AUTONOMIC NERVOUS SYSTEM Flashcards
what does the ANS control?
controls the ability to maintain homeostasis in an ever changing environment
why is the ANS seen as a unique functional entity?
it is part central and part peripheral
how many neurons are connected to effector for SoNS+ANS?
SoNS-1
ANS-2
what do SoNS+ANS connect to?
SoNS-skeletal muscle
ANS-smooth and cardiac muscle, glands, fat cells
do SoNS+ANS have excitatory or inhibitory effects?
SoNS- exitatory
ANS- I+E
what neurotransmitter do SoNS+ANS use?
SoNS- Ach
ANS-Ach and noradrenaline
where are the cell bodies located in SoNS+ANS?
SoNS-within the CNS
ANS-outside the CNS
are the axons non-myelinated or myelinated for SoNS+ANS?
SoNS-myelinated
ANS- pre-ganglionic myelinated
post-ganglionic non-myelinated
what is the function of the ANS?
regulates functions of daily living and functions at the subconscious level
Involved in regulating internal organs and involuntary actions
what are the 3 anatomical sub-divisions of the ANS?
Sympathetic
Parasympathetic
Enteric (or intrinsic)
what is the enteric/intrinsic sub-division of the ANS?
comprises the intrinsic nerve plexus of the GI tract, closely interconnected with the symp/parasymp systems
what are examples of ANS function?
Body temp. control Gut motility+secretion Heart rate+force Blood pressure Blood glucose & FA Micturition Defection expressive aspects of emotion
what is the fight to flight response?
Sympathetic system mobilises the body during extreme situations (fear, exercise, rage)
what is the rest and digest division?
Parasympathetic division performs maintenance activities and conserves body energy. Most effective in non-stressful situations
where do parasympathetic fibres emerge from?
from the brain and the spinal cord at the sacral level
where do sympathetic fibres originate from?
from the thoracic and lumbar regions of the spinal cord from T1 to L2
what length are the fibres for the sympathetic NS?
Short pre-ganglionic and long post-ganglionic fibres
where do the ganglia lie in the sympathetic NS?
near the spinal cord and vertebral column
do the axons branch in the sympathetic NS?
Axons branch profusely, allowing influence over many organs
what length are the fibres for the parasympathetic NS?
Long pre-ganglionic and short post-ganglionic fibres
where do the ganglia lie in the parasympathetic NS?
ganglia lie far away from the CNS, in or near the organs innervated
do the axons branch in the parasympathetic NS?
Axonal branching is diffuse and localised
what is the function of the fight or flight response?
Co-ordinating responses to emergencies or vigorous muscular activity, and discrete control of organs
are many organs affected by the F or F response?
In stressful situations several or all organs affected, i.e. system discharges as a unit, amplified by adrenaline release from adrenal medulla
what is the function of the R and D response?
Conservation and restoration of energy
Discrete and localised function on individual organs or regions
SLUDD
what does SLUDD stand for?
salivation, lacrimation, urination, digestion, and defecatio
give and example when the parasymp and symp innervations are physiologically antagonistic
activation of parasympathetic stimulation slows HR whereas activation of sympathetic nervous system increases HR
give an example when the parasymp and symp innervations are similar
Saliva secretion
what are the symp and parasymp response to saliva production?
P-causes large vol of watery, enzyme-rich secretion & increased BF to the salivary glands
S-small volume of thick viscous secretion, reduces BF to the salivary glands
give an example when the 2 systems oppose each other but aren’t equally important
In the gut, parasymp dominates over symp, parasymp is main motor nerve to drive gut functions
give examples of organs/tissues that are innervated by only one division
sweat glands, piloerector muscles, blood vessels receive only sympathetic innervation
can opposing effects still happen when innervated by one division and why?
yes eg. blood vessels depend on location due to different receptor subtypes for transmitter
explain the possible effects on blood vessels after sympathetic stimulation
dilates BV supplying skeletal muscles (β adrenoceptors)
constricts BV supplying skin & gut (α adrenoceptors)
in the sympathetic division what neurotransmitter do most post-ganglionic receptors release?
noradrenaline, fibres are names adrenergic
what other neurotransmitter can the sympathetic division release?
some innervation of sweat glands + BV uses ACh acting on muscarinic receptors (sympathetic cholinergic)
in the parasympathetic division what neurotransmitter do post-ganglionic receptors release?
ACh, these fibres are named cholinergic
what neurotransmitter so preganglionic axon terminals release?
always release ACh
what are the 3 types that nicotinic Ach receptors fall into?
muscle (NMJ), ganglionic and CNS
how many subunits do ligand-gated ion channels form?
5 subunits, the composition can vary
what type of receptors do muscarinic receptors have?
typical G-protein coupled receptors
how many subtypes are there for muscarinic receptors?
5 subtypes are known M1-M5
