Automatic nervous system Flashcards
What is the autonomic nervous system?
- part of the efferent division of the peripheral nervous system
What is the function of the autonomic nervous system?
- It regulates involuntary processes eg breathing, swallowing, digestion , arousal
what is an autonomic gangalion?
- a cluster of cell bodies in the ANS
- where pre ganglion and post ganglion neurons synapse
Compare and contrast somatic neurons with autonomic neurons
- ANS - 2 neurons, pre ganglion and post ganglion, innervates smooth muscle, glands etc - can be excitation or inhibition
- somatic NS - uses a single motor neuron to innervate skeletal muscle ( alpha), only excitation
What are the functions of the 2 divisions of the ANS?
- Sympathetic - flight or fight response - eg increases heart rate, dilates pupils, inhibits digestion
- Parasympathetic - rest or digest - lowers heart rate, contracts pupils, promotes digestion
Describe the pre and post ganglion neurons in the sympathetic system
- preganglia neurons come from thoraic and lumbar regions of spine
- sympathetic ganglia lie close to spinal chord
- neurons arising from lumbar segment will stimulate noradrenaline production
Describe the pre and post ganglion neurons in the parasympathetic system
- preganglionic neurons exit the brain and spinal chord through the cranial nerves
- preganglionic neurons synapse with post ganglionic neurons in ganglia close to the organs ( nerve X)
What are collateral/prevertebral ganglia?
- Lie between the sympathetic ganglia and the target organ
What neurotransmitter does the parasympathetic neuron use?
Acetylcholine
What neurotransmitters does the sympathetic system use?
Acetylcholine and Noradrenaline
Compare neurotransmitters and synapses in symp vs parasymp
- All preganglionic neurons use acetylcholine as neurotransmitter ( & nicotinic receptors)
- Most postganglionic sympathetic neurons release noradrenaline
- Most postganglionic parasympathetic neurons release Ach
Contrast the structure of preganglionic neurons and post ganglionic neurons in symp and parasymp system
- preganglionic neurons are myelinated (short in symp and long in para symp)
- Post ganglionic neurons are not myelinated (short in parasymp and long in symp)
What receptors do effector target muscle/gland have for parasympathetic system
Muscarnic
What receptors do the effector muscle/gland have for symp system?
- Adrenergic receptors
What are adrenergic receptors and what are the 3 subtypes ?
Class of G protein coupled receptors that are targets of noradrenaline etc
3 subtypes are
- Alpha 1
- Alpha 2
- Beta
Compare the anatomical difference between somatic neurons and where they lie vs autonomic nuerons
- somatic : cell bodies of motor neurons reside in CNS ( brain or spinal chord) & their axons extend all the way to skeletal muscles
- autonomic : chains of 2 motor neuron, preganglionic lies in brain or spinal chord, postganglionic lies in cell body outside CNS
what is the parasympathetic nervous system also called?
- the craniosacral system - because all of its preganglionic neurons are in the brain stem or sacral levels of spinal chord
what is the sympathetic nervous system also called?
- thoracolumbar system because all of its neurons are in lateral horn of gray matter from T1-L2
What gland is an exception?
- the adrenal gland
- the neurons synapse in the gland which causes an ‘adrenaline rush or surge’
what is the ‘central control’ of the ANS?
- The Amygdala
- the main region for emotions
- function: stimulates sympathetic activity ( esp previous learnt fear related activity)
Give 2 diseases associated with the ANS
- Raynaud’s disease - hyperactivation of the sympathetic NS causing extreme vasoconstriction
- Horner’s syndrome - group of nerves @ sympathetic trunk are damaged - loss of sweating, vasodilation
