intro to autonomic nervous system Flashcards
3 parts of the CNS
autonomic NS (exocrine glands, smooth muscle, cardiac muscle, metabolism, host defence)
somatic NS (skeletal muscle, including the diaphragm and respiratory muscle)
neuroendocrine system (growth, metabolism, reproduction, development, salt & water balance, host defence)
define sympathetic and parasympathetic
sympathetic= fight and flight parasympathetic= rest and digest
balance of ANS in particular tissues:
- lungs
- eyes
- liver
- lungs = dominated by the parasympathetic (there is a p[atrial level of constriction so that it can be constricted further and dilate)
- eyes = dominated by the parasympathetic at rest as you need your smooth muscle to be partially constricted so it can change in both directions
- liver = largely sympathetic
Pupil in darkness- determine which ANS
branch is dominant
sympathetic
leads to pupil dilation- fight or flight response
stomach when there is food around- determine which ANS
branch is dominant
parasympathetic (via vagus nerve)
acid production stimulated
-rest and digest
basal control of the heart- how does it work?
influenced by arterial baroreceptors
- high BP
- high baroreceptor firing
- parasympathetic stimulated
- sympathetic inhibited
- heart rate decreases
parasympathetic dominated heart at rest
sympathetic is totally in control of the arterioles
principal targets and function of the ANS
see slide
differences between parasympathetic and sympathetic responses
parasympathetic = discrete and localised (1:1, preganglionic: post ganglionic)
sympathetic= coordinated and divergent
Identify the transmitters released from pre- and postganglionic fibres in the parasympathetic nervous systems.
(cranial/ sacral) long preganglionic neurone ACh short post ganglionic neurone ACh effector organ
Identify the transmitters released from pre- and postganglionic fibres in the sympathetic nervous systems.
(thoracic/ lumbar) short preganglionic neurone ACh long post ganglionic neurone NA effector organ
EXCEPTIONS: short preganglionic neurone ACh adrenal medulla A/NA effector organ
AND short preganglionic neurone ACh long post ganglionic neurone ACh effector organ such as sweat glands
what is the enteric nervous system
In action:
-responds to various stimuli within the GI tract
Sensory neurone connected to mucosal chemoreceptors and stretch receptors detect chemical substances in the gut lumen or tension in the gut wall caused by food.
Information relayed to submucosal and myenteric plexus via interneurons.
Motor neurones release acetylcholine or substance P to contract smooth muscle or vasoactive intestinal peptide or nitric oxide to relax smooth muscle
Identify the transmitters released from the somatic nervous system
ACh
Classify the receptors found in the parasympathetic NS
(cranial/ sacral) long preganglionic neurone ACh -nicotinic short post ganglionic neurone ACh -muscarinic effector organ
nicotinic receptors
- where each type is found
- the signalling systems they each employ
- what type
At all autonomic ganglia (usually at the start of postganglionic neurone)
Stimulated by nicotine/acetylcholine
Type 1 - Ionotropic
muscarinic receptor
- where each type is found
- the signalling systems they each employ
- what type
At all effector organs innervated by
post ganglionic parasympathetic fibres
Stimulated by muscarine/acetylcholine
Type 2 – G-protein coupled
Sub-types of muscarinic cholinoreceptors
M1 – Neural (Forebrain – learning & memory)
M2 – Cardiac (Brain – inhibitory autoreceptors)
M3 – Exocrine & smooth muscle (Hypothalamus – food intake)
adrenoreceptors
- where each type is found
- the signalling systems they each employ
- what type
At all effector organs** innervated by
post ganglionic sympathetic fibres
Stimulated by noradrenaline/adrenaline
Type 2 – G-protein coupled
Where are the a1,a2,b1,b2 receptors found
see slide
Summarise the processes involved in the biosynthesis, release and metabolism of acetylcholine,
- acety Co A + choline
- forms Ach + CoA
- ACh is packed into a vesicle
- Calcium influx in triggered by an action potential, causes the release f ACh
- ACh diffuses across synapse and binds to receptor
- ACh is then broken down by acetylcholinesterase
- this forms choline and acetate
Summarise the processes involved in the biosynthesis, release and metabolism of noradrenaline
-Tyrosine converted into DOPA via tyrosine hydroxylase
-DOPA is converted into Dopamine via DOPA decarboxylase
-Dopamine is packaged into vesicles and then converted to NA by Dopamine
Beta Hydroxylase
-NA is then released when the action potential comes along and triggers calcium
influx
-NA binds to the adrenoceptor
-NA is NOT broken down in the synapse. It is either removed by:
oUptake 1 -back into the neuronal tissue
oUptake 2-into extra neuronal tissue
-Once it has been taken up it
is broken down by:
oMonoamine Oxidase (MAO)
-mainly in neuronal tissue, into metabolites
oCatechol
Or Methyl Transferase (COMT)- degredation, mainly in extraneuronal tissue
Blockade of which of the following targets would cause the most significant rise in synaptic noradrenaline concentrations? Tyrosine hydroxylase DOPA decarboxylase Uptake 1 transport protein Monoamine oxidase Cathecol-O-methyl transferase
Uptake 1 transport protein