autonomic control of the CVS Flashcards
name the neurotransmitters and receptors involved in the sympathetic nervous system
pre ganglionic= ach and nicotinic receptors
post ganglionic = usually noradrenaline and beta/alpha receptors
name the neurotransmitters and receptors involved in the parasympathetic nervous system
pre ganglionic= ach and nicotinic receptors
post ganglionic= ach and muscarinic receptors
what is the enteric nervous system
surrounds GI tract and is controlled via para and sympathetic fibres
which GPCR’s allow contraction and dilation of the lungs
relaxation= beta 2 (sympathetic) contraction= M3 (parasympathetic)
how can sympathetic NS be increased without increasing the response of all tissues
can be very specific where only 1 thing is increased. however, also have fight or flight response which is a more coordinated overwhelming response of lots of tissues reacting to sympathetic stimuli.
what does the autonomic nervous system control in the CVS
controls heart rate, blood pressure and peripheral resistance BUT not electrical activity of heart - a denervated heart still beats but just much faster as usually heart is under vagal (parasympathetic) influence.
how parasympathetic NS inputs heart rate
vagus nerve connects to SAN and AVN in walls of heart releasing ach acting on M2 receptors decreasing heart rate (negative chronotropic effect) by decreasing AVN conduction velocity
how sympathetic NS inputs heart rate
sympathetic trunk (containing accelerator nerve) connects to AVN, SAN and myocardium. noradrenaline stimulates beta 1 receptors increasing heart rate and force of contraction. (positive chronotropic effect and positive inotropic effect)
how ANS affects pace maker cells (sympathetic)
beta 1 Gas- s stands for stimulating. this causes increase in cAMP (a type of cyclic nucleotide) meaning more HCN channel stimulation and increased rate of their activation leading to more frequent depolarisations.
how ANS affects pace maker cells (sympathetic)
m2 gai- I stands for inhibitory. this causing less cAMP meaning reduced stimulation of HCN channels decreasing the frequency of depolarisation and therefore contractions of the heart
how does noradrenaline increase the force of contraction
acts on beta 1 cells in the myocardium which release cAMP and therefore PKA. this leads to phosphorylation of ca2+ channels and a calcium influx which also increases the rate of CICR. = increased force of contraction
how the ANS affects the vascuculture (describe how this works at rest)
vessels receive sympathetic innveration, have alpha 1 receptors affected by noradrenaline. at their resting condition they have small amount of sympathetic activation. no need for parasympathetic.
discuss the effect of also having beta 2 receptors in the walls of some vessels regarding the affinity of adrenaline for these receptors
circulating adrenaline has much higher affinity for beta 2 receptors therefore they are more likely to bind to beta receptors. alpha 1 receptors activated by noradrenaline via neurone
explain how beta 2 receptors cause vasodilation and how alpha 1 receptors cause vasoconstriction
vasodilation- b2 activates as which produces cAMP and PKA which then inhibits MLCK which prevents muscle contraction
vasocontriction - alpha 1 receptor activates aq which results in IP3 causing increase in calcium conc and contraction
what is the role of local metabolites
adenosine, H+, K+ high pCO2 ensure perfusion of skeletal and coronary muscles
