L24 Control of the CV system in Exercise

Question 1

Define Central Command

Answer 1

Feed forward control. Activation of the motor cortex causes parallel activation of pathways that descend into brainstem areas controlling respiratory + CV function –> EFFERENCE COPY

Question 2

What is the exercise pressor reflex

Answer 2

1. Muscle metaboreflex - metabolically sensitive unmyelinated sensory afferents (group IV)
2. Muscle mechanoreflex - mechanically sensitive lightly myelinated sensory afferents. (group III)

Question 3

What are the experimental techniques used to investigate the mechanisms controlling the cardiovascular system during exercise?

Answer 3

Muscle Metaboreflex –> Rhythmic handgrip exercise

Question 4

Discuss the main actions of central command on the autonomic nervous system, HR and BP

Answer 4

Inhibits parasympathetic. Excites sympathetic nervous system
Increases heart rate via vagal withdrawal.
Little effect on blood pressure.

Question 5

Discuss the main actions of muscle metaboreflex on the autonomic nervous system, HR and BP

Answer 5

Increases muscle sympathetic nerve activity
HR increases.
BP rises

Question 6

Discuss the main actions of muscle mechanoreflex on the autonomic nervous system, HR and BP

Answer 6

Small increase in muscle sympathetic nerve activity
Increases HR
Increase BP

Question 7

Compare how the relative importance of the neural mechanisms controlling the cardiovascular system differs during dynamic vs isometric exercise

Look up answer to this

Answer 7

Central Command -->
Dynamic - 
Isometric -
Muscle Metaboreflex --> 
Dynamic -
Isometric -
Muscle mechanoreflex --> 
Dynamic -
Isometric - challenging to activate in isolation

Question 8

Explain the role of the arterial baroreflex during exercise

Answer 8

Stretch sensitive receptors that change their level of activity dependent on blood pressure.
Increases blood pressure and heart rate during exercise.

Question 9

Muscle mechanoreflex stimulation depends in:

Answer 9

• Force
  Stretch
  External Pressure
  existing chemical conditions in the interstitium (sets the sensitivity of the afferents t mechanical stimuli

Question 10

Where is the arterial baroreceptor located?

Answer 10

located within the walls of the carotid sinus and aortic arch

Question 11

What would a removal of baroreceptors lead to?

Answer 11

A marked increase in blood pressure variability

Question 12

What occurs when you stimulate the carotid baroreceptors through neck pressure and neck suction?

Answer 12

Neck pressure - Stimulation for acute hypotension. Increase HR, MSNA, BP

Neck suction = stimulation for acute hypertension. Decreased HR , MSNA, BP