Autonomic Nervous System Flashcards
What is the difference in the somatic and autonomic nervous systems?
Somatic = we have control of this Autonomic = this is automatic and done for us
What are the functions of the autonomic nervous system?
- Stress response
- Mucturition
- Cardiovascular control
- Sex and reproduction
- Digestion
How can the autonomic nervous system be split up?
Sympathetic and parasympathetic
What are some similarities between the parasympathetic and sympathetic systems?
- Synapse in ganglions
- Sensory and effector effect
- Acetylcholine in ganglion transmission
What are some differences between the parasympathetic and sympathetic nervous systems?
- Anatomical origin
- Location of ganglion
- Post ganglionic neurotransmitters
- Function
What is the anatomical origin of the sympathetic system and the exception to this?
Thoracolumbar origins
Exception is ones from the cervical ganglia
Where are the ganglia in the symapthetic system compared to parasympathetic?
Sympathetic- next to spinal cord
Parasympathetic- near site of action
What are the neurotransmitters in the sympathetic system?
Pre ganglionic synapse = acetylcholine
Post ganglionic synapse = noradrenaline
What are the exceptions to the neurotransmitters in the sympathetic system?
Post ganglionic neurotransmitter is always noradrenaline except from sweat glands and deep muscle vessels where it is acetylcholine.
What are the functions of the sympathetic system?
- Stress response (fight or flight)
- Sweat, to reduce heat
- Inotropy
- Chronotropy
- Adrenaline release
- More blood around body
- More O2
- Constipation and urinary retention
- Vasodilation
What receptors are used by the sympathetic system and why/when?
- Alpha 1 = arteriole constriction
- Alpha 2 = coronary and venous vasoconstriction
- Beta 1 = heart; increases heart rate, increases contractility
- Beta 2 = lungs, uterus, skeletal muscle, blood vessels, smooth muscle relaxation (can stop things being disadvantageous)
What is the anatomical origin of the parasympathetic system?
Craniosacral outflow
(Cranial nerves 3,7,9,10.
Sacral nerves 2,3,4)
What neurotransmitters does the parasympathetic system use?
Acetylcholine
What is the function of the parasympathetic system?
- Nasal engorgement, excess salivation
- Slow heart rate
- Help defecate, ejaculate
What types of receptors can the parasympathetic system use?
Nicotinic receptors (will be neuronal or muscular): N1- motor neurons N2- autonomic nervous system (also some in brain), used as ganglion blockers
Muscarinic receptors, has 5 subtypes:
M1- neural, emotional response
M2- in heart, cardiac inhibition
M3- in glands (eg. salivary glands, gut, bladder), have stimulatory effct
M4- in CNS, work on K and Ca ion channels
M5- in CNS, to regulate dopamine release
What are the principle functions of the autonomic part of the central nervous system?
- Cranial nerve function
- Conduit function (relays activity from brainstem to rest of body)
- Integrative functions (sleep cycle, respiratory cycle, conciousness)
What can happen due to brain stem death?
- Paralysis, unconciousness
- apnoea (lose respiratory centre)
- Loss of cranial nerve function
How can brain stem death occur?
Brain in non expandable box, so when pressure builds up it gets pushed through hole at bottom.
Causing tonsillar herniation
The pressure on the brainstem makes it choke itself and it cuts off its own blood supply
What are signs of brainstem death?
- Dilated pupils
- Single vessel supply to midbrain
How can brain stem death be tested?
Important that it is actually brain and brain stem death.
Exclusion criteria must be met
Must have known diagnosis
Must be unconcious and apnoeic
Should have normal temp. normal glucose, electrolytes and should be under no drugs.
2 doctors must be present (1 consultant and one with 5 years experience)
They test the 8 out of 12 cranial nerves and their functions.
What is the difference between a receptor agonist and antagonist?
Agonist- mimick action of receptor
Antagonist- does opposite
What is an eg of an alpha 1 agonist and antagonist?
Agonist-metaraminol; arteriolar constriction
Antagonist- doxazosin; vascular smooth muscle relaxation
What is an eg of an alpha 2 agonist?
Yohimbine-mild erectile dysfunction
What are eg of beta 1 agonist and antagonist?
Agonist- isoprenaline; complete heart block
Antagonist- Atenolol; lower blood pressure
What is an eg of a beta 2 agonist and antagonist?
Agonist- salbutamol; smooth muscle relaxation and bronchiolar relaxation
Antagonist- butaxamine; experimental use only
What is an eg of an M1 receptor agonist?
Xanomeline; alzheimers treatment
What is an eg of an M2 receptor antagonist?
Atropine; reduces effect of Ach on heart, increases heart rate.
What is an eg of an M3 receptor agonist and antagonist?
Agonist- Pilocarpine; treats glycoma
Antagonist- tiotropium; lungs
oxybutinin; bladder
Mebervine; gut
What is an eg of an N1 receptor agonist and antagonist?
Agonist- succinylcholine
Antagonist- burgarotoxin; muscle blocker
What is an eg of an N2 receptor antagonist?
Vercuronism
