Short Term Management of Blood Pressure Flashcards
What is mean arterial pressure?
The main force driving blood through the circulation
What happens if MAP is too low?
Fainting (syncope)
What happens if MAP is too high?
Hypertension
What two locations for baroreceptors are there in the body?
Aortic arch and the carotid sinus baroreceptors
What nerve transmits impulses from the aortic baroreceptors?
Sensory branch of vagus nerve
What nerve impulses transmits impulses from the carotid sinus baroreceptors?
The glossopharyngeal nerve
Where do both the vagus and glossopharyngeal nerve transmit impulses to in the brain?
The cardiac centre of the brain in the medulla
Outline the motor side of regulation of blood pressure
Vagus nerve innervates SA node, causes hyperpolarisation to reduce the speed of depolarisation and therefore slows heart rate.
Sympathetic nerve has opposite effect.
What else occurs during activation of sympathetic nervous system?
Adrenal medulla stimulated to release adrenaline
Ventricles also innervated to cause increased contractility
Venoconstriction and arteriolar constriction (alpha-1)
What effect does activation of central chemoreceptors on the CV system?
Increases hearth rate and contraction strength to accommodate increased PaO2
Increased use of joints/muscles causes what?
Joint/muscle receptors to be activated (movement taken as an indication of increased activity) - has effect on CV system
What function do higher centres serve?
Feed-Forward system to prepare body for physical activity
What are the two reflex responses?
Decrease vagal tone and increase sympathetic tone
What is the Valsalva manoeuvre?
Forced expiration against a closed thoracic output
Outline the mechanics of the Valsalva manoeuvre
Increase in thoracic pressure is transmitted through the aorta
Reduces venous return therefore decreases EDV
Produced weaker strength of contraction
Lowers MAP
Baroreceptors detect decrease in pressure - triggers pressure response
