PSC1002/L10 Control of Blood Pressure Flashcards
Give the 2 major control mechanisms in control of mean arterial blood pressure.
Short term
Long term - involves kidneys
Describe the baroreceptor reflex response in short term control of MABP. (3)
Baroreceptors detect change in BP
Signal cardiovascular control centre (brainstem)
ANS changes HR, SV, VR
Where are baroreceptors located? (2)
Aortic arch
Carotid sinuses
Where are nerve endings of baroreceptors located?
Adventitia layer of arteries
Where are the afferents of the aortic arch and carotid sinus found?
AA - carotid depressor
CS - Hering’s/IX glossopharyngeal
What is the role of afferents?
Sending information about MABP to cardiovascular control centre in brainstem (medulla)
What are baroreceptors?
Sensors of changes in stretch of the artery due to changes in BP - mechanoreceptors
What do baroreceptors respond best to?
Pulsatile changes in pressure
Adapt to maintained changes
Which mechanism of MABP regulation are baroreceptors important in?
Short-term
Describe the pathway from increased BP to baroreceptor response. (3)
Increased BP increases stretch of artery
Receptors fire more action potentials to CCC
Response
What is venous pooling? (2)
Approximately 500ml of blood from intrathoracic vessels into veins of lower limbs when standing up from lying
Takes about 15 seconds
What occurs as a result of venous pooling? (4)
VR decreases
SV decreases
CO falls (Starling mechanism)
ABP falls
Reflex action of baroreceptors due to venous pooling results in what? (4)
Reflex tachycardia
Positive inotropic effect
Vasoconstriction in skeletal, GI and renal beds
Restoration of MABP
Define postural hypotension.
Decrease in systolic BP of 20mmHg or more after 1 min of standing, compared to supine values
Can lead to syncope
What is involved in long-term regulation of BP?
Atrial pressure receptors
Renal receptors which control fluid excretion/reabsorption
Control of fluid intake
