Autonomic Nervous System Flashcards
What does the autonomic nervous system control?
Myocardium, smooth muscle (eg gut), internal organs, skin
Though what PNS division dies the brain receive information? How is this division split)
Sensory (afferent) division, which is divided into somatic and visceral
How is the visceral motor division split?
parasympathetic and sympathetic nervous system
How does the (para)sympathetic system affect the pupil?
Parasympathetic constrict pupil, sympathetic dilates pupil
How does the (para)sympathetic system affect the heart?
Heart rate increases (also contraction) with sympathetic stimulation, and decreases with parasympathetic system
How does the (para)sympathetic system affect the stomach?
Motility and secretions increases in parasympathetic system, and does the opposite in reaction to the sympathetic system
What happens if your baroreceptors’ firing rate increases?
It will increase its parasympathetic response, thus more acetylcholine is released to lower the heart rate and hence lower blood pressure. This charge will also result in a decrease in sympathetic activity. The opposite happens when the firing rate of baroreceptors decreases.
What part of the brain receives information from the autonomic nervous system?
Hypothalamus
Where do the nuclei of visceral motor cells originate?
Hypothalamus
What is the difference between the parasympathetic system and the sympathetic system in terms of pre-ganglionic fibre, post ganglionic fibre and ganglion?
Parasympathetic system have long pre-ganglionic fibres, short post ganglionic fibres, and a ganglion closer to effector organ. The opposite is true for the sympathetic nervous system.
What is the exception to the structure of the sympathetic nervous system?
The arenal gland, where there is no ganglion (so acts similar to post ganglionic fibre)
What neurotransmitter is used in the parasympathetic system?
Acetylcholine
What neurotransmitters are used in the sympathetic system and where?
In the preganglionic fibres, acetylcholine is used, and in the post-ganglionic fibres noradrenaline is used
What is the sensory information relayed in the bladder?
Pressure
What happens when pressure builds up?
The sympathetic system will relax the internal sphincter muscle, and the detrusor muscle will be stimulated to contract and empty the bladder
What muscle keeps the bladder closed and what nerves innervates this?
The internal sphincter muscle, which is innervated by the sympathetic nerve
What types of receptors are used in the autonomic nervous system and why?
Ion channel receptor, because this is the fastest
What is the benefit of G-protein coupled receptor?
It is more complicated, so cell has more control over response, as components of the receptor can be altered to control response, although response is slower than in ion gated channels
What type of receptors are needed at autonomic ganglia?
Acetylcholine receptor (nicotinic acetylcholine receptor)
Outline neurotransmitter biosynthesis and metabolism
1.Precursor enzymatically converted to neurotransmitter
2.Packaged into vesicles
3.Action potential causes Ca2+ influx and exocytosis
4.Exocytosis and neurotransmitter release
5.Receptor activation
6.Removal of neurotransmitter from synapse via uptake into pre-synaptic terminal or glial cell;
Can be metabolised in the synapse prior to uptake
Outline acetylcholine biosynthesis and metabolism
1.Choline + acetyl CoA enzymatically converted by choline acetyl transferase
2.Packaged into vesicles
3.Action potential causes Ca2+ influx and exocytosis
4.. Exocytosis and neurotransmitter release
5.. Receptor activation
(Muscarinic or nicotinic)
6.Acetylcholine rapidly degraded by acetylcholinesterase in the synapse.
Choline taken up into presynaptic terminal by choline uptake protein.
Outline noradrenaline biosynthesis and metabolism
1.Tyrosine converted to DOPA by tyrosine hydroxylase. DOPA converted to dopamine by DOPA decarboxlase
2.Dopamine packaged into vesicles with dopamine β hydroxylase. Noradrenaline is the product
3.Action potential causes Ca2+ influx and exocytosis
4.Exocytosis and neurotransmitter release
5.Receptor activation
(Adrenergic)
6.Removal of neurotransmitter from synapse via uptake into pre-synaptic terminal or glial cell;
Can be metabolised in the synapse prior to uptake
Outline adrenaline biosynthesis and metabolism
- Tyrosine converted to DOPA by tyrosine hydroxylase. DOPA converted to dopamine by DOPA decarboxlase
- Dopamine packaged into vesicles with dopamine β hydroxylase. Noradrenaline is the product
- Noradrenaline converted to adrenaline in the cytoplasm by phenylethanol methyl trasnferase
- Action potential causes Ca2+ influx and exocytosis
- Exocytosis and neurotransmitter release
- Adrenaline diffuses into capillary and is transported to tissues in the blood
What effect does the smell/test of food have on the ANS
Parasympathetic response increases whilst sympathetic response is lost, so more acid is released into the stomach.
What is the enteric nervous system
It is thought of as a ´mini brain`, which influences gut function
What effect does the bright light have on the ANS
Pupil constriction takes places, driven by the parasympathetic system.
How many sympathetic nerves innervate the lung tissue? And how does the sympathetic system stimulates the lungs?
Zero, but sympathetic control comes from the release of the hormone adrenaline rather than a neurotransmitter
What muscle contracts to fore urine out of the bladder?
The detrusor muscle, innervated by the parasympathetic nerve.
How does urine leave the bladder in terms of the ANS?
Sympathetic system is less active, making the internal sphincter relax, and the parasympathetic system activates the detgusor muscle to contract.
What is the micturition reflex?
Reflex involved in emptying bladder
What receptor are there in post-ganglionic fibres
Muscarinic (ACh) and adrenergic (NA) receptors
What receptors are there in receptor cells?
G-coupled receptors
Where is ACh metabolised?
Synapse, and then transported to the pre-synaptic neurone
Where is NA metabolised?
Pre-synaptic neurone, after being transported from the synapse
