L4. Cardiovascular control during exercise Flashcards
What are the key mechanisms controlling the cardiovascular response to exercise?
Central command and peripheral feedback
What is the role of central command in cardiovascular control during exercise?
It initiates cardiovascular adjustments in anticipation of exercise
What does the arterial baroreflex do during exercise?
It resets to a higher operating pressure to maintain perfusion during increased activity
What is Starling’s Law and how does it relate to exercise?
It describes how increased venous return stretches the heart and increases stroke volume
What is the role of the insular cortex in exercise?
It coordinates cardiovascular responses by inhibiting vagal output via the nucleus ambiguus
What did Krogh and Lindhard’s studies on cortical irradiation demonstrate?
The anticipatory rise in heart rate and ventilation prior to exercise
What is the effect of isometric exercise on cardiovascular function?
It increases blood pressure by activating the muscle pressor reflex
What happens to blood flow distribution during exercise?
It is redistributed from visceral organs to skeletal muscles
What did Eldridge’s study reveal about subthalamic nucleus stimulation?
It increased blood pressure and heart rate even in paralyzed animals
What is the importance of the muscle pressor reflex?
It maintains blood pressure during sustained contractions by sensing metabolites
What role does dynamic exercise play in cardiovascular regulation?
It facilitates gas exchange and heat dissipation through increased blood flow to muscles
How does heart rate change with graded exercise intensity?
It increases proportionally to the workload and effort perception
What was the significance of Gandevia’s study on whole-body paralysis?
It demonstrated heart rate and blood pressure responses driven by central command alone
What is the effect of denervated hearts on exercise response?
They rely on Starling’s Law and circulating catecholamines to increase output
How does vagal inhibition facilitate exercise initiation?
By reducing parasympathetic influence to allow heart rate to rise
What cardiovascular changes are induced by adrenaline during exercise?
Increased heart rate, stroke volume, and redistribution of blood flow
How does the PAG contribute to exercise-induced cardiovascular control?
It integrates nociceptive and cardiovascular responses for adaptive adjustments
What did Basnayake’s triceps vibration experiment show?
Increased central command and cardiovascular drive during perceived effort
What happens to the muscle pressor reflex during epidural anesthesia?
It is blocked, reducing blood pressure and heart rate responses
How is cardiac output redistributed during exercise?
Increased to working muscles, decreased to visceral organs
What is the role of the motor cortex in exercise anticipation?
It primes cardiovascular and respiratory systems for activity
What is the effect of vagus nerve inhibition on exercise capacity?
It prevents bradycardia, allowing for sustained increases in heart rate
How does the nucleus ambiguus modulate cardiovascular responses?
By controlling vagal outflow to the heart
What is the significance of blood pressure during isometric exercise?
It reflects the activation of the muscle pressor reflex and central command
What did the Goodwin experiment reveal about effort perception?
Higher perceived effort increases cardiovascular output even without physical changes
What role does central command play in perceived exertion?
It adjusts cardiovascular responses based on expected exercise intensity
What did experiments with the subthalamic nucleus in cats demonstrate?
It drives cardiovascular and locomotor responses during stimulation
What is the function of the dorsal lateral periaqueductal grey (PAG)?
Drives hypertensive responses during nociceptive stimuli
How does muscle occlusion demonstrate the muscle pressor reflex?
Trapping metabolites prolongs blood pressure elevation after exercise
What are the primary drivers of increased cardiac output during exercise?
Heart rate, stroke volume, and sympathetic activation
How does the respiratory system integrate with cardiovascular control during exercise?
Increased ventilation supports oxygen delivery and CO2 removal
What did Rowell’s study on circulation occlusion show?
Metabolite accumulation drives sustained blood pressure elevation
What is the relationship between sympathetic drive and exercise intensity?
Sympathetic activity scales with effort and workload
How does dynamic exercise differ from isometric in cardiovascular response?
Dynamic exercise improves blood flow, while isometric increases blood pressure
What is the anticipatory cardiovascular response to exercise?
Increased heart rate and ventilation before movement begins
How does effort feedback influence cardiovascular responses?
Greater perceived effort increases heart rate and blood pressure
What did experiments on paralysed animals reveal about central command?
It independently controls cardiovascular responses without muscle feedback
What is the significance of the insular cortex in exercise control?
It coordinates signals to optimize cardiovascular output during activity
How do central and peripheral mechanisms integrate during exercise?
Central command sets the initial drive, while peripheral feedback fine-tunes responses
What did Thornton’s study reveal about deep brain stimulation in cardiovascular control?
It showed that stimulation of specific brain regions can drive increases in blood pressure and heart rate
