine released into circulation from the adrenal medulla helps to amplify the sympathetic
response, including the effects of the NE that was released locally as a neurotransmitter. Remember,
when stimulated, the adrenal medulla releases 80% epinephrine and 20% norepinephrine into
circulation. Both act as hormones in this manner. The EPI released can bind receptors that aren’t
innervated by sympathetic neurons.
EXPLAIN what is meant by parasympathetic or sympathetic tone.
Parasympathetic and sympathetic tone means that it is the default state of continuous activity. The
sympathetic tone on arteries is what maintains blood pressure in the normal range. Parasympathetic tone
decreases heart rate (via vagal inhibition) from the intrinsic rate of the SA node to the normal HR range
APPLY your knowledge of the physiological effects mediated by each cholinergic receptor to
PREDICT the physiological responses that would occur with activation or blockade of the
cholinergic receptor subtypes.
The stimulation of nicotinic neuronal receptors will cause the stimulation of both parasympathetic
postganglionic neurons as well as sympathetic postganglionic neurons. The stimulation of these
receptors will also cause the release of EPI and NE into circulation from the adrenal medulla. Blocking
these receptors will block the stimulation of postganglionic neurons of both systems.
The stimulation of muscarinic receptors will stimulate the end organs of the parasympathetic nervous
system. Remember, sweat glands are innervated by postganglionic cholinergic fibers even though they
are part of the sympathetic nervous system. So, stimulation of these receptors will also cause
increased sweating. Likewise, if these muscarinic receptors are blocked, it will inhibit sweating
