ANS Flashcards
role of autonomic nervous system
maintains organismic homeostasis @ rest + during exercise
what are the two division of the ANS
sympathetic (fight or flight)
parasympathetic (rest + digest)
functions of the ANS
- maintains temp @ 37 degreees C
- HR regulation
- blood content/hematocrit
- metabolic adjustments
how does the ANS regulate HR
- can increase HR
- sympathetic tone –> increase contraction –> increasing venous return –> increase L ventricle SV –> increase in CO –> more blood to working tissues
- cause vasoconstriction
metabolic adjustments and ANS
- adrenaline release results in nervous input to fat = stimulation of beta-mediated lipolysis
- stimulation of hepatic glycogenolysis
- modulation of substrate metabolism like glycogen from non working to working muscles
- ANS input = alpha adrenergic modulation of lipolysis and hepatic gluconeogenesis
how does the ANS affect maximal aerobic capacity + exercise performance
- more training = more PNS tone to suppress pacemakers
- can affect resting HR making it lower = more HR reserve
- regular exercise can modify ANS adjustments to acute exercise
what does a great HR reserve mean
larger capacity for heart to increase output during exercise
how to measure ANS activity
- cardiac vagal activity
- assessment of sympathoadrenal activity
- assessment of overall ANS effects
cardiac vagal activity measurements
looks at muscarinic receptor antagonists
- these receptors when bound to ACh affect HR variability by slowing it down
- it can also be coupled with G protein pathways either increasing cellular effects (Gs) or decreased cellular effects (Gi)
what are muscarinic receptors
a type of ACh receptor that also responds to muscarine
assessment of sympathoadrenal activity when measuring ANS activity
- looks at plasma norepinephrine concentrations
- neuropeptide Y
- neural recordings of sympathetic NS activity
- low frequency power of HR variability
- plasma concentrations + secretion of epinephrine
- adrenergic receptor antagonists
plasma NE concentrations and spillover
- NE + sympathetic NS = stimulus = body senses stress = increase in HR
- body doesnt understand specific stress so goes general
- spillover: the release of NE from the tissues into the bloodstream (increased spillover = increase in sympathetic NS activity)
neuropeptide Y
- released alongside epinephrine + nE under high intensity or prolonged sympathetic stimulation
- lasts in plasma for longer periods of time than epi or NE so detection in blood indicates the degree of sympathoadrenal activity
how are neural recording used to understand sympathetic NS activity
sympathetic tone is very loud and noticeable
what are prescribed to regulate the ANS
alpha and beta blockers
- PNS is specifically blocked via beta blockers
how to assess the overall ANS
- surgical ablation of parasympathetic and sympathetic NS structures (removed and looked at)
- transgenic animals: can be modified to remove genes and helped to better understand receptor density
ANS changes to acute dynamic exercise
- cardiac vagal modulation of HR
- sympathoadrenal response
- central and peripheral neural mechanisms
cardaic vagal modulation of HR after actue dynamic exercise
- at peak exercuse PNS tone is at a min
- prolonged or increased intensity of activity results in continued decreased in vagal tone
- once exercise stops PNS immedielty goes back up
- atropine and propanol also have an effect
how can you rell if PNS health is good
look at recovery post exercise it shouldnt take long for HR to return back to normal
(if it takes long could mean too much sympathetic input or adrenaline
sympathoadrenal response to acute dynamic exercise
- vagal tone is withdrawn followed by an immediate increase in HR to meet the needs of the body
- increase in intensity = increase in SNS input and catecholamin levels
- plasma lactate response and sympatholysis occurs
plasma lactate response in the sympathoadrenal response to acute dynamic exercise
- adrenaline/adrenal activity inversely realted to [lactate] in blood
- due to metabolism (more mitochondria activity and increase adrenaline = more metabolism of pyruvate = decrease in lactate acid)
sympatholysis in sympathoadrenal response to acute exercise
process where local metabolic and mechanical factors in active muscle soveride sympathetic vasoconstriction
- working tissues need/want blood so don’t want vasoconstriction
what are factors of change for ANS during acute dynamic exercise
- absolute vs realtive exercise intensities
- sex of individual
- size of active muscle mass
- ambient temp + internal temp
- hydration
- body position
- diet
- hypoxia vs hyperozia
- modulatory factors
how does sex factors affect the ANS changes to acute dynamic exercise
women have more SNS tone + men more PNS tone bc men have larger hearts so need more to help control
