Introduction to the Autonomic Nervous System Flashcards
Describe the sympathetic/parasympathetic function of the eye (3)
S: pupil dilation
PS: pupil constriction, and contraction (ciliary muscle)
Describe the sympathetic/parasympathetic function of the trachea/bronchioles (2)
S: Dilates
PS: constricts
Describe the sympathetic/parasympathetic function of the liver (2)
S: glycogenolysis, gluconeogenesis
PS: N/A
Describe the sympathetic/parasympathetic function of the adipose tissue (1)
S: Lipolysis
PS: N/A
Describe the sympathetic/parasympathetic function of the kidney (1)
S: increased renin secretion
PS: N/A
Describe the sympathetic/parasympathetic function of the ureters and bladder (6)
S: relaxes detrusor, contract trigone and sphincter
PS: contracts detrusor, relaxes trigone and sphincter
Describe the sympathetic/parasympathetic function of the salivary glands (2)
S: Thick viscous secretion
PS: Copious watery secretion
Describe the sympathetic/parasympathetic function of the skin (2)
S: piloerection, increased sweating
PS: N/A
Describe the sympathetic/parasympathetic function of the heart (4)
S: Increases HR + contractility
PS: opposite
Describe the sympathetic/parasympathetic function of the GI tract (6)
S: decreased motility and tone and sphincter contraction
PS: increases motility and tone and secretions
Describe the sympathetic/parasympathetic function of the skeletal muscle blood vessels
S: Dilates
PS: N/A
Describe the sympathetic/parasympathetic function of the blood vessels of the skin/mucous membranes/splanchnic area
S: constricts
PS: N/A
What branch of the ANS deals with the liver and why is it mainly this?
The liver is generally sympathetic, glucose availability is important in situations where there is sympathetic activity so sympathetic discharge stimulates an increase in glycogenolysis and gluconeogenesis
What branch of the ANS dominates the lung and why
Lungs are generally dominated by the parasympathetic NS, there is a partial level of constriction so the lungs can still constrict or dilate as necessary. PS causes constriction in the lungs.
What branch of the ANS dominates the eye
Eyes are generally dominated by the parasympathetic at rest. Pupil dilation is controlled by the sympathetic nervous system. Pupil constriction is controlled by the parasympathetic nervous system.
Which PS nerve stimulates stomach contraction and secretions
Vagus
Describe how heart rate is regulated by baroreceptors
Arterial baroreceptors firing stimulates parasympathetic nerve, and inhibits sympathetic nerve. The lower the firing of the baroreceptors the higher the firing of the sympathetic nerve. They fire more with increased BP
Describe the coordination and divergence of the SNS and ANS
SNS is very coordinated and divergent (1:20 pre:post ganglionic neurons), whereas the PSNS is discrete and localised. SNS responses need to be able to be quick and on the ball (fight/flight).
What are the lengths of PNS neurone, and the neurotransmitters
Parasympathetic NS is simple, one long preganglionic fibre releasing ACh and one short post ganglionic fibre releasing ACh onto the effector organ.
What are the lengths of SNS neurone, and the neurotransmitters
Always short preganglion and long post ganglionic fibre (APART FROM ADRENAL GLAND). Usually ACh released from pre and noradrenaline NA from post to target the effector organ. SOMETIMES there is also ACh released form the post ganglionic fibre onto the effector organ, e.g. in the case of sweat glands.
Where are nicotinic receptors found (3)
at the ganglions of both PS and S NS neurons, and the adrenal medulla
What type of receptor are nicotinic receptors
Type – 1, ionotropic
Where are muscarinic receptors found
receptor tends to be found in the effector organ in parasympathetic nerves and the odd sympathetic nerve (e.g. in sweat glands)
What is the main clinical consideration of prescribing nicotinic or muscarinic blocking drugs
Nicotinic drugs will interfere with all of the ANS where as Musca drugs will only interfere with para and sweat gland activity
What type of receptor is a muscarinic receptor
a type – 2, G-protein coupled receptor
Which type of receptor is faster 1 or 2
1 ionotropic receptors
What is a type 1 receptor what is a type 2
1 ionotropic, 2 G-protein coupled
What type of receptor (1/2) requires a second messenger
2
What is an ionotropic receptor
Activates and opens allowing an ion to flow through very quickly
What activates a nicotinic receptor
Nicotine and ACh
What activates a muscarinic receptor
Muscarine and ACh
What are the 5 subtypes of muscarinic receptor
M1- neural (forebrain - learning and memory)
M2 - cardiac (brain - inhibitory auto receptors)
M3 - exocrine and smooth muscle (hypothalamus - food intake)
M4 - periphery
M5 - striatal dopamine release
What are the NA and A receptors and what type of receptor are they
alpha1/2 and beta1/2, all G-protein coupled
What does Alpha 1 receptor in vasculature do
COntricts
What does beta 2 receptor in vasculature do
dilates
Describe the synthesis, release and metabolism of ACh
ACh is made from acetyl co A and choline, using choline acetyl transferase. This is packaged into vesicles and released. Acetylcholine esterase breaks it down into choline and acetate.
Describe the synthesis, release and metabolism of NA
Tyrosine is converted to DOPA by tyrosine hydroxylase which is then converted to dopamine by DOPA decarboxylase. Dopamine is packaged into vesicles and converted to NA by dopamine beta hydroxylase. NA is packaged into vesicles and exocytosed. NA is NOT broken down in the synapse. It is taken up in the post synaptic membrane and degraded by COMT and the presynaptic terminal by MAO-A
What enzymes break down NA and where
It is taken up in the post synaptic membrane and degraded by COMT and the presynaptic terminal by MAO-A
What converts tyrosine into DOPA
tyrosine hydroxylase
What converts DOPA into dopamine
DOPA decarboxylase
What converts dopamine into NA
dopamine beta hydroxylase
