Autonomic Control in Exercise

Question 1

autonomic nervous mediates … adjustments to meet the … demands of the exercising muscle performance and sustainment

Autonomic nervous system is the part of the … system controlling functions …
* Sympathetic nervous system
* Parasympathetic nervous system

• A reduction of parasympathetic (vagus) nerve activity increases …, …, …, and thus, … output
• Also evoked by activation of sympathetic activity and sympathetic stimulation of … release from the adrenal medulla

Dyspnea - how uncomfortable you are with your breathing

Answer 1

autonomic nervous mediates cardiovascular adjustments to meet the metabolic demands of the exercising muscle performance and sustainment

Autonomic nervous system is the part of the peripheral nervous system controlling functions below the level of consciousness
* Sympathetic nervous system
* Parasympathetic nervous system

• A reduction of parasympathetic (vagus) nerve activity increases heart rate (HR), ventricular contractility, stroke volume, and thus, cardiac output
• Also evoked by activation of sympathetic activity and sympathetic stimulation of epinephrine release from the adrenal medulla

Dyspnea - how uncomfortable you are with your breathing

Question 2

Sympathetically mediated vasoconstriction redistributes cardiac output to the …
In the active muscles, … is reduced, because of metabolites, called FUNCTIONAL …. what is it?

Patients with autonomic failure cannot maintain the … Even if they are performed in the supine position
In autonomic failure, people cannot activate …

what does Parasympathetic act on in the heart and why?

what does sympathetic act on in the heart and why?

Answer 2

Sympathetically mediated vasoconstriction redistributes cardiac output to the active skeletal muscles
In the active muscles, vasoconstriction is reduced, because of metabolites, called FUNCTIONAL SYMPATHOLYSIS. localized dilated change in global vasoCONSTRICTION

Patients with autonomic failure cannot maintain the lightest exercise loads. Even if they are performed in the supine position
In autonomic failure, people cannot activate sympathetic vasoconstriction properly.

para only on SA and AV

sympathetic on everything, need to survive by any means necessary
as well as epinephrine and nor from the medulla

Question 3

Heart rate increases instantaneously upon exercise
* Because of …

cardiac … is greatest at … and becomes less as … increases, HR exceeds ∼90-100

cardiac … increases along with exercise workload
* Occurs from both … and … (norepinephrine/epinephrine) sources

Answer 3

Heart rate increases instantaneously upon exercise
* Because of parasympathetic withdrawal

cardiac parasympathetic withdrawal is greatest at lower exercise workloads and becomes less as exercise intensity increases, HR exceeds ∼90-100

cardiac sympathetic stimulation increases along with exercise workload
* Occurs from both neural and endocrine (norepinephrine/epinephrine) sources

Question 4

both parasympathetic and sympathetic contribute to cardiac responses to exercise
Sympathetic nervous system is essential for the … adjustments to exercise

… sympathetic response is delayed by ~30-60 seconds
* Bc of … and muscle …

Immediate increases in sympathetic activity to the … and …, causes vasoconstriction, which helps redirect blood flow to the active muscles.
These sympathetic signals increase in proportion to … and stay … during exercise, so blood flow to the … and … stays reduced

Answer 4

both parasympathetic and sympathetic contribute to cardiac responses to exercise
Sympathetic nervous system is essential for the peripheral vascular adjustments to exercise

Peripheral muscle sympathetic response is delayed by ~30-60 seconds
* Bc of metabolites and muscle afferents

Immediate increases in sympathetic activity to the skin and kidneys, causes vasoconstriction, which helps redirect blood flow to the active muscles.
These sympathetic signals increase in proportion to exercise intensity and stay elevated during exercise, so blood flow to the skin and kidneys stays reduced.

Question 5

sympathetic activity increases in an … manner during sustained levels of dynamic exercise in humans

Aside from exercise intensity, the …. of exercise has a major impact on sympathetic tone
* Increases in plasma … after 10 min of treadmill walking, keep increasing as exercise continues
* Similar increases in … activity during 30 minutes of cycling

Changes in cardiac and peripheral autonomic control during exercise come from three main mechanisms:
- Central command
- Exercise pressor reflex
- Arterial baroreflex

Answer 5

sympathetic activity increases in an intensity dependent manner during sustained levels of dynamic exercise in humans

Aside from exercise intensity, the duration of exercise has a major impact on sympathetic tone
* Increases in plasma norepinephrine after 10 min of treadmill walking, keep increasing as exercise continous
* Similar increases in muscle sympathetic activity during 30 minutes of cycling

Changes in cardiac and peripheral autonomic control during exercise come from three main mechanisms:
- Central command
- Exercise pressor reflex
- Arterial baroreflex

Question 6

Central command is … that make skeletal muscle contraction and control of autonomic neural outflow to the … system

Idea of central drive comes from HR increased in …
* central command-induced cardiac … HR up right away

During hypnosis, … and … change similarly to actual handgrip exercise because the body responds to the …, just like … would

• Modest effect on skeletal muscle sympathetic at … levels, bigger role during …

Answer 6

Central command is descending neural signals that make skeletal muscle contraction and control of autonomic neural outflow to the cardiorespiratory system

Idea of central drive comes from HR increased in anticipation of and immediately at the onset of exercise
* central command-induced cardiac vagal withdrawal. HR up right away

During hypnosis, heart rate and blood pressure change similarly to actual handgrip exercise because the body responds to the perceived effort, just like central command would

• Modest effect on skeletal muscle sympathetic at moderate exercise levels, bigger role during high intensities of exercise

Question 7

Exercise Pressor Reflex
During exercise both … and … sensitive sensory fibers provide feedback. Type … and …

muscle mechanoreflex is primarily activated at…
* Group … afferents fire at the …

The rapidity of the … responses may be related to III afferents

Group …, muscle metaboreflex, require … before it responds due to the delay in production of …, they play a minimal role at the … exercise
* May contribute to the … of autonomic responses during early stages of exercise

During steady-state exercise, … increase muscle sympathetic activity
* Includes metabolic byproducts such as: potassium, adenosine, arachidonic acid, nitric oxide and prostaglandins

Answer 7

Exercise Pressor Reflex
During exercise both mechanically and metabolically sensitive sensory fibers provide feedback. III and IV

muscle mechanoreflex is primarily activated at the immediate onset of muscle contraction
* Group III afferents fire at the onset of muscle contraction

The rapidity of the cardiac autonomic responses may be related to III afferents

Group IV, muscle metaboreflex, require time before it responds due to the delay in production of metabolites, they play a minimal role at the onset of exercise
* May contribute to the fine tuning of autonomic responses during early stages of exercise

During steady-state exercise, metaboreceptors increase muscle sympathetic activity
* Includes metabolic byproducts such as: potassium, adenosine, arachidonic acid, nitric oxide and prostaglandins

Question 8

arterial baroreflex plays a major role in … adjustments
arterial baroreflex is NEEDED for a neural … response

the ability to reset the baroreceptor to will greatly improve the … and … adjustments to exercise

makes sure we can maintain … as effectively …

Arterial baroreflex resetting during exercise is because of … and sensory feedback from III and IV afferent (…)

Answer 8

arterial baroreflex plays a major role in blood pressure adjustments
arterial baroreflex is NEEDED for a neural cardiovascular response

the ability to reset the baroreceptor to will greatly improve the autonomic and cardiovascular adjustments to exercise

makes sure we can maintain BP as effectively as at rest

Arterial baroreflex resetting during exercise is because of central command and sensory feedback from III and IV afferent (exercise pressor reflex)

Question 9

SUMMARY
Exercise onset increases in HR due to actions of …, … and vagal withdrawal
* Leads to a reduction in cardiac … (less heart rate variability)

During exercise, HR increases approximately linearly with …
* Reductions in cardiac parasympathetic activity primarily mediate the increases in HR during …
* Whereas cardiac sympathetic activity contributes as…

SUMMARY
Sympathetic constriction + local metabolite-induced dilation(…) = more blood flow to …(…)

Neural reflex mechanisms underpinning the parasympathetic and sympathetic adjustments to exercise are complex with clear evidence for the involvement of:
* …
* … reflex
* … reflex

SUMMARY
Sympathetic outflow to skeletal muscle have a… during exercise, bc of … and the activation of … afferents (Group …)

During steady-state exercise, the arterial baroreflex resets to the …, allowing it to regulate … effectively. This ensures …, not just …, get enough blood flow.

Answer 9

SUMMARY
Exercise onset increase in HR due to actions of central command, muscle mechanoreflex and vagal withdrawal
* Leads to a reduction in cardiac baroreflex control (less heart rate variability)

During exercise, HR increases approximately linearly with oxygen uptake
* Reductions in cardiac parasympathetic activity primarily mediate the increases in HR during low intensity steady-state dynamic exercise
* Whereas cardiac sympathetic activity contributes as exercise intensity increases

SUMMARY
Sympathetic constriction + local metabolite-induced dilation(HYPEREMIA) = more blood flow to active muscles(SYMPATHOLYIS)

Neural reflex mechanisms underpinning the parasympathetic and sympathetic adjustments to exercise are complex with clear evidence for the involvement of:
* Central command
* Exercise pressor reflex
* Arterial baroreflex

SUMMARY
Sympathetic outflow to skeletal muscle have a latency of 30 to 60s during exercise, bc of metabolite accumulation and the activation of metaboreflex afferents (Group IV)

During steady-state exercise, the arterial baroreflex resets to the higher blood pressure, allowing it to regulate BP effectively. This ensures all organs, not just active muscles, get enough blood flow.