Autonomic Physiology Flashcards
What does the autonomic nervous system control?
Unconscious activity.
What are the divisions of the autonomic nervous system?
Sympathetic
Parasympathetic
What is the sympathetic nervous system associated with?
Fight / flight response.
What is the parasympathetic nervous system associated with?
Rest / digest response.
What does the somatic nervous system act directly on?
Skeletal muscle for voluntary movement.
What synapse characterises the somatic nervous system?
Neuromuscular junction.
What type of receptors are featured in somatic control?
Ionotropic receptors (those that act as ion channels).
Does the somatic nervous system always excite a response?
Yes.
What type of synapse characterises the autonomic nervous system?
CNS synapse.
What type of receptors are featured in autonomic control?
Metabotropic.
Does the autonomic nervous system always excite a response?
No- can excite/inhibit.
What regions of the sign do the sympathetic nerve fibres exit from?
Thoracic and lumbar.
Where do the ganglia lie in sympathetic nerve fibres?
Close to the spinal cord.
What are the autonomic neurotransmitters?
Acetylcholine
Noradrenaline / adrenaline
What type of receptors does acetylcholine act on?
Cholinergic (nicotinic/muscarinic)
What are the 2 types of cholinergic receptor?
Nicotinic
Muscarinic
What type of receptors do noradrenaline/adrenaline act on?
Adrenergic receptors (A/B)
What are the 2 types of adrenergic receptor?
Alpha
Beta
What type of receptors are nicotinic and muscarinic receptors?
Cholinergic.
What neurotransmitter acts on cholinergic receptors?
Acetylcholine.
What type of receptors are alpha/beta receptors?
Adrenergic.
What neurotransmitter acts on adrenergic receptors?
Noradrenaline / adrenaline.
What do preganglionic fibres release in the sympathetic nervous system and what does it bind to?
Acetylcholine- binds to nicotinic cholinergic receptors.
What do postganglionic fibres release in the sympathetic nervous system and what do they bind to?
Noradrenaline- binds to A/B adrenergic receptors.
What do postganglionic fibres of the adrenal medulla do?
Have no axons but release adrenaline/noradrenaline into the bloodstream.
Does the sympathetic nervous system have a hormonal component?
Yes- the adrenal medulla postganglionic fibres can release adrenaline/noradrenaline.
Where do parasympathetic nerve fibres exit the spinal cord?
Cranial and sacral regions.
Where do ganglia lie in the parasympathetic nervous system?
In or around the target- away from the spinal cord.
What do preganglionic fibres release in the parasympathetic nervous system and what do they bind to?
Acetylcholine- binds to nicotinic cholinergic receptors.
What do postganglionic fibres release in the parasympathetic nervous system and what do they bind to?
Acetylcholine- binds to muscarinic cholinergic receptors.
What do characteristic responses of the sympathetic and autonomic nervous system depend on?
The neurotransmitters released and the receptors acted on.
What are the sympathetic effects on the eyes?
Ciliary muscle relaxes, radial muscle of iris contracts to dilate pupil and allow long-distance sight.
What receptors are involved in the sympathetic effect on the eye?
B2 on ciliary muscle
A1 on radial muscle of iris
What are the parasympathetic effects on the eyes?
Ciliary muscle contracts, radial muscle of iris dilates to constrict pupil and allow short-distance sight.
What receptors are involved in the parasympathetic effect on the eye?
Muscarinic receptors.
What are the sympathetic effects on the heart?
Increases heart rate and strength of contraction.
What receptors are involved in the sympathetic effect on the heart?
B2 receptors on pacemaker cells
B1 receptors on myocytes
What are the parasympathetic effects on the heart?
Decreases heart rate and strength of contraction.
What receptors are involved in the parasympathetic effect on the heart?
Muscarinic on pacemaker cells
No myocyte effect
Does the parasympathetic nervous system have any effect on cardiac myocytes?
No.
What are the sympathetic effects on the lungs?
Relaxes smooth muscle and dilates airways.
What receptors are involved in the sympathetic effect on the lungs?
B2 receptors on smooth muscle.
What are the parasympathetic effects on the lungs?
Contracts smooth muscle and constricts airways.
What receptors are involved in the parasympathetic effect on the lungs?
Muscarinic receptors.
What is the therapeutic relevance of parasympathetic action on B2 receptors to promote airway dilation?
B2 agonists can be used in therapeutic lung conditions such as asthma- e.g. SALBUTAMOL.
What are the sympathetic effects on the blood vessels?
Makes smooth muscle contract- BF
What receptors are involved in the sympathetic effect on the blood vessels?
A1- contraction
B2- dilation
What are the parasympathetic effects on the blood vessels?
No effect.
Does the parasympathetic nervous system have any effect on blood vessels?
No.
What are the sympathetic effects on the gut?
Decreased motility and inhibited enzyme secretion.
What receptors are involved in the sympathetic effect on the gut?
Alpha/beta.
What are the parasympathetic effects on the gut?
Increased motility and increased enzyme secretion.
What receptors are involved in the parasympathetic effect on the gut?
Muscarinic.
What are the sympathetic effects on energy stores?
Stimulate glycolytic / gluconeogenetic processes
Stimulate lipolysis
What receptors are involved in the sympathetic effect on energy stores?
A/B receptors.
Does the parasympathetic nervous system have any effect on energy stores?
No.
What are the sympathetic effects on the salivary gland?
Stimulation of thick enzyme secretion.
What receptors are involved in the sympathetic effect on the salivary gland?
B-receptors.
What are the parasympathetic effects on the salivary gland?
Stimulates profuse watery secretion.
What receptors are involved in the parasympathetic effect on the salivary gland?
Muscarinic.
What is autonomic action on the salivary gland an example of?
Dual innervation with non-antagonistic actions.
What are the sympathetic effects on the bladder?
Relaxes bladder wall smooth muscle and releases pressure
Contracts sphincter smooth muscle and stops urination
What receptors are involved in the sympathetic effect on the bladder?
B2 bladder wall
A1 sphincter
What are the parasympathetic effects on the bladder?
Contracts smooth muscle of bladder wall and increases pressure.
Constricts sphincter smooth muscle and stops urination.
What receptors are involved in the parasympathetic effect on the bladder?
Muscarinic.
What are the sympathetic effects on the reproductive tract?
Contracts urethra smooth muscle and causes ejaculation.
What receptors are involved in the sympathetic effect on the reproductive tract?
A1
What are the parasympathetic effects on the reproductive tract?
Relaxes smooth muscle and causes erection.
What receptors are involved in the parasympathetic effect on the reproductive tract?
Muscarinic.
What is autonomic action on the reproductive tract an example of?
Dual innervation with a complementary effect.
What controls action of the autonomic nervous system on organs?
Autonomic reflexes- e.g. baroreceptor reflex (BP) Central control (hypothalamus- homeostatic mechanism).
What is the baroreceptor reflex?
Reflex monitoring blood pressure.
What can dual innervation be?
Antagonistic or complementary.
What is single innervation controlled by?
Tone.
