Lecture 17- Autonomic nervous system Flashcards Preview

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Flashcards in Lecture 17- Autonomic nervous system Deck (31)

What is the effect of the sympathetic nervous system on the kidney?

1.beta 1 receptor=increase in renin secretion rates 2.alpha 1B receptor=decrease in Na+ absorption 3.alpha 1A receptor= decrease in renal blood flow -more retention of water in tubule, lower blood flow


What does most of visceral activity need?

-visceral motor system


What are the differences between somatic, sympathetic and parasympathetic nerves?

-somatic motor neurons= have body in CNS and protected form the environment by the blood brain barrier and go to target -ANS- has an intrevening synapse, in ganglia


What is the difference in sympathetic and parasympathetic nerves?

-parasympathetic= the ganglia are within the tissue of the target so the postganglion fibre is short

-opposite with the sympathetic


Why is it good that the ANS neurons have that extra synapse?

-the ganglion, the extra neuron gives us more modulation, which we want in ANS where have to weigh more factors


Where are the cell bodies of sympathetic neurons?

-intermediolateral cell column

-in thoracic and lumbar spinal cord only


What does the sympathetic trunk look like?

sympathetic trunk= ganglia, in the swelling is where the ganglion cells are pregaglionic= myelinated -postganlionic cells= grey -another group of ganglionics= prevertebral ganglion = goes to the gut -these are usually in the midline of the gut


Where are the cell bodies of parasympathetic neurons?

-parasympathetic cells=

1. in the brainstem

2-sacral spinal cord in=midbrain and medulla

-long projections, many project via the vagus nerve

-preganglionic in different regions! symp vs parasym


Where in the midbrain are the parasympathetics?

-nucleus ambiguus

-dorsal motor nucleus of vagus

-salivatory nucleii


What innervates the blood to penis?

-parasympathetic (ejaculation is stimulated by sympathetic)


Do tissues receive innervation from both parasympathetic and sympathetic?

-yes -often the innervation goes to different cells in the tissue, -pupil size= para=constricts, symp= makes them bigger -each goes to different muscles -same in pancreas


What is the special example of sympathetic and parasympathetic innervation?

-the same muscles or cells get the innervation from sympathetic and parasympathetic--- heart pacemaker cells parasympathetic= slows heart rate, sympathetic= faster heart rate (faster firing of the pacemaker cells)


Via which receptor and transmitter does the somatic nervous system work?

-N1 nicotine acetylcholine receptor

-via acetylcholine


What receptor and neurotransmitter does the parasympathetic nervous system use (both pre and postganglionic)?

-preganglionic= N2 receptor, (Acetylcholine)

-postganglionic= M (muscarinic acetyl choline receptor)

-in both acetylcholine


What receptor and neurotransmitter does the sympathetic nervous system use (both pre and postganglionic)?

2 types:

1. pre-N2 receptor (acetylcholine) then post alpha and beta adrenergic receptors (norepinephrine)

2. pre- N2 receptor (acetlycholine) and release eponephrine via adrenal medulla


Where does adrenal medulla receive innervation from?

-adrenal medulla= receives input from pre ganglion neuron and releases adrenalin into the circulation -adrenal medulla part of the sympathetic


Which nerves constrict blood vessels?



What is the cascade of adrenaline?

-catacholamines -adrenergic receptors -dopamine is precursor to noradrenaline


How do dopamine and norepinephrine get made?

-activate postsynaptic and presynaptic receptors

-noradrenaline gets taken back in as does dopamine= cycling

-many drugs (cocain etc) block the transporters that take up the noradrenaline and dopamine


What input do most organs receive?

-receive input from the autonomic nervous system, not all organs receive input from both e.g. many blood vessels = SNS only


What does the autonomic nervous system consist of?

-of two neurons connected in series -the neuron innervating the target occurs outside the CNS


What are the preganglionic axons of the sympathetic division like?

-short -the ganglionic axons project long distances to contact the target tissue


What are the preganglionic axons of the parasympathetic division like?

-long -the ganglionic axons are locate in ganglia in the target tissue


What does the stimulation of sympathetic and parasympathetic innervation have?

-often reciprocal actions -in life work synergistically or under different conditions


What neurotransmitter do preganglionics (ANS) use?

-acetylcholine -acts on ionotropic nicotine receptors N2


What transmitters do ganglionics use?

-sympathetic= noradrenaline (adrenoceptors) -parasympathetic= acetlycholine (muscarinic receptors)


What nervous system does the intestine have?

-extensive nervous system that receives input from the autonomic nervous system but can function independently = enteric nervous system


Where are complex inputs integrated?

-complex sensory inputs from the viscera and higher senses are integrated to enable co-ordinated functioning of the autonomic nervous system -hypothalamus is a major conductors of these co-ordinated responses


What is the anatomy of the pituitary, thalmus etc.?



What is the pathway of viscera(ANS) informing the higher centres?

-the preganglionic neurons on their own do not do that much,

-how the brain integrates information to drive the output according to need

-the motor pattern

-end organs provide feedback(the end organ that is important is brain, provides feedback to itself to tell if it is getting enough glucose)

-(baroreceptor reflex)

-the feedback goes to the medulla, the nucleus of the solitary tract

-within the medulla there are loops that can go back to the end organ (baroreceptor reflex is one of these)

-when you get up = barocreceptor reflex makes sure that the blood doesn't pool in your limbs but goes to the head! so you don't faint

-unconscious control 2nd loop= from nucleus of solitary tract to hypthalamus, then amygdala then to the cortex= this is the signals that we are aware of= constricted gut etc.

-the info gets processed in the brain, in hypothalamus is important= conductor, from there many projections (to brainstem, etc.)

-hypothalamus sends lot of information and regulates amygdala plays an important role in fearful situations,


Why is hypothalamus key?

-hypothalmus is key, projects to the motor neurons and the endocrine system (via vasopressin for example)

-receives info, contextual and sensory