autonomic nervous system Flashcards
what does autonomic nervous system include + control
includes both central and peripheral nerve components and controls body element such as smooth muscle, cardiac muscle and glands
what does the autonomic consist of
autonomic sensory neurons, intergrating centres in the cns and autonomic motor neurons
what is the autonomic nervous system regulated by
hypothalamus and medulla oblongata
types of peripheral motor neurons
pre-ganglion = efferent neuron leaves ventral horn from spinal cord (cell body in cns) nuclei in cns
post-ganglion = afferent neuron motor runs from ganglion to target tissue nuclei in ganglia
features of post ganglia
usually unmyelinated
appear gray
can excite or inhibit
branched
greater spatial activation
slower response
difference between sympathetic and parasympathetic
sympathetic is fight or flight response
parasympathetic is rest and digest
difference between autonomic sensory and motor neurones
sensory side detects body temp, blood pressure ect = afferent
motor side modifies body temp, blood pressure ect = efferent
key feature of post ganglionic neurons
unmyelinated
contrast smooth muscle nmj ( ans) with a skeletal muscle nmj ( sns)
skeletal muscle nmj- typically have one or collection of neurones that have terminals on different fibres - activate more/less to get different degrees of contraction
smooth muscles nmj - 2 types : one similar to sns - neurones acting on individual nerve fibres to cause graded contraction , also have nerve axon running through muscle with varicosities (lumps) that act like end plates + release neurotransmitter all the way along
what functions does sympathetic do
dilate pupils, inhibts saliva, relaxes bronchi, increases heart rate, inhibits acid secretion, increases glucose production and release, causes adrenaline secretion, inhibits bladder contraction
what functions does parasympathetic do
constricts pupils, stimulates saliva production, constricts bronchi, slows heart rate, stimulates digestion, stimulates bile secretion and constricts bladder
where is emergence of sympathetic nerves from spinal cord
between t1 ( first thoracic segment) and l2 ( 2nd lumbar segment) - middle of spinal cord. no cranial nerves
where is emergence of parasympathetic nerves from spinal cord
cranial nerves, vagus nerve and splanchinic nerves ( top and bottom of cns) brainstem and sacral spinal cord
difference in position of ganglion in para and sympathetic
parasympathetic - ganglion is near to effector organ or even in tissue ( short post ganglionic neurone )
sympathetic - ganglion closer to spinal cord ( longer post ganglionic neurone) most in sympathetic trunk
what does the sympathetic contain that the parasympathetic doesnt
sympathetic trunk - where most of the ganglion are found (others are called distinct ganglion - have names)
what system is the adrenal medulla controlled by
the sympathetic system
what do the cortex and outer layers of the adrenal gland do
produce steroid based hormones - hydrocotrisone in human and coritocstirone in animals
what does the adrenal medulla do
produces adrenaline and noradrenaline ( main neurotransmitters in sympathetic nervous system )
does the adrenal medulla have a post ganglion neurone
no
ratio (approx) for adrenaline to noradrenaline
17:3 - more adrenaline than noradrenaline
where is noradrenaline also released from
sympathetic postganglionic nerve fibres (adrenaline only by adrenal medulla)
4 different routes of sympathetic nervous system
1) bunch of neurones leave spinal cord, synapse in sympathetic trunk leave together and then spread out to effectors ( skin and sweat glands )
2) one singular neurone synapse in sympathetic trunk and then goes to effector
3) ganglion separate from sympathetic trunk, still goes through but doesn’t synapse
4) medulla - no post ganglion neurone
what part of brain controls fight or flight response ( sympathetic)
allocortex if removed ‘dampens’ down sympathetic response = angry
limbic system = collection of structures in brain centre that controls emotions - main control of autonomic nervous system
hypothalamus = (part of limbic system) if just left - always in aggressive fight or flight mode, controls the sympathetic nervous system
what does the limbic system contain
hypothalamus, amygdala and hippocampus are main parts
sympathetic nervous system pathway in brain
goes through medulla
where is the only source of adrenaline
adrenal medulla
what does to much stress response do to horses
causes ulceration
what does the shorter preganglionic neuron release in the sympathetic neuron
acetylcholine
what does the longer preganglionic neuron release in the sympathetic neuron
noradrenaline
what do the neurons (pre and post) release in the parasympathetic
both release acetylcholine
what does the adrenal medulla release
adrenaline and noradrenaline
what do the somatic neurons release
acetylcholine
what are the two types of receptors
nicotinic and muscarinic
where do you find muscarinic receptors
in the post ganglionic dendrites
What is a catecholamine
any of a class of aromatic amines (both adrenaline and noradrenaline)
two types of postsynaptic receptors for adrenaline and noradrenaline
alpha 1 + 2 and beta 1,2 + 3
differences between alpha 1 and 2 receptors
alpha one = effects most sympathetic target tissues and activates phospholipase c as a secondary messenger
alpha two = effects GI tract and pancreas, decreases cAMP as a secondary messenger
differences between beta 1,2 and 3 postsynaptic receptors
beta 1 = effects heart muscle and kidney,
beta 2 = some blood vessels and smooth muscle
beta 3 = effects adipose tissue
ALL increase cAMP as a secondary messenger
what is homeostasis / how is it related to nervous system
is a dynamic balance between the autonomic branches
what receptors respond to acetylcholine
cholinergic receptors (divided into nicotinic and muscarinic)
what receptors respond to noradrenaline from presynaptic neurone + circulating noradrenaline (or adrenaline) from the adrenal gland
adrenergic receptors
differences between nicotinic and muscarinic receptors
nicotinic receptors are channel proteins (allow cation diffusion when acetylcholine binding) , muscarinic receptors are membrane proteins that cause opening of ion channels indirectly through a 2nd messenger by phosphorylating
nicotinic = excitatory muscarinic = excitatory and inhibitory
example of autonomic reflex
baroreceptor (heart?) when blood pressure increases sensory neurones fire faster + excite NTS which decrease sympathetic + increasing parasympathetic to slow down heart rate
